LECTURES IN BIOLOGICAL SCIENCES 



early success of the mammals. Proper reception of information 

 about the smell of a dangerous or attractive object does not 

 require that the head be turned in a proper direction. Mam- 

 mals can smell in any direction where molecules are diffused 

 through the air. Even when asleep we can smell smoke before 

 seeing the flame. The amount of trade-goods all peoples spend 

 on odorants and deodorants testifies to the continued impor- 

 tance of the sense of smell in our mammalian heritage. But 

 vision is relatively much more important; contrast the handi- 

 cap of not being able to smell with that of not being able to see. 



Some of you may wonder why, if in fact the olfactory sense 

 is of diminished importance in hominids, man has such a large 

 external nose. Man, indeed, does have a large external nose. 

 It is one of the ways you can tell your human friends from 

 your simian friends. 



Historically it is correct to call our nose a "nose." Func- 

 tionally it would be more correct to call it a "respirator." Our 

 nose is the only peripheral organ of smell we have, but only a 

 small part of it is directly concerned with the sense of smell. 

 Its business part is really the inside surface area, which is a 

 little larger than a dollar bill. Most of this area functions pri- 

 marily for respiratory purposes. The total area of the olfactory 

 end organ is about that of a dime. 



Man has retained a large nasal area for respiratory and ol- 

 factory use. The external nose was left sticking out in front of 

 the face for rather complex reasons having to do with the ex- 

 pansion of the cranial part of the skull along with the contrac- 

 tion of the muzzle or the smelling, feeding, and breathing part 

 of the skull. And as we will see, the position of the face and 

 jaws with reference to the cranium changed when man's ances- 

 tors acquired upright, bipedal posture and locomotion. 



There is not time to go into a full comparative inventory of 

 the primate senses. The sense of hearing is of obvious impor- 

 tance in human behavior. For example, it is more difficult to 

 socialize and enculturate a deaf child than a blind child. But 

 aside from some differences in auditory range, the acoustic sense 

 of higher primates and many other mammals is much the same, 

 whereas the visual sense of the higher primates has undergone 

 considerable evolutionary change. 



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