across our planet, a range of ancient habitats provide eerie testimonies to the lives of creatures that once ruled the land. In Brazil, more than 100 tree species produce giant fruit that evolved to be dispersed by elephant-sized creatures called gomphotheres, while in Madagascar many plants grow thin zigzag branches to protect themselves from 10ft-high elephant birds, which used to populate the island.  These animals, like the mammoth and mastodon, are now extinct - their disappearances having followed the relentless conquest of the globe by Homo sapiens. Few doubt there is a link. Environmentalist Mark Lynas is certainly convinced that humans slaughtered these huge animals, creatures whose only living legacy today are those specialised fruits and protective thorny bushes that still await their attention. and with no living animals to disperse their seeds properly, these trees and plants are now themselves endangered.  Humans have a lot to answer for, in short. We have wiped out countless species and are now heating the planet, poisoning the oceans, and transforming the atmosphere. Having culled so many of the world's large beasts, we are now preparing to eradicate animals and plants of every size. as Lynas states: "Nature no longer runs the Earth. We do."  and you can see his point. Homo sapiens have acquired God-like powers to transform the world and destroy life. Hence the title of Lynas's book, in which he outlines the measures he believes that humans - as responsible, benign deities - should now adopt to save the planet. Many of these proposals are surprising, coming, as they do, from a former green activist who once trashed GM plant trials and railed against corporate greed.  Consider nuclear power. an anathema to greenies but which turns out to be a particular favourite of Lynas: an energy source that should be seen as "one of the strongest weapons in our armoury against global warming". Those who protest against its introduction are dismissed as doing as much harm to the climate as big oil companies.  Genetically engineered crops also get the thumbs-up. Only they can provide the food for the billions of future inhabitants that will populate our planet, Lynas claims. as for those midnight raids he carried out against plant trials, they occurred because "I was caught up more in an outbreak of mass hysteria than anything resembling a rational response to a new technology".  as Damascene conversions go, this is a belter. With luck, it might even start a trend - for as Lynas now admits, it is now "time for a change of tack by the Green movement, for the benefit of farmers, consumers and the environment". amen, is all I can add.  The core of The God Species relies heavily on the work of the "planetary boundaries" group, a collection of scientists who recently produced strict recommendations about levels of disturbance beyond which humanity should not push the planet. These propose specific limits on carbon dioxide emissions, farming land use, biodiversity loss, chemical pollution, and ocean acidification. Stick to these and earthly life should remain tolerable, Lynas states.  Nor is there a need for an economic revolution to achieve these goals. Good old-fashioned capitalism is quite sufficient. as Lynas says: "a successful environmental movement must work with people's aspirations for prosperity and comfort, not try to suppress these impulses." This is a fair point, though Lynas is vague, to say the least, about how un