Evolution of Sex

Evolution of Sex

Why do men exist? It seems natural that we need two sexes to reproduce, but from an evolutionary perspective it’s not as efficient because only half the adults produce offspring. Prof Matt Gage has conducted pioneering research into the role that ‘sexual selection’ plays, proving that two sexes are definitely better than one for preserving the genetic health of populations.

There are plenty of examples in nature of asexual, all-female populations that, at first glance, have a more efficient system of reproduction. In asexual species, every adult is capable of breeding, while in sexual species like ours only half of us (daughters) will produce offspring.

Why then do two sexes exist in most species on our planet? It’s a question that’s puzzled biologists since Darwin: if a defining feature of natural selection is ruthless efficiency, why bother to produce males?

To answer that question, Prof Matt Gage from UEA’s School of Biological Sciences has conducted pioneering research into the role of ‘sexual selection’ in species survival, explaining how sex can persist as a dominant mode of reproduction in nature. It turns out that competition among males and choice by females acts as an important filter against deleterious mutation build-up, protecting populations against eventual extinction. In Prof Gage’s words:

“To be good at out-competing rivals and attracting partners in the struggle to reproduce, which is what sexual selection acts upon, an individual has to be good at most things, which depends on genetic quality right across the genome. Sexual selection therefore provides a really efficient filter for maintaining and improving genetic health against the constant threat in every lineage of mutation build-up.

“Our findings, following years of experimental evolution, provide direct support for the idea that sex persists as a dominant mode of reproduction because it allows sexual selection to act and therefore provide these important genetic benefits.”

This research is part of a huge body of ground-breaking work that takes place at UEA – we’re internationally renowned for our expertise in the Life Sciences, being part of the most cited research centre outside of Oxbridge and London, with a highly regarded School of Biological Sciences.


The Expert

Professor Matthew Gage

Professor of Evolutionary Ecology
School of Biological Sciences
Professor Gage is an evolutionary ecologist with primary interests in reproduction, sexual selection and conflict, and especially the evolution of sperm form and function. Research uses a number of animal models (insects, fishes, mammals) in both field and laboratory studies to answer questions of the functional and adaptive significance of reproductive strategies and mechanisms. His research funding mainly comes from NERC, Leverhulme and the Royal Society.