4 EVOLUTION AND GENETICS 



ture, or of warfare {fig, 3) illustrates the history of 

 human progress. There is an obvious and striking 

 similarity between the evolution of man's inventions 

 and the evolution of the shells of molluscs and of the 



IHON HAT 1-iNINO 

 -^•YJ-^ POT 



THi- pakt.s of a hklaict 



boo A-jD 



HELMETS 



THCIR KIXDS AND DE\ El.OPMENT DURING 



THE CENTURIES 



SPANGENHELM 



A.r> 600 



Fig. 3. — Evolution of helmets. {After Dean.) 



