300 HUMAN BIOLOGY 



would doubtless disappear by reason of starvation, exhaus- 

 tion or failure to reproduce. The nearest approach to a hmit 

 imposed by the wind is probably found in western Tierra 

 del Fuego. There the winds of the "Roaring Forties" make 

 hfe one long, cold, miserable struggle. A handful of lowly 

 Ahkaluf do indeed manage to survive in the more protected 

 spots, but even they cannot Hve everywhere. In eastern 

 Persia the almost equally violent "Wind of a Hundred 

 and Twenty Days" prevents the growth of trees and makes 

 hfe scarcely worth hving throughout the summer, though 

 it does not prevent the existence of a fairly abundant and 

 moderately civilized population. But such a wind throughout 

 the year, in the cold winter as well as the hot summer, 

 might render the region uninhabitable. 



Although the various kinds of chmatic hmits are not 

 always sharply drawn, I have dwelt on them because the 

 physiological relationships of all types of inhabited chmates 

 can best be grasped by thinking of them as lying between the 

 hmits and the optimum; we do n-ot know of any chmate 

 which enjoys the optimum in all respects. Thus every 

 chmate is more or less unfit, a fact which entails most 

 serious consequences as to health and progress. Another 

 important generalization concerning man's climatic limits is 

 that in practically all cases they fall not far from the most 

 extreme conditions that now exist upon the earth. Perhaps 

 this merely means that man's mentality has enabled him to 

 overcome most of the climatic handicaps which he has 

 yet encountered. Presumably the limits can be pushed back 

 still farther, but for thousands of years to come they are 

 likely to be a vital factor in human existence. This becomes 

 more obvious when we remember that there are at least three 

 great sets of limits — individual, racial and cultural. Even in 

 the earth's uninhabited chmatic borderlands such as the ice 

 sheets of Greenland and Antarctica and the hot desert of 

 southern Arabia, individual members of the human race can 

 undoubtedly survive indefinitely; therefore such regions 

 are not beyond the outer climatic limits, but whether they 

 are beyond the limits where healthy children of our own race 

 can grow up is by no means so certain. And even if they lie 

 within the racial limits, does the physiological handicap of 



