Most know that Neanderthals and humans once existed at the same time thousands of years ago. Yet while humans survived and thrived, Neanderthals went extinct. So what gave modern humans the leg up over other species? Scientists have taken a closer look and may now have a few answers.

Early in our history, Homo sapiens wasn't the only human-like species to roam the Earth. We were joined by Neanderthals and the recently-discovered Denisovans of Siberia. Yet while other species went extinct, Homo sapiens managed to survive. That's why researchers decided to take a closer look at DNA in order to see whether there was something in our genetic makeup that gave us an evolutionary advantage over other species.

The scientists actually reconstructed the epigenome of the Neanderthal and the Denisovan. They then compared this ancient epigenome with that of modern humans in order to get a closer look at what traits we have these species did not possess.

The researchers identified genes whose activity had changed only in our species during the most recent evolution. Among these genetic pattern changes were ones associated with brain development. Numerous changes were also seen in the immune and cardiovascular systems, while the digestive system remained relatively unchanged.

Yet not all of the changes in humans were good. The researchers also found that many of the genes unique to modern humans are linked to diseases like Alzheimer's, autism and schizophrenia. This seems to suggest that some recent changes to the brain leave humans open to certain psychiatric disorders.

The findings reveal that humans did have different evolutionary traits from other species, which means that we may have possibly had an advantage when it came to survival. By reconstructing how genes were regulated in the Neanderthal and the Denisovan, the scientists have gained insight into the evolution of gene regulation along the human lineage.

The findings are published in the journal Science.