Lecture 4 Flashcards
How much probability do parent and offspring have of sharing genes
50%, relatedness = 0.5
How much probability do full siblings have of sharing genes
50%, relatedness = 0.5
What is Hamilton’s rule?
r B > C, where r is the coefficient of relatedness, B is the benefit to the recipient of the altruistic act and C is the cost to the actor. Therefore the relatedness multiplied by the benefit must be greater than the cost. This is the theory of kin selection. The more closer related we are to someone, the more generous and kind we are to them.
Do people really behave according to this rule?
Find research
What research is there for Hamilton’s rule
Prairie dogs give alarm calls 20-30% of the time when there is no close genetic relatives in the group compared to 40-45% when there is non-descendant close genetic relatives and compared to 45-50% with offspring. (Hoogland)
Does evolution always favour those who look after relatives?
No, there is a trade off. And there is also other ways that altruism can evolve, reciprocal altruism (Trivers, 1971). As well as sometimes individuals do share with unrelated others; like group working. But there is things that this depends on in case someone cheats the system.
How can we explore Hamilton’s rule?
Perceived investment in others via questionnaires.
Actual investment in others; wills (Barrett et al., 2002), expenditure and experimental procedures (Madsen et al., 2007).
We can look at lack of investment; neglected children, abuse of children and patterns of murder.
What did Barrett et al., 2002 find?
In wills, people left the largest amount to offspring (r = 0.5) and spouse. However, siblings of r = 0.5 get considerably less maybe because the offspring will need more care as well as if there sibling is a male, there is paternity uncertainty.
What is Madsen et al., 2007 find?
They got people in a lab in an uncomfortable position, and rewarded them with money either for them, or a someone related. They found that participants spent significantly more time in the pose when they got the reward themselves, and less time was spent with the less related person got the reward.
Does Hamilton’s rule work if you don’t know who your relatives are?
Women are certain of their offspring, however men are uncertain; this is called paternity certainty. Apicella & Marlowe (2004) produced a questionnaire of men and their investment in their children. They found the more the father resembled his children the more investment was given. As well as the more the male thought his wife was female, the more investment he put in.
Discuss Platek et al., 2004?
Men said they were more likely to invest in morphed offspring than women. However, there was no difference with negative questions; would you ignore this child.
How does paternity certainty affect grandparenting?
Child knows mother is mother and her maternal grandmother is her maternal grandmother. Euler & Weitzel (1996) estimated how much investment a child received from their grandparents. Maternal grandmother gave more than maternal grandfather, who gave more than paternal grandmother who gave more than paternal grandfather.
Relatedness is not the only thing to take into account with Hamilton’s rule, what about the potential reproductive output of the kin member?
Barrett et al., 2002. One individual could be worth many, thus affects kin selection. A study also found that when people were asked who they would save, young people would save young and old equally, whereas old people save the young a lot more than the old as they can’t reproduce as much.
Is adoption an exception to Hamilton’s rule? **
Many cases of adoption in traditional and industrialised cultures. In traditional societies it is usually kin who are adopted, and maybe it is because they are an economic benefit. In modern societies it is usually non kin. Adoption is favoured because opportunities are…. ***
Who loses out from kin selection?
Daly & Wilson (1988), were inspired by the social psychological observations that families are the most violent group which disputes kin selections. Non-relatives and spouses are more likely to be victims than kin than offspring, parents and other relatives. Other research has found a child living with a step-parent is more likely to be killed than a child living with both natural parents. This risk decreases as the baby gets older. This may be if the male is the step-parent the mother may be more likely to reproduce with him; like in lions.
