Our ancestors were attaching spear points to wooden hafts as long ago as 500,000 years - a good 200,000 years earlier than thought.
The news follows the recent discovery that projectiles such as arrows have also been around for longer than once believed.
Attaching stone points to spears, or 'hafting', was an important advance in hunting weaponry for early humans. Hafted tools require more effort and planning to manufacture, but give a big boost in killing power.
"There is a reason that modern bow-hunters tip their arrows with razor-sharp edges," says Benjamin Schoville of Arizona State University.
"These cutting tips are extremely lethal when compared to the effects from a sharpened stick. Early humans learned this fact earlier than previously thought."
The points were recovered during 1979-1982 excavations at the South African archaeological site of Kathu Pan 1. The team compared the wear on the points with the damage inflicted on modern experimental points used to spear a springbok carcass target with a calibrated crossbow.
When points are used as spear tips, a lot of damage forms at the tip of the point, with large distinctive fractures. The damage on the ancient stone spear points was found to be remarkably similar to those produced with the calibrated crossbow experiment.
Hafted spear tips are common in Stone Age archaeological sites after 300,000 years ago. But this new discovery shows that they were also used in the early Middle Pleistocene - the era of Homo heidelbergensis, the last common ancestor of Neanderthals and modern humans.
"Rather than being invented twice, or by one group learning from the other, stone-tipped spear technology was in place much earlier," says Schoville.
"Although both Neanderthals and humans used stone-tipped spears, this is the first evidence that this technology originated prior to or near the divergence of these two species."