For a long time we regarded our Neanderthal cousin with contempt, even condescension. It is true that, with his patibular look of a thick brute, his low forehead and his slightly demure look, he made a bit of a mess in our family picture of distinguished Homo sapiens. Weary! It was without counting on the progress of genetics. Now we must admit, we have a lot of him in us. We all have Neanderthal hidden deep in our genes. And it is this tiny part of our inheritance that conditions some of our weaknesses, diseases or addictions.
Sbote Pääbo, a Swedish geneticist and Director of the Max Plank Institute in Leipzig, has undertaken a study of the Neanderthal genome. His first revelations date back to 2012, when he discovered traces of Neanderthal in our genes.
Shocking revelation, but in the end, quite logical. About 50,000 years ago, Sapiens and Neanderthal cohabited in the same regions of Europe, the Middle East and Central Asia. As encounters were inevitable, the crossbreeding was bound to go well at a time when distractions were not common. Exchanges, mating and great love stories help, so we all have something Neanderthal in us: 1 to 4 % of our genes are common with our distant ancestor, who disappeared from the surface of the Earth more than thirty thousand years ago. Svante Pääbo, who is often mentioned in the list of future Nobel Prize winners, would like to point out in L'Express the importance of this discovery: " We share from 1 to 4% of our genes. It may seem small, but it's huge ... After mating with his cousin, modern man has continued on his way to populate the rest of the globe. As far as China and Australia, which explains, for example, why Australians also have Neanderthal genes, even though Neanderthal has never left Europe"..
Svante Pääbo studies ancient DNA sequences to better understand our history and that of humanity. Photo: Olivier Colin, L'Express
This part of our genetic heritage could have remained buried in human memory, like a well-kept family secret. This was without relying on researchers at Vanderbilt University in Tennessee who, pursuing Swedish research, have just revealed in an article published in Science of February 12, the significance of this legacy from the fund of ages. « We have discovered that Neanderthal DNA has an influence on many clinical features of modern man, on the immune, dermatological, neurological, psychiatric, etc. level. "says John Capra, an evolving geneticist responsible for this study.
The genome map reveals its secrets
The incidence of Neanderthal is subtle but not negligible. The study consisted of comparing the Neandertal genomic map with the personal and medical record genome of 28,000 patients identified through the EMERGE network (Electronical medical records and genomics network), founded by the National Research Institute for the Human Genome.
The results of this study of cross-referencing and cross-matching hundreds of thousands of data are irrefutable. They have found more than 135,000 genetic variants in the DNA of modern man from the Neanderthals. They then determined the links between these variants and diseases and found that some of these Neanderthal genetic variations were closely linked to an increased risk of twelve diseases including depression, myocardial infarction, blood disorders, allergies and a number of addictions.
These traits handed down by our old cousin were competitive advantages in their time. For example, Neanderthal had thick blood that clotted very easily. A very useful characteristic when one had to hunt, fight for survival. An advantage that becomes harmful and turns into a risk of stroke or pulmonary embolism when you lead a sedentary life and eat very rich foods. Similarly, a team from the Max Planck Institute, and another from the Pasteur Institute, have newly demonstrated that our allergies would be made worse by three Neanderthal genes. These genes were used at the time to boost the immune system, a competitive advantage useful for survival in hostile environments. Today, these defences are turning against us in the form of allergies, asthma and susceptibility to hay fever.
As another example, Neanderthal DNA affects the keratinocyte cells that cover the epidermis and help protect the skin from ultraviolet rays and pathogens. Researchers were surprised to discover that some of these neanderthal genes increased the risk of nicotine addiction. Smokers now know where to turn to find the causes of their addiction...