Botswana is the ancestral home of mankind? Maybe not

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According to the study, the first people lived in the swamp, which is now northern Botswana. Credit: April / Shutterstock

A recent article in the journal You don't have to It is argued that modern humans originated some 200,000 years ago in the northern Botswana region. For me, for a scientist studying human origins, this is an interesting story. If this is correct, this article suggests that we finally know where our species comes from.

But in fact, there are a few reasons why my colleagues and I are not quite sure. In fact, there is reason to believe that our species has no origin.

Beyond new science research, many African genetic data from the Josefian peoples of South Africa are thought to be living where their ancestors lived for hundreds of thousands of years. Researchers have used their new data on people around the world (including other areas traditionally associated with the origin of mankind) to reconstruct the tree branch of the human family.

We can think of the early human group as the basis of a tree with a specific source of genetic data – the gene pool. Each of the different subgroups that separated and migrated from humanity's original "homeland" took with them a subset of genes. But most people, and most of these genes, are left behind. This means that living people today, with different subspecies of our species, can be grouped into different branches of the human family.

Groups of people with the most diverse genomes are likely to be those that originated directly from the original group at the foot of the tree rather than small subgroups split from it. In this case, the researchers named KhoeSan – a group around northern Botswana – as the main seabed, using geographical and archaeological data to back up their conclusions.

When you compare this process to building your own family tree, it makes sense to think that you can use information about who lives, where they are today, and how everyone relates to each other to reconstruct where that family came from. For example, many of my relatives live on the beautiful canal of Alderney, and one branch of my family is truly an island of many generations.

Obviously, there is always some uncertainty as a result of the variability in the data. (I currently live in Wales and have cousins ​​in England.) But as long as you look for broad patterns rather than focusing on specific details, you will still get a reasonable impression. There are even a few statistical techniques you can use to evaluate the strength of your interpretation.

Botswana is the ancestral home of mankind, says a great study - well, in fact…

Leading research author Vanessa Hayes with Yuhoan Hunters in Namibia. Credit: Chris Bennett, Evolutionary Picture

But there are many problems with drawing such a detailed conclusion from the human family tree construction process, as this new study suggests. First, it is important to note that the study did not observe the entire genome. It focused only on mitochondrial DNA, a small part of our genetic material that (unlike most others) is transmitted almost exclusively from mothers to children. This means that it is not mixed with DNA from fathers and is thus easy to track for generations.

As a result, mitochondrial DNA is commonly used to reconstruct evolutionary histories. But that's just part of the story. New research does not tell us the origin of the human genome, but the place and time where our mitochondrial DNA appeared. Of the approximately 3.3 billion cells in our cell, there are only 16,569 genetic letters, a very small part of mitochondrial DNA.

Other DNA

The fact that mitochondrial DNA comes almost exclusively from mothers also means that its inheritance history is much simpler than the histories of other genes. This implies that our genetic material may have different origins and has gone the other way. If we did the same reconstruction using the Y-chromosomes (only passed from father to child) or the whole genome, we would get another answer to our question of where and when humans originated.

In fact, there is some debate as to whether a woman from whom all of our mitochondrial DNA ("mitochondrial Eve") descends can ever meet even the man who produced the Y-chromosome of all living men ("Y-chromosome Adam"). By some estimates, they may have survived for 100,000 years.

All of this ignores the possibility that other species or populations may also incorporate DNA into modern humans. After this mitochondrial "origin", our species merged with the Neanderthals and a group called the denizens. There is also evidence that the two mate together, at a time when they were hybridizing with us. Earlier modern humans probably interacted with other human species that lived alongside them at other times.

All of this, of course, suggests that the history of modern humanity, as well as that of modern primates, was much more than a mere tree, with straight lines of inheritance. It is much more likely that our distant ancestors in other species and populations have mixed bands of gene pools than that we create a beautifully clean tree that can be genetically reconstructed. If this is the case, we may have no clue, we are hoping for reconstruction.

Homeland of Mankind: That is why everyone today can call home to Northern Botswana alive

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