Homo erectus was the first species in our line of evolution
to expand their range beyond tropical
and subtropical environments into temperate climatic zones of the Old World where they
encountered relatively cold winters. This evidently occurred by at least 1/2 million years ago in Asia
and a bit earlier in Europe. It was made possible mainly by the success of new inventions and
new
subsistence strategies. The most important change may have been increased meat consumption
as a result of hunting and more successful scavenging. The greatest difficulty living in temperate
areas was probably not the cold weather but obtaining something to eat during the winter when
fresh plant foods are scarce. It is in that season that meat would have been the most important
calorie source. The ability to create and use fire for cooking and heating may also have been
significant. However, the first convincing evidence of regular fire use does not come until 400-
300,000 years ago, when the Homo erectus were evolving into archaic Homo sapiens.
Implications
The cultural developments of Homo erectus essentially
began a new phase of our evolution--one in
which natural selection was altered by cultural inventions. This has been referred to as biocultural
evolution. Culture can affect the direction of human evolution by creating non- biological solutions
to environmental stresses. This potentially reduces the need to evolve genetic responses to the
stresses. Normally, when animals move into new environmental zones, natural selection operating
on random mutations causes evolution. In other words, the population's gene pool is altered as
a
result of adapting to a new environment. When late Homo erectus moved into temperate
environments, nature should have selected for biological adaptations that were more suited to
cooler climates. Such things as increased amounts of insulating body fat and insulating hair
covering most of the body would be expected. Homo erectus evidently achieved much of the same
adaptation by occupying caves, creating fires, and becoming more capable at obtaining meat. By
using their intelligence and accumulated knowledge, they remained essentially tropical animals
despite the fact that they were no longer living only in the tropics. However, natural selection
continued to select for increased brain size and presumably intelligence. This pattern of culture
altering natural selection accelerated dramatically with the evolution of modern humans. Today,
most of us live in cities and towns that are essentially unnatural environments and the rate of
culture change has accelerated dramatically. We have occupied most environmental zones on
land, and yet we are still essentially tropical animals. As a result, we perish rapidly if our
cultural
technology is taken away from us in environments in which the temperature drops to freezing.
