How do we differ from Neanderthals, and why did we outlive extinct humanoid types?

Dr. Liran Carmel, Prof. Eran Meshorer and David GokhmanJuly  2014: In parallel with modern man (Homo sapiens), there existed other now extinct types of humans with whom we lived side by side, such as Neanderthals and the recently discovered Denisovans of Siberia. Yet only Homo sapiens survived. What was it in our genetic makeup that gave us the advantage?

Little is known about our unique genetic makeup as distinguished from our archaic cousins, or how it contributed to the fact that we are the only species among them to survive. Even less is known about our unique epigenetic makeup, but it is exactly such epigenetic changes that may have shaped our own species.

While genetics seeks to understand the DNA sequence itself and the heritable changes in the DNA (mutations), epigenetics deals with heritable traits that are not caused by mutations. Rather, chemical modifications to the DNA can efficiently turn genes on and off without changing the sequence. This epigenetic regulatory layer controls where, when and how genes are activated, and is believed to be behind many of the differences among human groups. Researchers at the Hebrew University of Jerusalem and Europe have now shown that many epigenetic changes distinguish us from the Neanderthals and the Denisovans.

In an article recently published in Science magazine, Dr. Liran Carmel, Prof. Eran Meshorer (ELSC) and David Gokhman of the Alexander Silberman Institute of Life sciences at the Hebrew University, along with scientists from Germany and Spain have for the first time, reconstructed, the epigenome of the Neanderthal and the Denisovan. By comparing the ancient epigenome with that of modern humans, they identified genes whose activity had changed only in our own species during our most recent evolution.

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, 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 provided the first insight into the evolution of gene regulation along the human lineage and open a window to a new field that allows the study of gene regulation in species that went extinct hundreds of thousands of years ago.

Source: Hebrew University, Edmond and Lily Safra Center for Brain Sciences