Ileret footprints

In 2009, scientists working at Ileret, east of Lake Turkana in northern Kenya, reported a set of fossil footprints preserved in layers of silt about 1.5 million years old. The tracks were left on a muddy surface by walking hominins and later buried gently, then exposed by erosion. They were probably made by Homo erectus, the species whose bones are common at nearby sites. Matthew Bennett and Craig Feibel were among the team that studied them. Later excavations, reported in 2016, found more tracks at the same locality.

The prints show a foot much like our own. It has a clear arch, a big toe lined up beside the others (in apes it sticks out to the side), and a pattern of pressure under the heel and ball of the foot that matches how we walk. The Laetoli footprints, made about two million years earlier by Australopithecus afarensis, show a smaller and different foot, so Ileret marks a further step toward the body built for striding long distances. The size of the prints and the length of the steps allow estimates of body size, and the 2016 study suggested that a group of mostly larger individuals, perhaps males, walked the same lake shore.