The Biology of Senescence 



(1953), upon the basis of tooth sections. Captive records include 

 Otaria byronia, 23 years, Eumetopias stelleri, 19 (Flower, 1931); 

 £alophus calif ornianus, 23; Arctocephalus pusillus, 20 (Bourliere, 

 1951); Phoca vitulina, 19 (Sivertsen, 1941); Halichoerus grypus, 

 41-2 (Matheson, 1950). In the wild, Callorhinus ursinus has 

 reached 21 + years (Schaffer, 1950); Mirounga leonina $ 20; ? 18 

 (Laws, 1953). 



The maximum age records of horses and domestic pets are of import- 

 ance because these animals are the only mammals kept through- 

 out life in sufficient numbers to give any estimate of the extreme 

 age for the species. In spite of the likelihood of exaggeration and 

 mistake, records of domestic pets kept singly, throughout life, 

 by intelligent witnesses, provide evidence as good as that from 

 laboratory stocks and sometimes better than that from zoos, 

 since reliable mnemonic evidence is better than unreliable 

 documents. 



The known range of maximum ages for some domestic species 

 is given below. The figures in brackets represent unauthentic- 

 ated claims within the range of possibility, based as a rule on 

 evidence which can be neither assessed nor dismissed. 



Horses certainly exceed 40, may perhaps exceed 50 years — 

 most higher claims refer to ponies. Smyth (1937) reported a 

 46-year-old brood mare which foaled for the 34th time at 42 

 — this case appears authentic. (Horse, 62 — Flower, 1931; jennet, 

 reputed 60 — Wright, 1936; pony, 54 — Rothschild/^ Flower, 

 1931; Shetland pony, 58 — The Times, 3/5/44; roan pony, 52 — 

 The Times, 12/4/44; Iceland pony, 47— The Times, 7/8/34; 

 many records between 40 and 45.) A zebra has reached 40 in 

 captivity (Weber, 1942). Asses — probably exceed 40 (47 — 

 Flower MS. from a press report; but an 86-year-old ass in The 

 Times, 29/11/37, can hardly be taken seriously). A 48-year-old 

 mule is reported (Galea, 1936). 



Domestic goats, 15 and probably up to 20 years (20 years 

 9 months — female wild goat, London Zoo). 



Carnivora: cats are the longest lived of the small domestic 

 mammals. Mellen (1940) from questionnaires sent out in 

 Canada and the U.S.A. obtained these records: gelt males, 21, 

 21, 22, 23, 24, 24, 25, 28, 31 years; entire males, 23, 24, 26; 

 females, 21, 21, 22, 31. These were owners' estimates, but at 



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