Darwin moved to Cambridge, where he began to train to be a clergyman--a common path for affluent young Englishman with an interest in nature.

But the affluent, who typically have lots of assets and good access to borrowing, are much less likely to be in that situation.

But that in affluent countries, in places where each person on average annually eats 80-120 kilos of meat, a lot can be done to reduce emissions at the consumption level.