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No. 560:
We Are One Species

Today, we find out why humans hang together. 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.

Two anthropologists, Malcom Smith and Robert Layton, tell a strange tale about the integrity of the human species. They begin by visiting an African lake that teems with strange fish. They're called cichlids. The cichlids in the lake come in 200 different species. They're all pretty similar. Only their lips, jaws, and teeth have all evolved differently.

Some have evolved into fin eaters -- some into worm eaters. Some cichlids eat snails. Each has evolved into a tiny niche of the ecology. That kind of subdividing is pretty common. That's why we count 25,000 species of fish, 9,000 species of birds, and 4,500 species of mammals.

So why haven't we splintered like that? Humankind is only one species. One young hunter can chase down a rabbit. Another can spear a fish. Yet we haven't specialized into one race of rabbit catchers and another of fish spearers. Why are we alike in all but the most minor features -- things like skin color?

We're not like the fish in that African lake. We've faced every environment on earth. It certainly seems plausible that we too would've divided in that way, and become different species with specialized abilities.

The reason we haven't lies in one key attribute. Humans share! We share in complex ways that no other animal does. Back in camp, the rabbit chaser and the fish spearer exchange food. We've done that as long as we've existed.

Of course, it helps that we're very omnivorous. We eat almost anything. If it lives, we've eaten it at one time or another. More important, we've also shared it.

Our sharing goes beyond food. Most societies have taboos about mating across the lines of clan, ethnicity, or race. But the important thing about those taboos is that we break them. Intermarriage is another kind of sharing that holds our species together.

Sharing goes beyond food and beyond mating. We also share the techniques for gathering food and fulfilling other needs. One cichlid fish had to develop its own specialized jaw for crushing and eating snails. We can share our knowledge of snail catching, of rabbit chasing, or of fish spearing.

That's what technology is. It's the lore, or science, of technique. Technology is our primary act of sharing. Technology shapes us into one body, instead of a thousand subspecies. We're bound in a unique and instinctive tether of generosity. And our technologies are right at the core of that generosity.

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

(Theme music)

Smith, M.T. and Layton, R., On Human Nature. The Sciences, January/February 1989, pp. 10-12.


Photo by Theresa Kavanaugh-Lienhard

We are one species because humans share —
their food, their genes, and their techniques