Laetoli - Interpretation and Significance

Interpretation and Significance

Before the discovery of the Laetoli footprints, there was much debate as to what developed first in the evolutionary time line: a larger brain or bipedalism. The discovery of these footprints therefore settled the issue proving that the hominids found at Laetoli were fully bipedal before the evolution of the modern human brain, and were even bipedal close to a million years before the earliest known stone tools. The prints are classified as belonging to Australopithecus afarensis.

Some analysts have noted in their interpretations that the smaller trail bears "telltale signs that suggest whoever left the prints was burdened on one side." This may suggest that a female was carrying an infant on her hip but this cannot be proven for certain.

The footprints themselves were an unlikely discovery because they are almost indistinguishable from modern human footprints, even being almost 4 million years old. It is noted that the toe pattern is much the same as the human foot, which is much different than the feet of chimpanzees and other non bipedal beings. The footprint impression has been interpreted as the same as the modern human stride, with the heel striking first and then a weight transfer to the ball of the foot before pushing off the toes.

Based on stratigraphic analysis, the findings also provide insight into the climate at the time of the making of the footprints. Pliocene sediments show that the environment was more moist and productive than now. Climate changes that caused a shift from forest to grassland environments has a strong correlation with upright posture and bipedalism in humans. This could have initiated the evolution to bipedalism of the hominids found at Laetoli.