For decades, paleoanthropologists have had a heated debate that has focused on the origin of modern humans. In essence, some experts maintain that our species evolved in different places on the planet; others, that this process took place in Africa, from where our ancestors would spread throughout the world.
At present, the majority favor the latter hypothesis. However, it is not yet clear how this phenomenon took place, if there were one or more migrations or to what extent the first Homo sapiens mixed with other populations of hominins – upright walking hominins. Now, a team of researchers from the Department of Anthropology at the University of Hawaii, in Manoa, and the Max Planck Institute for the Science of Human History, in Jena, Germany, has presented a comprehensive study that sheds some light on this. affair.
Trickle of migrations
In an essay published in the journal Science , these scientists point out that it is necessary to reassess what we think we know about these displacements. For example, numerous manuals and textbooks record that the first modern humans left Africa in a single wave of migration, some 60,000 years ago. But, in his opinion, advances in different fields allow us to affirm that the real scenario is much more complex. “In fact, there is growing evidence to suggest that there was not one but several of these episodes, at least 120,000 years ago, and that these Homo sapiens interbred with other hominins, such as Neanderthals and Denisovans, in different ways. zones ”, points out the professor of Anthropology Christopher J. Bae, of the aforementioned American institution, one of the co-authors of this work.
Bae and his collaborators draw special attention to the interactions of these groups in Asia, where numerous remains have been found in the last decade, especially in Chinese sites, which are between 120,000 and 70,000 years old. Other recent findings have determined that our ancestors reached Southeast Asia and Australia more than 60,000 years ago. As they indicate, as a whole it could be said that humans began to leave Africa 120 millennia ago; the first migrations, of minor importance, were followed by another, much more relevant, which took place 60,000 years ago . “Those first movements were carried out by small groups that have left a slight genetic imprint on modern human populations. Not all of them reached a dead end from an evolutionary point of view, ”explains Michael Petraglia, who also signs this review, from the Max Planck Institute.
Reporter genes
In their essay, these researchers also warn that the analysis of ancient DNA that has been recovered shows that the first modern humans intermingled with the other hominins with whom they came in contact, such as the aforementioned Neanderthals and Denisovans and at least with one other human species. not yet identified. All these groups appear to have coexisted in Asia and to have developed some degree of interaction, which can be traced in our genome. Thus, in 2010 a study already revealed that non-African humans share between 1 and 4% of genes with Neanderthals ; something similar occurs with the Melanesians, in which 5% of them coincide with those of the Denisovans.
Finally, the study draws attention to what could be called the cultural dispersion that accompanied these population movements and which, like them, is much more complex than has been believed up to now. The authors point out that it did not consist of a simple implementation of the models that the first Homo sapiens carried with them, but that it was influenced from contacts with indigenous populations to all kinds of ecological incidents.
Reference: On the origin of modern humans: Asian perspectives . Christopher J. Bae et al. Science . December 2017. Vol. 358 (6368). DOI: 10.1126 / science.aai9067
Images: Sémhur via Wikimedia – CC / Christopher J. Bae et al.
