The Difference between the Sexes - From Biology to Behaviour

Download Poster

Nick Lane

University College London, United Kingdom

Biography

Nick Lane is a biochemist and writer. He holds the first Provost's Venture Research Fellowship in the Department of Genetics, Evolution and Environment at University College London, and is a founding member of the UCL Consortium for Mitochondrial Research. His research is on the role of bioenergetics in the origin and evolution of life. He studied biochemistry at Imperial College London and earned his doctorate at the Royal Free Hospital on oxygen free radicals and mitochondrial function in transplanted organs. He is the author of three books, Oxygen: The Molecule that made the World (OUP, 2002); Power, Sex, Suicide: Mitochondria and the Meaning of Life (OUP, 2005) and Life Ascending: The Ten Great Inventions of Evolution (W.W. Norton, 2009), which have won praise in the academic and popular press, been shortlisted for three literary prizes and named among the books of the year by the Economist and the Sunday Times. He is a regular contributor to Nature and New Scientist, and was described by Nobel Laureate Frank Wilczek as "a writer who is not afraid to think big - and think hard." For more information, visit www.nick-lane.net

Abstract

The power behind the sexes: why energy coupling requires sexual coupling

The existence of two sexes across most of the living world is strange. While sex and recombination is genetically beneficial, there is no obvious need for two sexes. All that is required is the fusion of two gametes, which could in principle be identical. The frequency of mating could potentially be doubled if all individuals were the same sex, which would offer a large selective advantage in widely dispersed populations. Yet even when gametes are identical, as in many algae and fungi, each gamete can only fuse with the opposite mating type, to the exclusion of 50% of the population. Many studies suggest that the unifying explanation is the inheritance of organelles, notably mitochondria. The deepest biological distinction between the sexes is that one sex (usually female) passes on mitochondria to the next generation, whereas the other sex (usually male) does not: male mitochondria are destroyed. In this talk I will put forward a new bioenergetic hypothesis for the evolution of two sexes. To achieve optimal energy coupling (the coupling of cell respiration to the synthesis of ATP by way of a proton gradient) mitochondrial genes need to be selected to function properly against the nuclear background of the new individual. This functional selection is optimised by the uniparental inheritance of mitochondria. In animals, selection for optimal energy coupling sets up an evolutionary tradeoff, in which the cost of high physical (aerobic) fitness and long lifespan is low fecundity and poor adaptability to different environments.