A、A very popular food plant: B、A plant with limited uses. C、A food plant which has been thoroughly used. D、A plant used as a mai

One of the reasons for our success as a species is our ability to eat and thrive on a large variety of foods. Many animal species have become extinct or are on the edge of extinction partly because they lack this adaptability. They need to feed on a particular kind of plant or a particular kind of animal or insect. If this source of food is for any reason re- moved, then the animal concerned is unable to change to a different diet. Gradually it becomes extinct. We know that many animal species have died out, but so have some human species such as the early form of mall that is called Neanderthal man. Perhaps part of the reason for his failure to survive was his lack of adaptability in diet. But modern man is almost entirely free from the limitation of any particular food requirements. We are able to survive on a wide variety of foods both animal and vegetable. For example, the Eskimos are almost totally meat eaters: seal, bear, whale meat and fish form their whole diet; the Aborigines of Australia, living in dry desert regions, have learnt to survive by making use of forms of insect life as food to supplement their diet of fruits and roots. Men have learnt to survive in the deserts and in dense rain forests; they have learnt to raise domestic animals, which live at high altitudes so that they can inhabit the mountainous regions of the world like Tibet; and they have made the coconut their chief food on the Pacific islands.