Scientists Discover a Single Gene Alteration That may have Separated us from Neandertals
One single gene alteration in the brains of modern humans may be all that separates us from our extinct Neanderthal cousins, according to a new study.
Researchers catalogued differences between the genomes of diverse modern humans and those of our long-dead cousins – the Neanderthals and Denisovans.
They found 61 genes that were different, with one – NOVA1 – the key to what makes us ‘modern humans’ because it influences other genes during early brain development.
The researchers used the discovery to create a ‘mini brain’ that mimics a Neanderthal mind with stem cells. This enabled them to create a direct comparison with modern humans.
They found that the ‘Neanderthal-ized’ brain organoid ‘looked very different’ to that of a modern human, with a distinctly different shape and different protein functions.
This single genetic alteration could explain modern capabilities in social behaviour, language, adaptation, creativity and use of technology, the team from the University of California San Diego School of Medicine explained.
For the study the researchers, including lead author Alysson R. Muotri, set out to understand how the human brain evolved and differed from that of our extinct relatives.
Evolutionary studies rely heavily on two tools – genetics and fossil analysis – to explore how a species changes over time.
But neither approach can reveal much about brain development and function because brains do not fossilise, Muotri said. There is no physical record to study.
So Muotri decided to try stem cells, a tool not often applied in evolutionary reconstructions, to attempt to replicate a Neanderthal brain.
Stem cells, the self-renewing precursors of other cell types, can be used to build brain organoids – ‘mini brains’ in a laboratory dish.
Muotri and colleagues have pioneered the use of stem cells to compare humans to other primates, such as chimpanzees and bonobos, but until now a comparison with extinct species was not thought possible.
To create a brain they first needed to understand the differences in the genetic code of each of the human species under investigation.
They catalogued the differences between the genomes of diverse modern human populations and the Neanderthals and Denisovans, who lived during the Pleistocene Epoch, approximately 2.6 million to 11,700 years ago.
The researchers used CRISPR gene editing to engineer modern human stem cells with the Neanderthal-like mutation in NOVA1.
Then they coaxed the stem cells into forming brain cells and ultimately Neanderthal-ized brain organoids.
‘It’s fascinating to see that a single base-pair alteration in human DNA can change how the brain is wired,’ said Muotri.
/Scientists Discover a Single Gene Alteration That may have Separated us from Neandertals/