The evolution of Gaia by Tim Lenton (University of Exeter)

Today, nearly four billion years after life first appeared on Earth, the planet hosts an abundance of complex life. The varied and complex life on the planet today both maintains, and is supported by, fertile land and oceans and an oxygen-rich atmosphere, interacting via myriad feedback mechanisms. Furthermore, life and the global environment have co-evolved such that neither would exist in its present form without the other. With a sample size of only one Earth, many have questioned whether the self-regulating of the Earth is just a lucky accident, which had to be that way for us to observe it. However, some basic principles of complex adaptive systems would suggest that it is not an accident and rather that the co-evolution of life and its host planet should tend to converge on self-stabilising attractors. The search for life elsewhere in the solar system and on extrasolar planets should ultimately help us test such theories. In the meantime I will show the results of some experiments in silico where we seed many virtual worlds with artificial life forms and see how they evolve. We predict that self-stabilising outcomes – i.e. ‘Gaias’ – should be a frequent though not inevitable outcome wherever simple life forms are able to evolve (or arrive) on a potentially habitable planet. However, the likelihood of such biospheres evolving to a stage of complex, self-aware life, appears far more difficult. Even from our sample of one Earth, it is clear that it only got to its present state of being able to support complex, self-aware life (i.e. us) through a series of highly improbable system-wide ‘revolutions’, each of which was contingent on the previous one and each of which could have gone catastrophically wrong.

About Tim Lenton

Tim studied Natural Sciences as an undergraduate at the University of Cambridge. Reading Jim Lovelock’s books on Gaia ignited his passion for studying the Earth as a whole system. This led to his PhD studies on what regulates the nutrient balance of the ocean and the oxygen content of the atmosphere, supervised by Professor Andrew Watson at Plymouth Marine Laboratory and later the University of East Anglia (UEA). After gaining his PhD, Tim worked at the Centre for Ecology and Hydrology, Edinburgh, where he built a simple coupled carbon cycle and climate model, and then coordinated the development of the GENIE family of Earth system models. In 2004 he returned to UEA and built up an Earth system modeling group, working on key events in the coupled evolution of life and the planet, including human-induced global change. He  published a book on this with Andrew Watson called ‘Revolutions that made the Earth’ (OUP, 2011). Tim moved to the University of Exeter in 2011, where he and his group are focusing on understanding these past revolutions, on developing an evolutionary model of the marine ecosystem, and on early warning of climate tipping points.

Tim’s work identifying the tipping elements in the climate system won the Times Higher Education Award for Research Project of the Year 2008. He has also received a Philip Leverhulme Prize 2004, a European Geosciences Union Outstanding Young Scientist Award 2006, the British Association Charles Lyell Award Lecture 2006, and the Geological Society of London William Smith Fund 2008. Tim is a Fellow of the Linnean Society and a Fellow of the Geological Society.