Evolution claims : natural selection, Tthe mechanism of survival of the fittest. However, we can attribute some serious human health problems to the 'accidental deviations' in human evolution, such as obesity, cancer, cardiovascular disease and diabetes.
In 2009, a Gallup poll announced that 44% of Americans in the past 100 centuries believed that people like this were created by God (JONES, 2009), and quite a few of them think the design of the body structure is perfect. However, lots of anthropologists, geneticists, paleontologists, and biologists all believe tThe human iofn today is the product of a series of compromises by our ancestors to adapt to changing circumstances (natural and human) and even to withstand emergencies (JONES, 2009). “In many ways, our bodies have evolved in error to adapt to the modernization of human society.” said evolutionary biologist Stephen Stearns of Yale University. (Nesse & Stearns, 2008).
For example, the immune system is designed to help the body fight epidemics such as malaria and cholera, which are accompanied by human urbanization. According to the hypothetical hypothesis theory, the number of patients with asthma and various types of autoimmune diseases is growing because humans are now in a cleaner environment and the human immune system is not exposed to enough external challenges. Instead, it starts with the body's own physiological system.
What is going wrong
In the history of human development, some components of the human body have played a beneficial role, but now they are dragging our hind legs. Lewis I. Held Jr., a geneticist at Texas Tech University, called this phenomenon “bislagiatt ”, which was “but it was a good idea at the time” (It seemed likes a good idea at the time.) corresponds to the English acronym.
Rudolph Leibel, an obesity expert at the Columbia University Medical Center, said that even the phenomenon of 'yo-yo dieting' can't be separated from the effects of evolution (Higginson & McNamara, 2016). He and other geneticists discovered leptin, a hormone that usually signals the body to stop eating. When people are on a diet, the level of leptin in the body is drastically reduced, triggering a series of physiological changes that cause the body to burn less calories and restore its original weight. 'This worked well during the famine, but it is now out of date,' Professor Rebec said (Higginson & McNamara, 2016).
Scientists studying genetic variation worldwide say that in the past 10,000 to 40,000 years, about 1800 genes, accounting for 7% of the human genome, are rapidly evolving (JONES, 2009), many of which have evolved. The impact is not yet clear, but researchers have found that there are several variations that make people more suitable for survival and survive by inheritance. Many of the more recent genetic mutations are human responses to infectious diseases, especially when people start large-scale settlements.
In Africa, 25 new genetic variants and a new blood type have emerged over the past 10,000 years to help people fight malaria. However, many evolutions that are beneficial to humans are accompanied by some drawbacks. For example, as previously known, some genetic mutations that protect Africans from malaria now make them more susceptible to sickle-cell anemia (JONES, 2009).
Genes that early Africans retained in their bodies to prevent dehydration in tropical climates predispose some African Americans today to high blood pressure (JONES, 2009).
In the process of human evolution, an important cause of obesity is the evolutionary gene. Human geneticist James V. Neel first proposed the concept of “thrifty gene” in 1962, arguing that humans today include obesity, diabetes and hypertension. The genes for metabolic disorders are selected because the physiological system is adapted to adapt to the changes in food affluence and food deficiencies in the ancient environment. It allows ancient humans to rapidly increase fat in a short period of food abundance in order to cope with the lack of food at any time. A certain gene has great advantages in the environment at the time, but it is the opposite of today's food-rich society. The case of Prof. Neil’s hypothesis of the thrifty gene was also found in Nauru. The impoverished and industrious ancestors of the islanders passed on the “Frugal Genes” generation to the Nauru (Pond, 1998) .
When the foreign Western lifestyle was brought into the island, the genes in the Nauru’s body could not adapt to the sudden arrival. Abundant life. Europeans have long been accustomed to modern lifestyles, and thrift genes have gradually disappeared in their bodies, so the same living environment has not brought them more diabetes. The formation of this gene does not even need to be hundreds of years. For example, in the 1960s, Chinese people were extremely hungry, and a considerable proportion of this group of people suffered from diabetes after enjoying a stable standard of living today. This is related to their subconscious 'preparation famine again', but the thrift gene is obviously exert more physiologically influence (Bradley et al., 2009).
The evolutionary stage of obesity
In the era of hunting, the genetic basis of metabolic diseases emerged. The daily work of human ancestors is mainly hunting, collecting wild fruits and making barbecues. Their food structure is high in protein and low in carbohydrates, and they also maintain a daily high energy consumption hunting fitness exercise, without the conditions of getting fat. Z. Hochberg of the Institute of Medicine at the Technion University of Israel believes that it can be assumed that the genome of the Homo is fully adapted to this lifestyle. In the case of low intake of carbohydrates for a long time, the insulin sensitivity of the Homo sapiens is very low, forming a 'thrift gene' (which allows the body to produce a small amount of insulin, consumes less carbohydrates) (Pond, 1998), It also laid the genetic foundation for obesity and hypertension
Ancestors guaranteed high energy consumption hunting exercise, high protein, low carbohydrate water intake. (POBINER, 2016)
The era of farming: natural choice to retain 'thrift genes' With the change of climate and population pressure, about 10,000 years ago, human ancestors tired of this daily unrestrained, unresolved wandering life, created another The farming era where families live and wait for harvest (Misha Ketchell, 2012). In the process of collecting wild fruits, they gradually observed and familiarized with the growth laws of certain plants, and slowly learned how to cultivate crops. According to archaeological data, there are three regions in the early farming center, namely West Asia, Southeast Asia, Central and South America. The people of West Asia are good at planting barley, wheat, lentils, etc. People living in the middle and lower reaches of the Yangtze River in China and the middle and upper reaches of the Yellow River like to grow rice and millet, and Mexico (Wang, Zhang & Ding, 2004), Peru and Bolivia in Central and South America prefer corn, beans and potatoes (Wang, Zhang & Ding, 2004). These crops are converted into carbohydrates in the human body after being eaten (Bradley et al., 2009). Compared with the hunting era, the human diet has undergone a qualitative change. Low protein and high carbohydrate have become the mainstream culture of three meals a day. In this comfortable life of sunrise and sunset, with the reduction of hunting activities, the amount of human movement has also dropped significantly. Z. Hochberg writes in the article, “Cultivation of crops brings low protein, high carbohydrates and a sedentary lifestyle. These changes in diet and life require adjustments in the genomes of ancient humans and the need to improve insulin sensitivity.” (Weickert, 2012) However, due to the frequent famine in the farming era, “saving genes” can help people to survive the famine. In this way, although “saving genes” are not suitable for farming, they have been preserved by natural selection. (Misha Ketchell, 2012)
The Industrial Age: Obesity is just an accident in evolution. After the end of the long farming era, mankind entered the industrial revolution in the 18th century, and this revolution has greatly increased social productivity. Humans bid farewell to the lack of food almost overnight, and entered the era of great food. Throughout human history, this transformation has taken place too suddenly, and some scholars call it 'hunger escape.' (Misha Ketchell, 2012 ) However, the instinct of human food has not changed, and the high-calorie, high-carbohydrate, high-fat diet is still a tireless preference and pursuit. Regrettably, from this period until now, many of our modern people still retain the 'thrift genes' from Homo sapiens. Faced with abundant food and calories, modern people who have “thrift genes” have developed serious discomfort, and there have been rare obesity and diabetes in the hunting and farming eras. However, some lucky people have introduced high-calorie, high-carbohydrate fertility-selecting genes that help modern people metabolize excess carbohydrates and energy. People who carry the 'fertility selection' gene are at a much lower risk of obesity, diabetes, and cardiovascular disease than those who still have 'thrift genes' in their bodies. According to Z. Hochberg, studies have shown that individuals who still retain 'gene-thrift genes' in the body are prone to obesity after the age of 3 under the influence of modern life, and for individuals carrying the 'fertility selection' gene, because they Infant metabolism is not suitable, so it is easy to have infancy obesity within 6 months after birth (Weickert, 2012).
Why evolution can make people 'fat'
When researchers compared DNA samples from some human fat samples and primates, they found that changes in packaging affected the way humans handle fat. Humans have between 14 and 31 percent fat, compared with less than 9 percent in other primates. In addition, human DNA regions are more concentrated, which limits the availability of genes involved in fat metabolism. The researchers also found that chimpanzees and monkeys have 780 more accessible DNA regions than humans (Weickert, 2012). This means the body is less able to convert bad fats into good ones. Researchers believe that genes make humans 'obsessed with primates.' The body's fat has the function of protecting organs (lubricating) and storing energy, which shows that the presence of fat is essential. We produce important hormones from the diet every day and help to extract the nutrients we need. From trans fats, polyunsaturated fats, saturated fats, but unsaturated fats make up dietary fat, while saturated fats and trans fats increase the level of 'bad cholesterol' or low-density lipoprotein (LDL) (Wang, Zhang & Ding, 2004), which is important for obesity (McKie, 2012). The reason may come from them, and polyunsaturated fats and monounsaturated fats are products of human organic energy. Any imbalance in this process can lead to obesity, because blood consumption keeps the body running.
The researchers found that in order to maintain the warmth of the human body, the early humans developed the brain and protected the internal organs, thus storing fat. During the evolution process, the size of the human brain was 200% of the original size and consumed more calories than other organs (McKie, 2012).
References
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