Today, we find that whales and elephants have more in common than just size. 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.

W e humans, you and I, are members of one of the larger animal species. Maybe a look at the largest species, at elephants and sperm whales, would tell us something about ourselves.

Whales and elephants have the largest brains of any creature. (By the way, large brains don't necessarily go with large body sizes. Dinosaurs had much smaller brains than whales or elephants. So too does the huge rhinoceros.) A recent article in the American Scientist magazine tells us that whale and elephant behavior is not only complex, it's also alike in both species. Here's a quote:

... the females [of either species] live in highly social family units that rely on well-developed communication ... the much larger males live separate, more solitary lives, roving between female groups during the breeding season ... delaying breeding until they are large and dominant.

Yet those matriarchal family groups, as well as the loosely organized bands of males, are marked by physical contact and care for one another. Groups of whales, or of elephants, spend many hours a day together, rubbing up against one another, caressing each other with flippers or with trunks, and quietly talking among themselves.

Conversation among sperm whales takes the form of patterned sets of clicks whose frequencies can vary from 200 to 32,000 Hertz. Elephants use very low frequency sound -- below the threshold of human hearing -- to speak with one another.

There are other human qualities. Both species live to the age of about 60. Both almost certainly remember long-past events. And individuals of both species act heroically to protect other members of their group.

Like humans, whales and elephants are adaptable. Their diets, like ours, are varied and flexible. During the Miocene epoch, various kinds of elephants lived everywhere on Earth except Australia and Antarctica. Sperm whales today range the oceans from Antarctica to Greenland. Now, of course, we gradually hem in whales and elephants as we mindlessly carry out their extermination.

The consequences of that ongoing extermination are huge. Both whales and elephants play large roles in the ecology. We humans don't yet kill quite as many fish as whales do, but we soon will. The problem is, our consumption is new to the ancient balance of nature. It threatens the very existence of whales themselves. And removing whales (or any of the large species) promises vast and unpredictable disruptions of the ecology.

It's a terrifying thought: we're eliminating what are, in ways we don't begin to understand, the most intelligent species on Earth. We might well get away with that killing and still survive. If we do, of course, it'll be in a greatly altered world.

What's heart-breaking is that it'll also be in a world where we never got to know these creatures -- and never had a chance to savor their wisdom.

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

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