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This is not the case, according to African-multiregionist supporters. They claim that Homo sapiens emerged from an ancestral hominid itself spread throughout Africa and had already separated into many isolated populations . We evolved within these groups, which sometimes mated with each other, and perhaps with other contemporary hominids like Homo naledi.
The best metaphor for this is not a tree. It's a braided river – a group of streams that are all part of the same system but sneak into each other.
These watercourses merge into the same grand canal, but it takes time – hundreds of thousands of years. For most of our history, a group of Homo sapiens had just some of the complete constellation of characteristics that we use to define ourselves. "At the time, people seemed more different from each other than current populations," says Scerri, "and it is very difficult to answer the question of homo sapiens . Indeed, the first people who had the complete set probably appeared between 40,000 and 100,000 years ago.
Our behavior probably evolved in the same disparate way: for a few million years, hominids did the same style of big stone axes from one millennium to the next, but this Technological stagnation ended about 300,000 years ago – the same age as the earliest fossils Homo sapiens .Since this period, archaeologists have discovered new types of sophisticated stone tools, like spikes and spear points
These tools of the so-called middle age of stone show that the modern human spirit developed roughly at the same time as the human body modern. that this transition has occurred on a continental scale, as such tools were found at Jebel Irhoud in Morocco, Olorgesaillie in Kenya and Florisbad in South Africa, with regional differences at each site.
There is a big potential problem with the history of African multiregionalism. Genetic studies of today 's African populations suggest that they diverged from each other between 100,000 and 150,000 years ago – much later than the early onset, at the continent scale, suggested by the bones and tools. This deep and broad origin might be right, "but, this is not something that we geneticists have formally tested," says Brenna Henn of UC Davis, who is an author on the new paper. "We have discussed ways to do it, but no published article says that there is a deep demographic structure in Africa."
But the DNA of Africans today has been shaped by more recent population upheavals that have obscured things. 300,000 years ago. What's more, the studies that analyzed this modern DNA largely relied on tree-based population models in which a single lineage develops from one place – exactly the scenario that proponents of African multiregionalism say is wrong . "In science, we use simple models for good reasons, because often we do not have enough data to inform more complex models," says Thomas, himself a geneticist. "But there is a difference between using simple models and believing them."
"We are just at the beginning of trying to figure out how to refine this new theory," says Scerri. "To find out more about what happened, we need to get more data on many of the gaps in Africa." The oldest Homo sapiens fossils come from 10% of Africa , and we extrapolate to 90% of the continent.Most of it remains unexplored.We say that these places are not worth seeing because we have the answer of 10 %.How can we know this ? "
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