Here on Earth
Flannery starts with a look at the development of the Earth and the evolution of life on it. He considers the idea of 'Gaia' - Earth as an organism - and goes on to look at the challenges that Gaia has faced, looking at the alternative 'Medea' hypothesis, that species will eventually destroy themselves through competitiveness. The book then gets on to the arrival of humans, showing the extinctions which have followed in their wake. Flannery considers the role of culture and society in the creation of 'superorganisms'. The later part of the book looks at the effect humans are having at present, through pollution, global warming and overexploitation, and Flannery discusses what we might do about it.
I felt that the book lacked a central theme. Sometimes Flannery's arguments seem vague and unconvincing. For instance in arguing against the idea of a 'selfish meme' (he prefers the word 'mneme') , he says that philanthropy probably won't lead to more offspring for philanthropists. But of course that's irrelevant, it's whether one person's philanthropy encourages philanthropy in others that's important. The book has a bit about the origin of the earth, a bit about early humans, and a bit about the damage we are doing to the planet. If Flannery is trying to argue that we should change our ways, then I feel that the whole book should be devoted to that argument.