Were we incapable of empathy – of putting ourselves in the position of others and seeing that their suffering is like our own – then ethical reasoning would lead nowhere. If emotion without reason is blind, then reason without emotion is impotent.

When fish experience something that would cause other animals physical pain, they behave in ways suggestive of pain, and the change in behaviour may last several hours.

Each of us spends money on things that we do not really need. You could take the money you're spending on those unnecessary things and give it to this organization the Against Malaria Foundation which would take the money you had given and use it to buy nets to protect children. And we know reliably that if we provide nets, they're used, and they reduce the number of children dying from malaria. Fortunately more and more people are understanding this idea, and the result is a growing movement effective altruism.

There is an obvious evolutionary explanation for the scarcity of altruistic saints: Without a strong predilection for their own interests, our ancestors would have been unlikely to survive, reproduce, and give their own offspring a chance of doing the same. Now conditions have changed and for most of us, surviving and reproducing isn't such a struggle but we still carry the genes of our ancestors and they influence - not determine, but influence - our behavior.

We are not especially 'interested in' animals. Neither of us had ever been inordinately fond of dogs, cats, or horses in the way that many people are. We didn't 'love' animals.

We should aim for our children to be good people, and to live ethical lives that manifest concern for others as well as for themselves.

In some parts of the world, what you are doing is already apparent.According to the World Health Organization, the warming of the planet caused an additional 140,000 deaths in 2004, as compared with the number of deaths there would have been had average global temperatures remained as they were during the period 1961 to 1990. This means that climate change is already causing, every week, as many deaths as occured in the terrorist attacks on September 11, 2001.