Longevity of English Thoroughbred Horses 47 



progeny in samples A and B of parents 16 years old or over, 

 154 lives were obtained, with e^^^ = 16-45 ±0-62 years, 

 which is less than any of the three global means, but not sig- 

 nificantly so. These results, taken as a whole, seem to afford 

 no good evidence of any consistent effect of parental age on 

 the longevity of mares. 



lOO 



9 PROGENY OF STALLIONS HERMIT . 

 GALORN & HAMPTON 



ALL (412) 



SIRE$20 YRS 

 (121) 



Fig. 3. Survival curves of lifetime brood mare progeny of Hampton, 



Galopin and Hermit (O O) and of mares got in or after their sire's 



20th year (Comfort, 1958a). 

 Reproduced by courtesy of the Editor, Journal of Gerontology. 



Correlation betw^een lifespans of parents and offspring 



Since age of death depends in part upon heritable factors 

 there should be a measurable difference in longevity between 

 the foals of long-lived and short-lived parents, though Beeton 

 and Pearson's (1901) results in man suggest that it would not 

 be large. All the mares in sample A were scored for the longev- 

 ity of their dam, and as many as possible for the longevity of 

 their sire; the date of death could be ascertained only for 

 stallions appearing in the obituary lists, or rather less than half 



