Steve McHenry's Blog: WAS ARDI OUR APE ANCESTOR?

Koinonia House
from the October 06, 2009 eNews issue

A major fossil find has made its splash in the news recently - a primate named "Ardi" who is believed to date to 4.4 million years ago, 1.2 million years earlier than the famous australopithecine Lucy. Paleoanthropologists are making a big to-do about Ardi, just as they have other ancient ape species found in northern Africa. Despite all the fuss, Ardi - like her neighbor Lucy - is still just an extinct species of ape.

For the past 15 years, the delicate remains of a number of Ardipithecus ramidus specimens have been carefully exhumed and studied. When the bones of Ardi and her fellows were discovered in the early 1990's, they had been trampled and smashed into the mud, and getting them back out for scientific purposes proved a difficult, sensitive task. The bones were not laid out in the matrix in a nice, articulated fashion. Instead, they were jumbled and smashed to "smithereens." Time reports that, along with Ardi's bones, more than 100 fragments from some 35 Ar. ramidus specimens were found at the site, but after putting them together and doing some digital reconstruction, scientists believe they have a good idea of who Ardi was.

Ardi is a unique extinct species, but she's still all ape. She had a small brain and an ape's large opposable toe good for grasping things. She doesn't neatly fit into a spot as humanity's missing link, which paleoanthropologists have expected to look like a cross between a human and a chimpanzee. The current excitement hinges on the fact that those who have studied her argue that Ardi was bipedal – that is, she walked upright. The males of her species also had smaller, gentler teeth than the huge fangs of chimps, and her hands were more dexterous than chimp hands.

"This find is far more important than Lucy," National Geographic quotes Alan Walker, a paleontologist from Pennsylvania State University who was not part of the research. "It shows that the last common ancestor with chimps didn't look like a chimp, or a human, or some funny thing in between."

While the popular news media readily state that Ardi walked upright, some researchers do disagree with that conclusion. First of all, the pelvis bones were seriously crushed, adding to the speculative nature of those bipedal claims. Also, Ardi's feet were nothing like human feet. She had that huge opposable toe and no arch.

Anatomist William Jungers of Stony Brook University is skeptical of the claims that Ardi was bipedal. He told National Geographic News, "This is a fascinating skeleton, but based on what they present, the evidence for bipedality is limited at best. Divergent big toes are associated with grasping, and this has one of the most divergent big toes you can imagine. Why would an animal fully adapted to support its weight on its forelimbs in the trees elect to walk bipedally on the ground?"

Kent State University's Owen Lovejoy believes that Ardi stood upright when she walked, but also acknowledged her comfort in the trees, saying, "She has opposable great toes and she has a pelvis that allows her to negotiate tree branches rather well. So half of her life is spent in the trees; she would have nested in trees and occasionally fed in trees…"

People are also excited about Ardi because she dates 1.2 million years older than Lucy (Australopithecus afarensis), who also allegedly walked upright. Yet, there is skepticism about whether even Lucy walked around on two feet. Anatomist Dr. Fred Spoor and his colleagues at University College, London, performed CAT scans on australopithecine inner ear canals, which are responsible for posture and balance, and came to the conclusion that these creatures did not regularly walk around upright as is so frequently claimed (Nature 369(6482):645–648, 1994). Anatomist Dr Charles Oxnard used multivariate analysis to show that Lucy's big toe was opposable, just like in chimpanzees. In fact, B.G. Richmond and D.S. Strait reported in Nature in 2000 that Lucy's wrists demonstrated she was likely a knuckle-walker like other apes.

A major reason Lucy is often portrayed with human feet, standing upright like a human, is that human footprints have been found in the area where Lucy was discovered. The hardened ash the Laetoli footprints walked through was dated to the time of Lucy using K/Ar testing, and since evolutionists have already decided humans and Lucy did not co-exist, they have concluded that Lucy must have made the prints herself. (According to the Biblical model, humans and apes were created the same day, and would have lived on the earth at the same time.)

While evolutionary writers make confident statements about the place of new skeletal discoveries in the history of human evolution, there is plenty of room for skepticism. The scientific community might assume an evolutionary relationship between humans and ancient primates, but still struggle to show a true relationship exists. It is wise to look closer at the evidence and question claims that our ancestors ever had feet with opposable toes.

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Thursday, October 08, 2009

WAS ARDI OUR APE ANCESTOR?

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