On 24 August at 14:15 Markus Valge will defend his doctoral thesis “Testing the predictions of life history theory on anthropometric data” for obtaining the degree of Doctor of Philosophy (in Zoology and Ecology).
Professor Peeter Hõrak, University of Tartu
Research Fellow Gert Stulp, University of Groningen (Netherlands)
Organisms must harvest and allocate limited resources between life history traits, i.e. traits that affect fitness. According to the life history theory, selection should favour behavioural and physiological traits in intercorrelated adaptive sets constituting life history strategies. Using life history framework to describe individual differences in humans remains controversial. While studies suggest that the genes associated with the variation of life history traits are intercorrelated in a predicted manner, evidence at the level of phenotype is ambivalent. Such research is complicated by the gene-environment interaction and rapidly changing cultural background. The aim of this thesis was to test the predictions of life history theory on human growth and reproduction, and to gain insight into cultural and environmental effects mediating these outcomes. The findings are most parsimoniously explained by the models of genetic coadaptation of life history traits. Early maturation was not induced by parental death, but the parents of early-maturing girls died younger. Psychosocial stress did not accelerate sexual maturation, but inhibited growth in boys. Children inherit life history differences from their parents, but propensity for earlier maturation may be expressed only under favourable conditions. Behavioural reproductive outcomes may manifest more consistently. Under different social settings, the same intrinsic traits can be related to cultural adaptation but these adaptations may have an opposite impact to fitness due to differences in reproductive strategies. I find that in contemporary humans the trade-offs between different fitness components can be predicted within the framework of life history theory.