With the successful sequencing of the genome of a Neandertal female who lived 50 000 years ago, we have deeper knowledge of our long-gone ancestors – but also of ourselves.
A team led by professor Svante Paabo of the Max Planck Institute in Leipzig published two articles on October 5 2017 in Science magazine regarding the successful sequencing of the genome of a second Neanderthal female, who lived 55000 years ago. The team studied the remains in the Croatian cave of Vindija, where Neandertals lived until 44 000 years ago. It is the second genome to be rebuilt – the first one belonged to another female found in the Denisova cave, in Siberia. This first study was only the result of the work of the team of Svante Paabo.
The second Neanderthal woman carried 1.6 differences per ten thousand base pairs between the two copies of her genome, fewer than present-day humans, suggesting that Neandertal populations were of small size.
Before they went extinct some 30 000 to 40 000 years ago, Neandertals passed down part of their genetic heritage. The data collected during this second sequencing proved that Neandertals and Homos Sapiens did indeed interbreed. It also enabled us to establish how much of this heritage we still hold in our own genome. With the exception of humans of Oceanian or African descent, modern day people hold between 1,8 and 2,6% of Neandertal DNA – with Asians boasting the highest share. By contrast, Africans are genetically closer to Homo sapiens – as the species originated on the continent.
What’s more, these new findings shone a light on our contemporaries. We now know that the Neandertal heritage in our genome in more significant than initially thought. And it is the very dosage of different DNA sources that explains health inequalities from one human to another: the tendency to build high cholesterol levels, various responses to antipsychotic drugs, mental illness. However, it is too soon to blame the Neandertals for passing down all our deficiencies before going extinct, as such defects may have multiple origins. “More genomes must be studied before we have an answer”, the study concludes.