Africa has long been recognized as the cradle of the human race. A fascinating discovery made in 1978, near the village of Laetoli in northern Tanzania, sheds light on some of our early ancestors.
In 1976, a well-known English archaeologist and anthropologist, Mary Leakey, led a field team on a dig near Laetoli. One afternoon, some of the younger members of the group were amusing themselves by throwing clumps of dried elephant dung at each other. One of the group, Andrew Hill, ducked to avoid a missile of flying dung, and noticed he was standing in a dry stream bed, on some exposed layers of ash. There were animal footprints visible in the ash but no serious effort was made to identify them at that time.
In 1977, Mary Leakey’s son, Philip and a colleague, Peter Jones, found a large number of elephant tracks at the same place. Beside them were tracks that closely resembled human footprints. Upon further investigation, it was found that two hominids, ( any of a family of two-legged primates including all forms of humans, extinct and living ), one larger than the other, had walked through the area sometime in the distant past. That the evidence had survived for so long was due to a series of remarkable coincidences.
Near Laetoli there is an extinct volcano, called Sadiman. At one time, nearly four million years ago, it was active. When it erupted, it emitted a cloud of ash over the surrounding countryside to a depth of about half an inch. Soon, rain covered the fine ash and it became pasty, like newly-poured cement. It recorded the tracks of every creature that walked through it: elephants, giraffes, antelopes, hares, pigs, even small insects, and the hominids.
The hot African sun had just hardened and dried the imprints, when the volcano erupted again, spewing more ash over the landscape, sealing in the evidence of the differing life forms. This happened a number a times, and the footprints eventually became fossilized, concealed under twelve to twenty-four thin layers of hardened ash.
Some of the layers had been exposed by erosion in recent years, and painstaking excavations uncovered fossilized tracks and footprints which had been hidden for millions of years.
The footprint fossils were dated by the potassium-argon method and found to be about 3.6 million years old, originating in the Pliocene era. The path of prints extended about eighty feet over level ground. The smaller set of footsteps, presumably made by a female, walked parallel to the larger, and showed that the couple were walking in step, side by side.
The skeletal formation of the feet is interesting. These imprints are definitely not the tracks of any species of ape. The toes are the same as human toes. The big toe is line with the others. Apes have big toes which stick out at a 45 degree angle, suitable for climbing trees and grasping objects.
Also, the impressions show that the heel struck the ground first, then the weight was transferred to the ball of the foot and finally the toes pushed off for the next step. This process is the same as a modern human stride.
The discovery of the Laetoli footprints renewed the controversy between those who favor creationism as opposed to those who argue for the theory of evolution. Heated discussions on the topic continue to the present day.
In an interview with the National Geographic magazine in 1979, Mary Leakey expressed her opinion:
” What do these footprints tell us? First…that at least 3,600,000 years ago, what I believe to be man`s direct ancestor walked fully upright. … Second, that the form of the foot was exactly the same as ours. … ( The footprints produced ) a kind of poignant time wrench. At one point, … she ( the female hominid ) stops, pauses, turns to the left to glance at some possible threat or irregularity, and then continues to the north. This motion, so intensely human, transcends time. “
Until scientists can come up with more definitive evidence to support either creationism or evolution, the proponents of each belief will undoubtedly continue their lively dialogues.