Our knowledge of the evolution of primate brains comes from two sources: the fossil record and comparisons between the brains of the various kinds of living primates. The fossil record of primate brains consists of casts of the insides of fossil braincases, called endocranial casts, or endocasts. These casts reproduce details of the surface of the brain, including the patterns of cerebral convolutions. Thus, fossil endocasts provide direct evidence of brain evolution, but the information they provide is only external. Comparative studies of the brains of living primates, on the other hand, while they can provide an enormous amount of information, can only be considered indirect evidence of brain evolution. Although it is tempting to arrange living species in a series of presumed primitive to advanced stages, a series of this sort may be misleading if they are taken to represent evolutionary lineages, because each species is specialized for its own ecological niche, and most species combine primitive and advanced features.
[The difficult words in this passage are primates (family of living beings consisting of apes, monkeys and human beings), cerebral convolutions (folds in the brain), lineage (ancestry) and ecological niche (place in nature)]
10. Deriving information about a brain from an endocast is most like deriving information about a
(A) tree from a picture of its shadow
(B) star from a photograph of its light waves
(C) tooth from its wear pattern
(D) foot from a mold of its footprint
(E) muscle from its tendons
This is an ‘extrapolation’ question which must be answered by evaluating each of the answer choices. From the second and third sentences, we learn that the endocasts are in the nature of molds of the surface of the brain. Among the choices, deriving information about the brain from an endocast is similar to deriving information about a foot of a person from a mold of his footprint. So, (D) is the answer.
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