Our culture lets us make up for having lost our strength, claws, long teeth, and other defenses. Instead, we use tools, cooperate with one another, and communicate in language. But these aspects of human behavior, or "culture", can also be found in the lives of certain animals.
We used to think that the ability to use tools was the dividing line between human beings and other animals. Lately, however, we have found that this is not the case. Chimpanzees can not only use tools but actually make tools themselves. This is a major step up from simply picking up a handy object and using it. For example, chimps have been seen stripping the leaves and twigs off a branch, then putting it into a termite nest. When the termites bite at the stick, the chimp removes it and eats them off the end—not unlike our use of a fork!
For some time we thought that although human beings learned their culture, animals couldn't be taught such behavior. Or even if they could learn, they would not teach one another in the way people do. This too has proven to be untrue. A group of Japanese monkeys was studied at the Kyoto University Monkey Centre in Japan. They were given sweet potatoes by scientists who wanted to attract them to the shore of an island. One day a young female began to wash her sweet potato to get rid of the sand. This practice soon spread through out the group. It became learned behavior, not from humans but from other monkeys. Now almost all monkeys who have not come into contact with this group do not. Thus we have a "cultural" difference among animals.
We have ruled out tool use and invention as ways of telling animal behavior. from human behavior. We have also ruled out learning and sharing of behavior. Yet we still have held out the last feature—language. But even the use of language can no longer separate human culture from animal culture. Attempts to teach apes to speak have failed. However, this is because apes do not have the proper vocal organs. But teaching them language has been very successful if we are willing to accept another forms rather than just the spoken word. Two psychologists trained a chimpanzee named Washoe to use Standard American Sign Language. This is the same language used by deaf people. In this language, "talk" is made through gestures, and not by spelling out words with individual letters. By the time she was five years old, Washoe had a vocabulary of 130 signs. Also, she could put them together in new ways that had not been taught her originally. This means she could create language and not just copy it. She creates her own sentences that have real meaning. This has allowed two-way talk. It permits more than one-way command and response.
Of course, there are limits to the culture of animals. As far as we know, no ape has formed social institutions such as religion, law, or economics. Also, some chimps may be able to learn sign language; but this form. of language is limited in its ability to communicate abstract ideas. Yet with a spoken language we can communicate our entire culture to anyone else who knows that language. Perhaps the most important thing we have learned from studies of other animals is that the line dividing us from them is not as clear as we used to think.
The text mainly tells us about

A. the history of animal learning.
B. the difference between animals' culture and that of human beings.
C. the various aspects of animals' culture.
D. the divding line between animals and human beings.