May, 1932 



EVOLUTION 



Page seven 



hard and relatively innutritious grasses of the plains, instead 

 of the soft green leaves of the forests. Necessarily the horse, 

 in order to survive, eventually had to become a grazer with 

 the new kind of teeth. But old ways cling and some horses 

 remained browsers in the remnants of forests that lingered 

 for a long time. Nature tried out both experiments, but 

 finally the drying climate rendered a decision in favor of the 

 swift, grazing plains horse that we know. 



For the horse was gaining swiftness. Increased size helped, 

 but the changes in his leg machinery were also important. 

 Eohippus was really heavyfooted, for he had a lot of bones 

 down in his foot. But evolution slowly got rid of this excess 

 weight, making the horse literally light-footed. If you want to 

 know how foot-weight handicaps, tie weights on your ankles 

 and try to run. Another aid was that even Eohippus walked 

 on his tip toes, for the horse's hock, half way up his leg, is 

 really his heel. On the dry, grassy plains, the ground was 

 hard, and even the narrow hoof of the middle toe would not 

 sink in it. Besides there was less danger of turning the ankle 

 and other joints on rough ground when the wide foot had 

 been gotten rid of. The joints themselves also changed to 

 prevent turning the ankles and similar injuries. With such 

 joints, he need put forth no effort to keep his legs straight 

 sideways, all his muscles can be devoted to moving forward, 

 to give him speed. Mechanically, he is a marvelous adaptation. 

 He is "on his toes," light-footed, without waste muscles, 

 strong and full-lunged to travel fast and far, to escape his 

 enemies, to cover a wide grazing range. 



Nature made parallel experiments with several relatives 

 of the horse who were also having a bad time of it in the 

 new hard conditions. Among them was a rhinoceros, small 

 and horse-like, swift on his feet, but somehow not good 

 enough to survive in the severe struggle. Some of the re- 

 latives went in for brainless bulk, the heavy-footed Titan- 

 otheres for instance, but they starved to death on the widen- 



ing grasslands, there being just too much bulk to feed. An- 

 other relative, the tapir, had specialised too well, found him- 

 self unable to adapt hmiself to the new world, and nearly 

 died out. 



In the end. the horse also died out in America where he 

 had evolved, but not before he colonised Asia and Africa 

 with wild species such as the ass and zebra and of course 

 the direct ancestors of our modern horses, whom man has so 

 changed that we hardly know what they looked like. At first, 

 for perhaps fifty thousand years, man just hunted the wild 

 horse for food, and but recently learned that the horse was 

 worth more alive than dead, when he harnessed the horse's 

 strength, placed his burdens on the strong back and finally 

 mounted there himself adding greatly thereby to his own 

 powers and prowess. It can safely be said that, without 

 that humble burdenbearer and mount, man could not have 

 built Western civilization, for his own puny strength was 

 unequal to the tasks he undertook. 



Having domesticated the horse, man took him along to 

 every corner of the globe, — repeopling (or should we say 

 "rehorsing") North and South America. He also remade 

 the horse by selection to suit his own purposes: the heavy 

 Percheron draft horse, a mountain of strength, that delicate 

 jpeed-machine, the race horse, and the tough little Shetland 

 Pony, sure-footed, heavy-coated, fit to survive where going is 

 hard. But now that man has built himself new horses of 

 steel, machines that swim or fly, that eat coal or oil, that 

 can be given any strength and much greater speeds, man is 

 discharging his good servant, Old Dobbin, to a lesser place 

 in the world. For man, as master, remakes his world to meet 

 his own desires. He became master by developing a hand 

 instead of a hoof, but that is another story. However, let us 

 not take too much pride in that, for we are just the lucky 

 favorites of fortunate circumstances that made us into men. 



This Tvas a radio talk by Mr. Broms. He speaks over WOR 

 every Saturday at 6:30 P. M. Listen in 



Formations in We5leni.Unite<l itales and Characterislic Type ot' Horse in E.ich 



Fore Fool 



Hind Foot 



Teeth 



[^uatenui^ 

 AieofMsn 



One Toe 



S(H."I, of 

 2^.~l v.'.!,,,,. 



One Toe 



Spl.nl. of 



Pliohlwpus 



Meryttiippiis 



Th ree T oes 



nol lOHiliinj Ihc drou 



Ttiree Toes 



Side toe* 



nol loi'di.nf rh<fn>k 



Mesotlippus 



Th ree To es 



Side Iocs 

 •vA lOuthing llwgroundi 

 ,pl„l ..<;■-' d,(,l 



Ttiree Toes 



Side loti 

 leufhing Ihr jfOund 



/^ If.-, s'.'d,,.,, 



M^ 



Short 

 _^ Crowned, 



^'^! wirhoui 



Cemenr 



'b'@ 



Hvpoiheiiidl AtKcstor5 with hive locj on tath Foor 

 2nd Teeth like tho^e of Monkeys eic 



The Premobr Teeth 



become more sod more 



like true mola's 



Courtesy AmcrUan Museum of Natural History 



