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All of us—assuming that “us” refers to homo sapiens—can trace our roots back to a small group of people who lived in Africa less than 200,000 years ago. The DNA evidence is fairly clear that modern humans originated in Africa. The highest levels of genetic variation are found in Africa. From here our species spread out to occupy nearly all parts of the planet.

Prior to the emergence of Homo sapiens, there were a number of other human species—designated with Homo—which lived not only in Africa, but also in other parts of the world. The earliest humans first evolved in Africa about 2.4 million years ago.

The transition from an earlier hominid, most likely the species Australopithecus, involved four basic changes: (1) the use of stone tools, (2) a reduction of sexual dimorphism (difference in physical size as determined by gender) which was reflected in human social organization, (3) a reduction in the size of the teeth which correlates to a change in diet, and (4) an enlargement of the brain.

Homo habilis:

A little more than two million years ago, the first species that can be considered to be human—Homo habilis—emerged in Africa. The behavioral hallmark of this first human species was the use of stone tools. There are a number of implications of tool use.

Homo habilis 1

Homo habilis 2

First, stone tools enabled Homo habilis to exploit new food resources, particularly meat from animal carcasses. This additional protein was particularly important for the larger brain, a body organ that consumes a lot of calories.

The use of stone tools by Homo habilis provides us with evidence of a new form of thinking. Many other animals, including chimpanzees, also make and use tools, but their tool use is opportunistic. That is, when they need a tool, they take local materials to make the tool and then discard it. With Homo habilis, stone is acquired at one location, carried to another location where it is made into a simple cutting tool, and then carried again to other locations where it can be used to butcher animals which have been killed by other predators. Homo habilis was a scavenger, not a hunter or predator.

The complex of stone tools used and made by Homo habilis was initially called Oldowan by archaeologists, and some archaeologists prefer to designate it as Mode One tools. It takes its name from Olduvai Gorge in Tanzania. The Oldowan tools include choppers, scrapers, and pounders. A chopper has an edge on one side. These stone tools would have been useful in processing dead animals into both food and leather, as well as for working with wood and cracking open bones and nuts.

Oldowan drawing

A drawing of Oldowan tools is shown above.

The Oldowan tools were made primarily from river cobbles of quartz, quartzite, basalt, or obsidian. The tools were made by striking the cobble with a hammerstone to produce a flake which could be used as a tool.

With regard to anatomy, Homo habilis was smaller than modern humans: males stood about five feet tall and weighed about 100 pounds, with females appearing to have been somewhat smaller. Their brains size was about half that of modern humans, but the overall brain shape appears to have been similar to that of modern humans.

Homo habilis was the first of our ancestors to live outside of a forested environment. Homo habilis appears to have inhabited a more open territory:  savannahs with trees and low vegetation either well dispersed or clustered between large expanses of grassland. The evolutionary emergence of Homo habilis coincided with a dramatic climate change: for four million years the planet had been growing continually colder and drier. About 2.8 million years ago, large masses of ice began to accumulate around both poles. The rain forest area in Africa shrank and the savannah expanded. The resulting changes in vegetation were accompanied by the evolution of various lines of mammals who adapted biologically to the new environment. Homo habilis was among them.

In the open savannah environment, food resources—both plant and animal—were more dispersed and less predictable than in the rain forest. With their enlarged brains, Homo habilis had additional capacity to make mental maps of large expanses of territory and to interpret animal tracks and other natural signs. They may have been able to understand things like changing seasons which would have enabled them to anticipate predictable events and plan for them. The larger brains also allowed for a greater complexity of social relationships. Research has shown that there is a close relationship between the complexity of a primate’s social group and the size of its neocortex.

One of the features that makes modern humans unique today is the presence of language. One of the questions, therefore, that paleoanthropologists ask about Homo habilis is whether or not this species had language. The brain of Homo habilis shows a small bump indicating that Broca’s area was present. Broca’s area is one of the parts of the brain that is associated with language. However, there is still insufficient data to suggest that Homo habilis had language.

Originally posted to Ojibwa on Sun Oct 16, 2011 at 08:22 AM PDT.

Also republished by History for Kossacks, SciTech, Progressive Friends of the Library Newsletter, Street Prophets , J Town, and Black Kos community.

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Comment Preferences

  •  Thanks (14+ / 0-)

    The radical Republican party is the party of oppression, fear, loathing and above all more money and power for the people who robbed us.

    by a2nite on Sun Oct 16, 2011 at 08:29:50 AM PDT

  •  A lot more calories is not necessarily a function (12+ / 0-)

    of meat eating. The fat that brings the most calories from meat can be obtained by better exploitation of nuts and other energy dense fruits and roots. And chimps do hunt, kill, and eat meat but their evolution has not gone the same direction as humans. Primary is control of fire that makes vegetation more digestible after cooking. (I am not a vegetarian).

    Bipartisan analogy: Both musicians and fishermen want more bass.

    by OHdog on Sun Oct 16, 2011 at 08:32:44 AM PDT

  •  Marvelous diary, Ojibwa (14+ / 0-)

    Thank you.  I'm reading Jared Diamond's Guns, Germs and Steel right now (finally).  Your post is a perfect companion piece.

    Vi er alle norske " My faith in the Constitution is whole; it is complete; it is total." Barbara Jordan, 1974

    by gchaucer2 on Sun Oct 16, 2011 at 08:45:53 AM PDT

  •  I really enjoyed this. (8+ / 0-)

    A nice overview of Homo habilis.

    I'm sure they must have been communicating on some level, but language as we know it seems unlikely. I wonder if the skeletal structure of the jaw gives any clues as to how articulate they could be.

    "Those are my principles, and if you don't like them...well, I have others." --Groucho Marx

    by Dragon5616 on Sun Oct 16, 2011 at 08:59:21 AM PDT

  •  Thank you for this - I wish all of us (10+ / 0-)

    could accept we have common African ancestry - and we are really only one race.  

    "If you're in a coalition and you're comfortable, you know it's not a broad enough coalition" Bernice Johnson Reagon

    by Denise Oliver Velez on Sun Oct 16, 2011 at 09:23:33 AM PDT

  •  I have to take issue with one point you make. (1+ / 0-)
    Recommended by:
    ER Doc

    You state: "All of us—assuming that “us” refers to homo sapiens—can trace our roots back to a small group of people who lived in Africa less than 200,000 years ago."

    That much is clearly true, but incomplete in my opinion. I do not accept that the Neanderthals of Western Eurasia and the newly-discovered Denisovans of Eastern Asia and Oceania were separate species from Homo Sapiens. I hate the term because it is loaded with history that I do not mean to invoke, but I think they were simply three different breeds of the same species Homo Sapiens who had drifted genetically since their separation from Africa ~800Kya.

    That left three "great clans" (is that a better term?) of humans to develop for the most part in isolation from each other until ~100Kya.

    Now, I agree that most of the skeletal structure like bone-length ratios and some very important brain, cultural, and linguistic developement of modern humans had its origins of the African clan ~200Kya, but a large part of what makes the modern human species "modern" originated in the European and Asian clans. In particular, I think that includes most of the trivial cosmetic differences among modern humans like eye-shape, but also some medically-significant ones, such as the skin/hair color and the tolerance for cold that are useful high-latitude-survival adaptations that were largely inappropriate for survival in warmer African latitudes.

    Recent research shows that our modern human family includes somewhere from 1%-4% of Neanderthal and Denisovan DNA in our modern European and Asian populations, respectively, but not in African populations. That is the main factor behind my opinions here, but also the acheological record that increasingly shows Neanderthal engaged in cultural behavior that was generally indistinguishable from any other humans prior to the emergence of modern human culture and behavior in Africa ~200Kya.

    My real point in all this, I suppose, is that I think that our completely-common ancestry goes back further than 200,000 years, although I agree that is when many of our most important modern features developed.

    There are two political aisles: Center-Left and Center-Right. It's impossible to cross them both. Republicans know this and govern accordingly; Democrats don't.

    by Jimdotz on Sun Oct 16, 2011 at 10:27:20 AM PDT

    •  Neanderthals didn't survive the competition (2+ / 0-)
      Recommended by:
      Jimdotz, Ojibwa

      ...or is there newer research that suggests differently?

      "There is nothing more dreadful than the habit of doubt. Doubt separates people. It is a poison that disintegrates friendships and breaks up pleasant relations. It is a thorn that irritates and hurts; it is a sword that kills.".. Buddha

      by sebastianguy99 on Sun Oct 16, 2011 at 10:43:16 AM PDT

      [ Parent ]

      •  Just in the last few years: (3+ / 0-)
        Recommended by:
        Portlaw, HoundDog, petral

        From the New York Times on December 22, 2010:

        An international team of scientists has identified a previously shadowy human group known as the Denisovans as cousins to Neanderthals who lived in Asia from roughly 400,000 to 50,000 years ago and interbred with the ancestors of today’s inhabitants of New Guinea.

        All the Denisovans have left behind are a broken finger bone and a wisdom tooth in a Siberian cave. But the scientists have succeeded in extracting the entire genome of the Denisovans from these scant remains. An analysis of this ancient DNA, published on Wednesday in Nature, reveals that the genomes of people from New Guinea contain 4.8 percent Denisovan DNA.

        An earlier, incomplete analysis of Denisovan DNA had placed the group as more distant from both Neanderthals and humans. On the basis of the new findings, the scientists propose that the ancestors of Neanderthals and Denisovans emerged from Africa half a million years ago. The Neanderthals spread westward, settling in the Near East and Europe. The Denisovans headed east. Some 50,000 years ago, they interbred with humans expanding from Africa along the coast of South Asia, bequeathing some of their DNA to them.

        From the New York Times on May 6, 2010:

        Neanderthals mated with some modern humans after all and left their imprint in the human genome, a team of biologists has reported in the first detailed analysis of the Neanderthal genetic sequence.

        The biologists, led by Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have been slowly reconstructing the genome of Neanderthals, the stocky hunters that dominated Europe until 30,000 years ago, by extracting the fragments of DNA that still exist in their fossil bones.
        ...
        Scientists say they have recovered 60 percent of the genome so far and hope to complete it. By comparing that genome with those of various present day humans, the team concluded that about 1 percent to 4 percent of the genome of non-Africans today is derived from Neanderthals.
        ...
        Experts believe that the Neanderthal genome sequence will be of extraordinary importance in understanding human evolutionary history since the two species split some 600,000 years ago.

        So far, the team has identified only about 100 genes — surprisingly few — that have contributed to the evolution of modern humans since the split. The nature of the genes in humans that differ from those of Neanderthals is of particular interest because they bear on what it means to be human, or at least not Neanderthal. Some of the genes seem to be involved in cognitive function and others in bone structure.

        From Science Daily on October 26, 2007:

        Ancient DNA retrieved from the bones of two Neanderthals suggests that at least some of them had red hair and pale skin, scientists report in the journal Science. The international team says that Neanderthals' pigmentation may even have been as varied as that of modern humans, and that at least 1 percent of Neanderthals were likely redheads.

        The scientists -- led by Holger Römpler of Harvard University and the University of Leipzig, Carles Lalueza-Fox of the University of Barcelona, and Michael Hofreiter of the Max Planck Institute for Evolutionary Anthropology in Leipzig -- extracted, amplified, and sequenced a pigmentation gene called MC1R from the bones of a 43,000-year-old Neanderthal from El Sidrón, Spain, and a 50,000-year-old individual from Monti Lessini, Italy.

        "Together with other genes, this MC1R gene dictates hair and skin color in humans and other mammals," says Römpler, a postdoctoral researcher working with Hopi E. Hoekstra in Harvard's Department of Organismic and Evolutionary Biology. "The two Neanderthal individuals we studied showed a point mutation not seen in modern humans. When we induced such a mutation in human cells, we found that it impaired MC1R activity, a condition that leads to red hair and pale skin in modern humans."

        To ensure that the MC1R point mutation was not due to contamination from modern humans, the scientists checked some 3,700 people, including those previously sequenced for the gene as well as everyone involved in the excavation and genetic analysis of the two Neanderthals. None showed the mutation, suggesting that Neanderthals and Homo sapiens followed different evolutionary paths to the same redheaded appearance.

        None of this is absolute proof that our human family connection goes back longer than 200,000 years, but it is very, very strong evidence. Personally, I believe it.

        There are two political aisles: Center-Left and Center-Right. It's impossible to cross them both. Republicans know this and govern accordingly; Democrats don't.

        by Jimdotz on Sun Oct 16, 2011 at 11:18:20 AM PDT

        [ Parent ]

        •  Another interesting piece about Denisovans... (6+ / 0-)
          Recommended by:
          Ojibwa, ms badger, Portlaw, HoundDog, RonK, ER Doc

          ...from National Geographic.

          In fact, living Pacific islanders in Papua New Guinea may be distant descendants of these prehistoric pairings, according to new analysis of DNA from a girl's 40,000-year-old pinkie bone, found in Siberian Russia's Denisova cave.

          This "new twist" in human evolution adds substantial new evidence that different types of humans—so-called modern humans and Neanderthals, modern humans and Denisovans, and perhaps even Denisovans and Neanderthals—mated and bore offspring, experts say.

          "We don't think the Denisovans went to Papua New Guinea," located at the northwestern edge of the Pacific region called Melanesia, explained study co-author Bence Viola, an anthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

          "We think the Denisovan population inhabited most of eastern Eurasia in the same way that Neanderthals inhabited most of western Eurasia," Viola said. "Our idea is that the ancestors of Melanesians met the Denisovans in Southeast Asia and interbred, and the ancestors of Melanesians then moved on to Papua New Guinea."

          Taken together with a May DNA study that found Neanderthals also interbred with modern human ancestors, the Denisovan finding suggests there was much more interbreeding among different human types than previously thought, Stanford University geneticist Brenna Henn said.

          "In the actual archaeological record, people have been talking about this for a long time. ... But before six months ago, there was no genetic evidence for any admixture between archaic humans and modern humans," said Henn, who co-authored an article accompanying the study in tomorrow's issue of the journal Nature.

          "Then these two papers come out, and I won't say they've turned the field on its head, but they certainly support a view that has not been well recognized for years" by geneticists, said Henn, who wasn't part of the study.

          Brian Richmond, a paleoanthropologist at George Washington University, said he expects the new study to spark much interest and excitement.

          "Nothing is more intriguing than learning new twists about our origins," said Richmond, who also didn't participate in the Denisovan-genetics research. "And this is another new twist."

          I agree with Prof. Richmond!

          There are two political aisles: Center-Left and Center-Right. It's impossible to cross them both. Republicans know this and govern accordingly; Democrats don't.

          by Jimdotz on Sun Oct 16, 2011 at 11:33:51 AM PDT

          [ Parent ]

  •  Great post, thanks (5+ / 0-)
    Recommended by:
    SoCaliana, Ojibwa, Jimdotz, mapamp, HoundDog

    Always interesting to see where we come from.

    15 years old and a proud progressive and Phillies phan.

    by vidanto on Sun Oct 16, 2011 at 10:37:33 AM PDT

  •  fascinating and compelling (5+ / 0-)
    Recommended by:
    SoCaliana, Ojibwa, Jimdotz, mapamp, HoundDog

    saw a program on this theme a while back called Journey of Man.

    The world that you are hearing now is the same world that I see. from "I Hear Your Hand" by Mary Jane Rhodes.

    by raina on Sun Oct 16, 2011 at 10:40:11 AM PDT

  •  So how does the Neanderthal (3+ / 0-)
    Recommended by:
    Jimdotz, mapamp, HoundDog

    fit into this?  I believe the last Neanderthal lived around 100,000 years ago which is basically yesterday in earth time.

    We have concluded here on the DKos that most of us carry about 5% Neanderthal dna which I'm actually kinda proud of.  They seemed nicer than the mercenary Cro-Magnon.

  •  great post (3+ / 0-)
    Recommended by:
    mapamp, Ojibwa, HoundDog

    too bad it's "controversial" to teach this in American schools. Thanks, fundamentalist Christianity!

    "I don't want to live on this planet anymore" -Prof. Farnsworth "I prefer to be a total bitch about my science"--me

    by terrypinder on Sun Oct 16, 2011 at 03:19:52 PM PDT

  •  Clearly, they had a brain sufficiently evolved to (1+ / 0-)
    Recommended by:
    Ojibwa

    appreciate Friends.  And America's Got Talent.

    "Try our product for 30 days, and, before you know it, a month will have passed."--Unknown

    by savio on Mon Oct 17, 2011 at 01:46:37 AM PDT

  •  Chimps are better at mental maps than us (0+ / 0-)

    As are various other species in various ways.  Although one could argue that verbal blinding masks our mapping ability and that having 'a sense of direction' certainly varies widely in our species.

    The more complex social relations would seem to be more directly related to larger brain size; especially, since larger brains indicate longer childhoods which requires stronger social groups which requires larger brains...

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