Some stone tools have a single sharpened edge, while others consist of double-edged designs

Stone artifacts found at an Ethiopian site alongside this 1.6-million- to 1.5-million-year-old Homo erectus braincase indicate that this hominid made an array of simple and more complex tools, researchers say. Michael Rogers/Southern Conn. St. Univ.

Hardly one-tool wonders, ancient hominids called Homo erectus relied on a toolkit that included relatively simple and more complex cutting devices, new discoveries suggest.

Excavations at two Ethiopian sites located about 5.7 kilometers apart uncovered partial H. erectus braincases alongside two types of stone tools, paleoanthropologist Sileshi Semaw of the National Research Center on Human Evolution in Burgos, Spain, and colleagues report March 4 in Science Advances. Some artifacts featured a single sharpened edge, while others consisted of double-edged designs such as pear-shaped hand axes. One H. erectus fossil dates to about 1.26 million years ago, the other to between around 1.6 million and 1.5 million years ago.

A Homo erectus braincase found near these double-edged stone implements (each shown from both sides) contributes to evidence that these now-extinct hominids created tools requiring considerable skill and planning as well as simple cutting instruments.Michael Rogers/Southern Conn. St. Univ.

Hominid fossils and stone tools are rarely found together, making the new discoveries particularly noteworthy. East African H. erectus made different types of stone tools over hundreds of thousands of years, apparently selecting implements based on the task at hand or perhaps the quality of rock available, Semaw’s team says. The Ethiopian evidence bolsters previous suggestions, stemming from stone tool finds, that neither H. erectus nor any other hominid made only one kind of stone tool but fashioned a greater variety of relatively simple and more complex implements than has often been assumed (SN: 3/23/15).

A large braincase with thick brow ridges, found at the younger Ethiopian site, came from an adult male, the researchers suspect. A small braincase with thin brow ridges, unearthed at the older Ethiopian site, belonged to an adult female, the team suggests.

A recent study found that another extinct, distant cousin to modern humans called Paranthropus boisei that lived in East Africa at the same as H. erectus had hands capable of making stone tools (SN: 3/3/20). But such artifacts have yet to be found with P. boisei fossils.