The Physical Environment
Perhaps the single most important factor in the health of a community is the quality of its physical environment. Genetic factors are also extremely important but, though they are of great interest to the physician and scientist, they cannot as easily be influenced. The standard of medical services is another factor, and much effort is spent in improving the quality of care. But in most fields of health, medical services play a subsidiary role to environmental factors. Improvements in the environment lead to better health more often than do improvements in medicine. How far a community is capable of modifying and improving its environment depends to a large degree on its social development, a subject discussed in the last chapter. We will now discuss how the physical environment of the Yemenite Jews changed when they moved from Yemen to Israel.
Yemen has four distinct geographical regions. The highlands extend north and south through central Yemen and range from 2,000 to 4,000 metres in height. The foothills fall in gradual steps down towards the narrow Tihama coastal plain in the west and to Aden in the south. To the north and east, Yemen borders on the Saudi Arabian desert, often with an ill-defined boundary. The main towns are San'a in the highlands, Taiz and Ibb in the middle heights and Hodeida on the coastal plain. The country covers 200,000 square kilometres and supports a population of between 7 and 10 million people.
The climate in San'a is mild, with mean temperatures in the shade falling to 15 degrees Centigrade in the winter and rising to 20 in the summer. Most rain falls in the summer months, about 35 centimetres in a year spread over 100 days. The mountains and table-lands are relatively free of vegetation, but the deep valleys in between support plentiful crops of fruit and qat ( Ganora 1930; Petrie