12 August 2012

Cradle of Humankind

About an hour southwest of Pretoria is a World Heritage Site called the Cradle of Humankind, which I got to visit a couple of weeks ago.  There's a very nice visitor's center that looks a bit like a large hobbit barrow, and houses a really excellent museum that I guess is technically a paleo-anthropology museum, and explains why this particular region of South Africa has yielded a tremendous number of early hominid (primate) fossils.

The area encompasses nearly 200 square miles of rolling hillside where there are extensive networks of limestone caves in which numerous important pre-human fossil remains have been found.  From the backside of the Visitor's Center, there is a wonderful vista of the surrounding countryside.

After touring the museum, we drove a few kilometers to the Sterkfontein Caves.  The caves were once the site of limestone quarrying (lime being necessary to extract gold, which was a burgeoning industry in the area at the same time), but in the late 19th century, some of the miners began discovering fossils inside the caves, and eventually the caves were transferred to the University of the Witwatersrand in Johannesburg.

In the 1930s, excavations began to extract the various fossils from the caves, and continues to this day.  In 1947, a nearly complete skull of Australopithecus africanus was found, estimated to be just over 2 million years old.  This species is considered to be a direct ancestor of humans, and the sample found is nicknamed Mrs Ples (sounds like 'place'), although recent developments in cranial identification seem to support a theory that she should probably be called Mr Ples.

We got to take a tour of the caves, including seeing the gate behind which additional excavation of "Little Foot" is ongoing.  In 1994, a researcher noticed some bones in a box of assorted parts that looked like they might not belong to the others in the box.  Over the next few years, other mislabeled bones were found in miscellaneous places, and the researcher sent some assistants into the caves to try to find where the bones had been excavated from.  Amazingly, in just 2 days, they found the rest of the tibia sticking out of the ground, and they began excavation.

Nearly 15 years later, they have found a nearly complete skeleton, and the findings are so well preserved and complete, that it may eventually be a more complete find than that of Lucy, in Ethiopia, in the 1970s.  

"Little Foot" is thought to have been a juvenile traversing the area where the caves are, possibly to evade  predators, when the theory is that he fell about 10 meters down into the cave, and broke bones in his legs, and eventually died in place.  He was mummified before being encased in breccia (cement-like composite of rocks and minerals), which preserved it, but makes it very tedious to be extracted from.  Little Foot is thought to have been up to a million years older than Mr/Mrs Ples, and a different species than the previous finds.

While evolutionary researchers agree that our species originated in Africa, the theory that South Africa is the precise origin is not universally embraced, currently.  The science behind evolution is relatively young, and I imagine that the real location of our origin will continue to evolve (sorry) as more fossils are found around the continent.