What is the origin of Homo sapiens?

A summary of what we know about the origin of our species, Homo sapiens.

The origin of Homo sapiensor, in other words, our species, has always been a topic of interest to the scientific community, especially when the idea of divine creation and the idea that all animals arose magically by spontaneous generation ceased to be believed.

There have been two main theories that have tried to explain how humans are the way we are today, with the theory that we come from Africa being the one that has achieved the most strength and scientific evidence. Let's see what evidence has been found.

The origin of Homo sapienswhat we know about the emergence of our species

Although today it is widely accepted that the first human beings must have arisen somewhere in Africa and then migrated around the world, this has not always been the case. Throughout the study of the origin of Homo sapiens two main theories have been put forward that have tried to elucidate the origin of our species.

The first is that of polygenism, also called the multiregional hypothesis, which argues that modern humans do not really come from one group of original humans, but from several groups of a previous species that evolved on their own.

The second, which is the most widely defended by current anthropology, is that the first humans lived in Africa and, from there, migrated to other parts of the world, thus extending the species and adapting to the climates, giving rise to the races.

Polygenism

Polygenism is a theory about the origins of human beings that postulates the existence of different lineages that have given rise to human races. that have given rise to the human races. The defenders of this theory said that, in reality, humans were a group of species, which were the result of different evolutionary processes that, coincidentally, coincided in some aspects.

The human races would be the result of the hominid link prior to what we understand today to be the Homo sapienshad split into different populations, which, with the passing of the millennia, would have given rise to different species that could be classified as part of the same genus, not a species, which would be that of humans. For this reason, polygenism polygenism is also called the multiregional hypothesis, stating that the current state of the human race is not a species, but rather a genus.It states that the present state of human beings is due to the evolution of different populations in various regions.

Those who defended these hypotheses tended to base themselves on religious and pseudoscientific criteria, or by taking empirical evidence in a very arbitrary way. Racism and slavery came to be justified on the basis of these theses, since, if one has the notion that blacks, Asians and other races are, in addition to being intellectually inferior to whites, different from Europeans as a species, the use of individuals of these races as one uses a mule or a horse to carry sacks would be equally legitimate.

African origin

But although racism and slave-holding positions defended the idea that blacks, whites, Asians and other races are the result of lineages that had evolved separately and were, in truth, different species, these theses were eventually set aside.

Nowadays, scientific evidence has shown that the origin of Homo sapiens is in Africa, probably somewhere in the Rift Valley, although this has become increasingly doubtful.although this has been increasingly questioned.

What is accepted is that the current human species must have descended from a group of primordial humans, some early Homo sapiens that must have spread around the world, changing their physical characteristics such as height, skin tone, hair and eyes, teeth and particular skull shape, but essentially remaining the same species.

Evidence in the paleoanthropological record, together with archaeological remains, historical inferences and genetic evidence has indicated that the origin of Homo sapiens would date back some 140,000 to 200,000 years ago in sub-Saharan Africa.. This is evidence accepted by virtually the entire scientific community.

History and evidence for the theory

The theory of the African origin of Homo sapiens dates back to the end of the 19th century, with the figure of James Prichard, an ethnologist who argued that there were sufficient reasons to consider that human beings descended from black Africans.an ethnologist who argued that there were sufficient reasons to consider that human beings were descended from black Africans, statements that, given the racist society of his time, needless to say were controversial. To claim that whites, who were seen as pure, intellectually superior and the pinnacle of animal evolution were, in fact, descended from blacks, was tremendously controversial.

Charles Darwin, with his studies of evolutionary variety in the Galapagos Islands, had already assumed that, of necessity, there had to be a common ancestor for all human beings. The first ancestor must surely be some hominid-like primate, which, in Darwin's opinion, must have lived in Africa. in Darwin's opinion, must have lived in Africa, since that continent was the habitat of great apes.The size and shape were very similar to that of humans, and some of them were able to stand in a bipedal position.

With the passing of the 20th century and thanks to the improvement of anthropological and genetic techniques, it was possible to establish with greater certainty where and when the origin of our species was found.

Fossil evidence

From the bones found in different places in Africa, it has been hypothesized that anatomically modern humans evolved in that continent during the last 200,000 years, from a pre-existing population of hominids.

Anatomically modern refers to hominids that had features very similar to those of present-day humansThe first fossils with these characteristics were found in the early fossil recordings of the first hominids, which were found in the early fossil recordings of the first fossils.

The first fossils with these characteristics were found in East Africa, near the Omo River (Ethiopia).being dated at 195,000. These remains are called the Kibish men, and are considered to be the first Homo sapiens oldest Homo sapiens.

Behavior and culture

Although it is logical to think that it is very difficult to know how hominid populations that lived long ago behaved, the truth is that they have left some remains behind that allow us to know, in a more or less suggestive way, what their cultures were like.

Modern human behavior gave rise to the Upper PaleolithicThis period was established in Europe 30,000 years ago, but in Africa it occurred earlier, about 70,000 years ago.

This is known from some paintings found in caves, as is the case in South Africa. These are abstract representations painted with red ochre. Objects have also been found, such as stone points and arrows made of bone, between 70,000 and 90,000 years old.

Paleolinguistic studies

Paleolinguistics is the discipline that studies ancestral languages, i.e. languages that were spoken millennia ago.Paleolinguistics is the discipline that studies ancestral languages, that is, languages that were spoken millennia ago, of which it is only possible to make assumptions based on the living languages spoken today, as would be the case of Indo-European, reconstructed from European and Indian languages.

But prior to Indo-European, and to any other language, protosapiens, the original language, must have been spoken before it split as in the legend of the Tower of Babel.

Paleolinguists have proposed the hypothesis that languages present more phonemes the more they are related to populated regions with greater antiquity.. That is, populations derived from a founding population, but which have distanced themselves from it, reduce their phonetic repertoire, having fewer sounds.

One should not fall into the error that these languages, because they have fewer sounds, will necessarily have less vocabulary. Phonemes and vocabulary are not directly correlated, but phonemes and distance from the African continent are.

A total of 504 living languages of the world have been studied, and it has been found that those with the most sounds, some having the rare "clicks" or consonantal clicks (ʘ, ǀ, ǃ, ǂ and ǁ), are found in Africa, as is the case of the Joisan languages with more than 140 sounds.

In contrast, the languages with the smallest phonetic repertoire would be found in South America and the islands of OceaniaThe Hawaiian language, with only 140 sounds, is one of the regions that were probably populated by humans at a very late stage. Hawaiian, with only 13 phonemes, is the language with the fewest sounds.

Genetic evidence: Adam and Eve

Thanks to the study of human genetics, it is known that by studying the family tree of the entire human species, there would have been a common male and female ancestor, who have been called Mr. Adam, with the surname Chromosomal, and Mrs. Eve, with the surname Mitochondrial. The name is not accidental, given that, in reality, the entire human species would descend from these individuals, comparable to the Christian idea of Adam and Eve in the Garden of Eden.

The difference between the biblical characters and these common human ancestors is that the latter did not know each other, since they lived at very different times. The mitochondrial Eve must have lived 190,000 years ago, probably somewhere in Tanzania.probably somewhere in Tanzania, while the chromosomal Adam is not very clear, but he could have lived between 270,000 and 60,000 years ago.

Mitochondrial DNA, that is, the circular DNA, very similar to that of bacteria, found inside the mitochondria, is inherited maternally. The most recent common ancestor that would have given us this mitochondrial DNA had to be female, and that is why the existence of the mitochondrial Mrs. Eve has been proposed.

The Y chromosome can only be inherited through the male pathway, and it is the sex chromosome that defines male sex. Roughly speaking, it would have happened as in the case of mitochondrial Eve. All males would have a common ancestor, a male who had the first Y chromosome, which would be Mr. Adam, the chromosome that defines the male sex.chromosome, who would be the chromosomal Mr. Adam.

The problem of establishing the line

Many people, when they hear about human evolution, imagine the classic image of various individuals, placed in line, going from a quadrupedal ape, passing through hominids from more to less hairy and arriving at the Homo sapienswith a spear and loincloth. This image, although quite illustrative, induces the erroneous belief that human evolution has occurred in a similar way as Pokémon do. Phase 1: monkey, phase 2: australopithecus, phase 3: Homo habilis ... final phase: Homo sapiens.

But really the process was much more progressive, and this is observed in the skeletal remains. It is not easy to delimit where a species begins and where it ends by looking at its fossil record.. It is clear that if you take two individuals that lived in very separate chronological eras, such as the australopithecus and the Neanderthals, you will see differences.

However, this is not so simple when comparing bones separated by only about 100,000 years or even from species that lived together but had not yet differentiated much, as must have been the case with the first Neanderthals and the first Homo sapiens. In fact, it is believed that a significant portion of the European population is believed to be descended from fertile hybrids of Homo sapiens with Neanderthals, the latter species being responsible for the fact that Europeans suffer more cases of Crohn's disease, type II Diabetes and biliary cirrhosis.

An example of this can be seen in the bone findings made in Jebel Irhoud, Morocco.. In the 1960s, bones belonging to two adult and one infant were found: two adult skulls, an infant mandible, an infant humerus and a coccyx fragment. Since these bones showed primitive or rather coarse features, they were classified as Neanderthals.

Decades later, and reanalyzing the bones, the opinion was changed. These bones must have belonged to Homo sapiensbut they must have been of a very primitive variety. This case shows how difficult it is to establish the line, given that, since evolution is a continuous process, it is difficult to establish the criterion that serves to clearly delimit between one species and another.

Bibliographic references:

• Hublin et al. (2017). New fossils from Jebel Irhoud, Morocco, and the pan-African origin of Homo sapiens, Nature. DOI 10.1038/nature22336.
• Ritcher et al. (2017). The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age, Nature. DOI 10.1038/nature22335.