Psychology · 2003 · November · Paper 2 · HLSL · Markscheme

MARKSCHEME November 2003 PSYCHOLOGY Higher Level and Standard Level Paper 2 19 pages N03/350/HS(2)M INTERNATIONAL BACCALAUREATE BACCALAURÉAT INTERNATIONAL BACHILLERATO INTERNACIONALc Comparative Psychology [20 marks] 1. To what extent can altruism in animals be seen as an evolutionary advantage? Refer to the markbands for paper 2 when marking this question. Responses should make clear wh at they mean by altruism and explain this in terms of reproductive fitness - the ability to reproduce successfully at some cost to the helper. Better responses will demonstrate to examiners a knowledge of different kinds of altruism, including reciprocal altruism and indu ced altruism. The former is exemplified by vampire bats (Wilkinson) in their exchange of regurg itated food when indivi dual bats have been unsuccessful in their foraging. High scoring responses should also discuss why altruism is beneficial in evolutionary terms and this will probably be explained by referring to the downside of “cheating”, not returning favours, and the implications this has for survival. Games theory and the prisoner’s dilemma (Axelrod and Hamilton) offer useful explanations for this behavioural phenomena. Induced altruism usually occurs between species, and is sometimes known as social parasitism or manipulation. The classic case is shown by most species of cuckoos and also by cowbirds both of which use brood parasitism. Holldober’s work with the larvae of the Atemelles beetle which mimics the behaviour of ants to obtain food from them is also relevant. It is likely that average responses will focus mainly on the shared genes argument proposed by Dawkins where altruism is shown mainly by closely related family members, e.g. the Florida scrub jay or Belding’s ground squirrels. Responses that merely describe incidents of altruistic behaviour but do not discuss the evolutionary advantages, should be limited to a maximum of [10 marks]. – 3 – N03/350/HS(2)M