One fine day, when Charles Darwin was still a student at Cambridge, the budding naturalist tore some old bark off a tree and found two rare beetles underneath.
He’d just taken one beetle in each hand when he spotted a third beetle.
Stashing one of the insects in his mouth for safekeeping, he reached for the new specimen – when a sudden spray of hot, bitter fluid scalded his tongue.
Darwin’s assailant was the bombardier beetle.
It’s one of thousands of animal species, like frogs, jellyfish, salamanders, and snakes, that use toxic chemicals to defend themselves – in this case, by spewing poisonous liquid from glands in its abdomen.
But why doesn’t this caustic substance, ejected at 100 degrees Celsius, hurt the beetle itself?
In fact, how do any toxic animals survive their own secretions?
The answer is that they use one of two basic strategies: securely storing these compounds or evolving resistance to them.
Bombardier beetles use the first approach.
They store ingredients for their poison in two separate chambers.
When they’re threatened, the valve between the chambers opens and the substances combine in a violent chemical reaction that sends a corrosive spray shooting out of the glands, passing through a hardened chamber that protects the beetle’s internal tissues.
Similarly, jellyfish package their venom safely in harpoon-like structures called nematocysts.
And venomous snakes store their flesh-eating, blood-clotting compounds in specialized compartments that only have one exit: through the fangs and into their prey or predator.
Snakes also employ the second strategy: built-in biochemical resistance.
Rattlesnakes and other types of vipers manufacture special proteins that bind and inactivate venom components in the blood.
Meanwhile, poison dart frogs have also evolved resistance to their own toxins, but through a different mechanism.
These tiny animals defend themselves using hundreds of bitter-tasting compounds called alkaloids that they accumulate from consuming small arthropods like mites and ants.
One of their most potent alkaloids is the chemical epibatidine, which binds to the same receptors in the brain as nicotine but is at least ten times stronger.
An amount barely heavier than a grain of sugar would kill you.
So what prevents poison frogs from poisoning themselves?
Think of the molecular target of a neurotoxic alkaloid as a lock, and the alkaloid itself as the key.
When the toxic key slides into the lock, it sets off a cascade of chemical and electrical signals that can cause paralysis, unconsciousness, and eventually death.
But if you change the shape of the lock, the key can’t fit.
For poison dart frogs and many other animals with neurotoxic defenses, a few genetic changes alter the structure of the alkaloid-binding site just enough to keep the neurotoxin from exerting its adverse effects.
Poisonous and venomous animals aren’t the only ones that can develop this resistance: their predators and prey can, too.
The garter snake, which dines on neurotoxic salamanders, has evolved resistance to salamander toxins through some of the same genetic changes as the salamanders themselves.
That means that only the most toxic salamanders can avoid being eaten— and only the most resistant snakes will survive the meal.
The result is that the genes providing the highest resistance and toxicity will be passed on in greatest quantities to the next generations.
As toxicity ramps up, resistance does too, in an evolutionary arms race that plays out over millions of years.
This pattern appears over and over again.
Grasshopper mice resist painful venom from scorpion prey through genetic changes in their nervous systems.
Horned lizards readily consume harvester ants, resisting their envenomed sting with specialized blood plasma.
And sea slugs eat jellyfish nematocysts, prevent their activation with compounds in their mucus, and repurpose them for their own defenses.
The bombardier beetle is no exception: the toads that swallow them can tolerate the caustic spray that Darwin found so distasteful.
Most of the beetles are spit up hours later, amazingly alive and well.
But how do the toads survive the experience?
That is still a mystery.
Right now, you're probably sitting down to watch this video and staying seated for a few minutes to view it is probably okay.
But the longer you stay put, the more agitated your body becomes.
It sits there counting down the moments until you stand up again and take it for a walk.
That may sound ridiculous.
Our bodies love to sit, right?
Not really.
Sure, sitting for brief periods can help us recover from stress or recuperate from exercise.
But nowadays, our lifestyles make us sit much more than we move around, and our bodies simply aren't built for such a sedentary existence.
In fact, just the opposite is true.
The human body is built to move, and you can see evidence of that in the way it's structured.
Inside us are over 360 joints, and about 700 skeletal muscles that enable easy, fluid motion.
The body's unique physical structure gives us the ability to stand up straight against the pull of gravity.
Our blood depends on us moving around to be able to circulate properly.
Our nerve cells benefit from movement, and our skin is elastic, meaning it molds to our motions.
So if every inch of the body is ready and waiting for you to move, what happens when you just don't?
Let's start with the backbone of the problem, literally.
Your spine is a long structure made of bones and the cartilage discs that sit between them.
Joints, muscles and ligaments that are attached to the bones hold it all together.
A common way of sitting is with a curved back and slumped shoulders, a position that puts uneven pressure on your spine.
Over time, this causes wear and tear in your spinal discs, overworks certain ligaments and joints, and puts strain on muscles that stretch to accommodate your back's curved position.
This hunched shape also shrinks your chest cavity while you sit, meaning your lungs have less space to expand into when you breath.
That's a problem because it temporarily limits the amount of oxygen that fills your lungs and filters into your blood.
Around the skeleton are the muscles, nerves, arteries and veins that form the body's soft tissue layers.
The very act of sitting squashes, pressurizes and compresses, and these more delicate tissues really feel the brunt.
Have you ever experienced numbness and swelling in your limbs when you sit?
In areas that are the most compressed, your nerves, arteries and veins can become blocked, which limits nerve signaling, causing the numbness, and reduces blood flow in your limbs, causing them to swell.
Sitting for long periods also temporarily deactivates lipoprotein lipase, a special enzyme in the walls of blood capillaries that breaks down fats in the blood, so when you sit, you're not burning fat nearly as well as when you move around.
What effect does all of this stasis have on the brain?
Most of the time, you probably sit down to use your brain, but ironically, lengthy periods of sitting actually run counter to this goal.
Being stationary reduces blood flow and the amount of oxygen entering your blood stream through your lungs.
Your brain requires both of those things to remain alert, so your concentration levels will most likely dip as your brain activity slows.
Unfortunately, the ill effects of being seated don't only exist in the short term.
Recent studies have found that sitting for long periods is linked with some types of cancers and heart disease and can contribute to diabetes, kidney and liver problems.
In fact, researchers have worked out that, worldwide, inactivity causes about 9% of premature deaths a year.
That's over 5 million people.
So what seems like such a harmless habit actually has the power to change our health.
But luckily, the solutions to this mounting threat are simple and intuitive.
When you have no choice but to sit, try switching the slouch for a straighter spine, and when you don't have to be bound to your seat, aim to move around much more, perhaps by setting a reminder to yourself to get up every half hour.
But mostly, just appreciate that bodies are built for motion, not for stillness.
In fact, since the video's almost over, why not stand up and stretch right now?
Treat your body to a walk.
It'll thank you later.
I'd like to start, if I may, with the story of the Paisley snail.
On the evening of the 26th of August, 1928, May Donoghue took a train from Glasgow to the town of Paisley, seven miles east of the city, and there at the Wellmeadow Café, she had a Scots ice cream float, a mix of ice cream and ginger beer bought for her by a friend.
The ginger beer came in a brown, opaque bottle labeled "D. Stevenson, Glen Lane, Paisley."
She drank some of the ice cream float, but as the remaining ginger beer was poured into her tumbler, a decomposed snail floated to the surface of her glass.
Three days later, she was admitted to the Glasgow Royal Infirmary and diagnosed with severe gastroenteritis and shock.
The case of Donoghue vs. Stevenson that followed set a very important legal precedent: Stevenson, the manufacturer of the ginger beer, was held to have a clear duty of care towards May Donoghue, even though there was no contract between them, and, indeed, she hadn't even bought the drink.
One of the judges, Lord Atkin, described it like this: You must take care to avoid acts or omissions which you can reasonably foresee would be likely to injure your neighbor.
Indeed, one wonders that without a duty of care, how many people would have had to suffer from gastroenteritis before Stevenson eventually went out of business.
Now please hang on to that Paisley snail story, because it's an important principle.
Last year, the Hansard Society, a nonpartisan charity which seeks to strengthen parliamentary democracy and encourage greater public involvement in politics published, alongside their annual audit of political engagement, an additional section devoted entirely to politics and the media.
Here are a couple of rather depressing observations from that survey.
Tabloid newspapers do not appear to advance the political citizenship of their readers, relative even to those who read no newspapers whatsoever.
Tabloid-only readers are twice as likely to agree with a negative view of politics than readers of no newspapers.
They're not just less politically engaged.
They are consuming media that reinforces their negative evaluation of politics, thereby contributing to a fatalistic and cynical attitude to democracy and their own role within it.
Little wonder that the report concluded that in this respect, the press, particularly the tabloids, appear not to be living up to the importance of their role in our democracy.
Now I doubt if anyone in this room would seriously challenge that view.
But if Hansard are right, and they usually are, then we've got a very serious problem on our hands, and it's one that I'd like to spend the next 10 minutes focusing upon.
Since the Paisley snail, and especially over the past decade or so, a great deal of thinking has been developed around the notion of a duty of care as it relates to a number of aspects of civil society.
Generally a duty of care arises when one individual or a group of individuals undertakes an activity which has the potential to cause harm to another, either physically, mentally or economically.
This is principally focused on obvious areas, such as our empathetic response to children and young people, to our service personnel, and to the elderly and infirm.
It is seldom, if ever, extended to equally important arguments around the fragility of our present system of government, to the notion that honesty, accuracy and impartiality are fundamental to the process of building and embedding an informed, participatory democracy.
And the more you think about it, the stranger that is.
A couple of years ago, I had the pleasure of opening a brand new school in the northeast of England.
It had been renamed by its pupils as Academy 360.
As I walked through their impressive, glass-covered atrium, in front of me, emblazoned on the wall in letters of fire was Marcus Aurelius's famous injunction: If it's not true, don't say it; if it's not right, don't do it.
The head teacher saw me staring at it, and he said, "Oh, that's our school motto."
On the train back to London, I couldn't get it out of my mind.
I kept thinking, can it really have taken us over 2,000 years to come to terms with that simple notion as being our minimum expectation of each other?
Isn't it time that we develop this concept of a duty of care and extended it to include a care for our shared but increasingly endangered democratic values?
After all, the absence of a duty of care within many professions can all too easily amount to accusations of negligence, and that being the case, can we be really comfortable with the thought that we're in effect being negligent in respect of the health of our own societies and the values that necessarily underpin them?
Could anyone honestly suggest, on the evidence, that the same media which Hansard so roundly condemned have taken sufficient care to avoid behaving in ways which they could reasonably have foreseen would be likely to undermine or even damage our inherently fragile democratic settlement.
Now there will be those who will argue that this could all too easily drift into a form of censorship, albeit self-censorship, but I don't buy that argument.
It has to be possible to balance freedom of expression with wider moral and social responsibilities.
Let me explain why by taking the example from my own career as a filmmaker.
Throughout that career, I never accepted that a filmmaker should set about putting their own work outside or above what he or she believed to be a decent set of values for their own life, their own family, and the future of the society in which we all live.
I'd go further.
A responsible filmmaker should never devalue their work to a point at which it becomes less than true to the world they themselves wish to inhabit.
As I see it, filmmakers, journalists, even bloggers are all required to face up to the social expectations that come with combining the intrinsic power of their medium with their well-honed professional skills.
Obviously this is not a mandated duty, but for the gifted filmmaker and the responsible journalist or even blogger, it strikes me as being utterly inescapable.
We should always remember that our notion of individual freedom and its partner, creative freedom, is comparatively new in the history of Western ideas, and for that reason, it's often undervalued and can be very quickly undermined.
It's a prize easily lost, and once lost, once surrendered, it can prove very, very hard to reclaim.
And its first line of defense has to be our own standards, not those enforced on us by a censor or legislation, our own standards and our own integrity.
Our integrity as we deal with those with whom we work and our own standards as we operate within society.
And these standards of ours need to be all of a piece with a sustainable social agenda.
They're part of a collective responsibility, the responsibility of the artist or the journalist to deal with the world as it really is, and this, in turn, must go hand in hand with the responsibility of those governing society to also face up to that world, and not to be tempted to misappropriate the causes of its ills.
Yet, as has become strikingly clear over the last couple of years, such responsibility has to a very great extent been abrogated by large sections of the media.
And as a consequence, across the Western world, the over-simplistic policies of the parties of protest and their appeal to a largely disillusioned, older demographic, along with the apathy and obsession with the trivial that typifies at least some of the young, taken together, these and other similarly contemporary aberrations are threatening to squeeze the life out of active, informed debate and engagement, and I stress active.
The most ardent of libertarians might argue that Donoghue v. Stevenson should have been thrown out of court and that Stevenson would eventually have gone out of business if he'd continued to sell ginger beer with snails in it.
But most of us, I think, accept some small role for the state to enforce a duty of care, and the key word here is reasonable.
Judges must ask, did they take reasonable care and could they have reasonably foreseen the consequences of their actions?
Far from signifying overbearing state power, it's that small common sense test of reasonableness that I'd like us to apply to those in the media who, after all, set the tone and the content for much of our democratic discourse.
Democracy, in order to work, requires that reasonable men and women take the time to understand and debate difficult, sometimes complex issues, and they do so in an atmosphere which strives for the type of understanding that leads to, if not agreement, then at least a productive and workable compromise.
Politics is about choices, and within those choices, politics is about priorities.
It's about reconciling conflicting preferences wherever and whenever possibly based on fact.
But if the facts themselves are distorted, the resolutions are likely only to create further conflict, with all the stresses and strains on society that inevitably follow.
The media have to decide: Do they see their role as being to inflame or to inform?
Because in the end, it comes down to a combination of trust and leadership.
Fifty years ago this week, President John F. Kennedy made two epoch-making speeches, the first on disarmament and the second on civil rights.
The first led almost immediately to the Nuclear Test Ban Treaty, and the second led to the 1964 Civil Rights Act, both of which represented giant leaps forward.
Democracy, well-led and well-informed, can achieve very great things, but there's a precondition.
We have to trust that those making those decisions are acting in the best interest not of themselves but of the whole of the people.
We need factually-based options, clearly laid out, not those of a few powerful and potentially manipulative corporations pursuing their own frequently narrow agendas, but accurate, unprejudiced information with which to make our own judgments.
If we want to provide decent, fulfilling lives for our children and our children's children, we need to exercise to the very greatest degree possible that duty of care for a vibrant, and hopefully a lasting, democracy.
Thank you very much for listening to me.
(Applause)