Friday, 9 November 2012

While I'm At It. What's Up With Patricia Ann Kramer and Lucy's Lagging?

I miss some beauties if I'm not hyperdiligent about checking the blogs for the latest news that I don't always see on the ticker. Case in point. Another bit from Hominid Hunting, this on Nov. 5. One Patricia Ann Kramer published this in the American Journal of Physical Anthropology, 'Could Kadanuumuu (KSD-VP-1/1) and Lucy (AL 288-1) have walked together comfortably?'

A perfect fit for the Kramer article. Lucy the Lagger and her mate imagined before the discovery of a 1.5-m tall conspecific. 
Kramer's is a splendid example of tackling a research question that's the equivalent of a gnat using methods and techniques that are akin to an 8-pound mallet. Lucy, you'll remember, is the ~1-m tall Australopithecus  afarensis specimen. Kadanuumuu, on the other hand, is estimated to have stood about 1.5 m tall. After some cleverly conceived research involving a treadmill, 36 children and 16 adults. Many exhausted humans later, and much calculation, Kramer arrives at the conclusion that bipedal apes with longer legs walk faster than those with short legs [tibiae, to be exact]. I'm not given to making fun of people. So I won't. I just want to make a couple of points about this research. 
     First of all, if, and it's a big if, Lucy and Mr. Unpronounceable are the same species and contemporaries, it matters very little how fast she walked in relation to him. That's because, regardless of Lucy’s walking pace, as the female she is the one responsible for giving birth to those big males. She, therefore, is just as big as the species needs her to be. Nothing more to be said.
     Second. If the size difference between Lucy and Mr. U is typical of a single species, it represents a greater degree of sexual dimorphism than is usually considered by most workers (look again upon the evocative painting shown above). If so much sexual dimorphism existed within A. afarensis, we cannot compare them to humans. Instead, one must look at other great apes to find similar within-species size difference. And it turns out that the ape with the greatest sexual dimorphism is the orangutan. 
Adult male (at left) and female Bornean orangs. Photo by Holly Carroll (link to original on Flickr).
And, unlike chimps and gorillas, orangs don’t live in social groups, nor do they live with their mates. Yet, conventional wisdom has it that all bipedal apes behaved like chimps and gorillas do, today. If Lucy and her male counterparts were so different in size, why shouldn’t we consider the possibility that the australopithecines were solitary, just like the orang?
     Just sayin'...

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