Tech UPTechnologyBones, stones and genes. The evolution of our species

Bones, stones and genes. The evolution of our species

Since time immemorial, humans have always felt a great curiosity to know how our origins as a species were . Luckily, our ancestors left a series of traces that tell us about our most remote past. Through the application of archaeological methodologies — such as prospecting and excavation of deposits — and through the comparison of fossils and stone tools that we find, we can reconstruct how, little by little, the species evolved until it became what we define today. like humans.

Almost all of us are interested in the history of our family. Who was our grandfather? What was his job? Did they always live in the same place or, on the contrary, did they come from far away? Science gives us the possibility to extend and sometimes resolve this natural curiosity in space and time. Who were the first settlers? How did they live? Answering these questions can help explain why we are the way we are and where we might be headed in the future .

We are in a transcendental time for the understanding of human evolution. The spectacular fossil discoveries of recent years combine with great advances in the field of dating techniques, genetic analysis and many other scientific disciplines to offer us a new, surprising and much-discussed image of the origins of humanity.

The origin of species

A century and a half ago, the English biologist Charles Darwin published The Origin of Species , a book that would change human thinking and lay the foundations for evolution . With his theories, it was confirmed that the current species come from others from the past, which in turn come from a common root, a first living being, a single-celled being that appeared on Earth 3.6 billion years ago.

All living human beings form a large family, the monkeys being our closest relatives . The similarities are obvious, you don’t have to look too hard to discover the similarities we share with chimpanzees and even, although to a lesser extent, with gorillas and orangutans that live in the jungles of Asia and Africa.

That was the stage where human evolution began. Nearly seven million years ago the great apes of Africa divided into three branches ; gorillas, chimpanzees and humans. Although the ancestor that unites us to chimpanzees is still unknown, there were a series of fossils prior to Homo that show changes in body shape in order to adapt to the environment. One of the first and most transcendental was, in addition to the reduction of the canines, beginning to walk bipedally. The earliest ancestors of humans were the size of chimpanzees, roamed the savannah and climbed trees almost as well as chimpanzees.

The last australopithecines

Later, the australopithecines would enter the scene, of which we have more information. They lived in forests, always looking for large spaces in which to ensure the warmth of the sun. Their brains were slightly larger than those of chimpanzees and they walked upright , although not as agile as us. Their diet was based on fruits, leaves and tender stems, although they may also have been hunters.

Two and a half million years ago, the Earth began to cool and dry out. The direct result of this process was that, in addition to the humid forest, an open savannah-type environment appeared. Therefore, australopithecines would alternate both means.

As the environment began to become more arid, the last australopithecines, called paranthropes , an unsuccessful branch of human evolution that only thrived for a million years, became extinct. Its main difference with the australopithecines that preceded them was in the size of its skull and, above all, its molars. They were great vegetable food grinders because they needed to chew continuously to obtain the precise calories to live, since, in addition to fruit and vegetables, they ate seeds, nuts and roots.

departure from africa

Lithic technology must have arrived with the last australopithecines. We would be talking about Homo habilis , who inaugurated the beginning of the physiological change that characterizes us so much; a three times larger brain , less facial projection, and a reduction in molars. These individuals seem to have been the first to hit one stone against another with a clear objective, to get a flake that would allow them to generate a cutting edge. This changed everything, because it provided cutting edge tools to some hominids with little chance of survival in an environment full of predators. His successor was Homo erectus /ergaster . Hunting became a more common activity and, although they dared with larger animals, they did not waste carrion. They were characterized by their physical strength , their longer legs, greater intelligence, and by their stone tools of standardized shapes and more efficient functionality. With them began the expansion around the world.

The departure of our ancestors from Africa occurred approximately two million years ago. Some skulls found in the Caucasus, specifically in Georgia, have attested to intermediate characteristics between Homo habilis and ergaster/erectus . But this area is not too far from Africa, so it cannot be considered as part of an expansion towards Eurasia of the hitherto typically African savanna biomes. The oldest fossils found, up to now, in the European and Asian continents are located in the deposits of Java (Indonesia) and Atapuerca (Burgos).

In Atapuerca, specifically in the Sima del Elefante, a human jaw almost a million and a half years old has been found. In this same enclave, but in another place known as the Gran Dolina, numerous remains of individuals with signs of cannibalism have appeared. These fossils are called Homo antecessor . It is not possible to talk about the Sierra de Atapuerca without mentioning the Sima de los Huesos, a site that has provided information of great scientific relevance. In this place, a 14 meter natural well, some thirty bone remains have been found from half a million years ago and have been classified as Homo heidelbergensis , showing pre-Neanderthal features.

If we continue advancing in the evolutionary scale that will take us to the current humanity, to Homo sapiens, the Neanderthals enter the scene, who were shorter, of a broader constitution and with a more developed musculature than that of the Europeans of today in day. His facial features were characterized by protruding eyebrows, a flat forehead, and a jaw with an absent or poorly developed chin or chin. Although there is something very important in which they were like us: the size of the brain.

While Neanderthals evolved throughout Eurasia, today we know, thanks to advances in the field of DNA isolation in fossil remains, that another group developed in Siberia: the Denisovans. Their contemporaries in Africa are represented by fossils from Ethiopia that are more than 200,000 years old.

Blombos Cave

Human encampments from 75,000 years ago have been excavated off the coast of South Africa in a cave called Blombos . Those who occupied this place were humans with anatomical features almost identical to those of the current populations of Africa. They fed mainly on what they hunted, but they also turned to marine animals for food. The shells that appear at the site are important not only for their food information, but also because they were used as pendants, we suppose that in necklaces.

45,000 years ago, these populations of African origin expanded into Eurasia, where they met the Neanderthals, who disappeared a few thousand years later. Some think that the best hunting areas were taken from them and they were displaced towards territories less suitable for their survival. The number of Neanderthal descendants would not be enough to replace the adults who were dying, so the groups were reduced and separated more and more. Therefore, they ended up extinct.

This view is often held by those researchers who think Neanderthals belonged to a different species, Homo neanderthalensis . Another theory is that, as the genetic data indicates, the mixture between the two populations led to the predominance of the characteristic features of the most numerous, which was of African origin, since, in the Ice Age, the population that Europe could support (that is, the Neanderthals) was much smaller, due to the extent of the tundra deserts and ice caps (in the north of the continent and in the mountains). According to this theory, the Neanderthals would not have been driven to extinction but assimilated, forming a minority component, although important, of our biological ancestry; that is, they would have formed a regional variety (“race” or subspecies) of Homo sapiens .

art of great beauty

The humans of these times (which archaeologists call the Middle Paleolithic and the beginning of the Upper Paleolithic, between approximately 125,000 and 25,000 years ago) camped in the entrances of caves and shelters protected from rain, snow and wind. ; in case of not existing, they were established in the open air. The cold, arid climate of the last ice age created open herbaceous spaces that gave rise to grassy prairies, providing an optimal environment for grazing deer, antelope, reindeer, horses, aurochs, bison, and rhinos. The abundance of large herbivores was accompanied by a large population of carnivorous animals such as wolves, hyenas, lions and bears, as well as brown and gigantic cave bears. Human hunters naturally followed these packs closely as well. Some of these species became extinct when the Ice Age ended.

Towards the end of this stage, Paleolithic humans will develop an art of great beauty . They made small sculptures that they carried with them and adorned them with necklaces and pendants. But, above all, they painted and engraved signs and figures on the walls of caves or on rocks in the open air. We don’t know why they did it, but today there are dozens of caves with signs and animals, painted in black and red, which bring us directly closer to how their world must have been or how they perceived it.

Neolithic Revolution

In this very long human history lasting over millions of years, we find ourselves for “only” ten thousand years in a completely new situation. At that time, agriculture and livestock began to be practiced in the Near East, later moving to other parts of the world. This process is commonly known as the Neolithic revolution.

The extension of agricultural tasks and the presence of herds caused the population that inhabited the planet at that time to grow and begin to concentrate in towns and cities. At the same time that this was happening, the great forests and the wide wild prairies were shrinking. Currently, science does not rest in its infinite search to answer all those questions that arise whenever we think about our origins. Since Charles Darwin we have advanced a lot in knowledge, but there are still many unknowns to be resolved. The debate is still open.

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