I Love Ardi

Huge news in the field of paleoanthropology: in an unprecedented publication of eleven papers in Science, researchers will release today the fruits of 15 years of investigation of fossil remains, including much of a skeleton of Ardipithecus Ramidus.

Evidently, the research argues for a shake-up* of the evolutionary tree. John Hawkes:

What’s the big deal?

If you want a basic description of the facts, here they are. Today’s series of papers is basically unprecedented in paleoanthropology. There are eleven papers in total, giving comprehensive coverage of the anatomy, paleoenvironment, and evolutionary interpretation of a new skeleton of Ardipithecus ramidus and dental remains representing more than 30 additional individuals. They have been published simultaneously in a coordinated effort including excavation, faunal correlation, microscopy, palynology, CT-scanning, three-dimensional reconstruction, isotopic analysis, and lord knows what else.

It’s the closest thing we’ll ever see to a big science effort in the little field of human evolution – like Tim White was building a supercollider under everybody’s noses.

The skeleton has been nicknamed, “Ardi” and it is 4.4 million years old. The site is Aramis, Ethiopia, in the Middle Awash field research area. The skeleton includes most of both arms, except the humeri, both hands, both feet, the right leg, the left ox coxa and part of the right ilium, a bit of sacrum, a couple of vertebrae, and a near-complete skull and dentition. It’s a bit more complete than Lucy, although preserving different parts.

See John Hawkes’s Ardipithecus FAQ

Anthropology.net Ardi page

* White and colleagues 2009b give a long table of “derived” characters in Ardipithecus and Australopithecus, but they are “derived” only with reference to their inferred state in the human-chimpanzee LCA. But elsewhere in these papers, they argue that some of these “derived” characters are actually primitive morphologies for apes, for which chimpanzees are independently derived. For many of the dental features, if we supposed a Miocene ape ancestor, the broadened mandibular body, thicker enamel and so on would look primitive, not derived. In the table, they list upper and lower canine traits separately, and break them up into six or more for each. That’s a quick way of making one morphological change look like twelve or more instances of independent evolution. Talk about atomizing traits!

So I wonder if a real cladistic analysis might not place Ardipithecus with the australopithecines. Especially if it included a proper sampling of Miocene ape taxa.

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