How climate affects the size of the human body

In the process of evolution, not only the appearance and habits of a person changed, but also the size of his body, the dimensions of the brain. Exactly what mechanisms underlie these changes – scientists are still debating.

It is assumed that the main factors are environmental, demographic, social, nutritional and technological. And recently, a group of researchers from the University of Cambridge and Tübingen found evidence that the dimensions of the human body and brain at different stages of evolution changed under the influence of climatic conditions.

The relationship between the dimensions of the human body and climatic conditions

Over the past 4 million years, there has been a tendency to increase the body weight and height of a person, as well as the volume of his brain. It is assumed that over the past 2 million years, the average body weight of Homo representatives has increased from 50 to 70 kg. As for the brain, its volume increased most intensively between 800 thousand and 200 thousand years ago ^[1]. However, the mechanisms underlying these changes are still poorly understood.

One theory is climate change. Scientists from Cambridge and Tübingen decided to test it. Experts analyzed how the size of the body and brain in representatives of the genus Homo changed over the past 1 million years under conditions of environmental change. To do this, experts studied the parameters of more than 300 fossils of representatives of the genus Homo found in different parts of the world. The scientists compared the data obtained with the climatic conditions that were typical for the region for the period of life of each object of study.

As a result, experts came to the conclusion that there is a direct relationship between climatic conditions and the size of the human body.

After analyzing the size of human bodies in different climates, scientists came to the conclusion that in relation to representatives of the genus Homo, as in the animal world, Bergman’s ecogeographical rule works.

Carl Bergmann is a XNUMXth-century German biologist who proved that animals of the same species living in different climatic zones have different sizes: larger individuals develop in colder conditions. The logic of this theory is that a large body is more efficient in terms of thermoregulation and conservation of resources. Thus, for people inhabiting cold regions, a larger physique is characteristic.

How climate affects brain size

Another hallmark of human evolution is the expansion of the brain. Compared with representatives of the earlier species Homo habilis, the brain of a modern person is almost 3 times larger. But exactly what factors became key in such changes is the subject of scientific disputes. However, according to experts from the University of Cambridge who took part in the study, climatic conditions played an important role in changing the volume of the brain.

In particular, scientists drew attention to the fact that even modern people living in colder climates, as a rule, have a larger brain volume than those living in warm regions. According to scientists, a similar relationship could be observed millions of years ago.

But there is another factor that affects the size of the brain. Scientists have found that ancient people living in regions with poor vegetation (for example, in the steppe) had a larger brain volume than the rest. It is assumed that the need to hunt large animals and think over a strategy for obtaining food contributed to the evolution of the organ ^[2].

Scientists are convinced that the human body and brain continue to evolve, adapting to changes in temperature regimes. Therefore, modern people have a larger physique. But as for the volume of the brain, it is decreasing. And according to the researchers, given the dependence of modern man on computer technology (when the solution of complex tasks is delegated to computers and smartphones), the trend towards a decrease in the brain will continue.

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