We all know what Neanderthals looked like: protruding superciliary arches, thick nose, elongated skull, powerful bone structure and, probably, red hair and freckled skin. Perhaps you squint at the redheads when you meet the subway, or maybe not. But you probably would like to take a close look at the hunter-gatherers who lived in Europe 7-8 thousand years ago, the DNA of which scientists are currently analyzing.
They had dark skin and, very likely,bright blue eyes. This combination almost disappeared in ancient Europe - it was replaced by light-skinned and brown-eyed farmers who came from Central Asia for several hundred years and which, in fact, looked like the modern population of southern Europe.
These first farmers who could not live withoutmilk, possessed a gene for immunity to lactose, which the old population of hunter-gatherers did not have. They ate much less meat and much more starch than European meat-eaters, and relied on milk and sunlight as sources of vitamin D — hence the light skin. As for the dark-skinned and blue-eyed people, they disappeared in Europe, as intruders gradually replaced them genetically.
This is what the story of fast humanevolution. The new principles of life - growing crops and cattle breeding instead of hunting - led to the rapid expansion of the genes that took advantage of these cultural devices. The ancient dark skin, probably inherited from our common ancestors from Africa, could have been a drawback if most of the calories came from cultivated grain rather than wild-animal meat rich in vitamin D. Blue eyes, however, remained, although the gene shape of the eyes was blue The color is recessive and is easily replaced by brown eyes. Therefore, after a certain time - it is difficult to say which one - the ancient Europeans began to look different. There was also an injection of East Asian genes from people who resemble modern Chukchi and other native Siberian groups closely related to native Americans. Ancient Europe became a smelting furnace, but certain alleles - light skin and brown eyes - began to dominate when the lifestyle of hunter-gatherers changed due to the transition to farming and agriculture.
We represent the evolution described by CharlesDarwin in 1859, like a slow dance: nature chooses the best-adapted organisms for reproduction, reproduction and survival in a particular ecosystem. As organisms adapt to changing environmental conditions over thousands of years, organisms that are best adapted to a particular environment thrive, allowing the species to grow and spread. This process is known as natural selection: organisms that are best adapted to their environment will pass more genes to the next generation than less adapted subspecies (of the same species).
The constant change that we see inpetrified annals takes longer. Just look at the trajectory of the ungulate Hyracotherium, a forest mammal the size of a dog that gradually lost its lateral toes (four on its front legs and three on its hind legs), and the central one lengthened. It took 55 million years for the animal to evolve into a giant horse, which we all know well.
Sometimes evolution moves fast. As biologists Peter and Rosemary Grant from Princeton University have shown, small beaks can turn into large beaks in just one generation, depending on climate conditions and the type of food found on harsh islands. Birds with a small beak can die out, and with a large one they can survive, at least for a while. But these quick changes do not always remain forever. Most of these changes are rolled back, over and over. Changes in vegetation may mean that large beaks will become uncomfortable. This process of displacement — small changes occurring over short periods of time — is called microevolution.
Evolutionary Biologists David Lati and Paul Ewaldargue that there is nothing exceptional in rapid evolution. A quick change, temporary or not, simply reflects the intensity of selection, the increased impact of "hostile forces of nature" according to Darwin, including predation, heat, cold, parasites. Difficult times mean extinction for some species - and rapid evolution for others. But to enable rapid evolution, there must be enough genetic variation in the gene pool for natural selection to choose from. As in the case of the quick replacement of hunter-gatherers by farmers in ancient Europe. Light-skinned genes surpassed black-skinned genes because they were better suited for living in Europe and a new way of life.
Lati adds that for people, social selectionacquires paramount importance: the presence of other hostile groups and human ability for intra-group cooperation led to the emergence of the social complexity of man and the evolution of the human brain. We do not know whether friendly or hostile contacts were European hunters and Middle Eastern farmers. There were probably clashes in ancient Europe, as well as peaceful exchanges. We cannot know: we see only the result, an obvious rejection of one set of traits in favor of another, which is established in a certain area.
Of course, blond hair and fair skin becamecharacterize Europe in the far north, among the Scandinavian population; there, pale skin probably became an adaptation to vitamin D deficiency. Dark skin remains a useful adaptation in hot, sunny climates. As the climate changes, other local changes in the appearance of people may occur, we do not know yet.
Human evolution and the forces that drive itnever stopped. Some people will always be preferable in terms of natural selection because of their genes, their offspring are more likely to survive. This is the essence of natural selection. Adaptation and evolution of man continues continuously. It is impossible to say that we are developing in a certain direction - large heads and frail limbs, as fiction enthusiasts often say. But at the local level, adaptation and natural selection do not stop their work, preparing us for new threats - new diseases, climate change, new social interactions - invisibly and imperceptibly.