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judge the men."

"Maybe," "aid Shedemei. "But it's not just the diggers who are suffering from our interference in their previous social patterns. This relationship, this connection between diggers and angels has been going on for millions of years. Forty million years, to be more precise. And in those countless generations, certain patterns have evolved. The twinning of the angels, for instance. Every pregnancy is double. This isn't accidental. It's only happened twice in all our observations, and never in our own angel village, but when a single birth takes place, the baby is destroyed and the mother is never allowed to mate again. In other words, single births are ruthlessly exduded from angel society. It looks to me as if this is a response to the feet that diggers follow angels wherever they go. The diggers have to follow the angels in order to get the statues. But then the diggers can't help but see the angels as an easy source of meat, especially when the angel infants are at that awkward age when they can't fty well at all, and yet they're too heavy for one adult to carry them alone and still fly. In effect, the twinning allows each generation of angels to have one death and one survivor. Over the years, community cooperation has enabled between two-thirds and three-fourths of the twin-pairs to survive intact. Now, though, in our village all the twins are living to adulthood. And all the damaged, weak, sick, and crippled angels are surviving, where in other villages the diggers cull them out. In short, the angels have evolved a strategy of reproducing far beyond their sustainaWe population in order to survive the depredations of the diggers. When the diggers no longer prey on them, their population balloons out of control"

"It's a delicate balance," Zdorab saki "I found one place where it reached a crisis. The diggers had lost discipline and were eating more than the infants and the strays. They were systematically wiping out the angels in their area. When I got there, only a few beleaguered families of angels survived. But the diggers were already paying the price. They had plenty of old statues, of course.

But no new ones. And so after about five years, their birthrate fell off. Just as it has here. Not so suddenly, of course, since they were still worshipping the statues they had, only the statues contained progressively less and less of the enzyme. Births became more and more rare. With fewer diggers to prey on them, the angel population was going to start recovering soon. When it did, eventually the few surviving diggers would also recover."

Shedemei took over again. "So there's a social balance, you see. The diggers can't harvest too many of the angels for food, because then they lose their own ability to reproduce. It's self-correcting."

"What's to stop the angels from taking off and starting a colony where there aren't any diggers?" asked Protchnu. "Nothing," said Shedemei, "and I'm sure it's happened many times. But they can only live where they can find clay that supports the flatworms. That means that they can only live where there's a pattern of rainy season flooding, and they can only live at elevations where the flat-worm can survive. It's a pretty narrow range, common enough on this massif but not elsewhere. And the diggers range far and wide. I don't think there's anywhere that angels can go without a digger finding them sooner or later. When the digger finds them, he goes home and reports that he's found a new spot that's favored by the gods, and so they send out a colony. It's actually to the benefit of the angels. Without diggers devouring their young, their populations reach climax very quickly."

"Are you suggesting," said Nafai, "that we should let the diggers go back to kidnapping and eating angel infants?"

"That's the question," said Shedemei. "That's really the question, isn't it?"

"Does any of this," asked Chveya, "have to do with the evolution of intelligence among the angels and diggers?"

"Some, I think," said Shedemei. "The way the angel females select their mates is by the intricacy, beauty, originality, and accuracy of their sculptures. Obviously, the more intelligent and creative the angel male, the better his chances of reproducing early and often. For the diggers, it's a little different. In order to kill angels, they have to be devious and smart. We don't see it that much now, of course, because the diggers are so smart that the angels