Scientists Map Neanderthal Genome 229
goran72 writes "In a development which could reveal the links between modern humans and their prehistoric cousins, scientists said they have mapped a first draft of the Neanderthal genome. Researchers used DNA fragments extracted from three Croatian fossils to map out more than 60 percent of the entire Neanderthal genome by sequencing three billion bases of DNA."
Re:Ethics and cloning (Score:5, Informative)
Just because they may look structurally similar to humans, they aren't human.
I really, really hope this is a troll; the same has been said of Jews, Black people, Irish, Native Americans and many more.
That is not what you think :-) (Score:5, Informative)
On a serious note, there are a few scientific issues at stake here.
First let me explain this "positive selection" stuff from the article. When a mutation within a coding region of a gene takes place, it can either be a silent mutation (no change in the resulting proteins) due to the redundancy of the genetic code, or it can change the amino acid sequence of the protein and thereby possibly its function.
Now, mutations happen at random. But depending on what kind of an effect the changes have, they might be wiped out by natural selection. For example, mutations in the "core system", the "kernel" of any living cell -- replication machinery usually are wiped out, because the machinery is so finely tuned that most mutations seriously screw it up. If the changes are largely neutral, the ratio of the mutations that have an effect divided by mutations that are silent (so called dN/dS ratio) is roughly equal to what we would expect based on random model, and we speak of neutral evolution.
On the other hand, environmental pressure, change of times, parasite pressure or many other things can lead to an accelerated rate of evolution -- measured by the fraction nonsynonymous mutations / silent mutations. Thus, one can detect whether a species, gene or genome was subjected to a specific pressure. And if we look at the whole genome, we can tell a lot about what this pressure was. And of course, it works both ways -- we can tell a lot about what the pressure was that shaped us, humans.
* of course, learn more about neanderthals -- who were they, did they mix with humans (current analyses say no, but who knows what one can find in the whole genome). Were they human at all? Did they really talk? What kind of culture did they have?
* by learning about divergence between neanderthals and homo sapiens, answer the fundamental questions of biology -- who are we? what makes us different from animals? What made us spread and neanderthals disappear?
* analysis of genome instead of single genes takes the whole thing up one level.
* tracing back evolution (in general, it is not only about human evolution) -- not by comparing sequences of organisms that live nowadays, but really going back in time. Among others, this will let us test the tools that we routinely use for phylogenetic analysis (that is, tracing back the evolution).
Regards,
j. (who currently works on genome evolution in bacteria)
Re:Ethics and cloning (Score:3, Informative)
"Neanderthals are probably not any different in that way (it is probable, though, they disappeared because we humans killed them off)"
One _theory_ is that they disappeared because we (or rather, Cro-Magnon Man, who also disappeared around 8,000 BCE) killed them off, but there are plenty of other theories which are equally probable in that none of them have much in the way of supporting evidence. The only real answer to the question of why they died out is therefore the same as the one for so many other extinct lifeforms, i.e. we do not as yet know why they disappeared.
"they're a different species (which means they can still interbreed with humans and produce fertile offspring)"
Nobody as yet knows whether they could interbreed with Cro-Magnon man, or for that matter, other early human ancestor species that existed at the same time (e.g. late period Homo Erectus). It should also be noted that even if we could interbreed, there's a distinct possibility that any offspring would have been sterile, so Neanderthal genes from cross-breeds might not have been passed on to subsequent generations.
A good example to consider here is chimpanzees and their close relatives the bonobos, both of whom are very, very similar to humans at a genetic level. There is however no scientific evidence to suggest that we could successfully interbreed with them using purely natural means (i.e. without some form of genetic engineering), even though some other closely related species such as polar bears and brown bears not only can, but sometimes do interbreed, even in the wild.
Re:60 percent (Score:5, Informative)
Since neanderthals are much more related to humans one would expect the number of gene orthologs between humans and neanderthals to be between 98% and 100%. All the genes they mapped will probably genes that humans also have, the interesting bits may come from differences in those genes between the two species. And of course the genes that humans have and naederthals not (or vice versa) but my guess is they haven't mapped those yet. It's easier to map a gene if you know what you're looking for (human ortholog).
Re:FOXP2 (Score:3, Informative)
FOXP2 is responsible for "language development" with songbirds and other animals(*), too. If your logic would be correct, birds would talk like humans - which they obviously don't. (*)
The FOXP2 protein sequence is highly conserved. Similar FOXP2 proteins can be found in songbirds, fish, and reptiles such as alligators.
see here [wikipedia.org]
Re:FOXP2 (Score:5, Informative)
Yes, it is fascinating, but you have to take into account that FOXP2 is a transcription factor that acts when "collaborating" (dimerising) with other transcription factors (or itself) to regulate a whole range of different genes, which in turn can affect a whole range of physical (phenotypical) features (like speech development). True, people who have a mutation in FOXP2 are normal, but are not able to coordinate the movements required to speak, and this is a quite specific effect. But FOXP2 has definitely other "applications" as well - it is required for correct brain development in general, for example.
This makes any changes (or lack of them) very hard to trace back to specific effects. The fact that neanderthals had the same "version" (allele) of this gene might be an indicator, but then -- it might just be a coincidence. Chimps are just two mutations away.
What complicates the picture even more is the fact that not only the actual sequence of the protein matters -- also the regulatory sites around it (where other transciption factors bind and promote / inhibit the activation of FOXP2). And these tend to be variable even when they work very similarily.
j.
Re:FOXP2 (Score:5, Informative)
Having or not having FOXP2 is not the point. The point is that neanderthals had exactly the same allele, the same sequence of FOXP2 that we humans have. And that small changes to this sequence render humans speechless.
In other words: having a gene for eye pigmentation does not make you blue-eyed. But having a particular version of this gene can. Some people think that this particular version of FOXP2 is necessary for correct speech development.
j.
It's not about appearances (Score:5, Informative)
It's not just about appearances. The Neanderthals:
- used tools to make other tools. Apes do make improvised tools like sharpening sticks, but only Neanderthals and Homo Sapiens would build a stone axe to use to build a stone spear, and then keep both.
- skinned animals and tanned the skins
- built elaborate shelters out of wood and skins
- used clothes (e.g., made from those skins)
- built (crude) musical instruments. And not just as in "something that makes noise", but as in, for example, a flute which can play more than one note. So they probably had music too.
- had a bit of work specialization, which would also mean a bit more complex a social structure, and possibly even some kind of commerce (at least as in, "I'll make you a strong spear if you give me a leg of antelope.")
- decorated themselves with primitive jewellery and paints (basically early cosmetics)
- had ritual burial, which would indicate some concept of afterlife or at least remorse. (You don't bother burying someone in the same position, and with his weapon, and stuff, unless you expect it to matter somehow.)
Etc.
And according to this research, they probably were as capable of speech as the humans, because they have the same gene.
Oh, and another bit of trivia: they actually had a higher average brain size than Homo Sapiens. And in a smaller body, too. So if we go by the popular brain-mass/body-mass metric, they should actually be a little smarter on the average.
So we're not talking just as in "looks like a human", but something that was definitely just as sentient and self-aware as a human. It could probably not just understand that you're experimenting on it, but understand the experiment if you bother explaining the science behind it.
And if you think that it still makes it ok, because it's still a different species... well, then I'd say your empathy is too broken to be the same as 99% of the humans. You're different. When can we start experimenting on _you_ then?
Re:That is not what you think :-) (Score:3, Informative)
Of course it isn't ignored. It's a whole field of research. And yes, there are plenty of tools, some of them quite old (and most of them requiring maths).
Question whether there was some degree of genetic exchange between Neanderthals and humans have been already asked decades ago -- and most probably, already answered. The answer is based on the sequences that have already been obtained and it is a "no".
j.
Re:what if (Score:3, Informative)
According to what was said on NPR this morning, there is less than a 1% difference between the human genome and the neanderthal genome.
The fact that there is a difference at all shows we and they were two distinct species. This doesn't even take into consideration the 2-3% difference between humans and chimpanzees.
Re:what if (Score:4, Informative)
By definition, two species are distinct if they cannot breed and produce fertile offspring. The whole point of this research is to determine whether this is true or not. So this:
The fact that there is a difference at all shows we and they were two distinct species.
misses the point entirely. You and I have different dna. Does the fact that there is a difference at all make us separate species? I very much doubt it.
The whole question being researched is precisely this: how much difference was there between neanderthals and modern humans, and was it enough of a difference that they could not have interbred. It is the inability to interbreed and produce fertile offspring, not the presence of any difference at all, that determines separate species status.
Re:what if (Score:4, Informative)
According to the researcher they had on NPR this morning, that question has not been answered. Here [npr.org] is the NPR link. The third paragraph talks about the divergence between humans and neanderthals. The next to last paragraph mentions the question of interbreeding. You of course can listen to the entire broadcast by following the link at the top of the article.
You and I have different dna.
That is true as individuals, but as we are both humans, we have the same overall genome and so could breed (assuming male-female of course). With neanderthals having a slightly different genome than humans, there could be enough of a difference to not have allowed that to happen, especially since we and they diverged to two different branches just as we and the great apes diverged even earlier. Obviously, those in the know will have to make that determination.
Re:That is not what you think :-) (Score:3, Informative)
Some of the world's leading authorities on Neanderthals disagree with your "no."
In particular, they point to the Lagar Velho skeleton [wustl.edu].
"the analysis has revealed that the child exhibits distinctive characteristics of both contemporaneous European early modern humans and preceding Neandertals. It therefore provides evidence of previous admixture between Neandertals and early modern humans in southwestern Europe."
Re:I kinda doubt it (Score:3, Informative)
It looks like that Wikipedia page may need to be updated. From TFA:
"The analysis showed it is highly unlikely that much interbreeding occurred as there was "very little, if any" Neanderthal contribution to the human gene pool, said lead researcher Svante Paabo of the Max Planck Institute."