By Bernie Douglas
The less ecologically rich environments of Europe and other non-tropical ecosystems when compared with the more varied and complex landscapes of tropical Africa can be convincingly argued to select for reduced levels of fine discernment and/or complex reasoning ability in various homo species. Evolutionary evidence relating to Homo erectus, for example, suggests that the further he traveled from equatorial Africa the lower his cognitive capabilities became in contrast with those of other erectus lineages that remained in Africa or closer to the African continent. The lineages of Homo erectus, in fact, can be hierarchically arranged in descending order from the most behaviorally complex to the least, based entirely on its lived distance from equatorial Africa. 1) Homo sapien sapiens remained and evolved in tropical Africa and is the most behaviorally complex 2) Neanderthals would evolve in ice age Europe, and 3) Peking man evolved in East Asia.
Brace (1964), argues that in environments where a particular trait is less pertinent for survival (for example, melanin levels in colder climates) one can expect that this trait will over time become less or negatively selected for (“The Probable Mutation Effect”). In tropical and sub-tropical climates, individuals must navigate a more hostile and multifaceted landscape which those in colder climates are not exposed. Things like poisonous snakes, lush and diverse plant life, varied insect and arachnid life, large predators (e.g. wild dogs, lions and leopards etc), the ever present threat of parasitic infection (requiring extensive herbal knowledge in order to remedy) and tropical disease are found in abundance in equatorial environments.
When Homo erectus migrated out of Africa, hundreds of thousands of years ago, the kinds of advanced cognitive abilities which evolved in tropical African Homo sapiens would not in those who left the continent (see Horan et al, 2005). So that, in theory, the further Homo erectus traveled from equatorial Africa (particularly, in latitude), the less pertinent the cognitive characteristics that define Homo sapien sapiens would become. Let us contrast Homo sapiens and Neanderthals for example: Both species share a common ancestral lineage that dates back between 500, 000 and 300, 000 years in Africa (McHenry 1994; Noonan et al, 2006). While one member of this lineage would leave the African continent to brave the harsh ice age conditions of Europe (Neanderthals), the other would remain in Africa to evolve within that continent’s more complex tropical ecosystems (Homo sapien sapien).
Much paleoanthropological evidence suggests that Neanderthals were considerably less intelligent than Homo sapien sapiens; lacking many of their/our complex behavioral traits. For example, Neanderthal living spaces were largely unorganized and showed no evidence that the spaces were divided according to different functions (Tattersall and Schwartz 2000). This behavior is typically observed among lower primate species. Neanderthals are also believed to have lacked complex social organization, a degree of innovative behavior, forward planning [sic], and the exchange of information, ideas, and raw materials (Horan et al, 2005). This strongly suggests that colder latitudinal climates put fewer demands on complex cognition and social behaviors. Moreover, as survival in these environments did not require that Neanderthals (who survived in these environments for nearly 500, 000 years) evolve complex “forward planning” or sophisticated social organization, it should thus be concluded that higher intelligence evolves in warmer tropical environments, where these traits and behaviors did evolve, and are seen in Homo sapien sapiens.
In addition, if Darwinian evolutionary theory is applied to the couple of dozen early modern Europeans who migrated out of Africa to find themselves in Europe, it should then follow that natural section would select for traits similar to the kinds that helped to make Neanderthals successful within their ice age European environments; while negatively selecting for the kinds of behavioral and cognitive traits necessary for survival within Africa. There is much paleoanthropological evidence, for example, that shows numerous craniofacial, dental, and postcranial traits in Europeans that are decidedly Neanderthal (Trinkaus, 2007, Brace 2005). Brace (2005, 1979) using craniofacial measurements to compare human populations found that the nuances of the cranial outlines of European Neanderthals are identical to the nuances of modern western Europeans (Brace, 2005; Brace, 1979).
The European continent would offer very few environmental challenges and provide a less elaborate and multifaceted environment than that found in tropical Africa. For example, tropical and sub-tropical regions of the world comprise an extremely complex array of ecosystems and support more than 70 per cent of the world's biota (organisms of a geographic region), all in a complex network of ecological interactions. In addition, Africa itself has an altitudinal range from depressions that are below sea level to mountain peaks that exceed 5000metres. As a result it has an incredible diversity of environments (Connah and Douglas, 2001). Connah and Douglas (2001) argue that the continent “contains some the driest deserts in the world, and yet has three of the world’s major rivers; the Nile, the Niger, and the Zaire (Congo). Some of the hottest places on earth are in Africa, and yet there are glaciers on its highest mountains. There are streaming rainforests and dry savanna grasslands, low-lying river valley’s and high plateaus, extensive deserts and gigantic lakes, mangrove coasts and surf-pounding beaches. This is to give only an impressionistic picture of the very large number of differing environments to be found in the African continent. In reality the major zones merge into one another, so that there are an even greater variety of conditions. Add to this the effects of climatic variation through time and you have an infinitely complex environmental situation (Connah and Hobbs, 2001 p. 1).”
In short, the elaborate biodiversity of the tropics and Africa, in particular; as well as the complex ecological environments that arise there, can be argued using evolutionary anthropological evidence, to select for higher cognitive and reasoning ability (as seen in Homo sapiens), while colder and less intricate environments can be argued to select for lower intelligence and a reduced need for finer cognition, as is seen in Neanderthals and Peking man.
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