[Morphological manifestations of primate adaptation to orthograde statics and upright posture]

Using lower primates (rhesus-monkeys) who were experimentally transformed to bipeds, we examined morphological signs of their musculo-skeletal adaptation to the upright walking pattern. It was found that the bipeds developed typical characteristics of the upright posture: complete erectness of the torso and legs and noticeable enhancement of lumbar lordosis. The maximum deviation of the lumbar arch in the bipeds (10.0 +/- 0.8 mm) was significantly greater than in the controls (1.5 +/- 0.5 mm). This was accompanied by distinct hypertrophy of leg muscles, primarily extensors, and increased mineral density of the tibia (by 38%), fibula (by 14%) and metatarsus (by 23%). This was also followed by slight hypotrophy of biceps and triceps muscles and the large muscle of the thorax. Forearm muscles and bone mineral content were unchanged. The data obtained give evidence that the genetic program of orthograde statics and erect posture which is typical of the entire primate order can find phenotypical realization in lower primates.