Human Evolution
My research in human evolution uses mathematical and computational models to investigate how distinctive features of human life history shaped human social behaviour. In particular, I am interested in the consequences of postmenopausal longevity, shortened interbirth intervals, extended male fertility, and sex-ratio structure in the fertile ages.
One part of this work examines how human fertility patterns interact with Fisher's principle. Female fertility ends in mid-life, while male fertility can continue for decades longer. This creates a male-biased fertile-age population in which males may have lower average fertility per year, but much longer fertile careers. My work explores how this age structure can maintain an equal offspring sex ratio while altering sex-specific reproductive value in overlapping generations.
A related part of this research investigates the transition from ancestral promiscuity toward pair bonding and mate guarding. Using age-structured agent-based models, I examine how longer adult lifespans and shorter interbirth intervals increase the number of males competing for available fertile females. This can produce a male-biased operational sex ratio, making mate guarding more successful than repeated competition for additional mating opportunities.
Together, these projects suggest that human social evolution was shaped not only by behaviour itself, but also by the demographic consequences of human life history. Grandmothering, postmenopausal survival, shortened birth intervals, and extended male fertility may have changed the reproductive environment in which pair bonding, mating competition, and persistent sex-specific social inequalities evolved.