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Small genetic changes separate modern humans from ancestral brain development.
Our closest human relatives are Neanderthals (split from modern humans at least 500,000 years ago) and their Asian relatives the Denisovans (split from modern humans around 800,000 years ago). The differences between Homo sapiens and these other groups are encoded in changes to the amino acids which are the building blocks of proteins in our cells and tissues.
About 100 amino acids changed in modern humans after these splits and spread throughout almost all of us. The biological significance of these changes, however, is largely unknown.
Researchers in Germany looked at changes to six of these amino acids occurring in three proteins. These amino acids play key roles in the distribution of chromosomes to the two daughter cells during cell division.
Since the remarkable work done in sequencing the Neanderthal genome this study furthers our understanding of the subtle differences between these ancient humans and modern humans. It may also shed some light on the evolutionary advantages that eventually saw modern humans outlive Neanderthals and Denisovans.
Authored by researchers from the Max Planck Institute for Evolutionary Anthropology in, the results are published in Science Advances.
Read more: Cue the Laos Cobra cave tooth, first clue in the Denisovan hunt down under
To investigate how these six changes impact brain development, the scientists introduced the amino acids from modern human variants into mice. Interestingly, in those six amino acid positions, mice are identical to Neanderthals. That makes mice brains perfect for testing what happens when these amino acids are changed.
Lead author of the study, Felipe Mora-Bermúdez, says the changes result in more accurate transfer of genetic data in cell division. “We found that three modern human amino acids in two of the proteins cause a longer metaphase, a phase where chromosomes are prepared for cell division, and this results in fewer errors when the chromosomes are distributed to the daughter cells of the neural stem cells, just like in modern humans.”
The team also checked to see if the opposite would be true. If they replaced the modern human amino acids with those present in Neanderthals, would they see faster and less accurate mitosis?
They introduced the ancestral amino acids in human brain organoids. Organoids are miniature organ-like structures that can be grown from human stem cells in the lab which mimic aspects of early human brain development.
“In this case, the metaphase became shorter and we found more chromosome distribution errors.” According to Mora-Bermúdez, this shows that those three modern human amino acid changes in the proteins are responsible for the fewer chromosome distribution mistakes seen in modern humans compared to Neanderthal and chimpanzees. He adds that “having mistakes in the number of chromosomes is usually not a good idea for cells, as can be seen in disorders like trisomies and cancer.”
“Our study implies that some aspects of modern human brain evolution and function may be independent of brain size since Neanderthals and modern humans have similar-sized brains. The findings also suggest that brain function in Neanderthals may have been more affected by chromosome errors than that of modern humans,” adds co-author Wieland Huttner.
Svante Pääbo, who also co-supervised the study, adds that “future studies are needed to investigate whether the decreased error rate affects modern human traits related to brain function.”
This article was originally published on Cosmos Magazine and was written by Evrim Yazgin. Evrim Yazgin has a Bachelor of Science majoring in mathematical physics and a Master of Science in physics, both from the University of Melbourne.
Tiny genetic differences do make a massive difference to performance and capability. It’s why certain groups like living one way and other groups are suited to other ways. Not every individual in the group is exactly that way, but the group as a whole is. Stop trying to get Jack Russells to pull your dog sled, and don’t make your Husky hunt rabbits. Just because they are 99.99999% identical, does not mean they are interchangeable. This has been proven to hold true for all creatures.
Now get your bibles and throw them on a fire and keep warm. Repeat when cold
Are you into book burning? One of those are you?
I keep telling Christians that word doesn’t mean ‘day’ in Aramaic, and the story is pre-babylonian anyway. It’s not seven days, it’s seven periods, or as we would call them, phases.
The Torah never says how he created anything. I mean, “Let there be light!” *** BANG *** “Well that worked. Phase 2, make some thing solid to stand on. That’ll take a bit longer than detonating a bomb did.”
There is reason why it is called”the theory of evolution “,and not the fact.
That’s right Noel,
Because science doesn’t pretend to know all the answers , as in Einstein’s theory of relativity , E=MC squared ( all proven beyond doubt and much better validated than that book of old wive’s tales ,designed to frighten the children and the week minded )
In my theory of life, it is only Psychopaths and religious maniacs who are totally sure they are unquestionably right . Do you think that ,that’s where ‘right’ in right-wing comes from ?
Cheers, G”)
The theory of relativity is actually not proven, in fact it has lots of holes. Go talk to the Quantum Physics guys, or the guy who invented GPS, or the guys that study black holes. General Relativity fails all over the place. Works some times and not others, just like Newton’s work that preceded it.
I like Evolution, but there are holes cropping up there too, which annoys me. Too soon to tell. The issues with the Big Bang also annoy me. How about the surface ripples Nasa found on the Sun! The Sun could be liquid metallic hydrogen. I mean come on, why did I bother going to school.
The Theory of Relativity is the most successful theory in the history of Physics. It has stood unchallenged for a century. Relativity deals with the large scale of the Universe while Quantum Mechanics deals with the very small scale. It is no secret that Relativity and QM have not been resolved into a single Theory of Everything but QM is not a basis to claim Relativity is wrong.
GPS depends on Relativity to work so claiming that we should ask the guy who invented GPS shows you clearly don’t have any idea what you are talking about.
Newton’s Laws also work perfectly. They are simply a special case of the laws of Relativity in a static frame of reference at low speeds where Einstein’s equations reduce to Newton’s.
Evolution is also one of the must successful theories in science. In fact, knowing what we now know about the way genes function, an explanation would be required to explain why evolution didn’t work if that were the case.
Theory of Relativity – NASA proved the universe in actually flat with Wmap. Whoops
General Relativity should work everywhere there is space and time. You can’t scale it down!
Stars are made of sub-atomic particles, add all the quantum values and it should equal the measurements for the star as a whole. Whoops, it doesn’t even get close. And don’t try to put either of them near a black hole. Thus the search for a ‘Unified Theory’ to replace them.
GPS – I’m just repeating the inventors observations over decades of monitoring he did. They had to keep manually adjusting the clocks because they don’t get the right amount of dilation using the big man’s math.
‘static frame of reference at low speeds’ That’s an oxymoron. The errors are low enough at low speed to be bellow the margin of error of our engineering. They don’t disappear at low speed, they’re just to small to stop your steam train working so to speak.
The Theory of Evolution keeps having to be changed to fit observations, that’s how science works. It’s shaping up that evolution, and genetics as a whole, works very differently to the current ideas. Epigenetics alone has massive implications.
Now go watch the James Web Space Telescope blow the big bang theory out of the sky. It’s changed more in the last few weeks than has happened in my life time. I knew inflation was BS. To many things point to a much older Universe. Hopefully it will take out ‘dark energy’ next. Keep your eyes on the sky.
Right wing / left wing. Einstein’s the master of common sense.
forget the rest.
Relativity is common sense? Is quantum mechanics common sense?
If you understand the propagation of electromagnetic radiation it becomes clear that Relativity is the only way it can work.
James Clerk Maxwell knew the fixed frame of reference implied in his Theory of Electromagnetism was its fundamental weakness but didn’t know how to resolve it. Tragically, Maxwell died of abdominal cancer aged just 48, some 26 years before Einstein published his solution.
And these are things that people commonly have a sense of?
‘Relativity is the only way it can work.’ how do you know. Seriously, definitive statements in science are rare with good reason, I studied electromagnetic wave propagation (and antenna design), there are other theories about EM energy (and magnetism), so can you please point us to this revolutionary research you have discovered.
The genes discussed have the effect of increasing the accuracy of replication of other genes involved in the development of the human brain. In themselves they are not a reason for higher intelligence in Homo Sapiens.
They are conserved because other genetic changes involved in the brain were incredibly important and conserving those changes was imperative to prevent regression of our intellect.
Evolution involves a fine balance between highly accurate gene replication which avoids degenerative mutations and the potential for new possibilities made available by inaccurate replication. Sometimes the benefits of precision outweigh the possibilities of serendipitous innovation.
However reducing the potential for mutation can be detrimental in the long term because it limits the possibilities for adaptation.
So a tiny genetic difference can cause a massive change as time progresses, butterfly effect style. You should see the difference it can make to the development of a civilisation over centuries.