The Environment of Human Origins

The Savanna hypothesis is the proposal that the major divergence between the hominins and other great apes was driven by the former moving out of the forests and onto the grasslands. Dating back to at least the 1920's, it is one of the oldest and most culturally established hypotheses addressing what separated humans from the other apes. The hypothesis, which suggested that the breakup of tropical forests led to our ancestors walking between rich areas and carrying food and other items. The easy to understand hypothesis has come under fire in recent years. On one hand, the earliest human ancestors are found in less-than-arid circumstances, woodland in fact. On the other hand, evolutionary biologists are less inclined to look at environment-only explanations for the selective pressures behind what makes us human, or, in more carefully worded terms, what led to the adaptations that we define ourselves as human with. Many suggest social pressures, like male parenting and presumably less fighting, led to reduced canines or that the intense social competition that emerged after we started using stone tools and eating meat led to a profound capacity for culture. It turns out that it is impossible to sort out the abiotic factors like weather and climate from the biotic forces like disease and competition. We have to settle for contemplating all of the possibilities without getting a final answer!

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