94 SCIENCE PROGRESS 



injury there may be a slight thickening of the lower part of 

 the capsule. This limits the movements, especially in the effort 

 to raise the elbow to a right angle with the body. The shoulder 

 adds very greatly to the usefulness of the hand, but this joint 

 was not produced by swinging clubs or throwing spears. The 

 gibbon, which perhaps comes next to man in regard to the 

 range of movement, has produced its joint by swinging by the 

 hands from branch to branch. This is the regular mode of 

 locomotion of this ape. Man may have produced his joint by 

 swimming and diving, and if the seaside theory is accepted, 

 these new movements were carried out in the search for food. 

 Food-supply from the sea thus makes the brain of survival- 

 value, establishes the upright posture, and causes the evolution 

 of the foot and leg, the hand and arm. A correlated series of 

 structures are thus evolved which became capable of carrying 

 out the behests of the brain when that organ had grown great 

 enough to think out other problems beyond those of mere 

 survival. 



The objection may be taken that this seaside theory should 

 have made the human child able to swim by instinct. The 

 reply is that human instincts have not developed since the 

 period when the brain became the organ of survival-value. 

 Nevertheless, in races which have kept up the habit of being 

 much in the water, the children appear to swim without any 

 special training. It is also true that the orang cannot swim, 

 a fact that may be accounted for by supposing that he left 

 the sands for the forest before swimming had become general. 



The number of years covered by each of the tertiary periods 

 is so great in comparison with the number of generations of 

 each species of animal that the time-limit is long enough to 

 account for the necessary structural changes. For instance, 

 in a million years there would be far more than a hundred 

 thousand generations. Suppose the height of the animal had 

 increased in that time by fifty inches, the advance would be 

 quite inappreciable, being only one two-thousandth of an inch 

 in each generation. The problem is to find a set of factors 

 which would account for a steady advance in the one direction. 

 This problem seems to be easier of solution if the advance was 

 begun when the animal was still comparatively small. The 

 improbable thing to happen is the change of plan. If the 

 needs of survival have produced great canines it is not likely 

 that these can be surrendered and the instinct to use them 

 forgotten. The animal then carries his own implements with 

 him as part of his body. When such organs have become fully 

 specialised the progress of the brain is stopped, because the 

 animal has become a self-contained and self-sufficient organism. 



So strongly did this idea appeal to the philosophic biologist 



