Lazarus (1987)- BPS “Concepts of Sociobiology”

Foundation Principles

a) Natural selection: resources are limited: populations can grow geometrically - thus there is a struggle for existence. We know individuals vary, thus the survival of the fittest. We know variable phenotypic characters are heritable thus individuals with adaptive heritable characters produce more offspring = natural selection.

b) Task of sociobiology is discover how social behaviour has been moulded by natural selection in the past, and how is maintained in its present for by present day selection pressures - which are simply particular cases of natural selection.

c) Genetic determinism? Not necessary to assume simple relationship between genotype and behaviour. May be very many genes, and interest is in differences in behaviour between species or individuals, without knowing degree of genetic determinism. We do not have to assume that behaviour is resistant to modification by experience in order to believe that there are natural selection causes as well - e.g. imprinting in birds.

d) Adaptation, optimisation and modelling. A major advance is theoretical models that go beyond theories of how and predict quantitative values for behaviour. They all test the hypothesis that natural selection has, given certain assumptions, produced the best possible solution to a behavioural problem. Parker (1978) and the dung fly : predicts male copulation time pitting the advantage of fertilizing more eggs with current female against cost of losing opportunities with other females. predicts 41.4 mins - actual time =35.5 minutes. What if data do not fit the prediction? either optimality hypothesis thrown out (rare) or model is modified. Optimization is not a necessary consequence of the theory of natural selection.

e) Evolutionary stability. Social behaviour is “frequency dependent” - it depends on others: therfore the Evolutionarily Stable Strategy. *This is mathematical not a strategy consciously done by the animal*

Parental care and sexual behaviour special since shared genes.
Hawks and Doves.
If benefit of winning is more than cost of injury then everyone should be a hawk - this is a “pure “ESS. If other way, then hawks could invade an all-dove population but doves would still spread when too many Hawks. - Thus most social behaviour is probably a “mixed” ESS

if individuals meet only once, then selfishness is best. But if meet frequently then a simple pure ESS - “tit-for-tatworks i.e. co-operate on first encounter then copy the other.
1. it retaliates 2. forgiving if opponent changes. 3. Never the first to defect.

see also mutual co-operation and symbiosis between species eg. cleaner fish.

Altruism and self-sacrifice
the gene-centered “Inclusive fittness” view rather than individual centred view - sibling co-operation and rivalry. discrimination of kin from non-kin is essential, - but sometimes fails e.g. the cuckoo