In today’s Academic Minute, Dr. Nick Royle of the University of Exeter asks if personality is genetically determined or learned.
Nick Royle is a senior lecturer in behavioral ecology at the University of Exeter where he is a member of the Behaviour group. His broad research interests include reproductive conflicts of interest, early and social environmental effects, signaling and mate choice, and the role of diet in mediating these behaviors. He earned his Ph.D. in zoology at the University of Durham.
Dr. Nick Royle – Is Personality a Product of Nature or Nurture?
Personality can be defined as consistent individual differences in behaviour over time or across contexts. For example, some individuals are consistently more aggressive or bold in disposition than other individuals across a range of different social situations. The existence of personalities is paradoxical in some respects, as it might be expected that animals should be behaviourally plastic, not consistent in behaviour, in response to changes in their environment. However, we know that such personality differences have been found in a wide variety of species, not just humans, from insects to primates, including reptiles, fish and birds.
Such variation among individuals is important in determining how natural selection acts on populations and how populations respond to changes in environmental conditions. For example, the productivity and dispersal ability of populations may depend upon personality variation because different personalities also differ in their use of habitat, and in their willingness to explore new environments: bold individuals may do better in some circumstances with shy individuals faring better in others.
As a result we need to know more about the mechanisms underlying differences in personality in order to understand how it affects population-level processes and how it evolves. Most previous studies have shown that a significant proportion of personality variation is genetically inherited, but few studies have focused on the potential for non-genetic inheritance of personality.
We measured a personality trait, exploration behaviour, in zebra finch parents and offspring and swapped young between nests (cross-fostering) so we could separate out genetic from environmental effects on the inheritance of personality. Our research findings are therefore surprising because they show that, for zebra finches, personality is primarily determined by the environment they experience after hatching (we know this because we cross-fostered eggs just before hatching, so any genetic parent effects on personality were limited to the time before hatching).
This shows that personality variation can be more rapidly transmitted across generations than previously thought. This may help species adapt to environmental change. For example, in response to changes in population density bold individuals are likely to do better when there is more competition, shy individuals better when the population is less dense. This would provide the potential for zebra finches to respond to short-term (predictable) changes in environmental conditions.
We don’t know what behavioural mechanisms are involved in the transmission of personality across generations but it might be that personality is imprinted or learned from parents, in the same way that sexual preferences are known to be transmitted in this species. It is speculation, but offspring may ‘learn’ their personality from their parents.