The earliest known record of the genus Homo -- the human genus -- represented by a lower jaw with teeth, recently found in the Afar region of Ethiopia, dates to between 2.8 and 2.75 million years ago, according to an international team of geoscientists and anthropologists. They also dated other fossils to between 2.84 and 2.58 million years ago, which helped reconstruct the environment in which the individual lived.

Scientists have possibly discovered the first human ever to walk the Earth, based on an ancient jaw fossil from Ethiopia dating back 2.8 million years ago, according to new research that also reveals the conditions under which the earliest humans evolved.

A fossil lower jaw found in the Ledi-Geraru research area, Afar Regional State, Ethiopia, pushes back evidence for the human genus --Homo -- to 2.8 million years ago, according to a pair of reports published March 4 in the online version of the journal Science.

On the basis of genetic and biological studies, it seems that the strict division of sex into two categories makes it too simplistic for reality.

The idea of two sexes is simplistic. Biologists now think there is a wider spectrum than that.