262 Morris Rockstein 



well as of their offspring on an individual, rather than on the 

 group population basis employed in all studies to date. 



In Drosophila suhohscura Comfort (1953) found no apprecia- 

 able change in longevity of the population resulting from 

 selection of eggs from old parents, over eight generations of 

 breeding. Tracey (1958), on the other hand, found that larvae 

 of eggs from week-old adult beetles of the mealworm, Tenebrio 

 molitor, had longer developmental periods than those from 

 eggs laid by five-week-old (middle-aged) beetles and consider- 

 ably longer than those from eggs laid by very old (nine weeks) 

 parents. The adult lifespan was likewise shortened for beetles 

 reared from eggs laid by oldest parents. Thus, as the parental 

 age lengthened, the entire lifespan of offspring was shortened 

 in this species. Although the above held true for animals reared 

 and maintained at 25°c, at 30° c some larvae from oldest 

 parents had much longer larval development periods than those 

 from younger parents ( ! ). However, increasing the temperature 

 to 30° c did not alter the shorter adult lifespan observed for 

 offspring from oldest parents. 



What role the age of parents plays in the lifespan of children 

 in humans is not statistically clear, although Murphy (1954) 

 reported that known abnormalities like congenital cardiac im- 

 pairment, Mongolian idiocy, spina bifida and stillbirth, and 

 possibly hairlip and cleft palate, increase in frequency as the 

 age of the mother at the time of birth increases, after 30 years 

 of age. However, Sonneborn (1957) has pointed out that the 

 age of the mother is frequently positively correlated with the 

 paternal age, for foetal deaths. Indeed, for data covering 

 foetal deaths and a 10 per cent randomized sample of 330,000 

 live births from 1954-55 New York City Department of 

 Statistics, he found there was a consistently higher foetal death 

 rate for older fathers, when single rather than five-year age 

 classes were employed for females over 30 years of age. 



