Human Genome Mostly Overlaps With Neanderthals, Other Human Ancestors


  • Just 1.5% to 7% of the human genome is unique to our species, a new study suggests.
  • Neanderthals, Denisovans, and other ancestors share most of the same genes found in modern humans. 
  • Genes unique to humans are involved in brain development, which may be what sets our species apart. 

Humans like to think they’re special, but our genes suggest that’s far from the case.

No more than 7% of the human genome is unique to Homo sapiens, according to a study published Friday in the journal Science Advances. 

We share the remaining chunks of our genetic material with other human ancestors, or hominins, including our Neanderthal cousins and the Denisovans first discovered in east Asia.

“The evolutionary family tree shows there are regions of our genome that make us uniquely human,” Richard Green, director of the paleogenomics lab at the University of California, Santa Cruz and co-author of the new study, told Insider. “Now we have a catalog of those, and it’s a surprisingly small fraction of the genome.”

Anthropologists already knew that our hominin ancestors all interacted and interbred — exchanging genes and stone technologies that altered the course of our species’ evolution. But these new findings further underscore just how frequently that intermingling happened in the last 300,000 years or so, since the first known population of modern humans emerged. 

“More or less everywhere we look, admixture is not the exception at all, but rather the rule,” Green said.

Genetic evidence suggests our ancestors interbred with mysterious hominins 

An exhibit shows the life of a neanderthal family in a cave in the new Neanderthal Museum in the northern town of Krapina, Croatia, February 25, 2010.

Reuters/Nikola Solic

To construct a hominin family tree, Green’s team sequenced and compared genomes from 279 modern humans — sampled from people all over the world — to ancient genomes from one Denisovan and two Neanderthals. Then, the researchers used a computer algorithm to determine out how each of those individuals are related to each other.

The analysis tool, which Green said took years to develop, helped them distinguish what parts of the human genome are devoid of admixture — meaning these sets of genes aren’t seen in Neanderthals or Denisovans. 

The algorithm also highlighted what genes humans inherited from an even older ancestor, one that lived 500,000 years ago or so, that eventually gave rise to our species as well as Neanderthals and other hominins.

The study results suggest mysterious populations of human ancestors that scientists haven’t even discovered yet may have interbred with Neanderthals and Denisovans before these species mixed with modern humans, Green added.

Genes unique to humans are related to our brain development

A scientist at work in a laboratory at the Max Planck Institute for Evolutionary Anthropology analyzing ancient DNA.

Max Planck Institute for Evolutionary…

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