EDUCATION 241 



not actually do so. The nestlings of the common moorhen, of the 

 porphyries, and of quite a number of birds that haunt reeds and 

 water-weeds have a well-developed claw on the thumb, and by 

 the help of this, use the wing in scrambling over the nest. The 

 nestling of a peculiar South American bird, the hoatzin or stink- 

 pheasant, has not only a thumb-claw but a claw on the index finger. 

 The nests are built high up in trees overhanging the water, and 

 for some time the little birds crawl over the twigs on all fours like 

 young reptiles. It is clear that the bipedal gait is a recent acquisi- 

 tion, and traces of the older form of walking are seen not only in 

 the structure of young birds, but in the difficulty which they have 

 in learning to walk. 



Little quadrupeds find it easy to walk as soon as their legs are 

 strong enough to support them. Young kangaroos, when they 

 begin to come out of the pouch, use their front paws a great deal 

 in walking, and only gradually acquire the hopping gait of the 

 adult. Most monkeys are really quadrupeds in gait, and when 

 they are running fast on the ground, gallop on all fours. Little 

 monkeys certainly do so, and it is only when they jump up on their 

 mother or on a branch that they use their hands as hands rather 

 than as paws. Even when they are climbing trees, the posture 

 of monkeys is not upright, and all the young chimpanzees and 

 orangs that I have seen get on all fours when they are moving 

 quickly. Gibbons run on their hind-legs, with their bodies 

 erect, but with an uneasy swaying movement, using their long 

 arms as balancers and holding them ready to give support at any 

 moment. Human children, of course, begin to crawl on all fours 

 and learn to walk only with much difficulty and with a good deal 

 of persuasion and help. 



The difficulty which bipeds have in learning to walk is thus due 

 to a double cause. In the first place the action, like most of the 

 actions of the higher animals, is not purely an instinct, but the 

 complex balancings and the varied movements are learned partly 

 by experience. In the next place, it is a comparatively recent 

 acquisition of the race, and the structure still contains many 

 elements which are not yet completely adapted to it. 



Learning to fly is a still more difficult task. Young swallows 

 are said to fly without any teaching or persuasion, and it may be 

 that these, which are, perhaps, the most completely aerial of birds, 

 have reached a stage which most birds are only on the way to 

 reach. In most cases, the mothers have to use persuasion or force, 

 C.A. Q 



