Tuesday, June 22, 2010

New Australopithecus Afarensis Skeleton

Scientists have described a new Australopithecus afarensis skeleton, dubbed "Big Man," because at over 5 feet tall, he dwarfs Lucy, his famous afarensis cousin.

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I asked my wife's back surgeon about inversion tables, and he said, "I have one. I use it every evening. What does that tell you?"

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The description is more a display of how hard it is to interpret 3.6-million-year old evidence than it is further insight into A. afarensis as a species.

Was Lucy's Last Name Walker?

The founders believe the skeleton proves that afarensis was an excellent walker and maybe even a runner. They cite long legs and the shape of the pelvis. They also say they have enough of the rib cage, plus a shoulder blade, to say that Australopithecus afarensis had a narrow chest like humans.

The part about the narrow chest didn't seem to be disputed, and it does appear that our ancestors are less chimp-like than we previously imagined.

Everything else, however, was disputed.

Critical scientists said that there's not enough of the leg, just one partial lower leg bone, to confidently assert that "Big Man" had longer legs than previously speculated for afarensis. They say the evidence for skilled walking is inconclusive.

On the other hand, we do have 3.6-million-year old footprints found 30 years ago in Tanzania. These indicate a longer stride than Lucy's, and if "Big Man" had the long legs his discoverers say he had, then he could have made those footprints.

The footprints also indicate A. afarensis had arches, another indication of advanced bipedality.

Australopithecus Afarensis and Climbing

The other controversy was swinging from trees. The discoverers of "Big Man" say that he indicates his species couldn't climb trees like apes.

In this case, whether I agree or not, I loved the critic's response ...

"Riddle me this," asks Jungers in considering Hailie-Selassie's emphasis on a ground-dwelling A. afarensis. "Where did they sleep? Did they wait for fruit to fall to the ground? Where did they go to escape predators?"

Riddle me this? Do you think he was a little irritated?

Scientists are human, too. That's what I got from this finding.


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