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Is this a Wolf Spider?

I live in Illinois and this came running across my living room floor.  After I stopped freaking out, I threw a bowl over it and called someone to come get it.  It was about 5” across.  My son thought it was a wolf spider but I didn’t think they got that big.  I hope someone can help to identify it.  Just the thought of there being more around is making me want to book a hotel!

That's not a Wolf Spider, although it's often mistaken for one.  The long, jagged-edged-banded legs, splayed out in a characteristic flat posture, and the large, round carapace are pretty characteristic indicators of a Dolomedes fishing spider - one of the terrestrial ones that have moved into drier, upland areas and hunt more like Wolf Spiders do.
There are two species this could be, but the fact that you don't see a full white underline beneath the 'w's on its abdomen tells you it's not Dolomedes scriptus, but its common relative Dolomedes tenebrosus.
These spiders are actually pretty mild-mannered and can make good pets (as spiders go), but they will bite if bothered too much (how much "too much" is seems to be different from spider to spider).  The bite can be painful because of their size and large fangs, but the venom is not particularly effective against humans.  I'd rate it as a lot less painful than even a mild wasp sting, although of course every individual spider and every individual human is different.
Here's a link to the Bug Guide page, which has more information and lots of photos..
https://bugguide.net/node/view/2011
I should also add that these guys eat beetles and other relatively large insects and small animals that you might or might not want to share your home, if that makes any difference.  I can't see its pedipalps clearly, but the large cephalothorax and relatively small abdomen make me suspect it's an adult male, just wandering around looking for love.  It's unlikely that you have all that many individuals living with you - unless you have a dirt cellar, of course; they seem to like places that are a bit cave-like.
I also forgot I'm supposed to include an image:


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Identify this unusually-shaped, orange-colored fruit that grows in pairs?
The photos below were taken on the island of Penghu in the Taiwan straight in October. This was in a public place and the small tree (about 3 meters tall, trunk perhaps 8 to 10 cm diameter) had probably been planted, so we can't presume it to be indigenous.
Each fruit was about 6 or 7 cm long, the skin was bright orange and seemed a bit waxy. The shape was a little bit like a banana-shaped American football in that it was divided into four quadrants. They attach to a stem in pairs and extend horizontally (sideways) rather than hang down.
Question: What could this gravity defying fruit-bearing tree be?
The first image is cropped, zoomed and sharpened in order to highlight textures.

The seed pods reminded me of the Apocynaceae, so I searched for "apocynaceae china" and found this University of Hawaii page where it is identified as Stemmadenia litoralis.  However, a little more looking it seems Tabernaemontana litoralis may be the preferred name.  There is some debate here.  This book may hold the final answer regarding the genus.
Your picture of the fruit is one of the best one I could find on the internet. There is another good one here with other pictures of the plant.
You were also correct that as a planted tree it might not be native.  This plant comes from Central America.

Wow that was quick, thank you for the thorough answer! I don't think this will become as popular as chili peppers (from the Americas as well I think) but it certainly is interesting to look at.

Locals call it the "Lanyu Tabernaemontana," (named after Lanyu island to the East) which may be classified as  Tabernaemontana dichotoma (Roxb. ex Wall.), Google images, or Tabernaemontana subglobosa (Merr.). Plants of Taiwan at the National Taiwan University.

@GenTest thanks for all the additional information! One of the images in your link leads to toxbaselanka. While I'd never thought to try to taste it, I was surprised to see it on a website of toxic plants!

@uhoh It's in the same dogbane family Apocynaceae as oleandor. The Tabernaemontana genus contains lots of toxin-producing species, and dichotoma's sap may cause redness and swelling if it comes in to contact with the skin. Though it does also contain medicinal compounds and uses..

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


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What's the name of this insect?
Here's a picture:

That's pretty much it, besides that it was found in Vienna, Austria.
Edit: Thanks to Magne Flåten; it's called Hausmutter in German.

This is probably a large yellow underwing not finished pumping up its wings: https://en.wikipedia.org/wiki/Large_yellow_underwing

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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What is this tree and fruits?
Please help me identify this tree and its fruits that have sweet taste and very small soft seeds:

It grows in the Mediterranean region.

Ficus sycomorus possibly...it's a type of fig (Ficus)

@user33690 Why don't you turn your comment to a proper answer?

It's a sycamore fig (Ficus sycomorus)- a type of Mediterranean fig.

For details: see this wiki page

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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What kind of spider is this? I have never seen one like this before

This was on my butterfly bush yesterday with a moth by the neck.  I have never seen one like this before.  Just wondering what the name is.  This is in southern Illinois.

Excellent picture!  Someone will know this -- might take a day or two.

On iNaturalist I found a very similar picture, of a White-Banded Crab Spider.  It is found in your area.  It's a possibility.


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what snake is this and is it venomous?
Found on my house on Khao Yai, Thailand

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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What plant is this? (Found in South Thailand)

Have tried to recognize with PlantSnap App, no results.

It looks like Desert Rose, commonly used for Bonsai plantings.

Good ID.  Adenium obesum, in the Apocynaceae as is Plumeria, but from Africa (I almost had it!).

Looks like a Plumeria but there are several species and many horticultural variants.  It's native to the New World.


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Can someone tell me what these cocoons are?
I am camping in Slovenia and have found some cocoon like materials.
They look like nests of some kind and are about 30cm long and 10-15 cm wide. Can anyone help me find out what these things are?
Found in Tolmin, Slovenia

I think you are actually looking at dried bottle gourds, a squash relative.  These are probably in the genus Lageneria.  These come in an extreme variety of shapes, and have been put to many ornamental uses. They were important as containers for early cultures.  Good background here and here.  Search for "dried bottle gourd" images and you'll see plenty.


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Does anyone know what are these birds?
Never saw them before, they appeared suddenly , the day my father died.
Place is Serbia in Europe.
Does anyone know what are these birds?

Looks like European Starlings (Sturnus vulgaris).  They are often seen in large numbers and are native to most of Europe, including Serbia.  They were introduced to North America (Central Park, New York City) as a project to introduce species of birds from works of Shakespeare and are now widespread.

Source: https://www.allaboutbirds.org/guide/European_Starling/id


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What is the family of this insect caught by my Drosera?
I am currently trying to find out what type of flies are flying around in my home. If they are fruit flies, fungus gnats or something else.
Currently my Droseraa caught one of them and I am currious what species it is.

It is a small fly, like fruits flies and fungus gnats. As seen in the third photo the length is about 1,5 to 2mm (The distance between each line is 1mm).
The location is Stockholm in Sweden (in my apartment).
Could you help me identifying it?

Can you get a closeup of the wing?  With what is visible at the moment, the best anyone can do is suborder.

Thanks for your answer! I have now added a zoomed in picture of the flies wings.

See here: https://biology.meta.stackexchange.com/a/3683/27148 and try to provide location and size information as well.

Thanks for your comment! I have updated with location and size. I have a picture avaible with the fly close to a ruler, but can't add it as I only have 1 in reputation.

@eternitysharp You now have more reputation. I don't know if this is enough to add more pictures.

@bli Thanks! I have now added the third picture showing its size.

This is a Dark-winged fungus gnat (family Sciaridae); the European species of the family are dealt with by Menzel, F.; Mohrig, W., 1999, Revision der paläarktischen Trauermücken (Diptera, Sciaridae) [A Revision of the Palaearctic Black Fungus Gnats (Diptera: Sciaridae)], Studia Dipterologica Supplement, (6):761 pages; copies are sold by Ampyx-Verlag (see http://www.ampyx-verlag.de/lilac_cms/de/4852,,refz,rd,368,2914,12/index.html).  Some species of the family have economic importance, but identification to species usually requires male specimens which must be at least temporarily mounted on microscope slides.

Thanks for your answer! I think I am good enough with just knowing the family. I will change the question from "species" to "family" and then accept your answer.


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Watermarks visible during DNA fingerprinting?
Let's say we have a human man that was somewhat genetically modified from the very beginning (conception?) by a team of scientists, and is also a product of careful selective breeding. They did this hoping to produce a specimen that would  certain physical characteristics such as superior size and strength, speed, vision, sense of smell, things like that that would result in a "perfect soldier" type of man.
Is it plausible that the team of scientists, like Craig Venter's team, could have installed Watermarks in this man's DNA that would show up on a DNA fingerprint? A DNA fingerprint done by the American FBI?
A user on this forum suggested this possibility in a former thread, so I mean no disrespect to that user by asking this question. I'm just interested in feedback from others. I am writing a novel and this is research for the story. Without getting too deep into specifics, I'm trying to find a way for the authorities to become alerted to the fact that this man is abnormal from other humans.
Any input greatly appreciated.
EDIT:
Basically, I am dipping my toe into the deep end of the pool. I know only the very basics of DNA fingerprinting and Genetic engineering, so technical language is hard for me to follow. I appreciate the answers very much but I'm still a little in the dark. Another user on this forum suggested that possibly "watermarks" might show up on the test, which is why I'm attempting to rephrase the question.
I have written a scene into my novel wherein my main character, a man that has been genetically engineered, unbeknownst to him, gets into a fracas with some bad guys and he wreaks havoc and escapes. The American FBI gets some of his DNA from the scene and works up a DNA Fingerprint on him, purely for the purposes of identification if they catch him. so, yeah, just like on CSI or whatever on TV. When the technicians complete the fingerprint, they recognize that something is different about this person and they contact the lead investigator to let him know. Perhaps they see some evidence of genetic modification or something that raises their eyebrows and they feel it's worth mentioning.
So, essentially all I'm asking is if that is at all possible, and what could they conceivably have seen in the fingerprint? If it's completely not plausible then I'll either delete the scene or rewrite it.
Thanks.

I'm not sure how this question is different from your other question. Importantly, DNA fingerprinting does not look at the sequence of DNA. Such modifications would only show up if they alter the length of a genetic locus being tested.

As was alluded to in your last question, it is plausible. It would require that the loci that DNA fingerprinting analyses be altered in length as canadianer said above. I would have thought that that would be enough 'support' for the case for a novel. It would be pretty easy to state that the FBI just sequenced the DNA sample though, then you could say much more about what they might find. Bearing in mind this is a science fiction novel, so what is 'plausible' is kinda up to you, and how far in the future the story is set?

It's not really in the future. There are no dates but the entire story takes place in a present day setting. The laboratory technicians notice something in the fingerprint that makes them curious about the suspect. They call the lead investigator to ask who their suspect is because something is odd about the fingerprint. The investigator informs them that he's just a man and asks what the problem is. What does the lab technician tell him?

This would only happen if the FBI was looking for that particular watermark or had some other reason to be suspicious. It would not show up as unusual on a standard DNA fingerprinting test for identification. There isn't really anything unusual that can show up on those tests. It also isn't scientifically sound to use those tests on a general database, this increases the odds for false positives tremendously. Instead, DNA tests are most useful when you already have a suspect and you want to verify that evidence at the scene is from that suspect.

The "watermarks" that you're referring to sound exactly like DNA fingerprints: stretches of DNA that are unique to an individual. These unique stretches occur naturally in all individuals, but specific artificial sequences could theoretically be inserted via techniques such as CRISPR.
Once inserted, these artificial sequences could be searched for specifically through PCR, if the sequence is known, or through traditional enzymatic restriction methods, such as described in the first link.
It's worth mentioning that in order to be easily detected, your watermarks would most likely have to be inserted into the germ line of these genetically modified humans. Otherwise, you'd only be able to get the watermark sequences into a small region of tissue. Once in the germ line, the body's own DNA replication mechanism takes over copying those sequences throughout the organism.
Good luck writing!

A "DNA fingerprint" is a set of about 13 loci which consist of repetitive elements, and you look at the size of those repetitive elements.  I guess you could if you could invent your own into someone's genome of unique sizes, there would be no functional purpose.
If you gave a person multiple alleles of those regions, such that it looked like the person had more than 2 alleles at each locus, that would probably get someone's attention, depending on how automated the software that assesses those PCR products is.  But there is no functional reason for someone to alter a genome like that.  You need to find a reason for researchers to go out of their way to do that.
If the researchers wanted the ability to find their creation with a DNA test, they could easily put in a region of sequence which most people would never intend to probe with appropriate PCR primers.  In the future, whole genome sequencing might be cheap enough that you could see everything, and a large section of unexpected sequence could in theory be detected and flagged.  A very small sequence might be ignored by anyone not looking for it as noise.
If your "careful breeding" means "inbreeding", your subject might be homozygous at lots, or all of the standard loci, and that might raise flags.  It wouldn't scream "genetically engineered" but it might be weird enough to get someone's attention.

In principle, sure--as long as you're not looking in his KIDS (remember 1/2 his DNA goes into kid; 1/2 lost). The technique could still work if the watermark were very close to or part of the 'special' DNA sequences.
Also depends somewhat on your meaning of 'fingerprint'; if you are adding new DNA, then besides the functional sequences, you could add a 'signature' of any sequence you wished. Since we know the sequence of many human genomes, you could pick a stretch that's very different from any known sequence. There are many techniques to ask "Is sequence 'XXXXXXXXXXX' present in this DNA sample?". It would not need to be very long, and for certainty, you could drop 3-4 different, unique 'watermarks'. It's also reasonable that the genetic modifications themselves are unique sequences, so no further signature would be needed.


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What's the smallest animal with hemoglobin running in its veins?
What's the smallest known animal with hemoglobin running in its veins?
Here I mean an animal that on its own is able to produce the hemoglobin that is running in its veins. For that reason this excludes mosquitoes that have filled themselves with blood from another creature, for example.
With smallest I mean either by mass or by spatial dimensions. Either would be interesting.

Smallest by mass?

thanks @AlanBoyd, I have now updated that in my question:-)

What kind of googling have you done? It sounds like a "homework" question to me (not that it comes from actual homework)

The scope of the question is still unclear. Some definitions of 'haemoglobin' include proteins found in invertebrates and even in microbes. By using the expression 'running in its veins' do you aim to exclude such organisms?

Why do you want to know this? What will it tell you? Anything other than an entry in the Guinness Book of Records?

Why veins? Why not arteries?

It depends how different from human hemoglobin it can be and still count as hemoglobin.  Here is a cool evolutionary tree of globins.

http://www.mhhe.com/biosci/genbio/enger/student/olc/art_quizzes/genbiomedia/0329.jpg
Here is the worlds smallest fish.  Fish have hemoglobin similar to that of humans.
from Wikipedia:  The world's smallest fish is Paedocypris progenetica1 from Indonesia, with mature females measuring 7.9 mm (0.31 in).

But I think bloodworms are even smaller. They have hemoglobin too.  It is evolutionarily more distant from us but they use it for the same reason we do.

from https://www.prestoninnovations.com/img/media/Seq-7.jpg
http://www.allaboutworms.com/the-basics-of-blood-worms

Blood worms are red because their blood plasma contains haemoglobin,
  like human blood. Also spelled “hemoglobin,” haemoglobin increases its
  ability to take up oxygen. The larvae commonly burrow in the
  oxygen-poor mud bottom of pools and rivers, so haemoglobin is of great
  value to the larvae.

If you are going to allow very distant relatives,  I think this snail is even smaller than the smallest bloodworm.  Less than 1 mm.  Molluscs have hemoglobin too.

from https://www.slideshare.net/fmoretzsohn/texas-seashellsmore-than-you

Paedophryne amauensis, the world's smallest vertebrate by length, 7.7mm. The coin by the way is an American dime.


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Name this green giant insect hanging on the wall
This Insect was found on the wall of the Party Hall, Where I went to my Girlfriend's birthday party. This insect looks very greeny. I am in India.

You simply found Parasanaa donovani, Which is the large bush-cricket found in India and various countries in Southeast Asia.

"Simply"? I'd be very excited to see one of those!


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Very small, light and dark "insects" - Italy - Infestation, healthy problems? - Insect identification
I'm currently in a town near Savona, on the coast in north-west Italy.
We had a problem with pigeons, that create their nests in the space between the roof and the ceiling.
Now, from the tube of the kitchen hood, that passes through this space, fell down these little insects. I'm a bit concerned it might be ticks, or something that could possibly transmit something bad. We have hundreds of them.
What's the best solution to make them go away? Also, should we leave the house during they permanence? I'm sorry for the bad quality pictures but they are very very small (probably between 0,5 and 1 mm) and very fast, so it's difficult to take good pictures.
Thankful for your help.
Dropbox link with more images and better quality

study protections for your drains, like spike wires to stop birds landing, and search for options that decimate the animals in the drainpipes, like bleach, vinegar, whatever the specialists say, and pour it on the roof regularly to take the mites out of the roof.

What do you mean by "...Also, should we leave the house during they permanence?..." Do you mean: "Also, should we leave the house whilst they are there (the insects)" ?

I suspect these will be bird mites. These are a range of species from two genera (Ornithonyssus and Dermanyssus) that mainly infest birds, but can also cause infestations in humans, causing a condition known as Gamasoidosis. I don't know much about them, but a bit of googling tells me they are commonly seen when a colony of birds is removed from a building and they no longer have a host to live on, so spread out trying to find new hosts.
Adults are in the range of 1/2 to 1 mm long, so quite small. They cause non-specific itchy papules in humans, which are where they bite to suck blood. I think you should be able to kill them with common insecticides.
Getting professional pest control advice is a good idea as it seems infestations can be hard to get rid of because they can live off human and pet blood.


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How pitch of a DNA Helix is 3.4 nm?

How pitch of a DNA Helix is 3.4 nm?
In the image that I have attached, the numbers with prime represent the number of base pair and normal numbers represent the number of gap elements between two base pairs. Everywhere to calculate the pitch (have 10 base pairs), number of base pairs (i.e. 10) is multiplied with length of gap element between two base pairs (i.e. 0.34 nm). BUT, to calculate pitch, the total number of gap elements should be multiplied with length of one gap element, Hence, the length of pitch should be 3.06 nm instead of 3.4 nm.

Welcome to Biology StackExchange! No, you have to include a space around basepair when thinking about one repeating unit. Think about it this way: If one pitch contains 10 bp, then half a pitch contains 5 bp, and the length should be one half of the whole pitch, right? But this isn't compatible with your calculation, because $\frac12 \times 3.06,{\rm nm} = 1.53,{\rm nm} \neq 4\times 0.34,{\rm nm}$. Perhaps it's easier to see why you have to count this way if you include half of space above and below.

@Domen "No, you have to include a space around basepair when thinking about one repeating unit"         Sir, with "space around basepair" do you mean the empty spaces left above bp 1' and below bp 10' (i used ' to show my numbering).

Those aren't empty spaces except in your diagram, they're the continuation of the chain in each direction.

i've tried to answer a related question here that somewhat includes this answer. https://biology.stackexchange.com/questions/112909/calculating-pitch-of-b-dna/113805#113805

When someone is gracious enough to explain their down vote, you should be gracious enough to thank them. They're doing you a favor; DVs don't need to be explained.

@anongoodnurse I am sorry for my misbehavior


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Can you identify this marine organism?
I found this in a beach located at Magnisia District in Greece. I found many more like this stuck in rocks, this however was loose. It was a bit hard and very smooth to the touch. It didn't seem to move.
The date I found this was 3rd of August 2023.

What are your first thoughts? Your first guess? On the name of this marine organism?

Looks like some kind of sponge or snail/mollusk type animal or plant?

@BrendanDarrer I believe it's a kidney sponge, although I am not sure.


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Start codon and 5' codon
Here it says:

For amino acid-based systems, the start codon of the mature protein is
labeled codon 1. The codon 5' to this is numbered -1.

So, I assumed the START codon is either -1 or 0.
But, when I align sequences on the HLA-A gene, both amino acids at positions -1 and 0, aren't a methionine which I thought was the only start codon possible.

There is however a Methionine at position -24.
Am I missing something? What are these amino acids numbered from -24 to 0. I've heard it's the "signal peptide", but cannot find any source about it, and I'm confused about the help page of this website. Any help is appreciated.

Beware, the manual says the start codon of the mature protein is labeled codon 1. Proteins undergo post-translational modifications and processing during which chemical modifications or protein cleavages happen. HLA-A has a signal peptide (see UniProt) which is 24 aa long. The term mature protein denotes the protein after processing, namely after the removal of signal peptide.

Thanks for the clarification. So is the start codon of the mature protein not necessarily a Methionine?

Correct. Protein is synthesized in its nascent form with methionine as the first amino acid. Later, the signal peptide is cleaved away, and therefore some other amino acid becomes the first one in the mature protein.

I understand, so almost all proteins are synthesized in their nascent form with methionine as their first amino acid but some have a signal peptide that is later cleaved away?


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Does blunt end have a hydrogen bond?
I am an undergraduate student of biology.
I saw a lecturer online, who said that sticky ends makes phosphodiester and hydrogen bonds cut. (also here).
But why blunt end just makes phospodiester bonds cut?
Thank you for answering.

Welcome to Biology StackExchange! Do you know how the structure of DNA looks like, and where phosphodiester and hydrogen bonds are located? Did your lecturer show you an image of sticky-ends and blunt-ends cuts?

Does this help? @ https://www.ncbi.nlm.nih.gov/books/NBK21129/

@BrendanDarrer thank you for sharing with me, but unfortunately the book didn't contains the answer that i'm looking for.

@Domen hi, thank you for your warm welcome. Yes i know the structure of DNA looks like and where are the bonds located. My lecturer shows me how the sticky-ends and blunt-ends looks like using GAATTC strand (for sticky-ends) and CCCGGG strand (for blunt-ends). Can you please enlight me about this cause i really need to know. Thank you so much

Have you found the answer or are you still looking for one?
In short - Hydrogen bonds occur between the 2 strands, whereas phosphodiester is within the each strand. so a sticky end has a few overhang nucleotides on one strand that are absent in the other strand, hence the hydrogen bond is missing..

Hi! i'm still looking for the answer. But thanks to you, your answer kinda enlight me. Thank you.


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Question about vitamin b6 product and cycling
Can the b6-product of a vitamin b6 reaction such as transaminase be recycled back to active vitamin b6 in man, and if so by means of what reaction?


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What did (domestic) cats evolve from?
I have received this question during a recent discussion about pet birds and cats. We know that birds evolved from the dinosaurs before the mass extinction that happened about 66 million years ago.
However, I could not find such clear information about the most prolific creature on the Internet.
This article suggests Felis attica (reclassified to Pristifelis attica) as an ancestor which seems to have lived about 12 million years ago.
I am interested in filling the gap between the mass extinction and Felis attica to have an answer for my question, but I cannot find an article diving even further in cats history.
Question: What did (domestic) cats evolve from?

I think you need to be a bit more specific: are you asking what cats in general (that is, the group felines like lions, tigers, jaguars &c) evolved from, which would be akin to "birds evolved from theropod dinosaurs", or are you asking which wild felines the domestic cats evolved from?  Which would be like asking which bird species my pet canary evolved from...

@jamesqf I am interested in a rather deep ancestry of domestic cats. This would be the first option from your comment.

Not an true answer to your question, but this Ologies episode with Dr. Mikel Delgado does a great job of explaining when cats came into our lives and how/if they were domesticated.
https://www.alieward.com/ologies/felinology

The carnivora can be seen in this phylogeny tree which comprises most of today's mammals. They suggest that rodents, elephants, monkeys, dogs and sea mammals all diverged from about 30 million years before the asteroid, until 5 million years after. The placentals and marsupials had a common ancestor previous to 100 million years ago.
Image from genomic study:

Previous to the Felix clade we have Feliforma, which includes mongooses and hyenas.
Image from wiki Feliformia:

There's a tree here
The last common ancestor of cats and dogs was about 40-55 million years ago. Feliforma family tree.
If you want to see previous to that, there are some basal carnivora, where the Feliforma are at the end of the tree.

Please reference where you've taken images from.

Ok, added reference. It's from wiki and the resizing is wrong. thanks.

Domestic cats ancestor was likely Felis silvestris or Felis lybica
Now this is actually just our best guess, little on the way of fossil evidence has been found but based on genetics Felis silvestris is the closes genetic match to the domesticated cat. However questions have arisen due to the risk of interbreeding, so it is possible Felis lybica may be it and Felis silvestris may only be a closely related sister group.
The big problem, Felis silvestris and Felis lybica form what is known as a species complex. That is a a collection of populations that may or may not be separate species. They are so closely related and physically similar that it  is difficult to be sure they even are separate species. There is a lot of debate over which population leads to the domesticated cat and evidence is tentative at best. Both species readily crossbreed with domesticated cats so a form answer may never be possible.
Source
Source 2


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Does human organism consume water or is it only used as solvent?
Dune (novel) describes a body suit called Stillsuit:

a stillsuit is a "body-enclosing garment" of Fremen design which
  performs the "functions of heat dissipation and filtering bodily
  wastes", as well as retaining and reclaiming moisture

For this question, I am interested into reclaiming property of this suit. The book argues about the fact that the losses were virtually only due to exposed skin.
However, I am wondering if the human body is actually consuming (through biochemical reactions) any water or it is used entirely as a dissolvent or maybe as a catalyst), so that its loss entirely depends on the ability of reclaiming it externally.
Question: Does human organism consume water or is it only used as solvent?

Humans and all other animals actually are net producers of water ("metabolic water") by oxidizing sources of energy including fats, proteins, and carbohydrates - effectively the opposite of the chemical reactions that photosynthetic plants use to turn water and atmospheric CO$_2$ into biological materials and oxygen gas. There are also many metabolic reactions in humans that consume water (in particular hydrolysis reactions), but it is less than the amount produced.
However, water is indeed important as a solvent, and there are non-negligible losses through evaporation (especially when sweating) and an important role of water in the kidneys to assist in flushing waste.
If one was able to reclaim all evaporative losses and excretion losses, no additional water would be necessary. However, the energy requirements to do so go up exponentially the closer you get to 100% reclaimation.
The International Space Station has several water recovery systems to reduce the incredibly expensive cost of supplying enough water for humans on long missions in space. These systems include both urine purification and atmospheric reclamation but they do not approach 100% capture.

evaporation from the lungs and urine are both big source of loss, so the suits would do a lot. a suit has some advantages over the space station.

@John The main advantage would be insulation, in that if you keep someone in a humidified environment evaporation would be decreased, but that doesn't solve the problem of evaporation in the lungs unless breathing is also contained in the suit, and I can't think of any advantages a suit would have over a space station in terms of urine recovery. The advantage the space station has, on the other hand, is that it is large enough to carry the necessary equipment, has available power, etc.

"The main advantage would be insulation, in that if you keep someone in a humidified environment evaporation would be decreased" 'Insulation' generally refers to heat, not humidity. And keeping someone in a humid suit in a desert seems like a really bad idea, and would likely just cause them to sweat more. A better to reduce water loss would be if the suit can keep the person cool.

@Acccumulation The only way sweat cools you is if you allow it to evaporate, so if a Fremen suit is collecting all water it can't be allowing the wearer to cool via sweating anyways. Insulation need not refer only to thermal insulation.

@Acccumulation the suits are described as trapping and collecting exhaled water,urine, and a large percentage of sweat. It is basically a nearly sealed environment suit designed with complex special heat exchangers.

There are some animals that can reclaim enough metabolic water that they do not need any external sources to survive. The desert kangaroo rat does this, using a nephritic system so dense that the loops of Henle descend all the way into the bladder!

@forest as far as I remember, saying that these animals do not require an external source of water is not entirely correct: they simply find food-bound sources sufficient.

@EliKorvigo No, this animal actually uses only metabolic water.


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Are there any detrimental effects to long term electrical muscle stimulation?
I know that different types of electrical stimulation can be used in fields such as physical therapy to get muscles to contract. However, these electrical stimulation sessions are not prolonged and contiguous.
Does anybody know if stimulating muscles to contract and retract for an extended and continuous period of time has negative side effects? Does it damage the muscle? Nerve?


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Why repolarization in ventricles start in last area which is depolarized "epicardium " rather than first area "endocardium"
About ventricular repolarization , l know it start in the last area which is depolarized ( that is why it has positive deflection on ECG ) but the question is why it start in that area ( epicardium ) although l think it can begain in first area depolarized "septum and endocardium" ?
- I heard answer about blood supply is differ because period of contraction is more in the "endocardium" than in"epicardium" which will generate high pressure inside ventricles that decrease coronary blood flow then slow repolarization phase ! If this true So how blood flow can effect repolarization ?

It isn't at all clear to me what you are asking. Also, "cardiophysiology" is not helpful as a title, your title needs to include your question or at least something close to a question.

I added some information and l hope you understand what l'm asking for .

Possible duplicate of Why is pericardium muscle repolarizated earlier than endocardium?


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Abnormal Spider Behavior?
A year or so ago, a spider that may have been a recluse, wolf or hobo (or anything visually similar), crawled up onto my bed. We locked eyes for a moment, and then it charged at me.
I don't recall whether I killed it or captured and released it, but it is definitely the most aggressive spider I've ever encountered. In fact, I've never known any spider to proactively attack (large mammals such as myself).
Is this a normal or even precedented behavior (in common species of spider in the U.S.)? Is there any specific reason that a spider might behave this way?

No, spiders do not charge at people or mammals to attack them. They can sometimes bite a mammal if the mammal is pinching one of its legs.
Spiders often run towards shadows. For many spiders, their eyes are merely light censors and darkness is a familiar safe spot for them. Many people misinterpret a spider's sprint towards them as some kind of 'charge' while it is usually an attempt to run to safety and not an act of aggression.
The spider family that you speculate on could be reduced if you include geography as the Hobo spider and brown recluse do not really share much distribution region. Wolf spiders can be found throughout North America, though.


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NMDA receptor mediated plasticity figure reference
Because most of this research is over a decade old, finding a paper with a figure that clearly shows that (neuronal) synaptic plasticity (such as long-term potentiation/LTP) is NMDA receptor mediated has proven very difficult for me.
Is there a good reference for this?

Not all types of LTP are NMDA-receptor mediated. To find a paper that shows a form that is, I would suggest searching terms like LTP and NMDA antagonist or blockade or similar.

One of the "Boss references" (nearly 11000 citations right now) for this is Bliss and Collingridge, A Synaptic Model of Memory: Long-Term Potentiation in the Hippocampus.
Being from 1993, it has references to some of the earlier work in this field (if that's what you're looking for).
It notes the different forms of NMDA-dependent and independent plasticity.
Another paper, also from 1993, on this topic is Malenka and Nicoll, NMDA-receptor-dependent synaptic plasticity: multiple forms and mechanisms
Some nice reviews with more recent work, focusing on the NMDAR itself include:

Paoletti et al, NMDA  Receptor Subunit Diversity:
Impact on Receptor Properties,
Synaptic Plasticity and Disease
Lau & Zukin, NMDA Receptor Trafficking in Synaptic Plasticity and Neuropsychiatric Disorders

and their references.

would you directly recommend a figure out of these papers?

@user2305193 What exactly are you hoping for the figure to show?

the NMDA receptor dependency within LTP

@user2305193 How about Malenka and Nicoll's figure 1 (which is actually taken from one of their references)? That shows its dependency experimentally. If you're talking about conceptually, maybe box 2 in Bliss and Collingridge?


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Do beneficial viruses exist? If so, what examples are there?
Typically, people call viruses some kind of organic compounds that cannot reproduce autonomously and which lower the fitness of their hosts. Even the word "virus" means "venom" in Latin.
But from the perspective of natural selection, one would expect those organic compounds that cannot reproduce autonomously, but which would increase the fitness of their hosts, to be more widespread. One can see an analogy with bacteria: people are more aware of harmful bacteria and even such words as "microbe" are perceived as somewhat harmful (among non-biologists for sure). But we know that an animal body contains many more useful bacteria than harmful ones, and animals have their own microflora, which are necessary for survival.
The same must be true for viruses: those viruses which were useful (or at least unharmful) to their hosts would be passed more easily to other organisms since their hosts would have a selective advantage.
So, do such beneficial for their direct hosts viruses exist? If so, what are they called? What are the examples?

Technically, since we do not know if a virus is alive or not, we cannot say it is "good"; akin to not being able to say a rock has good behavior.

@Phil, the question is not about the morality (and I even do not make such a distinction), and this is not a Phi.SE. Under "good" I mean its positive value for its possessor. Just like the water is good for you when you are thirsty.

Someone's been watching Red Dwarf :P

Are you only looking for naturally occurring viruses in your question?  We've engineered a few viruses (from existing viruses) which can overcome certain diseases.

@ReginaldBlue, that's also is interesting topic, would be interesting to read about that.

@russ9384: Well, then do not use the word "good" and keep the focus on fitness as you mentioned or other word like "survival probability" and "probability of passing on its genes"- terms that are objective and focus on things in terms of biology. One would think you are making this a "Phi.SE" discussion, when you throw in "'Phi.SE' terms" into a molecular biology discussion. This is a minor point that contributes littles to your goal. I think we can now end this.

@Phil, I couldn't predict that one would think of the word "good" as only in moral terms. I thought it's common to use the word "good" interchangeable with "useful". Because it's really common in my place to do it. But "useful" would be misleading as then bacteriophages would be useful.

@rus9384 - The word "good" has a variety of meanings. In general, readers will know that many words have multiple meanings. Choosing the intended meaning is often easy, as in this case. Nevertheless, you could substitute the word "beneficial" if you're looking for something more precise.

One of the theories of how viruses came to be in the first place is that they started as symbiotic organisms - perhaps in a similar way that mitochondria or chloroplasts are thought to be. Over time, they lost most of their machinery until possibly only the barest genetic coding remained, and either simply turned parasitic, or left the cell's environment and moved into other cells that weren't quite as welcoming (note how most human plagues are caused by viruses that were transmitted from other animals - the same virus that caused mild symptoms in e.g. a cow would kill a human).

I have gone ahead and made the beneficial edit discussed. We really cannot have questions imputing moral qualities to viruses when a functional descriptive adjective will do. Sloppy writing encourages sloppy thinking.

Even reworded I feel there's still a certain amount of ambiguity to this question.  Contracting Chicken Pox is "beneficial" if you consider the benefit of the immunity you gain.  Regular contact with Influenza is said to benefit the overall strength of the immune system as well, though tbh, I'm not sure if that's a myth or not. I see these types of benefits as analogous to the way lifting weights creates a short detriment but a long term benefit.  I'm not posting this as an answer because I know practically nothing about the subject - more just thinking out loud and wondering here...

@billynoah, I believe the word "good" itself created no much more ambiguity. In either way adding "for their direct hosts" after "beneficial" made it less ambiguous, right?

yes, it's less ambiguous.  do my examples above qualify as "beneficial" according to your intent?

@billynoah, regular pain reduces the sensitivity to pain. I can't say it's really beneficial. The mechanism is beneficial, but that's mechanism, not the disease (in your example) itself.

Do they exist? Yes
What are they called? Marilyn Roossinck calls them viral mutualistic symbiotes. She has an excellent review here.
What are some examples?
My personal favorite is GB-Virus C, or Hepatitis G, which appears to slow the progression of HIV using a number of different mechanisms:

Box 1. Summary of the effects of GBV-C infection in HIV-positive individuals

GBV-C infection downregulates HIV entry co-receptors CCR5 and CXCR4, and increases secretion of their ligands RANTES, MIP-1α, MIP-1β and SDF-1.
In vitro GBV-C NS5A and E2 proteins inhibit X4- and R5-tropic HIV replication, and NS5A protein downregulates CD4 and CXCR4 gene expression.
HIV-infected individuals positive for GBV-C E2 antibodies have survival benefit over HIV-infected individuals with neither GBV-C viremia nor E2 antibodies; in vitro GBV-C E2 antibodies immunoprecipitate HIV particles and inhibit X4- and R5-tropic HIV replication.
GBV-C induces activation of interferon-related genes and pDCs.
GBV-C promotes Th1 polarization and the NS5A protein contributes to this effect.
GBV-C infection reduces surface expression of activation markers on T lymphocytes, suggesting its role in T cell activation signaling pathways.
GBV-C protects the T cell from Fas-mediated apoptosis and as a result of its effect on immune activation may also play a role in protecting lymphocytes from activation-induced cell death.
GBV-C viremia reduces IL-2-mediated T cell proliferation suggesting a significant interaction between GBV-C, IL-2 and IL-2 signaling pathways.

Endogenous retroviruses
As @mbrig recalls in the comments, there are a number of retroviruses that have inserted themselves into the germ line. Those are called endogenous retroviruses, and they interact with the host genome in a number of ways. Some are even translated:

Proteins produced from ERV env genes have also been demonstrated to function as restriction factors against exogenous retroviral infection

Interesting answer. For future reference, it is not ideal to post text as images: it increase page loading time, prevents searching and presents various accessibility problems.

Oh, wow. Now it is interesting to know whether my hypothesis that these viral mutualistic symbiotes are integral part of almost any life form, like how micrpflora is such for animals. And hypothesis there are much more viral mutualistic symbiotes than viruses (which are causing diseases). But this is not within the scope of this question of course and has not been yet investigated, I believe.

@canadianer ok :) i typically post images of figures, and pulled a box instead. You're right this is better as quoted text. Thank you for making the edit.

Though I can't name any off my head, I have fuzzy memories of reading that a number of retroviruses have become permanent (and beneficial/essential?) parts of some species genomes.

@mbrig they're called endogenous retroviruses. They exist in the germ line. Some are beneficial, some are not.

@Mbrig I went ahead and added an example to the answer :)

These retroviruses (or by now also retrotransposons) are so ancient, that by now we have a couple of 'human' (and fly and ...) genes that probably evolved from them. One crazy example is Arc, which is important for brain developement and seems to have a very uncommon mechanism

@Nicolai I think that might have even been the one I read about, thanks! Amazing that a virus ends up not just harmlessly incorporated, but actually useful/needed :)

Endogenius retroviruses part apply perfectly for analogy with microflora.

@rus9384 well, they are germ line viruses (I"m not sure there is consensus on the distinction between an endogenous retrovirus and a retrotransposon), so I don't know if I'd agree that they are perfectly analogous to microflora. The gut virome and skin virome might, but much of that is comprised by phage viruses, so that's not perfect either.

Transposons cannot be passed to other individuals (except offsprings), right? I thought a virus is a virus, because it can be passed.

Another good virus would be a Bacteriophage, a virus that infects and kills illness-causing bacteria.  From Wiki:

A bacteriophage also known informally as a phage, is a virus that infects and replicates within Bacteria and Archaea. The term was derived from "bacteria" and the Greek φαγεῖν (phagein), "to devour". Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have relatively simple or elaborate structures.
They have been used for over 90 years as an alternative to antibiotics in the former Soviet Union and Central Europe as well as in France. They are seen as a possible therapy against multi-drug-resistant strains of many bacteria.

Intentionally using Bacteriophages medicinally is called phage therapy.

I'm aware of them, but it's not good for its possessor, as its direct possessor is that bacterium itself.

A bacteriophage is a virus that infects (not "eats") bacteria. That also doesn't mean they're good for the bacterial host. For instance, V. cholera does not produce the toxin that causes the symptoms of cholera unless it has been infected by the CTXφ bacteriophage. Along with its viral DNA, it also inserts the cholera toxin gene, turning the bacterial host (V. cholera) deadly for its own host (the unfortunate person who contracted the disease). This could arguably be considered "good" for the virus's host, since the definition of "good" seems pretty arbitrary in this context.

Phage therapy is largely ineffective given that not only can it increase the pathogenicity of bacteria (as @kadu points out) and can aid in spreading resistance factors (R plasmids), but because it triggers an extremely strong immune response against the otherwise harmless phage virions.

I would say that if any "good" viruses exist, they are already within us. Retrotransposons are genetic elements in our DNA that were likely ancient viruses and they move around from time to time either by excising themselves and moving somewhere else or by making a copy and inserting it somewhere else in the genome. Even though we are born with them, their activity is similar to modern viruses. When retrotransposons insert themselves in a new place they can cause disease, but the variation they cause likely brought us some beneficial advantage at some point because we have so many of them and they stuck around this long.

Interesting point. I'm just thinking about how plausible would it be to get increased intelligence, for example, from having sex with someone (sounds hilarious, I know), such kind of sexually transmitted advantage.

@rus9384 I don't believe the effects would be immediate, I'm not sure any kind of gene therapy can "increase the intelligence" of an already fully developed brain.

@JamesTrotter, some viruses are known to suppress intellectual functions. Why could they do the opposite?

@rus9384 because it's easier to switch a light off than it is to manufacture and install a circuit, bulb & switch and then switch it on.

@JamesTrotter, better example then could be metabolism... Any person with slow metabolism in developed society (who is either overweight or need to be on diet or go to gym regularly just not to be overweight) would like to get a virus of accelerated metabolism.

@rus9384 Well, now you run into another complex problem - there's no such thing  as "good" or "bad" without context. The same virus that would "cure" your obesity would kill you if you were poor (not to mention that a lot of viruses and bacteria already do that - a serious illness can make you lose quite a bit of weight).

@Luaan, would those people who are skinny even if they eat much, die if they would eat less? I'm pretty sure the mechanisms of those illnesses are different.

@rus9384 There's probably lots of variants. Which comes back to the original intent - context changes everything. I'm pretty sure it's incredibly unlikely for a natural virus to be 100% beneficial - remember, all they can do is make your cells produce proteins. Maybe they could make a diabetic's cells produce insulin in just the right amount - but at the same time being harmless to a non-diabetic? That seems to be stretching the probabilities way too much (unless you look at a population after everyone else was killed off :P). Of course, we might engineer such viruses, possibly.

@Luaan "all they can do is make your cells produce proteins" ... those proteins can do an awful lot, and transcription, translation, processing, distribution, activity, and turnover are all subject to co-evolving regulation.

We have engineered a few good viruses to treat certain diseases
Per my comment and response:
The most current example (at this time and based on my recollection) is the virus we have engineered to treat a certain type of macro degenerative eye condition:
Scientists Have Reversed Age-Related Blindness by Deliberately Infecting Eyes With a Virus
There are a few other cases out there, and, as always, xkcd is there to help:

Cowpox and smallpox viruses are structurally similar, and catching one confers immunity to both by immune system response, but one was a deadly disease and the other almost harmless. Once this was discovered, the days of smallpox were numbered. We had the means and the motivation to stamp it out.
On my last check a few years ago, we are deliberately keeping cowpox alive to ensure that we can kill smallpox should it ever come back.
The virus that ended a plague is a good virus.

So, do such beneficial for their direct hosts viruses exist? If so,
what are they called? What are the examples?

Bacterial viruses, termed bacteriophages or simply phages are normally killers of bacteria and thus occasionally useful for humans (e.g. phage therapy) but not beneficial for their hosts. However, some phages, called temperate phages, have a lysogenic life cycle, where the viral genome can become integrated into the bacterial chromosome and they replicate with the bacteria (at least temporarily) as a prophage. These prophages have a shared evolutionary fate with the bacteria and can be directly beneficial by carrying bacterial fitness factors such as virulence factors or antibiotic resistance genes. You might be interested to read more in our short review.


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What processes regulate the sex of offspring?
It is known that some species are more likely to born male than female (and some maybe vice versa). I understand that it is due to evolutionary perspective (average number of adult males is close to that of females), I want to know about how it is regulated.
What I thought is that spermatozoa are made by half as Y and half as X chromosome. Then mitosis and meiosis and the probability that one of them will die is equal for both types. So, somewhere I feel lost.
Also, can it be regulated by female body or not? According to this paper claiming that hormone levels in women affect the likelyhood to born son. Possibly it is just because they choose males that are more likely to have more Y spermatozoa than X, but if it is some chemical mechanism to regulate that I'd like to know.
I'm not asking only about humans, mechanisms can be similar in almost all mammals. I'm not asking about other species: I know some are regulated by temperature, etc. This question is only about mammals.

I think you are only asking about mammals. Males and females are not universally defined by chromosomes, or genitalia. They are defined by the size of their gametes. Female gametes are larger than male gametes. Some fish switch from males to females as they grow larger. The sex of some reptiles are determines by temperature. So are you asking ONLY about mammals?

You need to specify an organism. The process differs widely throughout the animal kingdom.

@David I guess mechanisms are similar throughout all mammals.

Probably. But birds, fish and fruit flies...

@David I tagged this question with mammals, not fish, birds or fruit flies.

Tags are for indexing. Anything central should be in the question.

No, all mammals are not alike.  Monotremes have very complex sex chromosomes, not much at all like that of other mammals.

@swbarnes2, but is their sex regulated in different way, not like of other mammals (which one present in spermatozoa)?

I don't really understand the question. The only question mark in your question is in the question Also, can it be regulated by female body or not? which, obviously does not stand by itself. Can you please try to rephrase and clarify your question.

@Remi.b, in fact, maybe I should have changed it to "Wgat processes in women regulate the sex of offspring?" Although since I have asked this question I have read that male and spermatozoa are somehow different and that vaginal acidness can affect the sex of offspring. Yet, I am not sure since that was not scientific article.

What processes regulate the sex of offspring?

The processes rulating the sex of offspring may occur in both males and females and be direct or indirect.

What I thought is that spermatozoa are made by half as Y and half as X chromosome. Then mitosis and meiosis and the probability that one of them will die is equal for both types. So, somewhere I feel lost.

This may not be entirely true. The phenomenon called "Meiotic drive" may change the ratio from 1:1. Meiotic Drive occurs through selfish genes. See "Selfish-gene theory" for more info.

Also, can it be regulated by female body or not?
if it is some chemical mechanism to regulate that I'd like to know.

Possibly, there is such in mammals. There is a bunch of mechanisms called "Cryptic female choice". Some of them are chemical. Although, the article is about birds, it can be the case similar mechanism is present in mammals.
Given that higher androgen level exposure in mothers affect make their offspring more male-typical in playing behavior we might consider that in general makes offsrpings more masculine. This would be a good reason for female organisms with higher androgen levels to favor sperm with Y chromosome present.

Possibly it is just because they choose males that are more likely to have more Y spermatozoa than X

Yes, this is possible. But considering cryptic female choice we may say the same for males. Some of them may seek those females who are more likely to get pregnant with particular sex spermatozoon.

Answering by my own since only now I occasionally came across with "Cryptic female choice" article.

Both can play a factor across mammalia.In humans it is difficult to study effectively (we can't lock people and cages and mate them in controlled patterns, nor will most parents volunteer to hormone injections for their fetus)  So we have less data on humans than for other species.
In other mammals we have had more luck and a variety of mechanisms exist, often several competing mechanisms withing the same species even.  Not surprising if you think about out what gender the males genes "wants" and what ratio the females genes want will not always coincide. In rats for instance the R2D2 gene (I shit you not) prevents female offspring by preferentially differentiating germ cells so only those that carry it become sperm. The gene sits on the Y chromosome so it is selfishly passing itself on at the cost of often wiping out populations becasue they have no females. this is the most extreme mechanism know but it illustrates the sheer variety that exist.
dominance and stress are often good predictive factors, while known mechanisms include Hormones driven differential implantation, differential ova production, differential spermatozoa formation, and differential sperm survival. More mechanisms almost certainly exist but the search for them is relatively new so it is not surprising most studies will list them as potential influences.
Many mechanisms actually makes sense evolutionarily speaking, since there are several competing factors preferring one sex or the other as far as the parents genes are concerned. For instance if the ratios get too far away from the normal ratios it creates a n increasingly strong advantage to produce offspring of the sex in the minority. Another factor is parenting style of the species, in more or less monogamous species the sex has little impact while if you are a species that has harems females are sure thing with low pay off (numbers of offspring) while males are high risk high reward, low chance of reproduce but those that do have LOTS of offspring. Even things like for genes on the Y chromosome every female is a failure is a factor. You mist also consider that chromosome profile is not the only controlling factor, sex phenotypes that do not match their genotype is surprisingly common in mammalian.
Source


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How does better sperm result in more viable offspring?
Quoting wikipedia:

Greater choice and variety of mates increases a female's chance to produce more viable offspring.

This led me to the question: "How sperm parameters are connected with entity parameters?"
Actually, sperm parameters are usually: motility and morphology. I am speaking about a single sperm, therefore any parameters involving their count or parameters of semen are not included.
On the other hand, what helps a particular entity to survive is determined by many parameters. Some of them are: speed, endurance, strength, agility, stealthiness and savvy. It is hard to find out how strength of being is connected with motility or morphology of sperm it has been conceived. And even less obvious is the connection of stealthiness with such sperm parameters.
But since sperm competition exist, it helps in natural selection, therefore there must be a connection. But how does it really work? How are stronger/faster/stealthier/etc. entities are the product of more motile or better in morphology sperm?
After some thinking about it I think that if there is some correlation between sperm parameters and genome, it can answer the question. E.g. presence of gene that increases fitness of organism makes sperm faster.

Greater choice and variety of mates increases a female's chance to produce more viable offspring.

The claim is a little hard to address because it is vague. However, one can give a simple example to give you a feeling of why this could be the case.
This example is based on Zaahavi handicap principle. Spermatozoids aren't free to produce. A male that can produce more and stronger spermatozoids can do so because he is a healthy males. As many of the traits that determine health, in a general sense are heritable, healthier males tend to have healthier offspring.

On the other hand, what helps a particular entity to survive is determined by many parameters. Some of them are: speed, endurance, strength, agility, stealthiness and savvy.

You are mainly listing traits that are very specific to human's sport ability. In reality, there are loads of other traits that are much more fundamental such as the efficiency of the potassium pump or of the mechanism to produce ATP.

[..] it helps in natural selection [..]

I don't understand what you mean by this sentence.

"I don't understand what you mean by this sentence." This is how biology works. Females who were involved in multiple-male relationships with sperm competition gave birth to more fit offsprings. Otherwise sperm competition would not exist. Also, you are ignoring the principle: why sperm competition is more efficient for females than sexual selection? (And males in many species are more sexually selective when it comes to how female looks).

"healthier males tend to have healthier offspring." Actually this should make female sexual selection superior to sperm competition but somewhy it really isn't. "You are mainly listing traits that are very specific to human's sport ability." Not really, speed is helpful for animal to run away from predator and it is helpful for predator to catch an animal. Same applies to stealthiness, for example. Instead, in humans intelligence massively outweights such parameters (well, strength is needed to make and use tools, but other parameters are not that essential).

@rus9384.Isn't that just biased stats? Ain't it possible that the females gave birth to more fitter offsprings precisely bc they mated with a more fitter guy?I mean they  mated with more people. And in monogamous relationships,you only mate with one person, ofc that one person can be either a very fit guy or a unfit guy. Its all on probability. Females who'll mate more people will have more odds of mating with a fitter guy rather than monogamous folks,I think its just a simple trick of stats you say,fitter here means in the evolutionary context.Sorry if I'm wrong,this is just pure speculation.

And that speed comes from more efficient ATP generation.That strength comes from more efficient potassium ion pumps in nerves and muscle cells.

You are over thinking sperm competition, just like two males can compete for access to a female, multiple sperm compete for access to eggs. If male A's sperm are faster than male B's sperm and both are present in the same female, more of her offspring will be from male A. So male A has advantageous genes. Additionally that female is going to have male offspring that may also engage in sperm competitions so having good genes for sperm competitions benefit her genes in the long run.
It benefits her in the same way having more males compete for her helps her: she is getting the best from a wider selection of individuals thus more likely to carry genes that will benefit her male offspring. Every mating is a roll of dice, those who can play the game more often have a better chance of getting a jackpot. If male A has Gene X and male B has Gene Y the female gets offspring with gene X and some with Gene Y. Since most genes are contextual it increases her chances of getting a better gene into her offspring.
Let's think of an example:
Female A mates once with the best male of 5.
Female B mates 3 times with the best male from three separate competitions of 10 males each.
Female B has an advantage because she not only has taken the best from a wider range of options, Thus by pure chance is more likely to get the best available genes, but also because she had three separate chances vs just one.
Now of course there are thousands of other factors at play like offspring cost this is just for understanding why competition helps both males and females in some cases.

"that female is going to have male offspring that may also engage in sperm competitions" The problem with such reasoning is following: sperm competition is the consequence of sperm competition itself while it can't be true. Females started to be involved in multiple mate sex not because of faster sperm being more competetive. If there are some genes (as I proposed) which both increase fitness of offspring and sperm, than I would like to see any research supporting this.

The gene does not have to make healthier offspring just healthier sperm, There are genes that reproduce themselves at the expense of the organism,(R2D2 in rats), genes do not have ot benefit the organism they just need to spread themselves. . to tweak a famous biology saying, sometimes a man is a just a sperm's way of making another sperm. There is nothing special about males or sperm they are both products of genes.

But how does it justify the sperm competition itself? E.g. if everyone stops sperm competition nothing differs according to your point (which is wrong, females with lesser fitness will give birth to the same amount of children, as opposed to polygamic species).

If peacocks stopped there displays and females stopped preferring displays both would be far better off, the costs are huge, but any adaptation to do so is quickly selected out of the population because it has to deal with all the other females who are looking for the display. sexual selection can be hugely detrimental to an organism as long as it favors the genes. All it takes ot start sperm competition is females who mate with more than one male which is not uncommon in the slightest, in many cases it is not even the females choice.

The reason why peacock females preferred displays is a coincidence of natural selection: it was easier for females to notice those peacocks who had more colorful tails. Therefore, their male offsprings became more colorful through natural selection at first and female offspring became to care about male tails through natural selection. But then they start to choose males who are too noticable. This is what I call sexual selection overkill.

What aren't you understanding about sperm competition then?

Let us continue this discussion in chat.

What part of sperm competition is giving your trouble then, a female mates with more than one male, thats all it takes to start sperm competition selection.

Then the question is: "Why females who mate with more than one male starts to have more offsrpings than ones who don't?"

They don't, they have more successful offspring on average. This is becasue they are using a wider pool of genes. Even this is not necessary, they could just have more successfully MALE offspring that carry whatever gene that let their father's sperm win the sperm competition. There are many genes detrimental to one sex and beneficial to the other. Not all females have a choice in mating with more than one male.

"This is becasue they are using a wider pool of genes." This was my starting point. How wider pool of genes help if we consider better genes do not affect sperm quality? E.g. the slow sperm could become a really fit entity, with the same probability as fast sperm. "Not all females have a choice in mating with more than one male." Some females, I claim, do not even have a chance for a single mate. And this reasoning (that sperm competition indirectly increased species fitness - so that fit females had sex with more males, therefore males would not have sex with less fit females) is more logical

whoa, better genes can absolutely affect sperm quality, better genes is does not mean the gnes have to benefit the individual organism and still be selectively favored. A gene can be beneficial to the sperm and detrimental to the organism. Species fitness is irrelevant to natural selection, natural selection does not occur on the species level, in fact many gene decrease the fitness of the species yet continue to spread. It seems the the source of your confusion is you don't understand how evolution operates.

Hm, but then nothing would favor polyandry. We may assume polyandrous female appeared, her male offsprings would have better sperm and female offsprings would have higher probability of polyandry. But we know there is such thing as inbreeding, therefore here male offsprings would be more likely to have ofssprings from not her female offspings, but other monogamic females. And there those better sperm would never helped. But I'm wondering if multiple-male sex increases birth rates then. Only then it would explain her female offsprings being bred.

inbreeding is pretty small risk, otherwise all non-monogamous animals would not evolve. Like I said not all females have a choice in their mates. but again as I said it can increase the average success of her offspring by producing a wide pool of genes in the offspring. It seems like you may want to aska sperate question about good reading for understanding sexual selection in general.


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Does the ratio between M and L cone cells vary in one indiviual?
Wikipedia says:

The ratio of M and L cones varies greatly among different people with regular vision (e.g. values of 75.8% L with 20.0% M versus 50.6% L with 44.2% M in two male subjects).

This made me wonder if other people then can perceive colors more or less green/red than me. But then I asked myself why do I perceive all colors similarly for both objects on my sightline and at sides (except 90+° from my sightline horizontally). Is that because the ratio of cone cells is similar on the whole retina (in one individual)?

The wavelength of light that appears unique yellow is surprisingly consistent across people even though the ratio of middle (M) to long (L) wavelength sensitive cones is strikingly variable.
Source: https://jov.arvojournals.org/article.aspx?articleid=2531368


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Comparison of humans and other primates in milk production amount
Do human females produce more milk (relatively to average child weight weight) than other primate females? Are human females more likely to feed several children through breastfeeding than other primates?

P.S. I am asking this, because it's what my antropologic hypothesis predicts: some women refused to nurse (and breastfeed) children born by them, so "nurses" - other women - fed those children. This, of course, would require those women to have extra (more than needed to feed their own children) amount of milk.

It seems certain. 1)There are twins fed by a single mother. 2)There were mothers who suckled a second child for payment. 3)The suckling period of an infant can be long and suckling of multiple babies can occur. But as the milk is adapted to the baby, the first one, if old enough, often stops, because the flavour changes. At least that’s what mothers say.

@Ludi, seems reasonable and p. 1. is what I already had in mind. However this is not scientific approach, of course. I'm pretty sure other species also can have twins.

I disagree with the close voter that this question has anything to do with personal health. I do think the question could be improved, however. The word "excessively" doesn't help you here, it doesn't seem to be what you are actually asking. What you are actually asking is "Is it typical for a primate mother to produce enough milk to feed more than her own offspring?" I think an edit like that would improve the reception of your question, and you can copy my wording if you'd like but I prefer not to make major edits to peoples' questions without their agreement.

Milk production (in all mammals, as far as I'm aware) is stimulated by suckling, and is limited by the health of the lactating individual, not the number of offspring produced. Provided they let you, you can milk a cow, goat, mouse, marmoset... I would speculate that wet-nurse behavior is more about the social behavior of a species than the maximum milk producing capacity.

@DanHall, I don't say it's limited by the number of offsprings produced. Won't you argue cows (especially on farms) have excessive milk? I'm rather asking if that's limit is higher in humans.

I'd say excess. The farmer certainly doesn't think the cows production is excessive

@DanHall, lol, excessive from the position of feeding it's own offsprings, of course, not the farmer.

I'd add to @BryanKrause 's suggestion. I think close and down voters may be reacting to your use of the word "excessively". It's a little confusing. I like Bryan's wording. You could also use "excess". "excess milk" sounds more neutral than "excessive milk".

The comparison to non-human primates and the behavioral question kind of threw me, but I think this is an X-Y problem. If you're asking:

Are humans capable of producing more milk than they need to feed their own offspring

The answer is yes
There is some data I don't think we'd be able to get anymore, but in Chapter 5 of Nutrition During Lactation, they break it down.

Several studies indicate that potential milk production in humans is considerably higher than the average intake by single infants. Kaucher and colleagues (1945) measured maximum milk output with intrusive and tedious mechanical methods to extract all the mother's milk and reported that production averaged almost 1,200 g/day at 6 to 10 days post partum. This level is much higher than the 500 to 700 g/day consumed by breastfed infants at the same age (Casey et al., 1986; Saint et al., 1984).

Kaucher's methods may not have been particularly good, because others showed limits more than twice that

Women who express surplus milk for a milk bank have been shown to produce as much as 3,000 g/day (Macy et al., 1930).

As my wife and many lactating mothers who use a breast pump will be able to confirm, this isn't a relic of the 30s and 40s. If you keep pumping, you keep getting milk.

In two separate studies, milk production increased by 15 to 40% when a breast pump was used to remove additional milk after feedings (Dewey and Lönnerdal, 1986; Neville and Oliva-Rasbach, 1987).

I'd add that this is how biology does almost everything involving regulating production of something, from small molecules to excreted fluids to tissues: use feedback to know when to increase or decrease production, rather than producing some specific magic amount automatically.

Thanks, this is useful info. Of course, it's not enough for say that women have more milk than primates, which should be true, if, of course, primates did not have such division of labor as humans. And as we know, they don't.

@rus9384 I don't know enough about non-human primates to answer authoritatively. Maybe Bryan does? But I'm not sure we can make a global statement about the social structure of all primates. As far as I remember from school, there's a lot of diversity in social structure across that order.

@DanHall, there is, but division of labor is proposed to be the effect of great level of intelligence. Lower than that of human, yet higher than what any existing primate has.

Well, sure women who produce for a milk bank produce more.  Women who produce less don't donate milk.  Quantifying outliers says nothing about how the data is distributed in the whole population.  If it takes a pump to get the excess milk out, then that milk shouldn't be counted as being available in communities which lack access to that technology.

@swbarnes2 you make a good point

@DanHall At least some non-human primates will foster nurse under certain conditions, so although I'd be very hesitant to make any global claims (especially, as you say, because social structure in different primate species varies dramatically), I'd feel quite confident in saying this is not a human-specific trait within primates. I have no idea if other primates would ever foster nurse in the presence of the natural mother, however.

@rus9384 I'm a bit skeptical that your statement "division of labor is proposed to be the effect of great level of intelligence" is anything besides just that: a proposal. To the contrary, my albeit limited anthropological understanding is that besides for possible male/female division of labor, division of labor among human groups is only understood as a recent cultural phenomenon

@BryanKrause, there always were politicians, warriors, craftsmen etc. as history knows it. So I don't understand that division of labor is somewhat new.

@rus9384 Citation needed if you really want to go the evolutionary psychology route, which based on your collection of questions and comments on SE seems like what you want to do. Evolutionary psychology is making pre-history arguments, not history ones. This is one of the major criticisms of evolutionary psychology and yet another reason I suggest you tread lightly: be wary of the just-so story.

@BryanKrause, as I say, division of labor based on abilities is good for society in all cases. Also, psychologically people already have different interests, which is seen as adaptation by me, while having particular interest in videogames (example) is a byproduct of that adaptation. In either way, I'm seeking arguments for the hypothesis.

Just because you think division of labor is good for society does not mean society has always had division of labor. Eating vegetables is good for me. Want to take a guess how many vegetables I've eaten so far today? You are not using good logic.

The vast majority of human existence is pre-historical.  It's not at all clear to me that there could be "craftpeople' in a hunter-gatherer group, in the sense of people doing nothing but making tools in exchange for everything else they needed.

@swbarnes2, if clothes are tools I see no problem. Except producing tools there are many other deeds like cooking food, cutting meat, etc.

@BryanKrause, division of labor started somewhen and it started prehistorically. Another question is when and the question that can give a clue is "What were the premises for it?". I can see no other premises than see that people developed different skills (varying more in their skills than most other animals) and used them accordingly.

This, of course, would require those women to have excessive (more
  than needed to feed their own children) amount of milk.

No it doesn't.  A wet nurse might be a woman whose infant died, or she might switch her child to all solid food or a milk substitute.

You seem to misunderstand what I mean by nurse. Nurse for me in hunter-gatherer society is somewhat like nurse in ants society, who deliberately cares about children (who are not necessarily her own).

If you are so sure that hunter-gathers and ants work the same way, why are you bothering to ask a question here?

Not the same, but similar. Also, one should not answer here something that is not the part of the question (it is just an explanation for motive) and that's not a part of biology. I don't even see any negative connection between my thoughts (regarding hunter-gatherer society) and the motive to ask.

Alloparenting is what's common in hunter-gatherers, the opposite of the specialization you seem to think is obviously innate and superior.

According to my hypothesis minority (15% or higher) of women did not care about their and others' offsprings in their early childhood preferring typically "mens' work".

I don't think you understand how testing scientific hypotheses works...You don't make a hypothesis and then try to fit every other piece of data to it. You create a hypothesis that you can test somehow. Only once you have an overwhelming amount of support for a theory can you use it to make predictions about novel things.


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Does estrogen increase muscular growth in females?
Regarding humans it is said that most psychological effects caused in men by testosterone are caused in women by estrogens. There are many studies on that, particularly regarding temporary shifts of hormone levels: Ovulatory shift hypothesis. Also, there are some studies (and possibly controversial) claiming such differences between individuals.
But this made me think if there are any similar physiological diffences caused by estrogens. It's known that in males testosterone affects muscular growth, which means higher testosterone levels will make it easier to gain muscular weight. So, I ask if higher estrogen levels in females affect muscular growth.
While this question is regarding humans, studies about other primates also can be acceptable.

The article named "Estrogen replacement and skeletal muscle: mechanisms and population health supports this hypothesis, when applied to postmenopausal women:

Evidence suggests that HT will also help maintain or increase muscle mass, improve postatrophy muscle recovery, and enhance muscle strength in aged females.

This particular passage suggests it might not be exclusive to postmenopausal women:

One of the reasons for the relatively new interest in estrogenic effects on skeletal muscle was the identification of estrogen receptors (ER) in this tissue.

Passage containing more specific information:

Although research findings over the past 20 yr have reported conflicting results of HT on muscle mass in postmenopausal women, the preponderance of more recent evidence has “tipped the balance toward a positive and measurable impact of HT” and have highlighted the “proanabolic” effects of HT on skeletal muscle. Several recent studies examining postmenopausal women showed significantly greater muscle mass in women taking HT relative to nonusers.


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Is there a purpose for nucleated red blood cells in reptile, avian and fish blood?
I have read, and read, and read documents on this subject but still have no conclusions.
Everything I have read explains why mammals don't have a nucleus (to make more room for the haemoglobin and allow for more oxygen to bind as well as making it easier for the RBC to fit through capillaries) but the reports don't explain why birds, reptiles and fish may still have nucleus in a red blood cell.
Is there really any other function a nucleus has within a red blood cell apart from being the 'brain of the cell?
It's doing my head in, all I've gained from this research is the understanding that birds have a far more advanced respiratory system and their capillaries are bigger than mammals, this still doesn't explain the need for a nucleus, it's actually suggesting they don't need one!
Any enlightenment will be great,
Thanks.
http://onlinelibrary.wiley.com/doi/10.1002/iub.490/pdf

+1 vote. I was also wondering this last time though I never bothered to research

Does there have to be an explanation? I personally would doubt the fairy story about mammalian red cells making room for haemoglobin. Typical post hoc justification. They just evolved differently.

Many good points already made above. I'd only add enucleate red cells confer a solid evolutionary advantage for many mammals. Apex land predators, eg cheetahs, probably couldn't sprint if they had the lesser capacity of nucleated red cells. Also allows some animals to occupy higher altitude niches - eg mountain goats etc

Small point: Camelids have enucleated erythrocytes, albeit elliptical ones. See https://vetclinpathimages.com/2018/03/27/normal-camelid-erythrocytes/

It's difficult for vertebrates to aquire/evolve enucleated cells, that's why they are very rare previous to the mammalian adaptation. Salamanders have evolved enucleated cells. Research suggests that it may be due to a salamanders big genome and big cell nucleus, compared to the salamanders small body size.
Mammals may have acquired the trait because they evolved from small animals with miniaturized capillaries and blood cells and large genomes, and the advantage was kept afterwards. Large genomes inhibit flow and flex of nucleated blood cells.

The smallest bird genomes are found in the most miniturized clades of birds at 1 Gb. Mammals of a similar size can have carry 2-3 Gb of chromosomes.
Lizards have lower energy than mammals.
Fish are most active in highly oxygenated water, i.e. salmon, which allows them to be very energetic, water is a more efficient breathing medium than air, hence the small size of gills. fish and humans both contain 6-7 percent blood by volume.
Birds have smaller haemoglobin including the nucleus, and have a different kind of capillary size and structure with advantages and disadvantages, and lighter hollow bones with less marrow. Birds didn't radiate to new shapes as well as mammals did.
Enucleate cells are fairly rare in the plant and animal world, so they perhaps have a hidden expense. Maybe it's not just a factor of shedding the nucleus, and in fact there is a cost of adapting the primary circulation system's immunity against paramecia and pathogens without a nucleus. various viruses can take advantage of enucleate cells.
Perhaps that is the reason why birds did not evolve backwards into dinosaurs. some factor made their genome comparatively small. It could be the lack of enucleated bloodcells that forced them to shed genes as an alternative. Perhaps that's why they lost the dinosaur genes which held code for quadrupeds, arms, jaws, horns and teeth and the things that birds don't have.

Thanks for all your answers, it's pretty much summed up what I had in mind!

May I ask what are your resources for your answer please? It's helped me a lot!

Thanks Steph, I mostly use google scholar for specific references, some of it is difficult to research, skeletal shape advantages and immunity and physiological adaptions of enucleosis is less easy to find specifics on.

enucleation is just one of multiple solutions to the same problem, and each has their own costs.
When compared side by side bird blood carries the same amount hemoglobin as mammalian blood. birds maximize oxygen content my evolving smaller hemoglobin molecules, mammals evolved smaller hemoglobin carrying cells.
Each solution has its own cost, bird erythrocytes still have mitochondria which reduces oxidative stress on the cells while meaning each cell is larger and thus capillaries need to be larger. But oddly, even though bird blood cells age slower (accrue oxidative stress slower), birds have a higher turnover of blood cells. Since enucleation limits the speed at which mammalian blood cells can be produced they cannot replace blood cells faster even though they are wearing out faster.
Once a group starts evolving down one of these strategies and starts evolving means to counter or at least mitigate the costs there is no benefit and quite a high cost in switching to a different method, much like both groups respiratory system they get locked in evolutionarily.
Only in mammals and birds is the demand for oxygen high enough for the costs to be worth it. They need to maximize blood oxygen carrying capacity and take the benefit outweighs the costs. Other groups don't evolve these specializations because for them the cost is not worth the benefit there blood oxygen capacity is more than adequate. Its the same reason they don't evolve the advanced respiratory systems of mammals and birds.
https://journals.physiology.org/doi/abs/10.1152/ajpregu.00276.2020
https://pubmed.ncbi.nlm.nih.gov/2012765/#:~:text=Mammals%20had%20more%2C%20smaller%20erythrocytes,exothermic%20groups%20such%20as%20reptiles.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3686644/
https://www.hindawi.com/journals/sci/2011/139851/