Monday, March 29, 2010

Ardipithecus ramidus – Newest member of the Human Family

Ardipithecus ramidus – Newest member of the human family
There are a number of traits possessed by humans that set apart members of the species Homo sapiens from all other primates. The most notable are the ability to walk upright, the opposable thumb and the size of the brain that allows higher order thought processes and the ability to communicate through the use of language.

Current evidence suggests that some five to eight million years ago, there lived the common ancestor of both humans and chimpanzees. The discovery of Lucy in 1974 represented the first relatively intact fossil remains of the earliest known hominin - the family that includes humans and our true human ancestors. Lucy lived some 3.2 million years ago, walked upright and had a brain roughly the size of a chimpanzee. The species to which she belonged was given the name Australopithecus afarensis.

In 1994, the relatively intact fossil remains of a hominin that was discovered to have lived 4.4 million was found in Ethiopia. It took a team of investigators some 15 years to excavate the fossil referred to as Ardi, and it was in October of this year that the skeleton was unveiled. Ardi is more primitive than Lucy and has been placed within a species defined as Ardipithecus ramidus. The base of Ardi’s skull is short from front to back and the upper blades of pelvis are shorter and broader than living apes. This lowers the center of gravity and permits balancing on one leg that is an absolute requirement for walking upright.

The sediments in which Ardi was found indicate that these ancient creatures lived on an ancient floodplain, covered with woodlands. Ardi probably coexisted with fig and palm trees, monkeys, kudu antelopes and peafowl.

Although the conclusions reached by the team that found these remains have been met with some skepticism, this discovery is a significant one and takes us closer to a more complete understanding of the evolution of our species on our wondrous planet.

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