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.

The traditional view of the sanctity of human life will collapse under pressure from scientific, technological and demographic developments.

By ceasing to rear and kill animals for food, we can make so much extra food available for humans that, properly distributed, it would eliminate starvation and malnutrition from this planet. Animal Liberation is Human Liberation too.

But I think the majority of cows, and even more so chickens and pigs, are leading pretty miserable lives.

Without in any way minimising the economic and psychological blow that people experience when they lose their jobs, the unemployed in affluent countries still have a safety net, in the form of social security payments, and usually free healthcare and free education for their children. They also have sanitation and safe drinking water.

So why don't we make ourselves the last generation on earth? If we would all agree to have ourselves sterilized then no sacrifices would be required - we could party our way into extinction!

Dolphins are social mammals, capable of enjoying their lives. They form close bonds with other members of their group.