The amazing success of man as a(1)_____ is the result of the evolutionary development of our brains which has(2)_____, among other things, to tool-using, tool-making, the ability to solve problems by logical(3)______, thoughtful cooperation, and language. One of the most striking ways(4)_____ chimpanzees biologically resemble humans(5)_____ the structure of their brains. The chimpanzee, with his(6)_____ for primitive reasoning, exhibits a type of intelligence more like(7)_____ of humans 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 that(11)_____ man made tools was considered to be one of the major criteria to(12)_____ them from other creatures. It is true that the chimpanzee does not fashion his (13)_____ to a regular and set pattern—but then, primitive man,(14)_____ 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 peoples minds of tools with man(18)_____ special attention has always been(19)_____ upon any animal able to use an object(20)_____ a tool; but it is important to realize that this ability, on its own, does not necessarily indicate any special intelligence in the creature concerned. (1)