Four decades ago, in 1972, the Koobi Fora Research Project discovered the enigmatic fossilized skull known as KNM-ER 1470, or "1470" for short, which ignited a now long-standing debate about how many different species of early Homo lived alongside Homo erectus during the Pleistocene epoch. Shown here, 1470's cranium combined with the new lower jaw KNM-ER 60000; both are thought to belong to the same species. The lower jaw is shown as a photographic reconstruction, and the cranium is based on a computed tomography scan.
By Charles Choi
New fossils from the dawn of the human lineage suggest our ancestors may have lived alongside a diversity of extinct human species, researchers say.
Although modern humans, Homo sapiens, are the only human species alive today, the world has seen a number of human species come and go. Other members perhaps include the recently discovered "hobbit" Homo floresiensis .
The human lineage, Homo, evolved in Africa about 2.5 million years ago, coinciding with the first evidence of stone tools. For the first half of the last century, conventional wisdom was that the most primitive member of our lineage was Homo erectus , the direct ancestor of our species. However, just over 50 years ago, scientists discovered an even more primitive species of Homo at Olduvai Gorge in Tanzania they dubbed Homo habilis, which had a smaller brain and a more apelike skeleton.
National Geographic Explorers-in-Residence Louise Leakey (left) and Meave Leakey search the slope in northern Kenya where KNM-ER 60000 was discovered while, in the background, members of the field crew screen the surface sediment hoping to find additional fragments of this fossil.
Now fossils between 1.78 million and 1.95 million years old discovered in 2007 and 2009 in northern Kenya suggest that early Homo were quite a diverse bunch, with at least one otherextinct human species living at the same time as H. erectus and H. habilis.
"Two species of the genus Homo, our own genus, lived alongside our direct ancestor, Homo erectus, nearly 2 million years ago," researcher Meave Leakey at the Turkana Basin Institute in Nairobi, Kenya, told LiveScience.
A skull known as KNM-ER 1470, found in 1972 in Kenya, was at the center of the debate over the number of species of early Homo living nearly 2 million years ago. It had a larger brain and a flatter face than H. habilis, leading some researchers to declare it a distinct species they dubbedHomo rudolfensis. [ See Photos of the New Homo Fossils ]
However, making comparisons between these fossils was difficult, because no single purported H. rudolfensis specimen contained both the face and the lower jaw, details needed to see if it was indeed separate from H. habilis. Any supposed differences between H. habilis and H. rudolfensis might, for instance, have been due to variations between the sexes of a single species.
The newly discovered face and lower-jaw fossils, uncovered within a radius of just more than 6 miles (10 kilometers) from where KNM-ER 1470 was unearthed, now suggest that KNM-ER 1470 and the novel finds are indeed members of a distinct species of early Homo that stands out from others with its uniquely built face.
Meave Leakey carefully excavates the new face KNM-ER 62000. Researchers might be able to reconstruct what this new human species might have eaten by looking at its teeth and jaws.
"It had very flat facial features — you could draw a straight line from its eye socket to where its incisor teeth would be," researcher Fred Spoor at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, told LiveScience. "This shows east Africa about 2 million years ago was quite a crowded place with many diverse species of early Homo," Spoor said.
The environment was more verdant back then than it is today, with a larger lake. "There was plenty of opportunities ecologically to accommodate more than one hominid species," Spoor said.
Other researchers suggest these new fossils are not enough evidence of a new human species. However, "these are really distinctive shape profiles — it really shows something completely different," Leakey said. "I feel pretty confident that we're not just dealing with variation in one species."
In principle, researchers might be able to reconstruct what this new species might have eaten by looking at its teeth and jaws. "The incisors are really rather small compared to what you'd find in other early Homo," Spoor said. "In the back of the mouth, the teeth are large, telling us a lot of food processing was going on there ... it may be possible it ate more tough, plantlike foods than meat."
Other extinct human fossils discovered in that area are thought to belong to H. habilis. As such, at least two different species once lived in that site in northern Kenya. However, it remains possible these other fossils do not belong to H. habilis, suggesting yet another species lived there at the same time, paleoanthropologist Bernard Wood at George Washington University at Washington, D.C., who did not take part in this research, said in a review of this work.
The scientists detail their findings in Thursday's issue of the journal Nature.
Comments
I agree with you about Romney, he is a lier but obama is also and two wrongs don't make a right. I say vote for non of the above. Ron Paul is the only honest candidate but the DC has pushed him out. They control all the elections which has been illegal sense bush. Time for a new party and a new govt. If not they will bring in the NWO if either one of them gets in. A two party system only breeds dishonesty. What to do now,revolution ? Adonai
Dear Rev. Joshua Skirvin,
You have posted in your blog many beautiful, positive, and instructive information, and me, and many
others appreciate very much your work. Yet, to my opinion, you keep posting a negative information
about the place of birth of the president Obama. Maybe he was not born in US, but for sure he is a US
citizen, and a good one. In my opinion, that rule of being born in US to qualify for a US president, has
very little significance, and should be discarded. Would you like more that greedy liar, Romney, than a
really good citizen, to be the next US president? I hope you remarked this good teaching from Jesus:
“After their fruits you will know them”. The fruits of Romney are disgusting. From many sources I got
the information that Obama is a light worker, protected from dark cabal, and for sure the next president
of US. Ooh, he is not perfect, but surrounded by the corrupt jackals of congress, what else he could do
more? I do not agree with the mandatory aspect of the Obama care, but that law it is much better than
the present one who permit to health care industry to be a dirty business, and not a service to people.
I was in a hospital in US just for a half hour, practically they did nothing special to me, and with a full
health insurance still they charged me with over $6,000. One doctor just came to my bed, presented,
but did absolutely nothing else, and in the bill he charged me with over 500 dollars. The net cost of my
half hour in hospital was over 30,000 dollars. The only service they did to me was to insert a caterer in
my urinary tract, and nothing else. Do you like such service?
For sure, many people might have some doubts about the birth country of Obama, but this has
so little significance for what we need now from our government and US president. Obama give us
some hope, Romney, none; he is a worker of the dark cabal, and he will not hesitate a second to lie and
to do any crime to serve his master.
Please, stop this negative action; it is not in the interest of the world and American people.
With brotherly love, Cornelius Constantine. corneliu41@gmail.com