Muddy footprints left on a Kenyan lakeside suggest two of our early human ancestors were neighbors some 1.5 million years ago.

(Reuters) - About 1.5 million years ago, individuals of two different species in the human evolutionary lineage trudged on a muddy lakeshore in northern Kenya, leaving behind intersecting trackways alongside the footprints of antelopes, horses, warthogs, giant storks and other animals.

A 1.5-million-year-old lakebed from Kenya shows two ancient human relatives cohabitating an environment, shaking up our ancestors' story.