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Earliest Human Ancestor Found in Ethiopia

Discussion in 'International Forum' started by Ab-Titchaz, Oct 1, 2009.

  1. Ab-Titchaz

    Ab-Titchaz Content Manager Staff Member

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    Ardi: The Oldest Human Skeleton Discovered
    Guest post by Jamie Shreeve, National Geographic Magazine Science Editor


    The big news in the journal Science tomorrow is the discovery of the oldest human skeleton--a small-brained, 110-pound female of the species Ardipithecus ramidus, nicknamed "Ardi." She lived in what is now Ethiopia 4.4 million years ago, which makes her over a million years older than the famous "Lucy" fossil, found in the same region thirty-five years ago.

    Buried among the slew of papers about the new find is one about the creature's sex life. It makes fascinating reading, especially if you like learning why human females don't know when they are ovulating, and men lack the clacker-sized testicles and bristly penises sported by chimpanzees.

    One of the defining attributes of Lucy and all other hominids--members of our evolutionary lineage, including ourselves--is that they walk upright on two legs.

    While Ardi also walked on two legs on the ground, the species also clambered about on four legs in the trees. Ardi thus offers a fascinating glimpse of an ape caught in the act of becoming human.

    The problem is it is doing it in the wrong place at the wrong time--at least according to conventional wisdom, which says our kind first stood up on two legs when they moved out of the forest and onto open savanna grasslands. At the time Ardi lived, her environment was a woodland, much cooler and wetter than the desert there today.

    So why did her species become bipedal while it was still living partly in the trees, especially since walking on two legs is a much less efficient way of getting about?

    According to Owen Lovejoy of Kent State University, it all comes down to food, and sex.

    In apes--both modern apes and, presumably, the ancient ancestors of Ardipithecus--males find mates the good old-fashioned apish way: by fighting with other males for access to fertile females. Success, measured in number of offspring, goes to macho males with big sharp canine teeth who try to mate with as many ovulating females as possible. Sex is best done quickly--hence those penis bristles, which accelerate ejaculation--with the advantage to the male with big testicles carrying a heavy load of sperm. Among females, the winners are those who flaunt their fertility with swollen genitals or some other prominent display of ovulation, so those big alpha dudes will take notice and give them a tumble, providing a baby with his big alpha genes.

    Let's suppose that some lesser male, with poor little stubby canines, figures out that he can entice a fertile female into mating by bringing her some food. That sometimes happens among living chimpanzees, for instance when a female rewards a male for presenting her with a tasty gift of colobus monkey.

    Among Ardipithecus's ancestors, such a strategy could catch on if searching for food required a lot of time and exposure to predators. Males would be far more successful food-providers if they had their hands free to carry home loads of fruits and tubers--which would favor walking on two legs. Females would come to prefer good, steady providers with smaller canines over the big fierce-toothed ones who left as soon as they spot another fertile female. The results, says Lovejoy, are visible in Ardipithecus, which had small canines even in males and walked upright.

    Lovejoy's explanation for the origin of bipedality thus comes down to the monogamous pair bond. Far from being a recent evolutionary innovation, as many people assume, he believes the behavior goes back all the way to near the beginning of our lineage some six million years ago.

    But there is one other, essential piece to this puzzle that leaves no trace in the fossil record. If the female knew when she was fertile, she could basically cheat the system by taking all the food offered by her milquetoast of a provider, then cuckold him with a dominant male when she was ovulating, scoring the best of both worlds. The food-for-sex contract thus depends on what Lovejoy calls "the most unique human character"--ovulation that not only goes unannounced to the males of the group, but is concealed even from the female herself.

    Regular meals, monogamy, and discretion--who would have thought our origins were so sedate?

     
  2. Ab-Titchaz

    Ab-Titchaz Content Manager Staff Member

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    A. ramidus (artist's reconstruction, center) was adapted both to climbing in the trees and walking on the ground, according to researchers who studied its fossils. In this illustration, a reconstruction of A. ramidus appears between a silhouette of a chimpanzee (left) and one of Australopithecus afarensis, all scaled to be the same height.
     
  3. Ab-Titchaz

    Ab-Titchaz Content Manager Staff Member

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    This row of images shows the male canine condition of Ardipithecus ramidus (center digital image) intermediate in size between humans (left) and chimpanzees. The reduced size of canine teeth is an indication of a shift in social behavior away from male-male aggression, and is one of the hallmarks of the human lineage.

    Finding the trait in Ardipithecus suggests that a social structure involving more cooperation between males evolved very early after the divergence between the chimpanzee and human lineages. A. ramidus' molars and premolars were small compared to those of later australopithecines and had thinner enamel, reflecting differences in diet.


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    So fragile they would turn to dust at a touch, the bones of the A. ramidus skeleton took 15 years to extricate from their surrounding rock, analyze, and compare with those of other individuals of the species found in the same deposits.

    "Ardi," the nickname for the newly revealed A. ramidus skeleton, predates "Lucy," the well-known Australopithecus afarensis fossil, by more than a million years.

    http://news.nationalgeographic.com/news/2009/10/photogalleries/oldest-human-skeleton-ardi-missing-link-chimps-pictures/index.html

     
  4. NGULI

    NGULI JF-Expert Member

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    Mkuu Archaeology ni uongo tu, inajaribu ku prove theory zao tu, am an archaeologist by profession, theres no any truth about dating processes, we relay on carbon 14 or radiocarbon dating which are truly fake. I have done a number of research with big names/profs on ARCH but they failled to ans my question on why every age of specie beggin with probably or its believed that..... since i rialiazed its fake I turned into another profession
     
  5. Babylon

    Babylon JF-Expert Member

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    Human evolution just got a million years older: woman-ape fossil skeleton is closest thing yet to 'missing link'




    Last updated at 6:54 PM on 01st October 2009


    She was just 4ft tall and weighed in at less than 110lbs when she roamed the forests 4.4 million years ago in what is now Ethiopia.

    Small in stature, but hugely significant in scientific terms the skeleton is humankind's oldest ancestor by almost a million years.

    The ancient remains - nicknamed 'Ardi' by scientists - could be the closest thing yet to the mythical 'missing link'.

    Her discovery, reported in detail for the first time today, sheds new light on a crucial period of human evolution when our ancestors were leaving the trees and learning to walk upright.


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    Ardi's skeleton (left) revealed she was 4ft tall and weighed 7st 12oz




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    'This is one of the most important discoveries for the study of human evolution,' said Dr David Pilbeam, curator of palaeoanthropology at Harvard's Peabody Museum of Archaeology and Ethnology.
    'It is relatively complete in that it preserves head, hands, feet, and some critical parts in between.'
    Ardi - short for Ardipithecus ramidus or 'root of the ground ape' - was more man-ape than ape-man.
    She lived a million years before the famous Lucy, the previous earliest skeleton of a human ancestor.
    According to fossil hunters, the discovery of Ardi challenges the common wisdom about the last common ancestor of people and chimps.
    'This is not that common ancestor, but it's the closest we have ever been able to come,' said Dr Tim White, director of the Human Evolution Research Centre at the University of California, Berkeley who reports the discovery today in Science.
    The first fossilised and crushed bones of Ardi were found in 1992 in Ethiopia's Afar Rift. But it has taken an international team of 47 scientists 17 years to piece together, analyse and describe the remains in detail.

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    Digital representations of Ardi's skull (left) and hand (right)


    The skeleton had been trampled and scattered, while the skull was crushed to just two inches in height.
    Researchers have pieced together 125 fragments of skeleton - including much of her skull, hands, feet, arms, legs and pelvis.
    The fragments were dated using the volcanic layers of soil above and below the fossils.

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    Analysis of the ape skeleton of Ardi, found in Ethiopia in 1994, reveals humans and chimps evolved separately from a common ancestor


    Ardi lived in woodlands with dense patches of forest and fresh-water springs.
    She has features of apes and people. Her upper canine teeth are more like the stubby teeth of modern people than the long, sharp ones of chimps. An analysis of her tooth enamel suggests she ate fruit, nuts and leaves.




    She had long arms but short palms and fingers which were flexible, allowing her to support her body weight on her palms while moving along branches.
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    Origins: A model of Lucy, left, who was previously the earliest skeleton of a human ancestor. Right, Lucy's bones after they were discovered in 1974

    Her feet were rigid enough for walking but still had a grasping big toe for use in climbing. Scientists believe she was a female because her skull is relatively small and lightly built. Her teeth were also smaller than other members of the same family that were found later.
    The latest study suggests she could climb on all fours along tree branches. But the structure of her arms and legs shows she did not spent much time in the trees and could walk on two legs on the ground.




    That discovery suggests that modern day African apes developed those characteristics after the split with human ancestors - and that the last common ancestor of chimps and humans was far less chimp-like than was previously assumed.
    Alan Walker, of Pennsylvania Sate University, told Science: 'These things were very odd creatures. You know what Tim (White) once said: If you wanted to find something that moved like these things you'd have to go to the bar in Star Wars'.
    Ardi was followed by another more human like "hominid" - or member of the human family tree - called Australopithecus. Its most famous member was Lucy, discovered in 1974 and who lived in Africa a million years later.
    Since the 1992 find, scientists have unearthed another 35 members of the Ardipithecus family.
    Ardi was found in alongside crumbling fossils of 29 species of birds and 20 species of small mammals - including owls, parrots, shrews, bats and mice.
    They also found porcupines, hyenas, bears, pigs, elephants, giraffes, monkeys and antelope close
     
  6. X-PASTER

    X-PASTER Moderator

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    A report titled “A short film of evolution” carried in the 13 April, 2006, edition of the Turkish daily Radikal announced the discovery of a fossil in Ethiopia. The fossil, first reported in the British scientific journal Nature (Tim D. White et.al, 2006. Asa Issie, Aramis and the origin of Australopithecus.

    Nature 440:883-889), belonged to Australopithecus anamensis, which is known from previous specimens, and was suggested as constituting a link between two other species in the imaginary human family tree (Ardipithecus ramidus and Australopithecus afarensis). Tim White, a palaeoanthropologist at the University of California, Berkeley, claimed that this fossil, together with certain others previously discovered in the region, constituted “a mini home video of evolution” and that some of the links in an imaginary chain extending from an ape-like ancestor to man had been proven.


    Read More: Ardipithecus ramidus
     
  7. M

    Manitoba JF-Expert Member

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    You probably are carrying a common misconception about what science is about.

    There are no proofs in science. Science just gives us the best possible explanations for the things we wonder about.

    Science is not about truth. It is about trying to best explaining the environment around us, its past and posibly its future. No wonder the use of "probably" or "believed". They are not there by mistake. If you expected them to say other wise, then u probably do not understand what science is about.

    What do u mean by carbon 14 being fake? What is the "real" method of age estimation?
     
  8. Abdulhalim

    Abdulhalim JF-Expert Member

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    Nijuavyo hakuna sayansi yeyote iliyoestablish missing link, baina ya binadamu wa kale ( wanaoaminika kuishi kabla yetu na kuwa sifa pungufu na binadamu wa leo in terms of akili na physiology) na binadamu wa leo. Machapisho ya kitaalamu at least sijawahi kusoma kuhusu kupatikana kwa hii link, na mara nyingi wanaotangaza kuhusu kupatikana kwa link ni waandishi vihiyo wasiojua wanachokiongea.
     
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