Today, a scientist wonders what sets us apart as humans. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Near the end of his book, Celebrations of Life, René Dubos tells us that the word "civilisation" was given its modern meaning by a French writer in 1757. When Samuel Johnson published the 1772 edition of his famous dictionary of the English language, he would not include the word civilisation. He felt it could never replace the older English word, civility.

For Dubos, the idea of civility calls up something basic -- a feature more than surface deep. The word suggests something about our essential humanity. And Dubos struggles with the question, "What, if anything, sets humans apart from animals?"

He finds huge similarities in civility among vastly different human societies -- the triggers for laughter and grief, the texture of human consideration. Our vocabulary of gesture varies, but under that surface are universal, and distinctly human, attitudes.

Our DNA hardly differs from that of apes. Still, our brains are larger and we speak richly evolved languages. People have worked very hard trying to teach language to apes, but apes don't get beyond isolated words and minimal phrases. We know many cases of human children, like the Wild Child of Aveyron, who grew up without language. We do no better at teaching them language than we do apes. In other words, the only creatures truly capable of learning language are young human children.

Then Dubos introduces a real shocker. It is that we talking humans are adapted to only one environment -- the warm grassy savanna. That includes the Eskimo and the Bedouin. They have to protect themselves -- the Eskimo with skins and igloos, the Bedouin with robes and tents.

We're one species with various skin colors and minor differences in our eyes, hair, and noses. We moved out of our African cradle (our true Garden of Eden) only after we had the technologies to protect ourselves from harsher environments. So technology, and that includes language, differentiates us from other animals.

Dubos sees humanity as a potentiality that exists in our species alone. And even for us, it's only a potentiality. Without the powerful force of community, we're right back with our brother apes -- from which we differ very little.

Community is where technology, the knowledge of technique, vests. And technique carries our humanity -- the technique of making clothes, building houses, finding food wherever we are -- the technique of speaking and of being civil to one another.

Our ability to transmit technique within the community is what asserts our identity as a species. It's a fragile difference. It's all that separates us from our cousins -- beasts without language, who cannot move beyond the constraints of their specialized nature.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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Dubos, R., Celebrations of Life. New York: McGraw-Hill Book Co., 1981.