The earliest Later Stone Age (LSA) industries from southern Africa are microlithic and unstandardized and include the bipolar technique. The dating of these industries is controversial and the earliest microlithic industry is said to occur at Border Cave at about 39,000 B.P. By 18,000 B.P. a bladelet tradition was established and this was replaced in many parts of southern Africa, at about 12,000 B.P., by a widespread and prolific nonmicrolithic industry, characterized by side-struck flakes. The late Pleistocene environment was colder than present, with particularly harsh conditions during the Last Glacial Maximum (LGM), between about 20,000 and 18,000 B.P. Populations may have been isolated because archaeological visibility is low during the LGM and decreases further after the LGM. After 13,000 B.P. there is a dramatic increase in sites and this implies that there may have been widespread colonization of territory previously unoccupied for tens of thousands of years. By the end of the late Pleistocene there was a change in hunting patterns, in parts of southern Africa, from an emphasis on the capture of large, gregarious grazers to an emphasis on small, solitary browsers. Social complexity increased during the late Pleistocene, and by 12,000 B.P. it seems possible that Stone Age people were observing some social practices recorded historically among Bushmen (San).