Humans share at least 93 percent of their DNA with two mysterious ancient peoples — study

Sorry human uniqueness, but we need to talk about our distinctively not-unique genome. According to a fresh dive into the human genetic fabric, we share some 98 percent of our genome with other ancient hominins.

The discovery — As little as 1.5 percent of the modern human genome may be distinct from two other, more ancient, human species, according to a paper published earlier this year in the journal Science Advances.

INVERSE is counting down the 20 science discoveries that made us say “WTF” in 2021. This is #9. See the full list here.

In comparing the modern human genome with that of the Neanderthals and Denisovans, four findings stand out:

• At least 93 percent of our modern human genome overlaps with our hominin forebears.
• At most, the human genome is 7 percent unique to us, or as little as 1.5 percent.
• In the last 600,000 years, our genetic adaptations mostly had to do with brain development and function.
• The extent of genetic overlap implies there was a great degree of interbreeding between ancient human groups.

How they did it — Sourcing publicly available data of modern human, Neanderthal, and Denisovan genomes, the researchers sequenced the genomes themselves and then applied an ancestral recombination graph tool, which is a form of genetic analysis.

With this tool, they sketched a genetic tree including the three species.

“If you sequence a bunch of people, you could make a tree that would show how everyone's related, on average, across the whole genome,” Nathan Schaefer told Inverse at the time. Schaefer is a bioinformatician at the University of California, San Francisco, and the paper’s lead author.

Digging into the details — The resulting trees can help researchers point to the moment when H. sapiens adapted and diverged from other archaic peoples. They can also help us trace when our species came into contact with other archaic hominins, and how they might have interacted.

In addition to the genes, what also matters is how those genes translate to proteins — and in turn, function. In that sense, “we are very similar to Neanderthals,” Schaefer says.

“We have, you know, around 20,000 genes, and somewhere around 40 of them have these actual coding differences that all humans have one version, and the Neanderthals have the other version,” he says.

That’s to say only a tiny fraction of the genes in our genome differ from those of Neanderthals. But while that difference may be small, it’s significant.

Why it matters — A 1.5 percent distinction in our genomes is tiny, but it could be what defines Homo sapiens — and especially our cognitive adaptations.

Whatever circumstances led to the evolution of our brains likely goes back hundreds of thousands of years. Schaefer and other researchers want to learn more about how the genes that govern our brain’s development and function work. A further step is asking how genetic mutations become functional.

There’s also the question of genetic mixing — how it is we came to share so much Neanderthal and Denisovan genetics? Knowing where we come from is the best way to know where we’re going.

INVERSE is counting down the 20 science discoveries that made us say “WTF” in 2021. This is #9. Read the original story here.