EVIDENCE OF VESTIGIAL STRUCTURES Nearly all the structures which have become greatly reduced or are mere vestiges in the body of man have undergone a similar fate in the bodies of the anthropoid apes. In them as in man the tail has disappeared, all save its basal part, which has sunk beneath the surface to form the coccyx. It is true that the vermi form appendix of man is smaller than that of any of the anthro poid apes, and that in half of the Europeans who reach the age of 70 its lumen has become closed, yet it is more than doubtful if this structure should be reckoned vestigial in the body of either man or anthropoid. The palmaris longus, the plantaris, and the pyrarnidalis, muscles which are reduced or fibrous in man, are in the same state in anthropoid apes. Such evidence points to a com mon origin for anthropoids and man, but it throws no light on man's more immediate relationship to any member of the anthro poid group.
There are two muscular vestiges, however, which point to man's kinship to the African anthropoids. There is a muscle in the neck of monkeys which helps to lift the shoulder; it is called the levator claviculae. It has almost disappeared from man's body; it is met with only once in a hundred dissections. This muscle
shows definite signs of reduction in the gorilla and chimpanzee, but not in the orang or gibbon. All monkeys have a strong muscle called the latissimo-condyloideus. When a monkey is climbing, and has seized a branch with its hand, it uses this muscle to pull the trunk upwards. It is a particularly strong muscle in the gibbon, well developed in the orang, somewhat reduced in the chimpanzee, partly fibrous in the gorilla, wholly fibrous in man, although in 5% of human bodies some muscle fibres may be detected. Lately Dr. A. H. Schultz, of the Carnegie Institution of Washington, has found a remarkable example of the persistence of a vestige in man's body (Amer. Jour. Physic. Anthrop., vol. vii., p. 149, 1924). Lemurs, which branched off from the primate stem at a very distant geological period, have a tuft of touch vi brissae at the wrist. Monkeys were supposed to have lost these vibrissae ; Dr. Schultz found them in foetal stages of monkeys both of the Old World and of the New. On examining the wrists of human foetuses in the second month of development he found a raised plaque at the spot where the touch vibrissae are situated in lemurs.