Friday, January 28, 2011

New Clue in Human Evolution: It's All in the Wrist

"Humans Left Trees 4.2 Million Years Ago"
Jennifer Viegas, Archaeology News, Discovery News (January 28, 2011 )

"Wrist bones of human ancestors reveal when humans switched from living in trees to on the ground.

"Early human ancestors stopped swinging in trees and started walking on the ground sometime between 4.2 and 3.5 million years ago, according to a new study.

"This key moment, when our ancestors became anatomically and behaviorally less ape-like, coincides with increased cooling, more defined seasonality, and a grassland growth spurt. All transformed former forest habitats into more varied ones, forcing our very early relatives to change their ways.

" 'With the trees being farther apart, it became energetically advantageous for hominids to cross the gaps bipedally,' said Gabriele Macho, lead author of the study that was published in the latest issue of Folia Primatologica.

"Macho, a paleoanthropologist at the Catalan Institute of Paleontology in Barcelona, and his colleagues made the determinations after analyzing wrist bones from two early hominid relatives: Australopithecus anamensis and Australopithecus afarensis (also known as the "Lucy" fossil). The former species is 600,000 years older than the latter and is believed to be its ancestor...."

The article is more paleontology news than "archaeology news:" but, never mind.

There's a fair amount of detail in the article - including a discussion of what it is about the wrist bones that tells about how they were used.

The bottom line seems to be that there's more evidence that we were 'us' earlier than we thought. Not that a haircut and new clothes would help one of the folks who made the earliest known kitchen blend into the crowd these days. But looks aren't everything - and that's another topic.

It still looks like we got started in east Africa. But it looks like some of us may have left quite a bit earlier than paleontologists thought until recently. And that's another topic, too, sort of:
  • "Ancestors may have left Africa earlier than thought"
    Amina Khan, Los Angeles Times (January 28, 2011)
    • Tools found at Jebel Faya, United Arab Emirates
      • Seem to be about 125,000 years old
        • That's around 60,000 years before we were assumed to have left Africa
      • The tools aren't like those found along the known migration route
    • Change happens
      • Including sea level
        • The Bab al Mandab strait was (fairly) dry at low tide back then
      • Lakes, rivers, and grasslands covered Arabia then
        • Good hunting
Nothing new there, in a way. The more humanity finds out, the bigger, older, and more complex the world turns out to be. And the Lemming is not going to get into the fine-structure constant, galaxies, cosmology, and just how many universes we're talking about. (September 16, 2010, November 3, 2009, June 4, 2008)

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