188 CHAPTER 8 | Early Homo and the Origins of Culture
they keep active. Below that temperature, hands and feet
cool to the point of pain.^18 Clothing, like many other
aspects of material culture, does not fossilize, so we
have no direct evidence of the kind of clothing worn by
H. erectus. We only know that it must have been more
sophisticated than was required in warmer climates. In
short, when our human ancestors learned to employ fire
to warm and protect themselves and to cook their food,
they dramatically increased their geographic range and
nutritional options.Hunting
Sites such as 400,000-year-old Ambrona and Torralba
in Spain provide evidence that H. erectus developed the
ability to organize in order to hunt large animals. The
dismembered scattered remains of several elephants,
horses, red deer, wild oxen, and rhinoceroses were pre-
served in an ancient swamp at Torralba. This finding,
which cannot be explained as a result of any natural geo-
logic process, indicates that these animals did not acci-
dentally get mired in a swamp where they simply died
and decayed.^19 In fact, the bones are closely associated
with a variety of stone tools—a few thousand of them.
Furthermore, the site contains very little evidence of car-
nivorous animal activity and none at all for the really big
carnivores. Clearly, the genus Homo was involved—not
just in butchering the animals but evidently in killing
them as well.
It appears that the animals were actually driven into
the swamp so that they could be easily killed. The re-
mains of charcoal and carbon, widely but thinly scattered
in the vicinity, raise the possibility that grassfires were
used to drive the animals into the swamp. This evidence
indicates more than opportunistic scavenging. Not only
was H. erectus able to hunt, but considerable organiza-
tional and communicative skills are implied as well.Other Evidence of Complex Thought
Other evidence of H. erectus’ capabilities comes from the
small island of Flores in Indonesia. Flores lies east of a deep-
water strait that throughout the Pleistocene acted as a bar-
rier to animals to and from Southeast Asia. Even at times of
lowered sea levels, getting to Flores required crossing open
water: at minimum 25 kilometers from Bali to Sumbawa,
with an additional 19 kilometers to Flores. The presencewith heavy jaws and large, sharp teeth (raw food is tougher
and needs more chewing), favoring instead further reduc-
tion in tooth size along with supportive facial structure.
Alternatively, the reduction of tooth size and support-
ing structure may have occurred outside the context of
adaptation. For example, the genetic changes responsible
for increasing brain size may also have caused a reduction
in tooth size as a secondary effect. The discovery of a ge-
netic mutation, shared by all humans but absent in apes,
that acts to prevent growth of powerful jaw muscles sup-
ports this hypothesis. Without heavy jaw muscles attached
to the outside of the braincase, a significant constraint to
brain growth was removed. In other words, humans may
have developed large brains as an accidental byproduct of
jaw-size reduction.^16
Soft foods may have relaxed selection for massive jaws.
But cooking does more than soften food. It detoxifies a
number of otherwise poisonous plants; alters digestion-
inhibiting substances so that important vitamins, minerals,
and proteins can be absorbed while in the gut, rather than
just passing through it unused; and makes high-energy
complex carbohydrates like starch digestible. Cooking in-
creased the nutritional resources available to humans and
made them more secure.
The partial predigestion of food by cooking also may
have allowed a reduction in the size of the digestive tract.
To establish this biological change, paleoanthropologists
do not have the benefit of fossilized digestive tracts. In-
stead they turn to comparative anatomy of the living
hominoids. Despite its overall similarity of form to those
of apes, the digestive tract of modern humans is substan-
tially smaller. The advantage of this gut reduction is that it
draws less energy to operate, thereby competing less with
the high energy requirements of a larger brain.
Like tools, then, fire gave people more control over
their environment. Fire modified the natural succession
of day and night, perhaps encouraging H. erectus to stay
up after dark to review the day’s events and plan the next
day’s activities. Though we cannot know whether H. erec-
tus enjoyed socializing and planning around campfires at
night, we do have evidence at least of some planning be-
havior. Planning is implied by the existence of populations
in temperate climates, where the ability to anticipate the
needs of the winter season by advance preparation for the
cold would have been crucial to survival.^17
Although considerable variation exists, studies of
modern humans indicate that most people can remain
reasonably comfortable down to 50 degrees Fahrenheit
(10 degrees Celsius) with minimal clothing so long as
(^16) Stedman, H. H., et al. (2004). Myosin gene mutation correlates with ana-
tomical changes in the human lineage. Nature 428, 415–418.
(^17) Goodenough, W. H. (1990). Evolution of the human capacity for beliefs.
American Anthropologist 92, 601.
(^18) Whiting, J. W. M., Sodergem, J. A., & Stigler, S. M. (1982). Winter tem-
perature as a constraint to the migration of preindustrial peoples. American
Anthropologist 84, 289.
(^19) Freeman, L. G. (1992). Ambrona and Torralba: New evidence and inter-
pretation. Paper presented at the 91st Annual Meeting, American Anthro-
pological Association, San Francisco.