HUMAN INTELLIGENCE 265Africa but soon migrated across wide areas of Asia and Eu rope. Th ey
encountered some of the harshest climatic conditions on the way. Th is is
what prob ably, in part, demanded an even closer cooperative lifestyle
(refl ected in the brain expansions just mentioned) and associated cognitive
and practical abilities.
Liane Gabora and Anne Russon have reviewed some of the evidence
as follows: “Homo erectus exhibited many indications of enhanced ability
to adapt to the environment to meet the demands of survival, including
sophisticated, task- specifi c stone hand axes, complex stable seasonal home
bases, and long- distance hunting strategies involving large game.”^9 By
1.4 million years ago, the species was also producing stone tools requir-
ing considerable cognitive imagination and dexterity of hand and eye.
Th e uniformity of shape evident in this tool manufacture also prob-
ably refl ects a group design, and thus a truly intercognitive culture of
shared imagination and action. Sites occupied by Homo erectus also in-
dicate large social groups, and their hand axes and fl ints have been found
around the remains of very large prey (elephant, bison, and so on), sug-
gesting advanced cooperative hunting skills. In addition, abundant evi-
dence at campsites indicates the use of fi re and perhaps cooking.
It seems safe to assume that such organ ization would have required
other cultural innovations such as rules for group be hav ior and a system
of communication more sophisticated than the thirty or so fi xed signals
of the chimpanzee.
MODERN HUMANSAnatomically modern Homo sapiens prob ably originated in Africa around
one hundred and fi ft y thousand years ago. By seventy thousand years ago
they had spread across Eu rope and Asia, replacing existing Neanderthals
that had already been there for hundreds of thousands of years. Fossils
indicate sophisticated, adaptable, and variable stone cultures.
Home sites suggest large social bands, with alliances among them, and
extremely successful social hunting and home- making skills. Fossil skulls
from that period also indicate a huge increment of brain expansion to the
modern human average of 1,400 cubic centimeters. Th is is about threeThis content downloaded from 139.184.14.159 on Tue, 17 Oct 2017 13:57:55 UTC