There is a place in Tanzania known as Laetoli. It is a magical place, not because of fire breathing dragons or voodoo witchdoctors, but because it is where our ancestors walked. It is where scientists (anthropologists) now study to get a glimpse of the past. It is a very important site that has evidence of an everyday activity of our distant ancestors - walking side-by-side.
At one point, humans started walking upright, but for the most part we had no record of this. That all changed, however, when in 1974 and 1975 Dr. Mary Leakey lead an expedition to Tanzania to study ancient human remains approximately three and a half million years old. So old in fact that the humans that left the footprints found at Laetoli were made by a species known as Australopithecus afarensis. This is a species on the tree of human evolution identified by 300 individuals found to date, a forward protruding face and a 430cc brain case.
The footprints of Australopithecus afarensis were discovered in Tanzania, as stated earlier by Dr. Mary Leakey and her husband. The Leakey's originally were headed to Olduvai Gorge just north of the site, but stopped on the way and made an important discovery. There, preserved in the mud (rock) was a set of footprints! There were seventy of them in two parallel lines thirty meters long. Apparently, the region that the two Australopithecines inhabited had been volcanic. At one point the volcano exploded sending lava everywhere and the two individuals just happened to walk over the lava as it cooled, preserving their footprints. After Dr. Leakey took samples of the prints using plaster casts and molds then she covered the site up and left markers indicating where they were.
Covering the footprints up helped to preserve them as they had already been exposed when Dr. Leakey stumbled upon them. They were then preserved against the ravages of erosion and vegetation. Scientists visit the site annually to kill any trees that are growing into the soil. It is very important to keep these footprints intact as they have not told us their whole story.
Scientists are still in debate about what the climate was like in this region and there is also a great deal yet to learn about Australopithecus afarensis. The debate continues on about the relationship between bipedalism, size of the brain and the ability to make and use tools. Some scientists argue that when humans began to walk upright, our hands were then free to make and use tools. Others argue that we could not make tools until we evolved the brain capacity necessary to make them. Laetoli proved that increased brain size led to toolmaking not bipedalism since tools were first made 2.6 million years ago well after humans began to walk upright. So by studying Laetoli we may still have a great deal to learn about our ancestors. Maybe we can find the footprints that lead all the way into the far-distant past.
Bibliography
http://www.mnh.si.edu/anthro/humanorigins/ha/laetoli.htm
http://www.getty.edu/conservation/activities/laetoli/index.html
Written by: Chris Peterson