单选题 .  The amazing success of man as a     1    is the result of the evolutionary development of his brain which has     2    to tool using, tool making, the ability to solve problems by logical     3    , thoughtful cooperation, and language. One of the most striking ways     4    which the chimpanzee biologically resembles man     5    the structure of his brain. The chimpanzee with his     6    for primitive reasoning, exhibits a type of     7    more like that of man than does any other     8    living today. The brain of the modern chimpanzee is     9    not too dissimilar to the brain that so many millions of years ago directed the     10    of the first ape man.
    For a long time, the fact     11    prehistoric man made tools was considered to be one of the major criteria to     12    him from other creatures. It is true that the chimpanzee does not     13    his tools to a regular and set pattern but then,     14    man, before development of stone tools, undoubtedly poked around with sticks and straws, at which     15    it seems unlikely that he made tools to a set pattern     16    .
    It is because of the close     17    in most people's minds of tools with man     18    special attention has always been     19    upon any animal able to use an object as a tool; but it is important to realize that this ability,     20    , does not necessarily indicate any special intelligence in the creature concerned.1.