22 THE BIOLOGY OF DEATH 



understanding that the figures are estimates, frequently 

 based upon somewhat general and inexact evidence, and 

 record extreme, though it is believed authentic instances. 

 While the figures, on the accounts which have been men- 

 tioned, are subject to large probable errors, the table does 

 give a sufficiently reliable general picture of the truth 

 to indicate the enormous differences which exist among 

 different forms of animal life in respect of longevity. 



TABLE 1 



Longevity of Animals 



Animal 



Approximate limits of maximum duration 

 of life in different species 



Under 100 hours to ? 



Insects Under 100 hours to 17 years 



? to 267 vpfl.rs 



Lower invertebrates 



Fish 



Amphibia 



Reptiles 



Birds 



Mammals 



? to 267 years 

 ? to 36 years 

 ? to 175 years 



9 years to 1 18 years 



1/^2 years to over 100 years 



We see from this table that life may endure in differ- 

 ent forms from only the briefest period, measured in 

 hours as in the case of Ephemeridae, to somewhere in 

 the hundreds of years. The extremely long durations 

 are of course to be looked upon with caution and reserva- 

 tion, but if we accept only extreme cases of known dura- 

 tion of life in man, the range of variation in this 

 characteristic of living things is sufficiently wide. 



It is probable that man, in exceptional instances, is 

 nearly the longest lived of all mammals. The common 

 idea that whales and elephants attain great longevity 

 appears to be not well founded. The absolutely authentic 

 instances of human survival beyond a century are, con- 

 trary to the prevalent view and customary statistics, 

 extremely rare. The most painstaking and accurate 



