The teardrop-shaped hand-axes date to about 1.76 million years ago, and would have been used for a range of tasks from chopping wood to cutting up meat.
They would have been so useful in fact that scientists describe them as the "Swiss army knife" of the Stone Age.

This was a bigger-brained, smarter and more dextrous creature than any human species before it.
Homo erectus ranged across Africa and Asia before going extinct about 70,000 years ago. Many suspect it was on the direct evolutionary line to modern humans - Homo sapiens.
Careful design Palaeolithic stone tools can be grouped into a number of different styles. The type unearthed at the Kokiselei archaeological site is referred to by anthropologists as Acheulian technology.
Such objects are larger and heavier than the pebble-choppers (Oldowan technology) that were used previously and which are associated with a more primitive human known as Homo habilis.