What is it Significant differences between modern humans and our close relatives, Neanderthals and Denisovans? For Neanderthals, there does not seem to be a clear distinction of any kind. He used sophisticated equipment, created art and established himself in some harsh environments. But, as far as we can tell, their overall population was not particularly high. When modern humans arrived at the scene in Eurasia, our numbers increased, we spread even further, and Neanderthals and Denisovans were displaced and eventually extinct.
With our ability to obtain ancient DNA, we now take a look at the genomes of both Neanderthals and Denisovans, which allows us to ask a more specific question: Could some of our differences be due to genetics?
The three species are close relatives, so the number of differences in our proteins is relatively small. But a large international research team has identified one and engineered it back into stem cells derived from modern humans. And the researchers found that the neural tissue made of these cells had a marked difference from the same tissue grown with the modern human version of this gene.
As a first step in their work, researchers had to decide on a gene to target. As we mentioned above, the genomes of all three species are highly similar. And the similarity only increases when you look at the parts of the genome that encode the protein. An additional complication is that some versions of the genes found in Neanderthal are still found in a fraction of modern human populations. What the researchers wanted to do is a gene where both Neanderthals and Denisovans had a variant and almost all modern humans had another one.
Out of tens of thousands of genes, he found only 61 who passed the test. The one he chose to focus on was called NOVA1. Despite the explosive-sounding name, NOVA1 Originally named after being found to be associated with cancer: Neuro-oncological ventral antigen 1. A glance through the vertebrate family tree shows that Neanderthals and Denisovans share a variant NOVA1 As with everything from other primates to chickens, it means that it was present in the ancestors that mammals shared with dinosaurs.
Yet almost all humans have a different version of the gene (in a database of a quarter million genomes discovered, researchers were only able to identify three examples of the Neanderthal variant). The difference is subtle – swapping of a closely related amino acid at the same place in the gene – but it is a difference. (For carers, this is isolekin in valine.)
but NOVA1 The type of gene is where small changes can potentially have a major impact. RNAs that are used to make proteins are initially composed of a mixture of useful parts separated by useless spackers that need to be ejected. For some genes, different parts can be put together in more than one way, allowing different forms of proteins to be made from the same RNA. NOVA1 Splicing regulates the process and can determine how many genes are formed in cells where it is active. For NOVA1Cells where it is active include many parts of the nervous system.
If that last paragraph was something wrong, the short version is this: NOVA1 Can change the type of protein made in nerve cells. And, since behavior is an area where modern humans may differ from Neanderthal, it is an intriguing goal of such studies.
Clearly, there are ethical issues with trying to see what the Neanderthal version would do in real humans. But some techniques have evolved in the last decade and now we allow this question to be adopted very differently. The first researchers were able to take cells from two different people and convert them into stem cells, which were able to grow any cell in the body. They then used the Crisp gene-editing technique to convert the human version of the gene to the Neanderthal version. (Or, if you’re less charitable, you can call it the chicken version.)