"The combination of physical dexterity and brain power has allowed humans to manipulate the environment to suit their needs. No other species has this conscious capability. Hands are crucial: highly intelligent animals with fins and flippers have no capacity to reconstruct their surroundings. In little time at all, advances in science and engineering have supported the rapid expansion of the human population and made modern life luxurious by burning fossil fuels. The attendant transformation of the atmosphere has caused the surface of Earth to warm."