From childhood to old age, we all use language as a means of broadening our knowledge of ourselves and the world about us. When humans first (47) , they were like newborn children, unable to use this valuable tool. Yet once language developed, the possibilities for human kind’s future (48) cultural growth increased. Many linguists believe that evolution is responsible for our ability to produce and use language. They (49) that our highly evolved brain provides us with an innate language ability not found in lower (50) . Proponents of this innateness theory say that our potential for language is inborn, but that language itself develops gradually, as a function of growth of the brain during childhood. Therefore there are critical (51) times for language development. Current (52) of innateness theory are mixed, however, evidence supporting the existence of some innate abilities is undeniable. Indeed, more and more schools are discovering that foreign languages are best taught in the lower grades. Young children often can learn several languages by being (53) to them, while adults have a much harder time learning another language once the (54) of their first language have become firmly fixed. Although some aspects of language are undeniably innate, language does not develop automatically in a vacuum. Children who have been isolated from other human beings do not possess language. This demonstrates that (55) with other human beings is necessary for proper language development. Some linguists believe that this is even more basic to human language (56) than any innate capacities. These theorists view language as imitative, learned behavior. In other words, children learn language from their parents by imitating them. Parents gradually shape their child’s language skills by positively reinforcing precise imitations and negatively reinforcing imprecise ones. A — involved B — biological C — claim D — interaction E — attainments F — reviews G — evolved H — psychological I — organisms J — rules K — exposed L — acquisition M — originated N — reaction O — reliable