Abstract: The earliest evidence for heat treatment of stone materials has been found in South Africa having appeared as early as 164ka and predominates among silcrete tools dated to 72ka years ago from Still Bay, South Africa. Use and control of fire are important behaviors for human evolution as deliberately heating materials improve the rock’s physical properties. Archaeologists have conducted experiments to investigate heat treatment since Shippe (1963) regarded this activity as an important research aspect in prehistoric archaeology. What and how physical properties of material changed by heat treatment are the two issues of this research. The following observations are noted. 1) Some changes are visible by the naked eye such as changes in color, a greasy lustre on heated siliceous rocks; heat damage; and a slowness or acceleration of development of a patina. 2) Macrostructural changes accompanying heat treatment include: fracture toughness is reduced with increased temperature; elasticity increases with increasing temperature;? loss? of? light? energy? by? thermoluminescence;? obliteration? of? fission? tracks;? and? loss? of water of hydration. 3) Microstructural changes accompanying heat treatment can be detected by X-ray diffraction, infrared absorption spectroscopy and with scanning electron microscopy. The following characteristics of heat-treated rock are: disintegration, pot-lid fractures, flake splitting, transverse fractures, and surface crazing. In addition, heated raw material could yield more flakes with less force, and with the flakes being longer than the ones from unheated materials. It is important to recognize that these characteristics are not consistently apparent in heat-treated materials.
Due to the raw materials constraints, no heat-treatment stone artifacts have been identified so far in China. Since heat treatment is considered as an important part of modern human behavior, we? suggest? that? Chinese? archaeologists? should? pay? close? attention? to? the? identification? of? heated? artifacts and more efforts should be emphasized in experimental work.

Key words: Paleolithic; Heat Treatment;Human Behavior; Experiment