POPULAR SCIENCE 87 



carnivora also visit the sands, and the kangaroo has been known 

 to swim across an arm of the sea two miles in width. Monkeys 

 in Sierra Leone sometimes visit the shore and eat the oysters/ 

 and baboons make use of sticks as levers to raise stones in 

 their search for food, and of stones wherewith to crack nuts. 

 The ease with which the apes are taught to use knives and 

 simple tools, and the readiness with which they learn to master 

 the secret of the lock in order to let themselves out of their 

 cages, bespeak their knowledge of external things. It is there- 

 fore in no way improbable that one family of the Late Eocene 

 primates may have chanced on some part of the beach where 

 shellfish are plentiful and there begun a course of evolution 

 different from all their former associates in the trees. The 

 epoch-making difference was the fact that they could live in 

 safety and plenty on the sand and not trouble about going 

 back to the trees at night. The necessary quota of carbo- 

 hydrates in the diet might have been obtained from seakale 

 and other plants which grow close to the beach. 



On such a beach as that at Port Said or Alexandria there 

 would be no difficulty in a man finding sufficient to eat. The 

 sand-crabs are very numerous, but they are not easy to catch 

 because they are so quick-sighted. Still, it may have been 

 their movements which first attracted the attention of our 

 hypothetical monkey. These crabs are on good terms with 

 the small sea-birds with whom they dispute for the possession 

 of anything that is eatable. A monkey would perhaps frighten 

 both away and pick up the morsel. At all events he might 

 have found sustenance on the beach without even using a stone 

 to crack a shellfish. On this hypothesis an improvement in 

 the powers of observation and imitation would be of greater 

 survival-value than a lengthening of the nose or of the canine 

 teeth. In other words, as soon as a monkey began to live 

 on the sandy shore, survival would depend on the growth and 

 elaboration of the brain. The cranial nerves were all already 

 sufficient for their new uses, but new centres were required in 

 the brain for functions which lead direct to the brain of man. 



Next we have to account for the improvement of the hand, 

 the broadening of the sole of the monkey foot and the gradual 

 approximation to the upright posture. These are all provided 

 for by the extension of the food-producing area to a rocky 

 beach. The power to identify stranded mussels on the sand 

 would lead to the recognition of living specimens attached 

 to the rocks. Oysters and other shellfish would soon be added 

 to the list. Stones would be used for cracking the shells and 

 sticks for levering them off the rocks. In this way the use of 

 tools began. We need not therefore be surprised if the 

 ^ Scott Elliot, Prehistoric Man, 1915, p. 28. 



