Chloe Coxshall

2022 PhD Studentship
The evolution of same-sex sexual behaviour
Disentangling the ‘Darwinian paradox’ of homosexual behaviour in primates
Imperial College London


Previous research has confirmed that same-sex sexual behaviour is a heritable trait. However, why this trait has evolved, is still largely unknown. A combination of different factors could influence the evolution of homosexuality.

Together with a research team at Imperial College London led by Prof. Vincent Savolainen, we aim to investigate the mechanisms behind same-sex sexual behaviour.

Taking an unbiased view towards the study of animal sexual behaviour has the potential to impact perceptions of same-sex sexual behaviour in a positive way, and ultimately improve our understanding of the natural world.

Data is collected from a population of rhesus macaques on the island of Cayo Santiago. Photo: Unsplash/Nagara Oyodo
Testing novel theoretical models

One theory for the evolution of same-sex sexual behaviour is the social bonding hypothesis. This suggests that same-sex sexual behaviour has a social function: an increased display of same-sex sexual behaviour will improve the social bonds between the individuals involved. Better social bonds improve fitness due to advantages in social hierarchy, resource access, protection, and help raising infants.

To further this line of research, my colleagues and I carry out behavioural observations on a semi-free roaming population of rhesus macaques on a small island off the coast of Puerto Rico. As part of our research, we aim to compare the behavioural data with personality factors, including extraversion and agreeableness.

Applying evolution to social questions

 I am excited by the opportunity to carry out fieldwork and observe behaviours exhibited in a semi-wild population. I am also excited to get to know the personalities and physical differences of each individual primate in the colony.

Research has always been the pathway I wanted to follow, particularly focusing on primates, behaviour, and human evolution.

During my undergraduate degree I became interested in the field of human evolution and how behaviours and cultures have evolved in different societies. For my Master’s degree I researched mental health in primates and how common mental health symptoms may have evolved.

I am interested in the way behaviour, biological mechanisms, and sociology interact in order to understand the complex relationships between different primate species. The EET scholarship gives me the chance to undertake a PhD, which will open more doors for me in this field.

Applying the Theory of Evolution to social questions is where I would like to continue to focus my research.