There are more than just the two species - there's also Denisovans and Floresiensis who appeared to be living next to Neanderthals and Sapiens. At this point I wouldn't be surprised if genetic evidence would show that pretty much all species somehow managed to leave their traces in our "modern human"-DNA pool - being directly responsible for the diversity and dynamics behind the development of our many different cultures and societies.
Photographs by David Liitschwager, National Geographic
Published October 21, 2013
In the ranks of prehistoric humans, Neanderthals were our closest relatives.
We were so close, in fact, that our species interbred with theirs. Tracing back our lineages, there must have been a last common ancestor of Homo sapiens and Neanderthals sometime in prehistory. (Related: "Geno 2.0 Can Reveal How Neanderthal You Are.")
But who was this mystery human?
Picking out direct ancestors in the fossil record is tricky. To figure out when the last common ancestor of Homo sapiens and Neanderthals lived, paleoanthropologists have been sifting through both genetic and anatomical evidence.
In the last five years, anthropologists have used DNA to reconstruct the evolutionary history of humans. Researchers have suggested a range of dates for when the last common ancestor of our lineage and Neanderthals could have lived. (Related: "Last of the Neanderthals.")
The dates range from more than 800,000 years ago to less than 300,000, with many estimates in the neighborhood of 400,000 years ago. According to some studies, this time frame would seem to match that of the extinct species Homo heidelbergensis, which has been found in Africa, Europe, and possibly Asia.
But this may not be so. A new study theorizes that the last common ancestor of H. sapiens and Neanderthals lived longer ago than previously expected, with fossil evidence yet to be uncovered.
In a study published on Monday in the Proceedings of the National Academy of Sciences, George Washington University anthropologist Aida Gómez-Robles and colleagues turned to teeth to test what had been gleaned from genetics.
Using a collection of 1,200 premolars and molars from a variety of prehistoric humans, the researchers pinpointed specific landmarks on the teeth. The landmarks were then used to reconstruct the tooth shapes of our common ancestors at critical points in evolutionary history.
The logic behind this method, Gómez-Robles says, is that "the most likely dental shape of an ancestral species is an intermediate shape between the one observed in both daughter species." In the case of H. sapiens and Neanderthals, the last common ancestor of both lineages would be expected to have teeth with a shape and anatomy in between those of the two species.
With that hypothetical shape in mind, Gómez-Robles and coauthors compared what was expected against fossils found so far.
"If a fossil species is very similar to the expected ancestral morphology, then that species is a plausible ancestor," Gómez-Robles says, though she stresses that such a match is a possibility rather than definite proof of ancestry.
Why is it important?
Estimates based on DNA show that the last common ancestor of H. sapiens and Neanderthals lived around 400,000 years ago. This made H. heidelbergensis, a widespread species alive at the time, seem like a good candidate for that ancestor.
The new study contradicts this idea. The tooth reconstruction of the last common ancestor of humans and Neanderthals created by Gómez-Robles and colleagues doesn't match the teeth of H. heidelbergensis.
In fact, the researchers found that none of the human species living during the time predicted by genetic data fit the tooth pattern generated by the new study. More than that, "European species that might be candidates show morphological affinities with Neanderthals," Gómez-Robles says, which hints that these humans were already on the Neanderthal side of the split.
This suggests that the last common ancestor of H. sapiens and Neanderthals lived sometime earlier, perhaps as far back as one million years ago.
What does it mean?
Paleoanthropologists have yet to find our last common ancestor with Neanderthals. Tracking this elusive human will require going back to museum collections and continuing searches in the field.
From the new study's results, Gómez-Robles says that "we think that candidates have to be looked for in Africa." At present, million-year-old fossils attributed to the prehistoric humans H. rhodesiensis and H. erectus look promising.
This critical window of human prehistory in Africa is still cloudy. "There are not so many African fossil remains dated to one million years ago," Gómez-Robles says, and those that have been found are often attributed to H. erectus.
But do they really belong to this species? There may be an as-yet-unknown human hiding in the mix, and this human may be key to solving the puzzle of when our ancestors split from Neanderthals.
Truth is, there are more than just the two species - there's also Denisovans and Floresiensis who appeared to be living next to Neanderthals and Sapiens. At this point I wouldn't be surprised if genetic evidence would show that pretty much all species somehow managed to leave their traces in our "modern human"-DNA pool - being directly responsible for the diversity and dynamics behind the development of our many different cultures and societies.
"...This made H. heidelbergensis, a widespread species alive at the time, seem like a good candidate for that ancestor... The new study contradicts this idea... At present H. rhodesiensis and H. erectus look promising."
Is this a joke? H. rhodesiensis and H. heidelbergensis are alternate names for the same species. This is common knowledge, folks.
The lack of evidence from Gómez-Robles and his team should really be taken into consideration. One study on tooth comparison just doesn't stand up next to years of fossil and DNA evidence, which has led paleoanthropologists to believe that H. heidelbergensis (AKA rhodesiensis) lived as early as 300,000 - 400,000 years ago and is most likely the common ancestor of us and the Neanderthals.
It would be interesting to know what the specific landmarks are that the study used. We have precious few Neanderthal teeth to look at and they are not unique nor are they all the same. Some Neanderthal teeth are not different from the modern norm for Homo-sapien.
Some Neanderthal teeth have shovel shaped incisors and so do many living humans. In fact there is a gene for that.
Some Neanderthals have taurodont molars and some do not. Taurodont molars range from 2% to 30% in modern human populations. Taurodont molars are characterized by a large or very large pulp chamber and short or fused roots.
Since the Earth is only 7000 years old, this seems highly improbable. I suspect the liberal media behind this hoax.
It seems a consideration of range would solve the dilemma. Homo sapiens emerged in southern or eastern Africa, while Neanderthal range was limited to southern Europe and the Middle East. The two ranges do not overlap. Therefore, the common ancestor must have been a species with a range that included parts of the ranges of both descendants.
Homo erectus is the species that fits the bill, which is now hypothesized to have been far more diverse and encompassing than previously thought. It's therefore logical to theorize that Neanderthal and Homo sapiens both branched off Homo erectus in different parts of the latter's range, inheriting local variations of the parent species. The picture was completed by some cross-breeding between the two descendants when their ranges overlapped.
I think that this theory of a glacially slow steady progression from one form to another is poorly supported when applied to human evolution.
If, for example we look at the dog world, we can see how rapidly a species can change when selected for specific traits.
And we can see that certain traits come as part of a package that changes a whole number of things that we would not have anticipated were related.
In hominids, rather than infinite variations in jaw and skull shape, there are only a few which actually work.
If you get the big teeth that can take 8 hours per day chewing and grinding then you need the big jaw, muscles and heavy attachment points for the muscles including a Sagittal keel.
And if that big jaw was exercised to full potential it would change the potential shape of the skull.
We have "homo sapiens" walking around today who have one, two, three or more of the "neanderthal" traits which some scientist will tell you make the neanderthal different.
If we were to actually try selective breeding in humans for "neanderthal" breeding it would probably not take many generations to make a better "neanderthal".
You won't find it if you believe we were genetically altered by the Annunaki. Problem I have with all of you is you will not acknowledge the obvious drill lines in items in Mexico, Southern United States and South America. This makes you dishonest and unworthy of my belief in any of your work
the different species of humans that evolved crossed paths and interbred that's a scientific fact,people with the most beneficial traits survived .the same thing happens to this day,better healthwise to be interracial,when and where it happened is interesting from a scientific prospective,im glad of the fact that its true.AS ONE!
This reasoning is a leap of logic equivalent to imagining skeletal hybrids to represent what a "missing link" might or should resemble. That type of imaginary morphological imperative has not held up over decades of discoveries.
Morphologies of species are plastic enough that there is no reason to expect that a common ancestor should have tooth morphologies somewhere between the two species, if correctly identified. A common ancestor's teeth might be more like, or even much more like one or the other. While tooth morphologies and sizes are significantly more static than, say, mandible shapes and dimensions, looking for calculated tooth shapes in the fossil record needs to be very carefully considered.
Suppose we arrived at exactly where we came from, and could trace back in time fully aware of how we began and how our evolution proceeded. How would that knowledge help us in moving out of the cesspool we have created and reach our highest potential on earth, within the galaxy, and withink the cosmos? Such knowledge is ineresting, but the human race is on a collision course with extinction. Should we not focus on what course to take to prevent our obvilion?
We are homo erectus. Environment shapes our physical appearance as much as genetics. Powerful jaw? Too much raw roots and meat. More gracile? Cooked food and more time running down prey. HE had 2 million years of mutations to change. Abstract thinking? You try to picture a spear being made from that sharp river rock and making one. HE made fire earlier more than 1 million yrs ago and I don't know
Or, perhaps, the more obvious conclusion: the genetic mutation rates are wrong. At this very early stage in archaeo-genetics research this is all pioneering work. Pioneering work on skull morphology with the aid of computer-based analysis yielded a very different picture of hominid evolution as I once read in a diagram in Klein's "The Human Career".
So perhaps, it is premature to assume what appear as objective genetics conclusions have the epistemological weight to overrule existing archaeological and paleontological research. It would be more logical to also try to recalibrate DNA mutation rates based on possible skeletons that exist, not vice versa.
The rate at which DNA mutates is the basis for all dating of common hominid ancestors if I understand the science correctly. The difficulty is that we have no real totally objective way to know the mutation rate of DNA over the course of thousands, not to mention millions of years. What if we've got the mutation rates completely wrong?
Suppose the two species of humans, ours the new comer out of Africa 60,000 years ago, and the Neanderthals over the last million years, had undergone separate trajectories that led to more intelligent creatures. What if the Neanderthals who appear to have buried their dead in at least one case with fresh flowers, and I've read had bone needles before the arrival of our ancestors in Europe and before they are found with the remains of our species, had made their own evolutionary cultural progress, different than our own. Like ourselves their culture may have continued evolving after, or faster, than their physical evolution. Perhaps then our species picked up some cultural advances that we didn't have in our original knapsack as we left Africa. We already believe we have picked up a couple of percent of DNA from this other, much older species of Man, maybe they coped with their world with a different, but not necessarily lesser mind or culture than our newer model. Maybe they had a million years to undergo their own cultural advances and when the two species met it wasn't so much a meeting of the new human with the old human but a strange meeting of two different types of human.
...then cro-magnon had plenty of time to develop his high forehead, strong chin,
fade the brow furrow, and develop a gracile but powerful body. his brain stayed
the same size as Neandertal, slightly larger than AMH, and eyes smaller less
recessed. the ivory male head at Dolní Vestonice, 26kya, has no forehead,
prominent eye brow ridge, snub nose, rather sunken eyes. the Venus
Brassenpouy, 26kya, has high cheekbones, net cap, pointed chin, flat nose,
and slanted eyes.
most important now is the information transfer: fire drill, ritual, language,
and there only appears to be one idiom, Nauatl, whose tributaries cover the
Neanderthal is DNA removed as an ancestor of Man, or as a possible breeding partner 20 years ago. Why the repeat of nonsense?
Species occur rapidly following a mass extinction, to opposite of evolution.
@Peter Kraus sounds like the regional hypothesis or candelabra model. Currently out of fashion.
Thomas, the earth is much older than 7000 years old. There is no hoax, is just science. There are not such a thing as liberal science, or conservative science; or religious science or atheist science. Science is just science.
BTW, this was meant to be humorous and a mean spirited jab at the Annunaki comments posted earlier. I hope those too are meant at humor, though I suspect not. Sorry for being mean spirited about your confusion between belief and science. Wait, that was also mean. Sorry, again.
@Geoffrey Sea Have you looked at H. heidelbergensis?
@Donna Foster The Annunaki were from the north mountains of Arattu, or Armenia. This IS mentioned in Genesis. They were "The Shinning Ones" who came down the mts into south Mesopotmia and married the beautiful earth women- the dark haired women of Sumer. See the ydna R1a migrations back into Mesopotamia 2000 BC and read some history. The Old Testament was oral Jewish history around 1500BC- see age of the Hittites- bible records were of that same historical date. See Sumerian Swastika signs going back to Armenia, going back to Russian-Siberia Poltavka- Sinshasta-Arkaim culture 2000 BC. Stop looking for aliens till you actually see one.
@Andrew Roberts How would this explain that African populations have no neanderthal DNA?
@Andrew Roberts That's not irony...;)
@El Gabilon we can do both...
@El Gabilon it would at least stop the religious nuts from claiming to own the truth - I'm hoping.
f/u I don't know too many modern guys that can do that, but I also cannot imagine HE sitting down to a computer. In all, there is so much we do not know. From what I understand, there has been very little archaeology exploration in Armenia where the Dmanisi skulls were found (Earliest known HE).
@charlie linebarger Neanderthals for what ever reason were never in Africa. African Populations have no Neanthertal DNA. There most have been some small Human population in northern Africa. Some moved across to the Middle East and Europe interbreeding with Neanderthals thus our 4% Nean. DNA. Others may have move south deeper into Africa mixing with other not discovered yet humanoid and may be carrying some portion of their DNA instead of Neanderthal DNA.
@John Tarver Speciation can occur at very different rates at different points in time in response to many factors, one category of which may be large scale local or universal extinctions. Coming out of each event, there are still plenty of organisms which can evolve rapidly into many eventually different species that take advantage of the niches newly available and create new niches.
S J Gould termed this "punctuated equilibrium," when rates of evolution of various types of organisms appear to have ebbed and flowed, some remaining static for long times, and others changing and diversifying in geologically short times.
This is hardly an "opposite" of evolution.
@Patrick Marshall @El Gabilon Ideally, and yet... ;(
I had a coworker who thinks that dinosaurs, and, really, anything older than 6000 years is a trick of the devil to cause the faithful to stray from the word. His support for this "logic" was based on all that begatting in the Old Testament.
So... there's that. I guess my point is don't hold your breath that anyone of the faithful will think logically about actual, found in the ground evidence when there's all those compelling reasons to think that the devil is a consummate archaeologist as well as the most evil tempter.
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