28 Francois Bourliere 



confirm European banding results. It thus appears that in 

 these mammals a reduced energy metabolism and a low 

 fecundity is definitely associated with a long lifespan. In- 

 versely, shrews with their high metabolic rate and fecundity 

 are probably the shortest-lived mammals, especially dwarf 

 species, like Suncus etruscus, whose adult weight seldom goes 

 beyond 2 • 5 g. 



The study of age-changes in those short-lived animals 

 would certainly be greatly rewarding, and we are now trying 

 to raise them under laboratory conditions. Temporary 

 poikilothermism, seasonal or diurnal variations of metabolic 

 rates and long duration of life seem likewise to exist in some 

 birds, like swifts, hummingbirds and goatsuckers (Pearson, 

 1950, 1954; Jaeger, 1949), and even in some primitive pri- 

 mates (Bourliere and Petter-Rousseaux, 1953; Bourliere, 

 Petter and Petter-Rousseaux, 1956). 



Furthermore, the comparative study of age changes should 

 not be limited to the various zoological groups, but should be 

 extended to the various human populations, especially those 

 whose genetic constitution, nutritional status and ecological 

 environment is so different from our West European or 

 North American standards. When teaching at the University 

 of Hanoi, Indochina, I was greatly impressed by the way most 

 Tongkinese peasants age, as compared with their own country- 

 men living in the big cities — and even more with westerners. 

 On the other hand, the so-called "premature ageing" of some 

 "primitive" populations would need to be investigated before 

 it is too late. I know that such studies are most difficult to 

 carry out. Even if laboratory facilities were available, it 

 might be hard to get an accurate knowledge of the actual age 

 of the subjects examined. Furthermore, any study of that 

 type needs to be completed by a careful anthropological and 

 nutritional survey of the population sample which is investi- 

 gated. There are, nevertheless, some countries like India, 

 Indochina, Mexico and the West Indies, where such studies 

 could be made. 



To sum up, one may conclude that functional age changes 



