Artist's impression of a Neanderthal hunter. New evidence suggests the Neanderthals and modern humans interbred.
Credit: American Museum of Natural History
SYDNEY: Modern humans contain a little bit of Neanderthal, according to a new theory, because the two interbred and became one species.
The theory is the latest addition to the ongoing debate about what happened to this early species of human.
In a paper published this week in the U.S. journal Proceedings of the National Academy of Sciences, a team of European researchers report a "mosaic of modern human and archaic Neanderthal features" in 30,000 -year-old human fossils from Romania.
Co-author Erik Trinkaus from Washington University explains: "[Some] closely related species of mammals freely interbreed, produce fertile viable offspring, and blend populations." This is what appears to have happened with Neanderthals and modern humans, he says.
Shorter and stouter than modern humans, but with larger brains, Neanderthals lived in Europe, central Asia and the Middle East for about 170,000 years before disappearing between 33,000 to 24,000 years ago.
Their extinction coincided with the migration of modern humans out of Africa and across Europe. Few mysteries in the history of human ancestry have been as hotly debated as what caused the extinction of the Neanderthals.
Some scientific theories have Neanderthals dying out because they were less well-adapted to the climate changes that occurred across Europe at that time. Others cite evidence of a more brutal end, in which Neanderthals were slaughtered by modern humans.
This new study helps to settle the controversy. According to the researchers, the populations probably blended together through sexual reproduction. "Extinction through absorption is a common phenomenon," says Trinkaus.
The human remains were found in Pestera Muierii ('Cave of the Old Woman'), an elaborate cave system in Romania. First uncovered in 1952, the fossils remained poorly dated and largely ignored until recently.
Using carbon dating techniques, Trinkaus and colleagues found that the remains were 30,000 years old. Their analysis of the bones revealed diagnostic skeletal features of modern humans, including smaller eyebrow ridges, very narrow holes where the nostrils join the skull, and a shin bone that is flat on one side and concave on the other.
However the mostly human skeletons also possessed distinct Neanderthal features; features that were not present in ancestral modern humans in Africa. These include a large bulge at the back of the skull, a more prominent projection around the elbow joint, and a narrow socket at the shoulder joint.
Further analysis of one skeleton's shoulder showed that these humans did not have the full set of anatomical adaptations for throwing projectiles, such as spears, during hunting.
According to the researchers, this mixture of human and Neanderthal features suggests that a complicated reproductive scenario existed as humans and Neandertals interbred. The hypothesis that the Neanderthals were simply replaced should therefore be abandoned, they suggest.
Trinkaus says we may carry some of the genetic legacy of the Neanderthals within us. However it would be difficult to determine which of us are more closely related to the Neanderthals: "there has been 30,000 to 35,000 years of human evolution since then," he says.
Two or more Trbes of man
Possible Two or more tribes of human the out of Africa theory doesn't hold enough weight when you look at the comparisons between our DNA, Neanderthal DNA.
how it happened..
sexy neanderthal chick walks past two cro mags
"hey Ugg, would you hit that?"
*shrug*
and there you go..
Whats a species? Whats a hybrid?
Part of the problem here is that many people assume a taxonomic level of species differentiation has a relationship to actual interbreeding potential.
Paleo-species are determined on the basis of observed anatomical differences based on extremely fragmentary fossil finds from the archeological record.
A population biologist will tell you that the distinction between species is whether, quite simply individuals are actually, or potentially capable of breeding.
So it might be perfectly posssible for a time travelling anatomically modern human to breed with, say, a Homo erectus or vice versa.
Population biologists think of gene variation as clinal gradients within populations not as 'races' or 'breeds' 'varieties' or species barriers.
The problems with the 'African' Eve hypothesis are multiple not least that it is really a biological metaphor for a particular kind of creationism.
Concentrating on mtDNA to tell this story of creation will not stand the revelations of possible recombination of mtDA, nor can it provide answers to the far more complicated evolutionary questions posed by recombining autosomal DNA.
A simple way of explaining this is to ask who did this African Eve born (perhaps)160,000 years breed with? and who would she have been capable of breeding with?
Probably she bred with someone geographically and genetically close to her.
But as she did not represent a speciation event I have never understood this over reliance on mtDNA.
She might well have been capable of breeding with populations of late homo erectus in Asia or she might have had offspring fathered by her half-brother (or father).
Either way the entire lineage of her mates' mother's mtDNA would be lost forever but not their autosomal DNA subject to sexual and natural selection.
To show how silly mtDNA creation stories are we can look at the latest view of the origin of the domestic cat.
We are told that it is not descended from either the African or the European wildcat but from 5 female near Eeastern cats in Mesopotmaia 9,000 ya.
This is dumb as any cat breeder will tell you. I have a Bengal/Maine coon cat and I know that it has two lineages of wild cat admixtures, one from an Asian Leapord cat only 4 generations ago. The Asian Lepord cat is a viverine a different genus with a split time from felis about 5-6 million yr ago.
No doubt my cat having been hybridised with a domestic cat has its mtDNA from Mesopotamia and as genetic testing stands there is no way of 'proving' the incredibly well documented hybridisation.
Morphologically and behaviourally my cats wild cat admixture is obvious (how common are cheetah spots and a mutation allowing him to run down trees head first on British Moggies?) yet genetic testing of autosomal DNA is in its infancy.
To my mind the most compelling evidence for neanderthal genetic input into modern human populations (aside from the obvious shared morphological features in neanderthals and eurasian populations that need more than a statement of parallel or convegent evolution to adequately explain) is the recent work on introgression of genes coding for microcephalin.
This is dynamite, revolutionary stuff for paleo-anthropologists (but not a surprise for population geneticists).
Perhaps finally human evolution will walk out of the bone closet and catch up with modern genetics, that together with population geneticists and anthropologist can start to put together the complex mosaic of ancient and modern that the human species represents.
(for a comparator look at the research on the genetics of British populations and how a sociological fact like an apartheid style society in early anglo-saxon England could have produced a massive increase in 50% germanic y chromosome haplotypes in just a few generations with just a 5-20% founder population)
Neanderthals might not have contributed much to modern European genomes but it seems that for at least one gene with a highly adaptive trait it has been highly significant.
mettaculture
Guessing game?
Regarding:
"Science is not a guessing game."
Submitted by Visitor on 31 August 2008 - 8:57am (on page 2 of comments)
Science arrives at practically useful theoretical models by testing hypotheses. Hypotheses represent the results of highly informed and intelligently structured guessing games. Science evolves via hypothetical "guessing games" that are then exposed to something metaphorically equivalent to an accelerated version of natural selection. It's called testing hypotheses.
Interbreeding, red hair, and prediction
Red hair is on both sides of my family, and all three kids have red hair. Interestingly, my mother was the only one of three sisters who was able to have children. My sister and I were also unable to have children. The cause in most of our cases was endometriosis. Interestingly, we have also inherited a whole passle of both homozygous and heterozygous recessive genes, some of which can be harmless but in my case they do cause problems. My family is Nordic/Scandinavian, from near the Artcic Circle, on both sides. My prediction is that when they finally do map the Neanderthal genome, the nearest human "match" will be brown-eyed redheads. They are disproportionately prone to things like ADHD, genius, autoimmune diseases, and so on. And if these genomes are compared, it may be that the brown-eyed redhead and the Neanderthal are very close indeed.
Nordic Girl
Neanderthals live among us.
My uncle is a Neanderthal.
Cultures
Europeans were lacking in any advanced culture if measured by speed in comparison to the ancient Chinese, some middle-eastern cultures and Egypt...
It wasn't until the Greeks did the Europeans gain any momentum for cultural advancement worthy of the http://www.cosmosmagazine.com/comment/reply/814word "civilized"
Neanderthal man and the bibles early predictions.
Funnily enough the King James sports a passage apparently a word of caution from god. I always wandered what it meant. The passage reads something like. Go forth and multiply but do not breed with the giants of the earth.
and another 'There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown'
Could these passages along with many others suggesting giants walked the earth refer to Neanderthal man.
Loved reading all this stuff
I am not a scientist but the subject has always interested me. I have read most of your comments and I find them fascinating and educational. I still go with the interbred theory. A H.Sapiens woman may very well have been attracted to a Neanderthal simply because he was bigger and stronger. Or, with an understanding of males throughout history, any port in a storm.... I am sure they attempted it, and it's quite possible some produced viable fertile female offsprings.
Okay, now for a laugh. You guys need to lighten up.
I am sure I dated some Neanderthals in my day.
Interbreeding? Very likely.
First of all, you must take into account the "INSTINCT" of the male of the species. When I was a teenager, I would go rabbit hunting with a dog. If that dog was a female, it would spend all of it's time hunting. But, if it was a male, it would only spend half it's time hunting, and the other half, "looking for someplace to PUT IT". Including the knot-hole of an old pine stump. Let me tell you, freeing a male rabbit hound from the knot-hole of a pine stump is very interesting, but another story.
Now, look at all the "sex-offenders" we have today. We seem to think that prehistoric man lived by a code of conduct, and such things were taboo. I would suggest that it would be far more realistic to consider that the male of the species would have been looking, much the same as those hunting dogs, for a place to put his as well. If Neanderthal woman was in the vacinity, she would have been "fair game".
The fact that Neanderthal once ranged far and wide across Europe and
Asia, then the last stronghold of Neanderthal seems to have been Iberia, would suggest to me that there were often confrontations between Cro-Magnon and Neanderthal. In any confrontation, Cro-Magnon had Neanderthal out-gunned. Superior weapons and technology, where Neanderthal did not throw his spear, and Cro-Magnon even had a device that increased the range of his spears, Neanderthal would have been beaten before he got close enough to use his spear. And, of course, to the victor go the spoils.
So, what spoils would Cro-Magnon have been interested in? A wooden tipped spear? Crude stone tools? Not likely, but the women would have provided increased sexual activity, even if there was no reproduction. The almighty orgasm that has moved countries to war since the beginning of time. (Helen of Troy) If reproduction took place, it did. If not, it didn't. I really don't think Cro-Magnon male really cared one way or the other.
Each time a conflict took place, Neanderthal's male number dwindled, and the women may have been taken as slaves to serve their new masters. Can you spell, "FIRST HOMINID TRAFFICING"? Without laws to the contrary, and a police force to enforce them, it's highly likely that this scenerio would be far more fact than fiction. And, as such conflicts sprung up across the rest of the world, Neanderthal's last band of survivers were reduced to Iberia.
From all the other theories I've read, this one has been left out, and is just as valid as any of them.