[A] capability [B] convey [C] decreasingly [D] evolutionary [E] genus

[F] increasingly [G] intellectual [H] intelligent [I] investigate [J] mapped

[K] origins [L] species [M] structural [N] trace [O] transport

Thanks to the field of linguistics we know much about the development of the 5000 plus languages in existence today. We can describe their grammar and pronunciation and see how their spoken and written forms have changed over time. For example, we understand the【C1】_____of the Indo-European group of languages, which includes Norwegian, Hindi and English, and can【C2】_____them back to tribes in eastern Europe in about 3000 BC.

So, we have【C3】________a great deal of the history of language, but there are still areas we know little about.

Experts are beginning to look to the field of【C4】_____biology to find out how the human【C5】_____developed to be able to use language. So far, there are far more questions and half-theories than answers.

We know that human language is far more complex than that of even our nearest and most【C6】_____relatives like chimpanzees (黑猩猩). We can express complex thoughts,【C7】__subtle emotions and communicate about abstract concepts such as the past and the future. And we do this following a set of【C8】__rules, known as grammar. Do only humans use an innate system of rules to govern the order of words? Perhaps not. Some research may suggest dolphins share this【C9】_____because they are able to recognize when these rules are broken.

If we want to know why we can use complex language, we should find out the difference between our brains and the animal brains. Our brains became able to make our mouths produce vowel and consonant sounds and any more progress in language was simply a response to our【C10】________civilized way of living together.

【C5】