Chapter 8 The Evolution of Social Behavior

Chapter 8 The Evolution of Social Behavior - Chapter 8 The...

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Chapter 8: The Evolution of Social Behavior Kinds of Social Interactions - Social interactions are behaviors that affect the fitness or more than one individual o Interactions that involve two individuals are called dyadic or pairwise interactions There are four main kinds of acts: Selfish, altruistic, mutualistic, and spiteful acts When talking about altruistic acts in nature, we are talking about the technical sense of the word It is impossible to determine to assess the effects of a single behavioral act; but it is possible to make inferences in the immediate costs and benefits of particular acts Altruism: A Conundrum - Altruistic behavior cannot evolve by ordinary natural selection o It decreases the fitness of the individual, so it cannot be selected for - Primates perform altruistic behaviors in nature o This might make sense if these kinds of actions are rare, like spiteful actions are o Primates will groom each other, give warning calls, form a coalition or share food In each of these cases, the fitness of the actor decreases - Altruistic behaviors cannot be favored by selection just because they are beneficial to the group as a whole o Even though the total benefit to the entire group exceeds the cost to the individual, this confuses the effect on the group with the effect on the actor o Alarm calls benefit everyone to the same extent; it has no effect on the relative fitness of callers and noncallers because they all benefit However, the caller incurs costs, so it is not favored This example can also be applied to other altruistic acts Kin Selection - Natural selection can favor altruistic behavior if altruistic individuals are more likely to
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This note was uploaded on 04/21/2009 for the course ANTH 200Lg taught by Professor Yamashita during the Fall '07 term at USC.

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Chapter 8 The Evolution of Social Behavior - Chapter 8 The...

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