Scientists Revise Timeline of Human Origins

Posted by on July 6, 2014 in Sci-Tech, Science with 3 Comments
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Between 2.1 and 1.8 million years ago, the oldest known species of the human genus, Homo, exhibited diverse traits. These species include the 1470 Group and the 1813 Group, based on the Kenyan fossils KNM-ER 1470 (left) and KNM-ER 1813 (second from left), respectively. By 1.8 to 1.9 million years ago, the species Homo erectus had evolved in Africa and started to spread to Eurasia. Early populations of this long-lived species are represented by the Kenyan fossil KNMER 3733 (right) and the Georgian fossil Dmanisi Skull 5 (second from right). The three lineages -- the 1470 group, the 1813 group, and Homo erectus -- overlapped in time for several hundred thousand years. The Kenyan fossils, from the site of Koobi Fora in the Lake Turkana region of Kenya, are housed in the National Museums of Kenya. Fossils from Dmanisi are housed in the Georgian National Museum. Credit: Kenyan fossil casts – Chip Clark, Smithsonian Human Origins Program; Dmanisi Skull 5 – Guram Bumbiashvili, Georgian National Museum

Between 2.1 and 1.8 million years ago, the oldest known species of the human genus, Homo, exhibited diverse traits. These species include the 1470 Group and the 1813 Group, based on the Kenyan fossils KNM-ER 1470 (left) and KNM-ER 1813 (second from left), respectively. By 1.8 to 1.9 million years ago, the species Homo erectus had evolved in Africa and started to spread to Eurasia. Early populations of this long-lived species are represented by the Kenyan fossil KNMER 3733 (right) and the Georgian fossil Dmanisi Skull 5 (second from right). The three lineages — the 1470 group, the 1813 group, and Homo erectus — overlapped in time for several hundred thousand years. The Kenyan fossils, from the site of Koobi Fora in the Lake Turkana region of Kenya, are housed in the National Museums of Kenya. Fossils from Dmanisi are housed in the Georgian National Museum. Credit: Kenyan fossil casts – Chip Clark, Smithsonian Human Origins Program; Dmanisi Skull 5 – Guram Bumbiashvili, Georgian National Museum

Many traits unique to humans were long thought to have originated in the genus Homo between 2.4 and 1.8 million years ago in Africa. Although scientists have recognized these characteristics for decades, they are reconsidering the true evolutionary factors that drove them.

A large brain, long legs, the ability to craft tools and prolonged maturation periods were all thought to have evolved together at the start of the Homo lineage as African grasslands expanded and Earth's climate became cooler and drier. However, new climate and fossil evidence analyzed by a team of researchers, including Smithsonian paleoanthropologist Richard Potts, Susan Antón, professor of anthropology at New York University, and Leslie Aiello, president of the Wenner-Gren Foundation for Anthropological Research, suggests that these traits did not arise as a single package. Rather, several key ingredients once thought to define Homoevolved in earlier Australopithecus ancestors between 3 and 4 million years ago, while others emerged significantly later.


The team's research takes an innovative approach to integrating paleoclimate data, new fossils and understandings of the genus Homo, archaeological remains and biological studies of a wide range of mammals (including humans). The synthesis of these data led the team to conclude that the ability of early humans to adjust to changing conditions ultimately enabled the earliest species of Homo to vary, survive and begin spreading from Africa to Eurasia 1.85 million years ago. Additional information about this study is available in the July 4 issue of Science.

Potts developed a new climate framework for East African human evolution that depicts most of the era from 2.5 million to 1.5 million years ago as a time of strong climate instability and shifting intensity of annual wet and dry seasons. This framework, which is based on Earth's astronomical cycles, provides the basis for some of the paper's key findings, and it suggests that multiple coexisting species of Homo that overlapped geographically emerged in highly changing environments.

Scientists revise timeline of human origins
Hominin evolution from 3.0 to 1.5 Ma. Green: Australopithecus, Yellow: Paranthropus, Red: Homo. The icons indicate from the bottom the first appearance of stone tools at ~2.6 Ma, the dispersal of Homo to Eurasia at ~1.85 Ma, and the appearance of the Acheulean technology at ~1.76 Ma. The number of contemporaneous hominin taxa during this period reflects different strategies of adaptation to habitat variability. The cultural milestones do not correlate with the known first appearances of any of the currently recognized Homo taxa. Credit: Antón et al., Science, 2014

“Unstable climate conditions favored the evolution of the roots of human flexibility in our ancestors,” said Potts, curator of anthropology and director of the Human Origins Program at the Smithsonian's National Museum of Natural History. “The narrative of human evolution that arises from our analyses stresses the importance of adaptability to changing environments, rather than adaptation to any one environment, in the early success of the genus Homo.”

The team reviewed the entire body of fossil evidence relevant to the origin of Homo to better understand how the human genus evolved. For example, five skulls about 1.8 million years old from the site of Dmanisi, Republic of Georgia, show variations in traits typically seen in African H. erectus but differ from defining traits of other species of early Homo known only in Africa. Recently discovered skeletons of Australopithecus sediba (about 1.98 million years old) from Malapa, South Africa, also include someHomo-like features in its teeth and hands, while displaying unique, non-Homo traits in its skull and feet. Comparison of these fossils with the rich fossil record of East Africa indicates that the early diversification of the genus Homo was a period of morphological experimentation. Multiple species of Homo lived concurrently.

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  1. selfprogrammed@yahoo.com' farang says:

    Here’s my problem with this entire scenario of the “out-of-Africa” theory:
    DNA science is telling us (DNA results released earlier this year) that “modern humans” (homo sapen sapien) arose in south Africa, and @ 130,000-70,000 years ago, migrated along the east coast of Africa, into the Arabian Peninsula and southern Indian sub-continent.

    Okay. Maybe DNA does show a “mutated” DNA migrating out of south Africa. But what about these facts:

    1. Same scientists state Neanderthals and “modern humans” branched off the same tree @ 1.8 million years ago.

    2. Neanderthals populated Europe and Asia. Homo Erectus, which “modern humans” and Neanderthals branched from, also populated Asia. Erectus has a distinctive “shovel-tooth” dental pattern, found only in “modern” northern Asian poulations.

    3. If Erectus and Neanderthals spread across the globe, why is it that only in “south Africa” supposedly “modern human” traits evolved into sapien sapien, and how do they prove this? Other than using their brains to spread across the globe and survive OUT OF AFRICA, they just “sat around and didn’t evolve?”

    4. Now, we see it alleged that Denosovans, along with Neanderthals, left DNA in “modern humans.” If you can mate and produce offspring? YOU ARE SAME SPECIES, PERIOD.

    5. I am stating this: for over 2 million years, “not-so-modern-humans” managed to spread across the globe, while “modern humans” evolved, FROM SAME ROOT STOCK, only in south Africa less that 150,000 years ago?

    I DOUBT THAT SERIOUSLY.

    The cogent point to be made: Define exactly what the term “modern human” specifies, exactly.

    I’m stating that 65,000 year old “hominid” found outside Manila, on the coast buried with his BOAT, was EVERY BIT as “modern human” as south Africans migrants to Arabia and India.

  2. travco1@live.ca' Travis says:

    One thing that bothers me about all this “CERTAINTY” is that we still have yet to cure cancer, aids, diseases/etc.
    But yet , we know for certain where we evolved from , how we evolved, and from where, and that there is NO GOD, you’d be silly to believe in that , as we KNOW FOR CERTAIN where we came from , we just continually change the outcome and knowledge of such , and take steps back a lot , and with new methods of dating , dates become skewed and different, and at times flawed.
    but WE KNOW FOR SURE! haha

  3. First human being was created on Friday. And each race has been made according to the ground he is being mould. That’s why we are of diffent color and features.

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