Human-Neanderthal relations – the plot thickens as bone DNA analysed

DNA analysis has revealed yet another surprising piece in the puzzle of our human ancestry – human-Neanderthal affairs may not have as been as ancient as we have previously assumed. New research suggests that our ancestors were relatively modern when they dallied with Neanderthals.

Many of us owe a tiny amount of our genetic make-up to these prehistoric liaisons – around 2% may be Neanderthal DNA. Previous studies were unable to rule out the possibility that this DNA is a result of interbreeding of a much earlier age, involving humans who were much less culturally advanecd.

The leg bone used (Bence Viola, MPI EVA)

The leg bone used
(Bence Viola, MPI EVA)

Scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig have been using the oldest modern human DNA sequenced to try and uncover the secrets of our Neanderthal heritage. He was found in Siberia and analysis indicates he died around 45,000 years ago. New analysis of the DNA from his leg bone has revealed that only up to 400 generations (up to 13,000 years) had passed between him and the human-Neanderthal breeding. This means that interbreeding probably occurred 50,000 to 60,000 years ago.

In was during an age called the Initial Upper Palaeolithic, a period from which more complex tool artefacts are dated, and human culture included music and jewellery. But this wasn’t the only time when humans and Neanderthals interloped.

We already knew that it was likely there were two periods when interbreeding took place. DNA sequencing and comparing the amount of Neanderthal DNA present in different populations of humans has some interesting results. Sub-Saharan Africans have none, Europeans have some and Asians even more. This suggests that there was interbreeding at some point not long after humans left Africa, and another involving the ancestor of Asian populations. This new study is a leap towards identifying the earlier period, but not quite as early as anticipated. Further investigations indicate there may even have been another even more recent period of interbreeding, but there were too few stretches of this DNA to be certain.

These new findings are particularly remarkable when taking into consideration the fact that it was only in 2010 that human-Neanderthal interbreeding was realised.  That science can go from discovering this to describing multiple interbreeding periods and even when these might have occurred is a testament to the progress that is being made in the exciting field of genomics.

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