Question

Minimally, how many half siblings would have to benefit for an altruistic action with cost (c) of 0.25 fitness units and a benefit (b) per relative of 0.10 fitness units to evolve?

a.11

b.10

c.0

d.3

e.158

Answer 1

British evolutionary biologist William D. Hamilton devised a formula, now called Hamilton’s rule

r x B > c;

r – genetic relatedness of the altruist and beneficiary,

B – benefit (in terms of off-spring) of the recipient of altruism,

c – cost (in terms of off-spring) suffered by the donor during altruism

Altruism or kin selection is behaviour where organisms help to survive other organisms of its own species, to generate off-springs and pass on the selective genes in return of not reproducing themselves. Basically, the individuals show selflessness in order to help other individuals within the same species. For example worker bees hep queen bees to reproduce.

The organism will follow altruism only when the Hamilton's rule is fulfilled- (all the options have been shown in details)

Option a and option e follows Hamilton's rule. However, Option a is the correct answer as the question asked minimum number of half-siblings (11 half-siblings) that is required to benefit altruism. Option b (10 half siblings) is the number of half-siblings that exactly equals the cost of the donor.