EDWARD Sanderson (ViewPoints, November 9) seems determined to prove that black is white by using obscure research to make his point that humans are herbivores.

To start with neither Bob Johnson, nor myself, said that humans were carnivores but did point out the known fact that we are omnivores.

At some point in the past, parts of Africa became very dry, killing the rain forest and converting the land to savannah. To survive, the apes that lived in, and were sustained by, that forest had to transfer to ground level and feed on what was available there, resulting in natural selection favouring those that were bipedal.

There seem to have been a number of ground-dwelling apes that followed, some being vegetarian while others fed largely on meat. The vegetarians became extinct, leaving the meat eaters as human ancestors.

Those areas that became savannah and the cold tundra became areas that supported vast herds of animals that fed on the vegetation.

It was only natural that humans would use these animals to survive because it seems unlikely that there would have been sufficient vegetable material to sustain a population.

If one switched to an exclusively vegetarian diet, where are the essential proteins to come from – eggs or milk products?

If so, then we are back on the meat chain. Being a vegan is only for the affluent.

Humans do not naturally feed on grasses and neither are adults designed to feed on milk. Many have evolved to use these as food but many still find that they intolerant to them.

DERRICK HOLT Fortnam Close Headington