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The spread of - Homo erectus on up a phyletic gradualist...

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The spread of Homo out of Africa is presumed to have taken place about 1.5 MYBP by Homo erectus . This species seems to be on a trajectory of brain size and body size that looks anagenetic , whereas one lineage that lead to Australopithecus robustus seems to be on another line. In a broad sweep of time, the notion of the chimp leading to the Australopithecine, to Homo, to the Neanderthal to the modern American family standing in their driveway is a myth. There were lineages that diverged in a branching cladogram, some of which did not make it to the present. Evidence for this is provided by more than one distinct morphological type of early humans present at the same time (see below). As time gets closer to modern humans, however (
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Unformatted text preview: Homo erectus on up), a phyletic gradualist anagenesis is more easy to accept. Once a big brain is achieved and this provides the intellect for an organism to anticipate its environment, the notion that an organism evolves in response to changes of the environment becomes too simplistic. Humans evolved the power to alter their environment so as to protect themselves from its abiotic pressures. This means that they are altering their own selective pressures and a dialectic emerges between the organism and the environment such that these cannot be separated. Other organisms do this (beaver dams, deciduous trees), but in humans this cycle is accelerating. The rest is history....
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