Practice question · Multiple choice
Haldane joked he would lay down his life "for two brothers or eight cousins." Why those particular numbers?
Hints
- Write down r for a full sibling and for a first cousin, then multiply until the totals match.
- Hamilton's rule weighs benefit by relatedness. The joke is that rule, priced.
Show the answer
D. Because relatedness is 1/2 to a brother and 1/8 to a cousin
Why
Two halves and eight eighths both come to one, exactly the genetic stake you would be spending. It is Hamilton's rule as a bar-room line, and the reason altruism toward kin needs no special explanation: from the gene's point of view it is not altruism at all.
Practise Social Behavior and Altruism
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