Four years ago, scientists showed that Neanderthals and present-day humans differ in genetic makeup by just a fraction of a percent. Now, the Hebrew University researchers, together with colleagues in Germany and Spain, are reporting that they found that certain genes were turned “off” in Neanderthals that are “on” in humans and vice versa.
In their article published in Science, Dr. Liran Carmel, Prof. Eran Meshorer and David Gokhman of the Alexander Silberman Institute of Life sciences at the Hebrew University, along with scientists from Germany and Spain, have reconstructed, for the first time, the epigenome of the Neanderthal and the Denisovan. Then, by comparing this ancient epigenome with that of modern humans, they identified genes whose activity had changed only in our own species during our most recent evolution.
They showed that chemical modifications to the DNA can efficiently turn genes on and off without changing the sequence.
Among those genetic pattern changes, many are expressed in brain development. Numerous changes were also observed in the immune and cardiovascular systems, whereas the digestive system remained relatively unchanged.
On the negative side, the researchers found that many of the genes whose activity is unique to modern humans are linked to diseases like Alzheimer’s disease, autism and schizophrenia, suggesting that these recent changes in our brain may underlie some of the psychiatric disorders that are so common in humans today.
By reconstructing how genes were regulated in the Neanderthal and the Denisovan, the researchers provide the first insight into the evolution of gene regulation along the human lineage and open a window to a new field that allows the studying of gene regulation in species that went extinct hundreds of thousands of years ago.