Based on fossil records, the original evolution of Hymonin (the modern man and his evolutionary ancestor since the division with other apes) took place in Africa about 7 million years ago. About 2 million years ago, various members of the genus Homo migrated from Africa to Eurasia and eventually to the world.
These migrations resulted in several different populations, including Neanderthals, Denisovan from parts of Europe, the Middle East and Asia. These are each classified as separate species. Homonanderthalensis and homo (the species' names are not settled) are in contrast to the completely modern human, homo sapiens, and the first homo sapiens to African first appearances, respectively.
These older populations eventually disappeared and apparently were replaced by “completely modern” humans in their final migration from Africa about 50,000 years ago. The question for many years was what happened to previous immigrants? Why do they seem to have disappeared and replaced by a late arrival?
In general, many theories have been proposed that assume different forms of more or less forced extinction in older residents. New research provides a more nuanced explanation.
One explanation is that modern humans were somehow superior. Perhaps it is a greater mental ability and higher skill. For example, the Neanderthals, where physical artefacts were first discovered in 1829, were long resembled as half the cruel and intellectually limited by their builds than modern humans. This assumed superiority of modern humans was extrapolated to support the idea that they caused the extinction of Neanderthals and forced them into marginal environments and direct physical violence. This explanation appeared to coincide with 19th century imperialist ideology. However, it was based on speculation without demonstrating evidence.
More recent studies have shown that in fact Neanderthals have rather sophisticated techniques (including recently discovered industrial-scale fat rendering facilities) and are well adapted to the Northern Hemisphere glacial environment during the Pleistocene (glacial age). Furthermore, genetic studies have shown that Neanderthal DNA is low in current populations in some European and Asian countries (1-4%). Similarly, several modern Asian populations have traces of Denisovan DNA.
A study published last year found traces of modern human DNA, particularly Y or male sex chromosomes, in Neanderthal fossils dating back 200,000 to 250,000 years ago. Another wave of African immigration left genetic traces 120,000 to 100,000 years ago. This suggests that there were multiple migrations from Africa by modern H. sapiens during that period. Nevertheless, these African immigrants did not overpower the indigenous Eurasian population as recent immigrants. Why the difference?
Compounding further the question, the discovery of shared DNA questions the idea that these three populations (modern humans, Neanderthals, and Denisovans have separate species. The established definition of species is based on genetic segregation. That is, if members of different populations cannot combine to produce viable and reproductively functional offspring, there is no flow of genes between them, and they evolve in separate directions. This is usually the result of geographical segregation, resulting in a combination of random genetic drift and evolutionary adaptation to different environments. Over time, these genetic differences are sufficient to prevent the success of mergers between members of individual populations.
The fact that modern non-African populations carry small amounts of Neanderthals and/or Denisovan DNA indicates that no complete genetic segregation has occurred, and at least to some extent these groups “made love, not war,” and therefore are members of the same species, most often representing various subspecies. The discovery of fossils of children, which appear to have a mixture of Neanderthals and modern human characteristics, gives weight to the view of cross-mates. Examples of Neanderthal/Denisovan hybrids have also been identified.
Furthermore, recently reported studies based on data from Tinshemet Cave in central Israel appear to demonstrate that Neanderthals and homo sapiens live side by side during some of the mid-Paleolithic Ages about 110,000 years ago, sharing everyday practices, burial practices.
This evidence raises the question of why the current population is primarily derived from the latest “Africa” immigrants.
A recently published study (“Major expansion of the predispersed human niche in Africa”, Nature, June 18, 2025) proposes a new theory of why later immigration from Africa overwhelmed and/or replaced Eurasia's existing population. This new theory argues that while Hymonin originally evolved millions of years ago in the East African savanna and adapted to its environment, thousands of years ago, homo sapiens in Africa spread to other environments, developing a variety of knowledge, cultural practices, and technologies that allowed them to exist successfully.
By reviewing large samples of suitable old archaeological sites from across Africa and assessing the environmental environment, the researchers found that “human niches began to expand significantly from 70 ka (million years ago), and that this expansion was driven by increasing the use of diverse habitats from forests to arid deserts.” They concluded that “humans dispersed from Africa after 50 ka had a distinctive ecological flexibility among the Hymonin in encountering climatically challenging habitats and providing an important mechanism for adaptive success.” A second wave of ecological expansion is observed, starting at about 29 ka. By then, “humans have occupied all African regions and ecosystems. Terminal Pleistocene society is engaged in a variety of new behaviours, including semi-seditiousness, evidence of sustained macroscale social networking, increasing territoriality and increased human violence.”
A “niche” of a species is the biological and physical environment in which it is adapted. The proposed interpretation argues that by developing cultural flexibility to succeed in a variety of African environments, modern humans can adapt to a wide range of geographical settings when they migrate to Eurasia. In contrast, the Neanderthals and Denisovans fit only a limited number of relatively narrow ecological niches that existed during the more stable early parts of the Pleistocene buffered by the large-scale glacial deviation attenuation effects. This effect caused what was known as the “Pleistocene Equilibrium,” which approached.
In contrast, the Late Pleistocene (approximately 129,000-11, 700 years ago) was characterized by dramatic climate change and significant environmental changes. During this period, stadiums alternated between cold ice ages and warmer periods, leading to changes in vegetation, animal distribution, and population. As a result, newly arrived modern humans, adapted to various African environments, were able to live in increasingly variable environments, thus spreading widespread throughout the Eurasian landscape, bringing larger groups and overwhelming the vast numbers of Indigenous peoples.
It is unclear whether there was a violent physical conflict between the residents and immigrant population, which cannot be ruled out, but genetic information suggests at least some degree of friendly interaction. With the mechanisms that completely modern homo sapiens have come to dominate the gene pool of the present population, this new evidence reaffirms that we are all of us ultimately relatively recent Africans. This understanding is particularly important when racism and xenophobia are adopted in fascist drive.
Another important observation is the importance of scientific research into human origins regarding the availability of substantial representative databases. In both cited studies on modern human migration and recent studies on the origins of social inequality, databases containing numerous archaeological sites were key to the derivation of new, well-documented interpretations. The Trump administration's reinstatement on general science, including archaeology, will have a devastating impact on future research.
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