Question

1. During the evolutionary history of hominins, there was a behavioral change: hominins began to cook their food. There were also two structural changes: a decrease in jaw muscle size and an increase in brain size. Explain the sequence of evolutionary events that may link these three changes. In your answer, explain how each changes altered the selective pressures on populations of early hominin.

Answer 1

All early hominins were nearly all vegetarians. They had to eat hard to digest cellulose in forms of twigs, leaves ,tubors etc. For digestion of those foods ,they needed to chew it very fiercely. It was both time and energy consuming for the hominids.

Then they discovered that fire could soften the food. They began cooking the food, which provided them with both more time and energy. Due to lack of force and energy for chewing, the jaw muscles started to loose their function and there was a decease in jaw size. Then there was an evolution of intellectual activity from there. As it took less time and energy to chew their food, they started doing creative works like drawing ,tool making etc. This enhanced their cerebral activity and helped in development of their brain.

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