62 



WHALES 



Figure 26. Comparison between the embryonic development of a Cetacean flipper and a human 



arm. 



past, they probably had fully developed limbs. In other words, whales 

 must have descended from terrestrial mammals. To discover what these 

 animals were like, we must first find out what position the Cetaceans 

 occupy in the Animal Kingdom, i.e. how they are classified. 



Aristotle (about 400 b.c), as we have already seen, lumped whales and 

 fish together, not because he was unaware that whales breathe through 

 lungs, that they have hair, that they are viviparous and suckle their 

 young, and that they have horizontal flukes instead of a vertical tail fin, 

 but because his criteria for classifying the animal kingdom were different 

 from ours. To Aristotle, aquatic life was, in itself, a crucial criterion, 

 and not only Pliny, but Belon (1553), Rondelet (1554), and even 

 Linnaeus at first followed in his footsteps. Ray (1693) and Linnaeus, 

 however, subsequently took the decisive step of classifying the Cetaceans 

 as mammals, and since that time their classification has never been 

 challenged. All that remains is to investigate the place of the Cetaceans 

 among their mammalian relatives. 



Now, if we examine all the characteristics of the Cetaceans, and if we 

 compare them with other mammals, it becomes clear that their nearest 

 relatives belong to two orders : the Carnivores and the Ungulates. It would 

 take us too far afield to muster all the arguments for this assertion; suffice 

 it to say that their close relationship, particularly to Even-toed Ungulates 

 (Artiodactyls) , e.g. cattle, sheep and camels, has become quite clear from 

 similarities in their protein structures. Protein comparisons tell us, inter 

 alia, whether two animals can be interbred to produce fertile offspring 

 or not. The method itself falls outside the scope of this book, but its results 



