JAVIER TRUEBA / MSF / SCIENCE PHOTO LIBRARY JAVIER TRUEBA / MSF / SCIENCE PHOTO LIBRARY
Early hominid footprints. Footprints of a human ancestor (probably Australopithecus afarensis) at Laetoli, Tanzania. The rock bed on which they are preserved is 3.7 million years old. Footprints from two individuals were discovered in 2015, 150 metres away from footprints discovered by Mary Leakey in 1977. They are moving in the same direction and on the same ash surface as the Leakey footprints. The footprints show that human ancestors had acquired an upright, bipedal gait by this stage in their evolution. Analysis of stride length has been used to estimate body size. One of the newly discovered tracks belongs to an individual estimated to be 1.65 metres tall. This is significantly taller than estimates for the other individuals and supports the theory that A. afarensis body size varied considerably, much like modern day gorillas.
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