Sleeping silhouettes, a smaller skull or even darker skin … What if the modification of the climate had an impact on human appearance? While the planet heats up quickly, our bodies may well be transformed by the rise in temperatures.
“Climate change influences human morphology, but it all depends on what populations we are talking about and what warmingraises Alain Froment, anthropologist biologist at the National Museum of Natural History. Depending on whether it is 1 ° C, 4 ° C or 10 ° C additional, it is not the same thing. ” Human evolution is indeed governed by the principle of natural selection, according to which the environment influences the appearance of living beings so that they adapt to their environment.
The climate is at the heart of the evolution of human appearance
This is called radiator theory. Depending on the region of the world and the hot or cold climate, typical morphologies are distinguished. “The Inuit have an interest in having a body close to the ball, with a significant body mass and short ends, since this is where the heat is lost”analysis Alain Froment, who specifies that these peoples of the North have short legs and arms, as well as a developed thorax, in order to limit exchanges with the outside. “Conversely, in very hot regions as in East Africa, morphologies are slender and thin.”
The explanation is simple. Body mass – which generates heat – is lower when the climate requires cooling the body. In the same way, the inhabitants of countries with high temperatures are often large, with a significant body surface. “This is called evapotranspirationdevelops Alain Froment. All human beings have sweat glands that secrete liquid (sweat) to refresh the body, but they are more stressed by hot climate. So the greater the body surface, the more efficient the perspiration! ” If science has proven that it is the environment that has influenced the physical appearance of human beings around the world, in particular their size, this evolution has taken thousands, even millions of years.
“In prehistoric times, the human being lived naked, so he was directly exposed to his environment. Today, we have a lot of technical solutions that make climate buffer. ”
“Environmental variables such as temperature, amount of sunshine or precipitation and humidity have a direct impact on some of our phenotypes (observable physical features, editor’s note). It plays on skin pigmentation, hair shape, etc. »Surgishness Lluis Quintana-Murci, geneticist of the populations, professor at the Collège de France and at the Institut Pasteur. Thus, the color of the skin differs depending on the regions of the world. Clear skin coincides with areas where ultraviolet rays (UV) are insufficient for the synthesis of vitamin D by epidermis, while dark skin is useful in hot climate to protect itself from the strong UV radiation.
As for facial features, like the nose, they also adapt to the ambient climate. “Africans have a wider nose, especially in the equatorial zone, because they breathe warm and humid so non -aggressive air for the lungsunderlines Alain Froment. On the other hand, in a drier and cold climate as in Europe, the nose is narrower and longer, to allow the breathable air to be directly in contact with the internal mucous membranes. It is thus directly humidified or heated, so that the bronchi is not irritated. ”
Global warming, catalyst for morphological adaptation?
The question now lies in the impact of the increase in temperatures on human appearance. Do physical developments that have appeared for thousands of years accelerate? Does global warming change the existing phenotypes? What is certain is that the scenarios envisaged grow for a morphology adapted to heat. “Originally, our ancestors had to adapt to a colder climate, after migrating from Africa to Europe. One can imagine that a reverse phenomenon occurs in the future ”advances Laure Ségurel, research manager in genetic anthropology at the CNRS, in an article in Le Figaro published in August 2023.
This trend is already observed in animals. Many studies highlight the physical adaptations of fauna upwards. Larger spins in birds, wider ears in foxes or the tails of the musarignes that lie down, all that in order to regulate their internal temperature. So many developments that are detectable in many species, on the entire surface of the globe, and which occur on a much shorter than usual period of time, compared to past morphological developments spread over millennia.
The example of the America’s hare (Lepus Americanus) is evocative. While its brown coat becomes white in winter to camouflage itself in the snow, the animal is increasingly retaining its dark hairs for the year in the face of the lack of flakes, revealed an international study published in the Revue Science in February 2018. This is also the case for other species, such as polar foxes or snow parts (alpine lagopèdes). Australian nocturnal parakeets have seen the surface of their beak increase between 4 and 10% since 1871, a lightning duration of a century and a half.
Adapt to the place of transforming
Intense warming of the planet could thus cause a modification of human morphology, which would tend towards larger and thinner silhouettes, wider noses or smaller skulls. However, counting on genetic evolution to cool bodies is nonsense. Human beings are now capable of adapting culturally to avoid heat.
“In prehistoric times, the human being lived naked, so he was directly exposed to his environmentargues Alain Froment. Today, we have a lot of technical solutions that make climate buffer: clothing, housing, air conditioning, etc. ” For the author of the book Impertinent anatomy – the human body and evolution (April 2013), these intermediaries would avoid a deep physical transformation. “What matters is the actual temperature to which the body is subjectsays the specialist. If you are constantly in an air conditioned environment, you can live in the tropics without any problem! ”
In addition, while adapting morphologically would take thousands of years, migration is an immediate solution. The most coherent hypothesis would thus be a massive departure of the regions which have become uninhabitable because of the heat. “Climate change does not necessarily require people to stay there and adapt. They can also move ”estimates Alain Froment.
What appearance in the medium and long term?
If there were still physical changes, they would be very limited and would take thousands of years. “Bacteria and insects will probably adapt much faster to climate change than humans”supports Laure Ségurel, which indicates that genetic changes in human species are slower. Especially since the scenarios envisaged by scientists remain at the moment measured. “4 ° C additional would not change the appearance of EuropeansSUPPUTE Alain Froment. It would take a radical upheaval in temperatures. However, there is no increase of 10 ° C or more. So I don’t think there is a big evolution of human appearance, even in the long term. ”
The anthropologist recalls that it is impossible to predict the climate of the planet and that no certainty exists on spectacular global warming. “Heat waves are not proof of” running of warming “or” climate collapse “”hammers the British climatologist Friederike Otto. Alain Complete Froment: “We are in an interglacial phase and we are going towards a glaciation in a few thousand years. By what biological adaptations take the time to appear, many things will have changed. ”
However, global warming may well disrupt this cycle and prevent the land from going into glaciation. And thus increase the probability of a transformation of human morphology. In addition to large and fine bodies, fat mass could be rarer on silhouettes, since this thickness prevents heat from effectively. Skin diseases would become more severe, the skin microbiome being influenced by climatic parameters. More acne and more eczema would then be a consequence of the rise in temperatures.
On the other hand, no risk that the skin color of the human being will evolve. “Even if the climate warms up, we should not be exposed to more UV rays, so the skin color should not be changedfinally specifies Alain Froment. On the other hand, if populations migrate to cooler areas, they could ultimately lose melanin and have lighter skin. ” An evolution which, too, would take thousands of years and could easily be bypassed by technological innovations.
