A New History of Life

It is striking how many new discoveries have been made about the history of life in the last 25 years, partly associated with new disciplines such as astrobiology and geo-biology. Peter Ward is a palaeobiologist while Joe Kirschvink is a geophysical biologist. In this well written and accessible book, they use three main themes: that the history of life has been more affected by catastrophe than the sum of all other forces, thus challenging the principle of uniformitarianism; that three molecules - oxygen, carbon dioxide and hydrogen sulphide - have had the greatest influence on the history of life; and that the evolution of ecosystems is central. This includes the key importance of the carbon cycle in regulating atmospheric temperature and the conditions for life - counteracted by the weathering process. They speculate that life might have originated from Mars and explain the history of multiple ice ages (Snowball Earth) in our evolution. The narrative makes it clear that greenhouse events have been responsible for many previous extinctions, and that we should pay close attention to this lesson from history given our current situation. The authors explain how conditions for life will eventually become impossible on Planet Earth but we ourselves could hasten our own demise if we do not get our carbon emissions under control – a very engaging read.