"In this study we looked for a correlation between the advent of stone-tipped spears, and the progressive decline in prey size.
"A more substantial wound induced by a stone-tipped spear is likely to slow it down and reduce the distance it can run before ultimately collapsing—increasing the hunter's chances of retrieving the fallen prey. This insight further elucidates our findings from hundreds of thousands of years ago, when stone-tipped spears were developed in response to the increasing scarcity of large prey.
"Homo Sapiens and Neanderthals, emerging about 300,000 years ago, upgraded their spears by adding stone tips, which they produced with the more sophisticated Levallois technique. These stone-tipped spears were apparently used for both thrusting and hurling. About 50,000 years ago more complex hunting systems like the bow and arrow and spear thrower, were used regularly by Homo Sapiens."
"Ultimately, we hypothesized that prey size had played a major part in human evolution: at the beginning the largest animals were hunted, and when these were gone humans went on to the next in size, and so on. Finally, when hunting was no longer energetically viable, humans began to domesticate animals and plants. That's how the agricultural revolution began."