other bands who spoke the same language and livedin neighboring territo-
ries in the same general environment. They occupied cavesor camps con-
structed ofportable materials and moved from one watering, foraging, and
hunting area to another as the seasons dictated. As in other preindustrial
societies, there was a division of labor between women, who stayed close to
the campsite and were responsible for childcare and most of the work of
collecting edible plants, and men, who were the hunters. They were skillful
in fashioning tools from wood and stone, clothing from animal hides,
musical instruments from wood, catgut, and ostrich quills, and bows and
arrows with tips smeared with poisons extracted from snakes or insects or
plants. Their artists have left an impressive record in the rock paintings and
engravings that have survived in protected places."
The population probably increased slowly over the centuries but re-
mained sparse by modern standards. Health and life expectancy varied
with the environment. The principal factors were the regularity and nutri-
tional value of the food supply and the exposure to disease. The major
scourges of tropical Africa, such as malaria and yellow fever, may have
affected some of the people who lived below the mountain escarpment in