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Faced with the difficulties of surviving in often hostile surroundings, early humans manufactured various flaked stone tools to increase the success of food gathering and the efficiency of food processing. Special-purpose tools increased the likelihood of obtaining food and were particularly important when it was hard to secure adequate food resources (1, 2). For example, projectile points are more likely to inflict a lethal wound if they have needle-sharp tips and symmetrical, straight, razor-sharp edges that reduce drag on penetration. Such sophisticated tools require not only special skills but also high-quality stone materials. When such materials were unavailable, early humans developed the ability to improve the quality of the available materials through controlled heat treatment by burying selected pieces of stone beneath a fire at a campsite or a specialized workshop, usually for a day or more. On page 859 of this issue, Brown et al. show that in coastal South Africa, the deliberate use of this technique dates back at least 72,000 years (and perhaps as long as 164,000 years), predating its use outside Africa (3).