Friday, October 02, 2009

Australopithecus overshadowed by Ardipithecus

If you're younger than 45, chances are that as a schoolkid, you were taught that Australopithecus afarensis was the oldest known human ancestor.

That's because Lucy, a female representative of that ethnic group, was found by Donald Johanson in Hadar, Ethiopia, in 1974. Lucy lived 3.2 million years ago.

It was widely believed - in fact, since the very era of Charles Darwin - that even earlier ancestors had to be closer to chimps: this hypothetical link remained missing but it was expected that more chimp-like ancestors would be found soon.

The status of this speculation just changed dramatically, assuming that the new findings will pass the tests that they should pass. An older ur-woman was recently reconstructed from bones found in the Ethiopian desert between 1992 and 2009.

Ms Ardi from the Ardipithecus ramidus species lived 4.4 million years ago but she looked nothing like chimps. (See her extra pictures and don't ask me why they think that her boobs were so small).

This fact makes it somewhat more likely that the common ancestor of the humans and the apes looked like neither. You may check an up-to-date sketch of the evolutionary tree. The improvement may be just quantitative but it will surely require some textbooks to be rewritten.

The experts claim that the skeleton looks very primitive to them. Let me admit that I don't see the "huge difference in simplicity" from the contemporary humans. Do you?

See also Google News.

1 comment:

  1. What is interesting are the far-reaching hypothetical conclusions the authors draw from the fact that small teeth, absence of sexual dimorphism, and incipient bipedality preceded tool use by millions of years. Here are two excerpts from Lovejoy's hypothetical interpretation (available free from Science with registration:

    "A unique advantage of bipedality is that it permits food transport over long distances, a behavior not generally feasible for an arboreal or quadrupedal hominoid. Bipedality also facilitates the regular use of rudimentary tools, both as carrying devices and as implements for resource exploitation. In a partially ateline-like social structure (but lacking extreme anatomical adaptations to suspension) coupled with a likely early hominid ecological context, females might readily have employed the frequent Pan strategy of exchanging copulation for important food (11, 75, 76) (e.g., especially valuable meat or fruits high in fat and/or protein), particularly if such items required protracted search time. If obtained by male exploitation of day ranges logistically too large for territorial defense or for effective optimal foraging by females with dependent infants, such dietary items may have become pivotal."


    "On the other hand, the common mammalian and avian strategy of provisioning provides myriad benefits directly associated with reproductive success (32, 79). Females and their offspring enjoy reduced predation risk, and males benefit from intensified mothering of their offspring. In such a context at the base of the hominid clade, temporary pair bonds based on sex-for-food exchanges would have further encouraged copulation with provisioning males, rather than males that relied on dominance or aggressive displacement of competitors abetted by large and projecting canines. Research has confirmed the selective advantages of such exchanges in Pan (11, 80). Even controlling for rank and age, chimpanzee males that practice meat-for-sex exchanges have elevated fitness levels, and provisioning on a long-term basis improves reproductive success, even after controlling for estrous state (81)"

    Does this last explain female propensity for prostitution?