A subject which seems to have been insufficiently studied by doctors and psychologist is t

he influence of geography and climate on the psychological and physical health of humankind. There seems no doubt that the general character of landscape, the relative length of day and night, and climate must all play a part in determining what kind of people we are.

It is true that a few studies have been made. Where all the inhabitants of a particular area enjoy exceptionally good or bad health, scientists have identified contributory factors such as the presence or absence of substances like iodine, fluoride, calcium, or iron in the water supply, or perhaps types of land that provide breeding places for pests like mosquitoes or rats.

Moreover, we can all generalize about types of people we have met. Those living in countries with long dark winters are apt to be less talkative and less lively than inhabitants of countries where the climate is more equable(稳定的). And where olives and oranges grow, the inhabitants are cheerful, talkative, and casual.

But these commonplace generalizations are inadequate—the influence of climate and geography should be studied in depth. Do all mountain dwellers live to a ripe old age？ Does the drinking of wine, rather than beer, result in a sunny and open character？ Is the strength and height of a Kenyan tribe due to their habitual drinking of the cow blood？

We are not yet sure of the answers to such questions, but let us hope that something beneficial to humankind may eventually result from such studies.

The author's purpose of writing this passage is to ______.

A．alert readers to the scarcity of natural resources

B．call for more research on the influence of geographical environment

C．introduce different elements in character cultivation

D．draw more attention to the health condition of mankind