A Nobel-Worthy Look at Ancient Genomes
How the first paleoanthropologist won a Nobel prize for Physiology or Medicine in 2022
The field of paleoanthropology asks the questions many of us have wondered about at one point or another. Where did humans come from? What happened to other similar species like the Neanderthals? Do we share any of our genomes with Neanderthals or other hominins — species closely related to modern day humans? Turns out, beginning to answer these questions can cop you a Nobel Prize.
In 2022, Svante Pääbo won the Nobel Prize for Physiology or Medicine — a first for a paleoanthropologist — “for his discoveries concerning the genomes of extinct hominins and human evolution.” Pääbo and his group have managed to sequence the genome of multiple Neanderthals and discovered some fascinating things about how our Neanderthal ancestry continues to shape our lives today.
Once Upon a Time
Neanderthals roamed the Earth until about 40,000 years ago, meaning humans lived alongside them for thousands of years. Did the two species interbreed? Do we have Neanderthal ancestry as a result? The answer, as discovered by Pääbo and many others, is yes!
While it seems the DNA in our mitochondria, one of the molecular machines working inside our cells, is fully distinct from that of Neanderthals’, it’s an entirely different story when it comes to our nuclear DNA — the DNA that dictates most of our cells’ functions.
When looking at the genomes (the collection of DNA) of modern day humans anywhere outside of Subsaharan Africa, there is a one to two percent overlap with the Neanderthal genome. Why only outside of Africa? It seems that Neanderthals never lived there, meaning there wasn’t a chance for interbreeding. Also fascinating is that earlier humans seem to have more Neanderthal DNA than later humans.
A New Species Emerges
Another important discovery from Pääbo and colleagues was the existence of hominin other than Neanderthals who lived at the same time as both Neanderthals and humans. These hominins came to be known as Denisovans, after the cave the first fossils were found in.
Interestingly, it seems that there were multiple somewhat distinct populations of Denisovans. Whereas the Neanderthals were a relatively homogenous group genomically, this wasn’t the case with Denisovans. And these different Denisovan populations also contributed to the genomes of some modern humans, particularly in East Asia.
Why It Matters
During his Nobel laureate lecture, Pääbo explained why he thought studying Neanderthals is so important. The one reason that stuck with me most was that Neanderthals, in a way, “define” humans. They are our closest evolutionary relatives. The areas where we converge and diverge as species holds a lot of significance, both biologically and, in my opinion, philosophically.
Thousands of poems have been written about the human condition, yielding the broad tool of literature to capture what it means to be a human. Pääbo and his team have tried to answer this question, but using a more precise tool: science.
More concretely, Neanderthal contributions to our genomes have some very real consequences. For instance, a study of an ion channel — a pathway for ions to travel in and out of cells — showed that having a Neanderthal variant of this channel was related to experiencing more physical pain.
Recently, it was found that having a Neanderthal gene variant is a risk factor for severe COVID-19. Interestingly, this variant is found in half of people in South Asia while its frequency is incredibly low in Africa.
As work on how Neanderthals and Denisovans have contributed to modern humans continues, we’ll continue to better “define” humans, and perhaps better understand human physiology along the way. Biology is always full of mysteries but combine that with history and anthropology and we’re left with enough mysteries to last us the rest of time.
About the Author
Parmin Sedigh is a stem cell and science communications enthusiast. She’s also an incoming second-year student at the University of Toronto, studying life sciences. You can usually find her on her computer following her curiosity. Connect with her on LinkedIn.
