John Capra, a scientist at Vanderbilt University, wants to know how evolution has shaped our genome and how the differences in it are different. Genetics can explain differences in species. In his latest work, he tries to get a better sense of what the old people ̵
Capra's new study takes advantage of the fact that Neanderthals mingle with modern humans (yes, Jean Auel was a genius of foresight). Overall, we have about one-third of the Neanderthal genome scattered across the nuclei of our cells, or at least the Eurasian populations. Most of this Neanderthal DNA is located in regions that do not code for proteins. This category includes gene regulatory regions that determine where, when and how much a gene is expressed.
Ancient or Modern
Much of the Neanderthal DNA conserved in the modern genome affects the immune system, hair and skin, as well as neurological development. To find out which genetic regions have different regulatory implications for ancient and modern humans, Capra's lab has not studied the Neanderthal DNA sequences that modern humans have. We examined the sequences that we did not receive .
First, Capra and his colleagues created an algorithm to estimate how much a particular DNA sequence can regulate the activity of adjacent genes. They trained it on the PredictDB data repository for genetic variants and gene activity profiles of modern humans. They then created two lists: those genes that lack an archaic regulator and those that have one.
To do this, the researchers used their algorithm on the genome of the Altai Neanderthal, a woman who spanned the Altai Mountains some 122,000 years ago, crossing the intersection of Russia, China, Mongolia and Kazakhstan. By comparing the predicted regulatory effects of the Neanderthal regions in the Neanderthal genome with the corresponding modern regions in our genome, the researchers concluded that we have 766 genes that lack archaic regulatory regions and that are probably regulated differently than in the Altai Neanderthals.
The genes are present on all 22 of our regular chromosomes and are active in all 44 tissues examined. Similar (though not identical) results were obtained when comparing modern genomes with those of two other ancient humans: a Denisovan who lived 72,000 years ago, and Vindija Neanderthal who lived in Croatia 52,000 years ago Those that are involved in a number of important clinical issues, including heart attack, miscarriage, and certain cancers. Usually, but not always, the Neanderthal sequence increases the risk of these events. Other aberrantly regulated genes made old hominins with different skeletal and dental structures hairier than we did.
Neanderthals differed from us and looked different, not necessarily because they had other genes than we did, but because our genes are regulated differently. This finding may not be groundbreaking, but it's definitely still cool. And maybe the methodology will reveal other phenotypic differences that could not be studied with fossils.
Nature Ecology & Evolution, 2019. DOI: 10.1038 / s41559-019-0996-x (About DOIs).