"Dr. Calhoun is famous for jumping to conclusions," said Smathers sharply.

O’Brien was grinning from ear to ear — he evidently hadn’t expected to get an impromptu Siskel and Ebert of science. "But, as I was about to say, if there are alien beings aboard, then I expect them to be at least vaguely familiar in body plan, and—"

"You’re hedging now, Woody," said Clete. "Couple years ago, I heard you give a talk arguing that the humanoid body plan would be adopted by purty near any form of intelligent life, and—"

Smathers was growing red in the face. "Well, yes, I did say that then, but—"

"But now that we’re actually goin’ to meet aliens," said Clete, clearly enjoying himself, "you ain’t so sure no more."

"Well," said Smathers, "the human body plan might indeed represent an ideal for an intelligent lifeform. Start with the sense organs: two eyes are much better than one, since two give stereoscopic vision — but a third eye adds hardly any value over two. Two ears likewise give stereophonic hearing, and they’ll obviously be on opposite sides of the body, to give the best possible separation. You can go right down the human body from head to toe, and make a case why each part of it is ideal. When that spaceship opens up, yes, I’ll stand by my contention that we’ll probably see humanoids inside."

The Clete on the TV set looked positively pained. The one sitting next to Frank aboard the Kitty Hawk shook his head. "Peckerwood Smathers," he said under his breath.

"That’s hooey, Woody," said the TV Calhoun. "Ain’t nothin’ optimized about our form — y’all only get optimization when you’ve got an ultimate design goal in mind, and there wasn’t one. Evolution takes advantage of what’s handy, that’s all. You know, five hundred million years ago, durin’ the Cambrian explosion, dozens o’ different body plans appeared simultaneously in the fossil record. The one that gave rise to us — the ancestor of modern vertebrates — weren’t no better than any of the others; it was just plum lucky, is all. If a different one had survived, nothin’ on this planet would look the way it does today. No, I bet there’s some critter inside unlike anything we’ve ever seen before."