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Tracing our Neanderthal ancestors

Thu, 30th Jan 2014

Kat Arney

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DNA from modern humans and Neanderthals reveals ancient interbreeding of the two species.

As the success of family history TV programmes shows, adult Neanderthalwe seem to be endlessly fascinated with our ancestors. But tracing your great-great-great-great aunt is nothing compared to what scientists have announced this week.

A pair of papers published in the journals Science and Nature, looks at how our Neanderthal ancestors have left genetic traces in our genomes today.

Modern humans, Homo sapiens, and Neanderthals split apart in Africa more than half a million years ago. But while humans stayed in Africa, Neanderthals went off to explore Europe and Asia.

When we finally left Africa less than 100,000 years ago, there's good evidence that these early adventurers interbred with the Neanderthals living between Western Europe and Siberia.

Comparing DNA from Neanderthal bones with our own tells us that around 2 per cent of the genomes of people descended from non-African populations is Neanderthal.

The Neanderthal genes are scattered across the genome, and different people have different ones. Previous research has pinned down a few of these, for example genes involved in responding to infections or UV radiation from the sun.

Now the new research, from two separate teams of researchers in the US, has looked at much larger parts of the modern human genome that probably came from our Neanderthal cousins, who died out around 30,000 years ago.

The scientists used computer programmes to pinpoint sequences in our modern DNA that looked like they were much older, and compared them with the Neanderthal genome to pick out regions that probably came from them.

One team of researchers found about one-fifth of the Neanderthal genome spread across the genomes of more than 600 currently-living Europeans and East Asians, while the others put together about 40% of the Neanderthal genome from the DNA of more than a thousand living people.

The data shows that while this interbreeding may have given our human ancestors useful genes for coping with the cold of northern Europe, the downside was that the Neanderthal/human hybrids probably had fertility problems.

There's also evidence that Neanderthals gave us gene variations linked to certain diseases, including type 2 diabetes, and depression, as well as immune system-related diseases such as lupus, biliary cirrhosis and Crohn's disease.

Curiously, the scientists also found that Neanderthals gave us smoking addiction, although this gene is probably involved in some other biological process, as there's no evidence at all that they liked to light up a cigarette in their caves.

Some genes are found in humans and not Neanderthals. One intriguing example is the gene FOXP2, involved in speech and language, which is in our DNA today but doesn't seem to exist at all in the Neanderthal genome.

There are also big chunks of the Neanderthal genome that are nowhere to be seen in our modern human DNA, suggesting these genes were harmful for us.

So far, the researchers have only looked at comparisons with Neanderthals and modern humans from populations that came out of Africa. But it would be interesting to look more closely at the genomes of modern Africans, as well as people all over the globe, to see if there's any more evidence of interbreeding with long-extinct populations way back in our family trees.



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If Neanderthals could and did interbreed with sapiens then it becomes clear that they were not separate species after all. And since Australian aborigines are essentially homo erectus then that would mean they were not a separate species either.

Methinks the scientists need to correct their terminology.  Otherwise one will conclude that our negro cousins are not truly homo sapiens either. There is no appreciable difference between calling Neanderthals a different species and calling negroids a different species.

If you are going to use terminology then make it consistent. Just because there are no living Neanderthals is no reason to be up front about it and then say something different when the exact same situation is presented with living members of another "species".

Either call them an extinct race or start calling their modern counterparts separate species. Either way, but the inconsistency is extremely annoying. I do not care what is chosen, but chose one for goodness sakes. You can't call one a species because they are all dead and another a race so they will not get their feelings hurt. It is scientifically dishonest. OokieWonderslug, Thu, 6th Feb 2014

The most recently announced research suggests that humans and neanderthals were right on the edge of being different species, and their offspring may have been of low fertility - similar to what happens when donkeys and horses breed, but to a lesser degree. This conclusion is based on the lack of neanderthal genes on modern human X and Y chromosomes.

Here is a quote:
"The team showed that the areas with reduced Neanderthal ancestry tend to cluster in two parts of our genomes: genes that are most active in the male germline (the testes) and genes on the X chromosome. This pattern has been linked in many animals to a phenomenon known as hybrid infertility, where the offspring of a male from one subspecies and a female from another have low or no fertility.

'This suggests that when ancient humans met and mixed with Neanderthals, the two species were at the edge of biological incompatibility,' said Reich, who is also a senior associate member of the Broad Institute and an investigator at the Howard Hughes Medical Institute. Present-day human populations, which can be separated from one another by as much as 100,000 years (such as West Africans and Europeans), are fully compatible with no evidence of increased male infertility. In contrast, ancient human and Neanderthal populations apparently faced interbreeding challenges after 500,000 years of evolutionary separation." cheryl j, Thu, 6th Feb 2014

Did the Neanderthals carry the Chromosome 2A/2B fusion?

Ok, according to this article, Denisovan and humans both have the Chromosome 2A/2B fusion.  They extrapolate from the data that the Neanderthals likely also carried the Chromosome 2A/2B fusion, and that the fusion occurred at an earlier time in human evolution.

The equines (horses, donkeys, zebras) have troubles with interbreeding because of different numbers of chromosomes, producing sterile offspring. 

Most canines (dogs) have the same number of chromosomes and can generally interbreed.  Foxes have different numbers of chromosomes, and can not produce fertile offspring with the dogs.

Anyway, there is a big difference between Neanderthal/Human hybrids, and mules. 

It is possible that if Neanderthal genes were related to several genetic disorders,  type 2 diabetes, Crohn's disease, lupus, & biliary cirrhosis (from the article above), that the issue was not fertility, but rather often unhealthy offspring, many of which failed to breed. CliffordK, Thu, 6th Feb 2014

Apparently people of non-African descent have about 2% of their genomes from Neanderthals, whereas the Africans have virtually none (as the Neanderthals had left Africa before the homo sapiens later left Africa and met them). 

With the "out of Africa" theory, it is quite possible there was much greater mixing in the gene pool within Africa.  Even those that were generally isolated might mix it up a bit every thousand years or so.  The greater isolation occurred with migrations to Europe and Asia, and thus Neanderthals and Homo Sapiens co-existing.

At this point researchers are struggling to recover quality nuclear DNA from hominid ancestors.  It is quite possible that we won't recover good DNA from much earlier hominids than the Neanderthals and Denisovans. 

There will be some that will be able to be done with protein sequencing of demineralized bone, but the data will be limited.

CliffordK, Thu, 6th Feb 2014

I don't think the genes that humans acquired from Neanderthals were necessarily unhealthy at the time. The genes that result in type II diabetes today (with our abundant and carb rich food supply,) may have been very beneficial when humans migrated out of Africa to colder climates, as were possibly the genes related to skin and hair. 

But the point I was making in reference to Ookiewonderslug's comments was that the division between species vs subspecies may not be all or nothing, but a bit more fuzzy for a period of time in evolution. And that is what the authors of the article I cited were saying as well - that when humans and Neanderthals met up, they were almost, but not quite, biologically incompatible.

Here's an article from Nature

Modern human genomes reveal our inner Neanderthal
Cross-breeding boosted Homo sapiens' ability to cope with cool climates, but the hybrids may have had trouble breeding.

cheryl j, Fri, 7th Feb 2014

The entire debate underlines the fact that "species" is not a defined term, any more than "race" is. We can assign living things to large arbitrary groups based on appearance but such assignments are of little predictive value. At the other end of the telescope we can in principle write down the entire genome for any individual, and this should be predictive, but in practice it is very difficult to do.  alancalverd, Fri, 7th Feb 2014

Silly question really, if you examine Homo "Sapien" (wise ??? - does this mean educated or clever???) and its relentless use of genetic filters to select a mate at the primary point of instigational motivation to breed.
Its selection criteria and boundaries of  i find no different to that of a small dog in the background of  a "FAILs compilation video" on youtube i saw, of the selection to breed was a rubber beach ball around the same size!
(incidentally (and i say dentally) FAIL compilation videos give great in-site into the accuracy levels Homo Sapiens have in this advanced modern developed(evolved) era at how to make a good decision with the evidence in front of them).

There seems to be something in what you say....hmmmm....
So if this is the modern "surviving" Hominid  "in progress" at making a decision surely it can tell us that a creature with a less educated and less accurate smaller brain could perhaps die out from its decision of breeding choice.
Why a modern present day dog (Canis Familiaris and Canis Lupus) is not a good depiction or comparison(meaning for use as a less capable and less intelligent creature alike a Neanderthal but something we have at hand at present to use to test with) is that it both has survived to the present day and era, and it has an encephalization  quotient rate of brain evolution reasonably identical to the rate of Homo Sapiens as the video link clearly shows(at 3:58) and the same is shown by modern humans here {the explicitness is "so the demonstration does not miss the defined point"! }
(note: buying p/piece in bulk can reduce the price and allow greater numbers of them for use at such an action but does not do much to propagate a personal family sub species).
Only Alpharisms' social community system could really explain how a species becomes extinct at such short or sudden time, it has the principle of one functional method of thought similar to instinct, that is to "copy" a better, such as babies do with parents, and in the higher level of it, Alpharism has the complete group "obliged" to copy.
The principle, "effectively" if we were to test groups by getting the Alpha to commit the mentioned here above and below in this post, in front of its group, we would/should see whole groups performing the same.
The video link does also establish some bizarre techniques may seem useless but do have some merit given by success(at 6:11),
And finally, all life evolved in the ocean and at some time humans ancestors left the oceans and arrived from the ocean(at 6:58). nicephotog, Sun, 9th Feb 2014

I agree that it is arbitrary. That was my point. I think there should be some solid definitions to the terms and we should follow them. We all have 2% Neanderthal DNA. So that proves they could breed with us and have viable offspring. The morphological differences in skeletal structure are no more than the differences between races today.

We should be calling Neanderthals and Denisovians extinct races. Or we should be calling our African and Asian counterparts different species. Either way, doesn't matter to me. But we need to be more consistent with our terms.  OokieWonderslug, Sun, 9th Feb 2014

'kn A... What has always disturbed me is in multi cultural countries such as Australia or the United States is the "appearance" of any individual by skeletal morphology says that outright nothing is impossible at the bare level of "not deformed" in a mechanically functional construction of any person. Some countries do have a "face" so to say, but the mechanical structures in those too indicate without bothering to measure, but "the species" may mean nothing by point of increment ratios of the skeletal structure.

I have always objected to another point about modern human being called "Homo Sapiens" meaning "wise" as the previous mentioned video of FAILs suggests, they are not particularly wise.
They often operate by trial and error and i have always believed it were better called "Homo Cautus" Cautious since its implication is there is some wisdom and some ability to complex reason but are generally in most cases no more than that ever.
It rates a massive megalomanial self gratuity for the self in the mirror to use Sapiens .
Homo Alpha for its behavior all through documented time appears a better choice again than Sapiens. (An immense short-cut to the point )

One point of difference between Neanderthal and Sapiens is speech gene mentioned in the article which i presume relates auralization and the ability to clearly produce sound by the shape of the throat and mouth and the control the associate muscles.
That itself is separated by modern DNA technique alike domestic dog from wild dog 300,000 years previous, but in many ways and nothing much more than skeletal is the difference, and again though in parallel with humans it appears the brain physically, and then again by that in applied thinking differences is the main difference between wolves and domestic dogs or Neanderthal and Sapiens.
So if you want to pick the differences based on what little is different by evolution look at this and consider there are real differences(inclusive skeletal that are not mentioned the following video) but not much.
(note: There is an interesting hiccup in their research in this video with the cattle dog and Australian law. It regards the seriousness of the offence of a dog found wandering and going beyond the family home fence. Cattle dogs are the breed of highest statistical "bite attacks" and require severe authoritarian assistance about boundary and territory and obedience to help prevent attack! so it is unclear how much that fence is affecting the test, second it may have learned not to touch another dogs food as an enforced rule too!) nicephotog, Sun, 9th Feb 2014

I think the FOXP2 gene codes for more than the ability to physically form the movements of speech, but also grammar. (a quote from Nature: "It isn't clear exactly what FOXP2 does, but in humans, mutations in this gene are known to cause a severe language problem in which affected individuals cannot grasp grammar and do not have the ability to control mouth movements to make words.")

Anyway, it's odd that the article on this site didn't make a bigger deal about it, because if you google it, there are articles from 2008, saying Neanderthals do have the FOX2P gene. Was it contamination?

Anyway, I don't know how you make up a perfect rule for separating species that only looks at morphology, and not function,  or only looks at DNA similarity but doesn't take into consideration what those genes actually do.

To me, language is a deal breaker, as far as calling Neanderthals and humans the same species, even if they could produce offspring, but that's just my opinion. cheryl j, Sun, 9th Feb 2014

As much as interbreeding, i really can only see that as a .."Silly question really"... because even if there were fertility differences at least one of the two parties to this day has surviving offspring with the other so called species that did want to go(of which the FOXP2 has left someone speechless about it).
I maintain ... fertility schmillity:

As for FOXP2 it's only southern US whites with Histrionics problems complain about this:

In determination of species differences that's up to whoever sets the rules. So perhaps the definition would be a good idea here, but in general i would have thought they were two extremely distinct sub species if there is dispute(my real way of reading some of that idea) but they can interbreed is stated, of which that comes to be how the DNA survives in people today.

At much risk of hijacking a thread a piece:

Of FOXP2 and the possibility there can be such a matching sequence (obviously not in species context), could there be an equivalent in dogs?
In the video "dog brain"they did mention how many words some dogs know the meaning of but they did mention they had done tests to indicate that for some dogs.

Trouble with FOXP2's usage characteristics causing me to wonder this next, is  from my personal experience that my first indication attempts to communicate by speech or mimicking back sounds by dogs and perhaps wolves(i have other theories about wolves) has come from puppies my dogs have had or pups i have acquired.
When Heidi had her first set of pups(back around 1985) they were in a box i put near the TV in the afternoon when a cartoon called "the trapdoor" was on. When some things occurred, one of the characters would laugh and it would echo through the dungeon. One day i heard the laugh and the pups were making a squealing noise in time with the laugh. A few days later it had developed to a weird noise similar because their throats can make sounds that deep. One of them had also learned to call out the characters name, which jumped me out of the chair because for a moment i thought someone else was in the house.
But all in all, Wally whom died around 1984 was a sausage dog and almost says the word "hullo"(sound more like a Chinese person saying hullo) as greeting whenever we comes back from town.
Here's a video of a creature whom i unfortunately never had filmed her in one of her states of actually mimicking voice and words but you can from some of this film understand her voice box as a canid is different.

She made immensely strange noises more than ever bark as you can here in this one. She was stolen from me when she was around 5 months old.

In this one the vocalisational aspect is much more pronounced but really you've heard nothing compared to what i have, there have been almost audible sequences copied from probably the children in the house she came from who obviously one sibbling is bigger than the other, and when she was worried for the first week i had here and had to grab her that's when the noises and imploring seemed to spill out.

She never makes any of the right noises, only barks when she's tied up and doesn't want to be. This one has some fantastic weird noises too!
For whatever reason she was able to pronounce words very well at 3 months when i got her. She was 5 - 5 1/2 months when she was stolen.

Dogs that vocalise in some way are often an old party trick before video and as much youtube material as entertainment.
But some really do much better than others at it for some reason, not dissimilar of likeness to the difference between Neanderthal and Sapiens!
It's a point that is not particularly funny to have overlooked in real terms of science.
nicephotog, Sun, 9th Feb 2014

I read an article that said that while kittens meow to attract the attention of their mother, they don't meow to one another after a certain age, but they do meow to people. And it's odd, that my cat's meow has speech like inflections, going up at the end like a question when she wants something or is looking for me in the house, but other times sounding more like a statement or exclamation. cheryl j, Mon, 10th Feb 2014

They are not deaf, they are babies , they are learning, they are certainly a multi cellular life form larger than a virus and perhaps thus more intelligent.
That's simply bonding, because to acquire the control and relationship it requires replacing or bettering the primary carer of is easy for a human the less self sufficient the cared for species. e.g. birds like Falcons and Eagles should just fly away and do not have much of a brain to think with but however are often trained to hunt and can be controlled by their human handler.
Stands to reason completely about your kitten, but about the dogs and wolves, it is quite something else, it probably can be done to some worthwhile effect to teach them to speak and an auditory ability to vocalize is there in many of them(I just don't know if anyone wants to hear the order at a take-away when going for a walk down the street! ). nicephotog, Mon, 10th Feb 2014

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