Human biology has affected the development of culture, since symbolic and learning abilities depend upon the physical composition of the brain and other anatomical adaptations, such as vocal structures that can produce speech or manual abilities that can manufacture tools. This biological substratum supports a generalized capacity for culture among all humans and explains universal features, such as language learning abilities. However, biological factors do not determine specific cultural traits, such as the ability to speak French, English, or Dani. All children are preprogrammed by genetics to learn languages through a fixed series of stages, but will acquire a specific language only through patient instruction. Thus biology determines our general capacity for culture and is responsible for appears of some cultural universals, i.e., traits that appear in some form in every culture in the world. However, cultural variations among peoples are attributable to learned traditions and not to innate or genetic propensities.
The replacement of genetic transmission of behaviour by learning in the course of human evolution has had a clear effect on our biological heritage. We adapt to our environment through cultural strategies rather than genetic predispositions. Accordingl y, human groups have spread to every part of the world and survived drastic differences in climate and diet without dramatic anatomical changes. The result has been that physical differences among peoples, which have developed over millions of years in thousands of diverse ecosystems, are remarkably superficial. Cultural differences, however, are profound and limitless and form a fascinating subject matter for anthropological enquiry.