Greedy Saving Genes: How Ancestor Legacy Makes Us Fatter

There is a remarkable theory of evolutionary predisposition to obesity. According to this theory, modern man inherited from his distant ancestors the “thrift genes” responsible for storing fat. Such genes play an adaptive role when food is scarce, but increase the risk of obesity when food is abundant (a person eats often and a lot), and energy expenditure is reduced (reduced physical activity).

In general, there are many such genes, but their number depends on the genetics of a particular person. The less a given population has historically suffered from hunger, the less their descendants will recruit.

The main idea is to understand that the mechanism of obesity initially has beneficial adaptive properties that helped our ancestors survive.



Theory of frugal (lean) genes and leptin



An important feature of the hunter-gatherer lifestyle was significant breaks between meals (from 1-2 days or more). Even during the day, people never ate more than twice (because there was no ready-made food, semi-finished products and food). Today, food is always present.

Two of the most harmful food factors:

1) increase in the number of calories eaten (hypercalorie food),

2) increasing the number of meals.



In the evolutionary plan of human development, such opportunities for storing fat in the body used to be of great importance. There is a fairly convincing theory of the “thrifty” or “lean” genotype, according to which the most adapted to survival representatives of primitive communities (“hunters-gatherers”), forced to rely on the cyclical availability of food resources on the principle of “feast or hunger”, gradually developed an “economic genotype”.

The term "economic genotype" It is used to refer to a gene or set of genes that reduce energy utilization when excess nutrients enter the body, and, conversely, maintain the level of energy exchange with malnutrition or hunger. In natural selection, this led to the selective advantage of people with an “economical genotype” at times of significant variation in food access (early periods of human history). As a result, with changes in lifestyle in modern society (constant and abundant nutrition, physical inactivity), many populations now have a high degree of predisposition to obesity, diabetes 2 and CVD.

As for leptin. At a time when our ancestors ate irregularly and there were long intervals between meals necessary to replenish the energy in the body (successful hunting of a mammoth or other wild beast, successful fishing), the role of leptin was to effectively store energy during the period when food was not available and large reserves of energy were required for survival.

Considering the metabolism of diabetes, J. Neel (1962) characterized this condition as due to “saving genes”. He proposed a concept that requires a “fast insulin trigger” that regulates the process needed to store energy with enough food. Such energy reserves in the form of fat depots ensure long-term survival of the body in adverse conditions combined with starvation. This type of insulin secretion, according to J. Neel, should lead to insulin resistance, which further contributes to the development of diabetes, provided that sufficient food is constantly available.

Taking into account the data obtained in recent years, M. Wendorf and I. D. Golfine (1991) proposed an revision of the theory of “saving genes”, believing that the main importance in the manifestation of this phenotype is insulin resistance of muscle tissue, accompanied by a decrease in glucose absorption. In accordance with this assumption, it is believed that insulin resistance of the muscles will be a kind of limiter of glucose utilization by the muscles, thus preventing the development of hypoglycemia during fasting. At the same time, during the period of abundance of food, such a phenotype will contribute to the development of hyperglycemia and the preservation of energy in adipose tissue.

According to J. S. Flier (1998), the concept of "saving genes" is directly related to leptin. Indeed, blood leptin levels decrease when food intake is limited or fat depots are depleted. The function of leptin is probably to give timely “notification” The CNS on the danger of starvation and death and the timely inclusion of mechanisms that prevent the development of life-threatening conditions, i.e. reducing the secretion of leptin in such situations.

Fasting of any kind is accompanied by:

• reduced fertility,
• inhibition of the main metabolism and secretion of thyroid hormones,
• increased conversion of thyroxine to reverse or reverse triiodothyronine, devoid of biological activity,
• moderate activation of the hypothalamic-pituitary-adrenal system, which ensures the survival of the body.

In such situations, there is a decrease in leptin secretion, which indicates the adaptive role of leptin in the body, that is, with a lack of energy in the body, its secretion decreases, and with overeating and obesity - increases..

Thus, The physiological function of leptin is most likely to prevent the development of obesity with excessive intake of food into the body.. Reducing leptin secretion during fasting is a kind of signal to increase energy absorption.



Hunger-holiday



The success of foraging in primitive hunter-gatherer society was never guaranteed, and this was very common in late Paleolithic (50,000 to 10,000 years) human development. Therefore, the community was forced to alternate periods of festival (during the sharing of food) with periods of hunger (during drought, unsuccessful search, or inability to search due to physical inactivity or illness). As a result, there was a cycle of hunger-holiday and a break in physical activity.

It is hypothesized that cyclical repetition of the accumulation of energy substances, insulin in the blood, insulin sensitivity, as well as proteins that regulate metabolic processes, controlled by cycles of hunger-holiday and break in physical activity, pressed the selection of “lean” genes and genotype, with some functions that manifest themselves for the preservation and replenishment of carbohydrates.

The pathological consequences of these preserved and inherited metabolic cycles in today’s society, which lacks hunger-feast cycles and break cycles in physical activity, must also be considered in this context.



Example of the hunger-holiday cycle



Europeans have always been surprised by the profligacy and tranquility of the Indians to starvation.

Wastefulness. The habit of immediately eating all the food available in the parking lot, even in objectively difficult times, "as if the game they were going to hunt was locked in a stall," Lejeune said of the Montagne Indians.

Bazedov wrote about Indigenous Australians:

Their motto, clothed in verbal form, might sound like this: “If there is much today, never worry about tomorrow.” Accordingly, the aboriginal is more inclined to arrange a single feast out of all available supplies than to stretch them into modest meals, made from time to time.”

(Basedow, 1925, p. 116).



Lejeune observed his montanya retaining such extravagance on the very brink of disaster:

“If in time of famine my master succeeded in catching two, three or four beavers, then immediately, day or night, a feast was held for all the savages in the district. And if the savages happened to get something, they immediately organized the same feast. So, coming from one feast, you could immediately go to another, and sometimes a third and a fourth.

I told them that they had mismanaged their food, and that it would be better to postpone these feasts until the following days—to do so would have avoided such severe hunger.

The savages laughed at me. “Tomorrow,” they said, “we will have another feast of what we have.”

Yes, but more often than not, they only got cold and wind.

(LeJeune, 1897, pp. 281-283)



The hunter-sympathetic authors tried to give rational explanations for this impracticality. Perhaps people were starving to lose the ability to reason rationally: they were eating to death because they had been without meat for too long, and then, they knew, the same thing would happen again soon. Or, perhaps, by putting all his supplies on one feast, a person fulfills the social obligations that bind him, follows the most important principle of mutual assistance.

Whatever the value of other interpretations, they must force a rethink of hunters’ imprudence. Moreover, there are some objective reasons: If the hunters really preferred immoderation to economic common sense, they would never give up hunting or become adherents of a new religion..

So, the practice of storing food is not developed by hunters.

“I saw them in distress and torment, emboldened by suffering. I was with them under the threat of severe trials. They said to me, "We'll be sometimes two, sometimes three days without food, because there's not enough food." Courage, Chikhine, may your soul be strong to endure suffering and hardship. Don’t let yourself be sad or you will get sick. Look, we don't stop laughing, even though we have almost nothing to eat.

(LeJeune, 1897, p. 283; cf. Needham, 1954, p. 230)







Contemporary example: the Amazonian Piraha tribe



The Piraha tribe is interesting because they have almost no culture, i.e. this lost tribe leads an almost animal way of life. But that’s why their dietary strategies are interesting, as they have been cleared of social taboos and prescriptions.

Pirahas do not store food, they just catch it and eat it (or do not catch and eat if the hunting-fishing happiness betrays them). The idea of drying, smoking, preparing something for the future simply does not occur to them. It’s also true: why try when a completely stranger might wake up next time? Let the scoundrel sweat by waving a spear on the river.

Their women plant vegetables and some cereals in small gardens in the jungle - this is the only example of economic foresight, it goes no further.

When a piraha has no food, he treats it phlegmatically. He doesn’t know why he eats every day, and several times more.

"Are you eating again? You're going to die! the neighbors said, visiting Everett with the family for a second breakfast or early afternoon.

Pirahas themselves eat no more than twice a day and often arrange fasting days even when there is a lot of food in the village.

Combination of food and physical activity



Reproduction, eating and physical activity are some of the essential factors that explain the survival of most animal species in the wild.

However, New cultural changes have engineered the need for physical activity in everyday life Humans and domesticated animals. For example, many people do not have to use physical labor to prepare food and build a home. As a result, The introduction of motor inactivity in normal daily activities increases the risk of at least 35 chronic diseases..

The main adaptations associated with food in a forced survivor were likely correlated with normal physical activity, including endurance and strength properties alternating with certain interruptions.

Lifestyle and dietary aspects were accentuated by cycles of celebration and hunger. Therefore, exercise and food preparation were inextricably linked to the survival of our ancestors, offering the possibility of such a link to overall gene selection.

On the basis of some of these facts, the concept of “lean genotype” was derived, which was originally proposed by J. V. Neel. He argued that certain genotypes were selected in the human genome because of their advantages when selected on cost-effectiveness criteria. The author determined that the lean genotype is exceptionally effective in eating and/or using food.

Subsequently, in times of famine, individuals with lean genotypes would have a life-sustaining advantage because they relied on previously stored energy to maintain homeostasis, whereas those without lean genotypes would be at a disadvantage and less likely to survive.

M. V. Chakravarthy, F. W. Booth embroidered the theory on the J. V. Neel genotype to genes. Survival during the hunger-feast in the hunter-gatherer selected genes to support a specific cycle of physical activity, in which the repetition of metabolic processes was initiated by a decrease in carbohydrate stores of skeletal muscle (glycogen) and triglyceride (fat) stores.

Thus, assumptions have been made of the influence of some "lean genome," and genotypes have been selected to maintain compulsory physical activity for survival. This process was under selective pressure 10,000 years ago in a physically active hunter-gatherer environment that formed most of the existing human genome, evolved and was thus selected.

The genes of our ancestors were not chosen for a low-activity existence. In fact, those individuals whose genes only supported sedentary living likely cleaved from the gene pool during isolation due to their inability to gather food or search for it.

M. V. Chakravarthy, F. W. Booth hypothesized that the threshold of physical activity is required for the proper pressing of inherited genes and genotypes that were isolated in the selection process to maintain physical activity in a partially efficient use of energy substances, since survival almost exclusively depended on physical activity to prepare food.

Falling below this threshold was defined as a lack of physical activity. Lack of physical activity is predicted to break the optimized pressing of "lean genes" and the genotype for the physical activity interruption cycle.



Current challenges



There are populations particularly prone to diabetes: it affects half of the adult Pima Indians living in the southwestern United States. Perhaps, trying to survive in a harsh climate, where most of the year there is very little food, Pima inherited the so-called “lean gene”: in times of hunger, it reduces the intensity of metabolism, which increases the likelihood of diabetes.

But in today’s America, where sweet soda is bottled up, this exposure to diabetes has become a disaster.

Another branch of the tribe lives in Mexico, farms, eats traditional food, and their diabetes rate is incomparably lower than that of American pim.

The most effective is energy conservation in the form of abdominal fat. In the process of evolution, selection was aimed at preserving genotypes that ensure the maximum transition of food energy into the energy of fatty acids of adipose tissue. The transition of people with such “saving genes” to the Western lifestyle with excessive food intake and little physical activity leads to excessive accumulation of abdominal fat, and this, as mentioned above, can provoke the development of IR, impaired glucose tolerance and, ultimately, INDS.

Now many agree with the hypothesis that the genetic predisposition to obesity can be both pronounced and latent. It gives a violent external manifestation in favorable conditions, for example, when the availability of foods that are high in fat is combined with a sedentary lifestyle.

For example, on the island of Kusai, the tendency to obesity was practically not manifested, while the only food of the islanders was fish and fruit, and to obtain this simple food required some effort. But when it became possible to simply take polished white rice, animal oil, fatty meat and beer from the store shelf, most residents became fat. But not all.

“People who spend a lot of energy regulate their food intake without much stress,” says Scholler. But as soon as mobility drops, the regulatory mechanism begins to falter. Over the past two or three decades, most of us have fallen below the minimum threshold, and here’s the result.

The most important reasons for the widespread progression of obesity are a change in the nature of nutrition, a decrease in motor activity, urbanization. Globalization, coca-colonization and the chronic disease epidemic: can the Doomsday scenario be averted? P. Zimmet notes:

The devastating effects of the Western way of life can be traced everywhere, from the Arctic Circle to the jungles of Brazil and the remote atolls of the Pacific.



Also interesting: Posture as a sign of sacrifice

20 Minutes Rule: The Most Effective Diet



The high rate of obesity spread, which has reached epidemic proportions in a relatively short period of time, indicates that the primary role in its development is played by changing the nature of nutrition (consuming high-calorie foods, increasing portions of food, increasing snacks, consuming large amounts of sugary drinks, eating out) in combination with a sedentary lifestyle. published



Author: Andrey Beloveskin



P.S. And remember, just changing our consumption – together we change the world!

Source: www.beloveshkin.com/2016/06/zhadnye-geny-ehkonomii-kak-nasledie-predkov-delaet-nas-tolshhe.html