Parker and Gibson's developmental model of evolution of language and intelligence in early hominids is described and discussed; data from a comparative study of object manipulation in two apes and a human infant are reported; and, human ontogenic developmental retardation in locomotion is discussed in terms of its implications for the differential…

The role played by neuroembryological forces in shaping brain development is well documented in Nowakowski's (1987) article. Additional mechanisms whereby experience may influence brain structure and function are outlined. Several routes exist by which postnatal experiential influences may produce long-term alterations in behavior and…

Recent studies on the biological development of the prefrontal cortex in rhesus monkeys are reviewed. These studies have elucidated the basic neural circuitry underlying the delayed-response function in adult nonhuman primates and suggest that a critical mass of cortical synapses is important for the emergence of this cognitive function. (BN)

The developmental pattern of concurrent synaptogenesis in rhesus monkeys is consistent with a straightforward model of relations between brain and cognitive development. Concurrent synaptogenesis is hypothesized to lay the primary cortical foundation for a series of developmental levels in middle infancy that have been empirically documented in…