Concord, solidarity, and mutual help are the most important means of enabling animal species to survive. Christian Lous Lange
Measles and TB evolved from diseases of our cattle, influenza from a disease of pigs, and smallpox possibly from a disease of camels. The Americas had very few native domesticated animal species from which humans could acquire such diseases. Jared Diamond
Survivors represent a separate species, just like an animal species. Imre Kertész
Eurasia ended up with the most domesticated animal species in part because it's the world's largest land mass and offered the most wild species to begin with. Jared Diamond
It's fair to say when you go out and walk in the woods or on a beach, the most conspicuous forms of life you will see are plants and animals, and certainly there's a huge diversity of those types of organisms, perhaps 10 million animal species and several hundred thousand plant species. Andrew H. Knoll