Humans Evolved From Tree Climbers

A research from Duke University by Daniel Schmitt, associate professor of evolutionary anthropology, and Tracy Kivell, a post-doctoral research associate, shows that human evolved from tree climbing ancestors, not from knuckle-walkers. Schmitt and Kivell examined and compared the wrist bones of humans and African apes. Their research, “Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor“, was published in the Proceedings of the National Academy of Sciences on August 10th, 2009.

They also found that knuckle walking evolved at least two different times; gorillas fundamentally knuckle walk differently than chimpanzees and bonobos.

Kivell and Schmitt think this suggests independent evolution of knuckle-walking behavior in the two African ape lineages.

Some scientists point to features in the human anatomy as our own vestiges of a knuckle-walking ancestry. One notable example is the fusion a two wrist bones that could provide us extra stability, a feature we share with gorillas, chimps and bonobos.

But some lemurs have that feature too, and they do a variety of different movements in the trees but do not knuckle-walk, Kivell said.

Altogether, the evidence leans against the idea that our own bipedalism evolved from a knuckle-walking ancestor, the pair wrote. “Instead, our data support the opposite notion, that features of the hand and wrist found in the human fossil record that have traditionally been treated as indicators of knuckle-walking behavior in general are in fact evidence of arboreality.”

In other words, a long-ago ancestor species that spent its time in the trees moved to the ground and began walking upright.

There are no fossils from the time of this transition, which likely occurred about seven million years ago, Kivell and Schmitt said. But none of the later fossils considered to be on the direct human line were knuckle-walkers.

Read more on Science Daily: Bipedal Humans Came Down From The Trees, Not Up From The Ground

Originally posted on The Prancing Papio

2 thoughts on “Humans Evolved From Tree Climbers

  1. 16th International Congress of the International Union of Anthropological and Ethnological Sciences (IUAES)

    THE PROCESS OF HOMINIZATION
    By Drs Aris and Daphne N. Poulianos
    Kunming, China 31-7-09

    The title of this paper may sound a little deterministic, but I am convinced we human beings went through a longer period of hominization, than usual historians, including marxists, allow to conclude today.
    We definitely come from apes, but not African ones. Once upon a time lived in Europe over fifty species of monkeys. But an ape, which I named Helladopithecus semierectus, lived on trees, seventeen million years ago (ANTHROPOS, V3, N01, Jan. 1976, pp3 – 30, Athens).
    The well known Pikermi fauna of the Miocene period is found from Hungary through Balkans to Iran: (Wagner, A1840: Fossile Uberreste Von einem Affen und anderensau getierren aus Griechenland. Abh. Bayer. Akad. Wiss, 3, Munchen). Among other finds, a very important of that period was Mesopithecus pentelici, whose range also extended over a large territory, beyond Greece, and which is known to be a terrestrial monkey. It’s wide extension over a large territory, presupposes, that some anthropomorphic monkeys could ’’descend from trees’’ (Roghinski, J.J. & M.G. Levin, 1963: Anthropologhia, Moskva, str. 184 – 185), and begun to walk. Consequently among those “descenders” could be some andecedent forms of man.
    Another lower jaw from Attica found by a german officer during the years of occupation (1942) and described by G.Von Koenigswald, (1972: Einunterkiefez eines fossilen Hominoiden aus dem unterpliozan Griechenlands. Konikl. Nederl. Akademie Van Wetenschappen. Series B, 75, No 5, str. 385 – 394, Amsterdam), seems to be an advanced form which does not belong to Dryopithecinae, and which might also represent the beginning of African Primates. Koenigswald gave him a not very successful name “graecopithecus”. Its age is about 9 million years old. The lower jaw of another specimen found by the French expedition in 1972 near Thessaloniki, was named Dryopethicus macedoniensis. But it is also of a more advanced type than the Dryopithecinae, and according to Koenigswald is more closely affiliated with the hominids. Its age is Upper Miocene (Vallesian).
    Finally, the find described in this paper (Helladopithecus), is the upper part of a left femur found by our expedition in 1974 near Tharounia, a village in the island of Euboea. The age established lately, is Lower Miocene, about 17 million years old, confirmed by its stratigraphy, as well, and kept now in the Anthropological Museum of the Archanthropus man at Petralona, Chalkidiki.
    It is fully described and decided to be a semierectus monkey, as these authors call the whole complex of similar finds from Attica and Makedonia too.
    The new bone find is 98 mm. long (given the signal name ‘’A.E. – 1’’, seems to belong to a rather young individual, and its whole length (proportionally counted) cannot be more than 350 mm. That is the standing height should be about 140-150cm. Its weight, according to Debetz index (ICVS), approximately should be about 40-42 klgms. The stoutness index then is about 22, 85 (the same index for Orang, Chimpanzee and Gorilla, being 32-33, while for man is 18-21.
    But among all these indirect methods of identifying a find, the best would be to measure exactly the Torsion angle, in order to establish the percentage of its erect position. Thus a new method was developed to measure the torsion angle in a broken femur bone. This method is based on the assumption that the torsion angle (Θ) of a bone is directly proportional to the angle of its cylindrical surface (α). (See designs 2 and 3). The axis of a bone is the line passing through all gravity centers of all its side section (AB). The edge of the cylindrical surface of a bone is the line uniting all corresponding corners of the cross – section (ΓΔ). That is: θ=Κ.α, where Κ – proportionality coefficient.
    And this assumption is based on
    a)the geometrical similarity of corresponding bones of different animals.
    b)The physico-chemical similarity of bones, and
    c)On the approximately constant ratio between animal weight and cross-sectional area, that is the stress of bone loading is almost constant (the animal weight per unit of cross-sectional bone area).
    In order to find Κ we take a similar unbroken contemporary bone, and measure its angles θ and α:
    Κ= θ. Unbroken / α. unbroken
    Then we measure the angle α of the broken bone and find angle
    θ.broken = K.a unbroken = θ. Unbroken . α. broken / α. unbroken
    Angle α is the average of angles β & γ.
    The angles β & γ can be found by photographing the bone and measuring these angles on the picture. In order to make edge ΓΔ clearly distinguishable we illuminate the bone from the side. Then ΓΔ becomes the border line of two differently illuminated surfaces. In our case we took 17 differently oriented pictures of both bones, broken and unbroken (see pictures in the text and table 1).
    The result of these procedures showed that θ (torsion) broken = 18ο , which means that this monkey was about 65% erect during his lifetime. That means he was pretty much erect, certainly more erect than most today’s African primates. Thus, it is concluded, Helladopithecus could be the forerunner of Homo.
    Finally, we raise to the rank of a separate family the whole complex of Helladopithecus finds from Greece, classifying it right after the Hominid family. As a result of the above process we have the first standing man on earth, Homo erectus trilliensis, spreading all over the world from this region of the Aegean, of the SE of Europe 13 million years ago.
    The over one hundred years long discussion among anthropologists (‘’polyphyletic versus monophyletic origins’’) sounds is ending. Monophyletic origin of man (from Helladopithecus to Homo erectus trilliensis) to our opinion is more or less confirmed who spread from Atlantic to Pacific and then all over the rest of the world. It seems every biological species on earth develops from one center, and then it spreads all over.
    In the mean time excavations are going on: A new find, a part of the skeleton of a young girl of 14 years old was found. The find was named Homo erectus trilliensis Daphnae, after the name of the lady present in this hall Mrs Daphnae A.Poulianos.

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