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Evolution

Walk This Way

Science magazine has just published an article on the oldest footprints found which correspond to modern day human biomechanical function. These footprints are about 1.5 Million years old and appear to belong to homo erectus, a species which predated homo sapiens.Old Foot Prints

The great toe was in similar alignment to modern day humans. An arch was present. Heel strike occurred at initial contact, weight transfer progressed forward with apparent foot function in the midfoot (midtarsal joint) proceeding in a modern manner. Weight bearing then went to the central metatarsals, (seemingly bearing more than the first metatarsal) followed by push off at the big toe.

The foot prints appear to show someone slowed to a near stop (or starting from a stop) and then picking up speed. To my eye, with an initial angle of gait being first high on the left, than on the right (about 24-26 degrees), followed by a narrow angle of gait (about 1 degree) as speed picked up, it looked as though the pre-human hominid was looking to the left, and then to the right. He likely would have been able to cross some of our streets, at least those with traffic bearing to the right side of the road. And in fact he may have avoided getting run over by a bovine, which blotted out part of one of his foot prints.

Bipedalism, walking on two limbs, was an important evolutionary step. Bipedalism is thought to have been present for about 6 million years.  It is energy efficient. It allows free hands to carry things, make tools, build things that are more complex than bird’s nests and beaver’s dams. It frees the hands  for hunting and fishing. Ultimately, it led to holding hands while walking. It led to artistic undertaking such as cave paintings, fashioning musical instruments, fingering the holes of a flute or playing chords and notes on strings. But, it also led some to throw stones at others. But that is another story.

The energy saved may have led to enhanced brain function. The energetics of bipedal walking, determined on an individual basis (some calculations have been done on chimpanzees) show a significant reduction in energy cost for walking in a bipedal manner. Some theorists believe that upright walking, and even running came before the larger skull and brain size.  That may very well have been true, based on these and other findings. There are many interesting adaptations and changes that occurred over the years. Some of the differences that occurred evolutionarily that are important to human bipedalism and are of significant, walking and running energetics include altered f0rm and function of the calf muscle, Achilles tendon, and the gluteal muscles. But, we can’t judge all of that from the footprints alone.

Science 323, 1197 (2009);  Early Hominin Foot Morphology Based on 1.5-Million-Year-Old Footprints from Ileret, Kenya. Matthew R. Bennett, et. al.

Science Now “Early Humans Toed The Line”