单项选择题

Language is one of the defining characters of our species, but we know virtually nothing about where it came from." We have a lot of (62) .but we don’t have a lot of data," admits Gary Marcus at New York University, U.S.
The biological basis of (63) people speak, listen and comprehend-and how all of this mental equipment evolved-is (64) mysterious. Researchers can study animals to gain insights (65) many psychological abilities, but this is not possible with language as no animal (66) stems are anywhere near as (67) as ours.
" (68) we know it’s (69) to humans and it evolved quickly," says Marcus. We developed the skill after we split from our last common ancestor seven million years ago. (70) he says, language probably (71) as recently as the last few hundred thousand years.
It has been difficult to (72) data, but developmental studies could provide new (73) he believes. So-called knockout studies, where mice are genetically modified to lack certain genes, have helped tease out the (74) of certain mental abilities and many genetic disorders. Though such experiments are not ethically (75) in humans, detailed observational studies on people with naturally-occurring genetic mutations (基因突变)related to language, could provide (76) data, says Marcus.
A systematic collection of such studies would help us (77) which parts of language share an origin (78) other mental abilities and which parts have evolved (79) . For example, sufferers of William’s syndrome have difficulty (80) the world and understanding why things happen-yet they have near normal linguistic abilities. On the other hand, autistic people have (81) understanding what other people have on their minds and this can also affect linguistic abilities.