they have fins for guidance, they are completely evolved for adult life in the water. Why would they ever have evolved that way if they are born on land, mate on land, and reproduce on land? As far as evolution is concerned, anything that happens after you reproduce is completely irrelevant, except if you nurture your young, and the watersnakes definitely don't nurture. Living in the water does nothing to enhance their ability to survive until they reproduce. They could slither into the water and drown and it wouldn't matter because reproduction is over."
"Yes," said the Speaker. "I see now."
"There are little clear eggs in the water, though. I've never seen a watersnake lay them, but since there's no other animal in or near the river large enough to lay the eggs, it seems logical that they're watersnake eggs. Only these big clear eggs - a centimeter across - they're completely sterile. The nutrients are there, everything's ready, but there's no embryo. Nothing. Some of them have a gamete - half a set of genes in a cell, ready to combine - but not a single one was alive. And we've never found watersnake eggs on land. One day there's nothing there but grama, getting riper and riper; the next day the grama stalks are crawling with baby watersnakes. Does this sound like a question worth exploring?"
"It sounds like spontaneous generation to me."
"Yes, well, I'd like to find enough information to test some alternate hypotheses, but Mother won't let me. I asked her about this one and she made me take over the whole amaranth testing process so I wouldn't have time to muck around in the river. And another question. Why are there so few species here? On every other planet, even some of the nearly desert ones like Trondheim, there are thousands of different species, at least in the water. Here there's hardly a handful, as far as I can tell. The xingadora are the only birds we've seen. The suckflies are the only flies. The cabra are the only ruminants eating the capim grass. Except for the cabras, the piggies are the only large animals we've seen. Only one species of tree. Only one species of grass on the prairie, the capim; and the only other competing plant is the tropeqa, a long vine that wanders along the ground for meters and meters - the xingadora make their nests out of the vine. That's it. The xingadora eat the suckflies and nothing else. The suckflies eat the algae along the edge of the river. And our garbage, and that's it. Nothing eats the xingadora. Nothing eats the cabra."
"Very limited," said the Speaker.
"Impossibly limited. There are ten thousand ecological niches here that are completely unfilled. There's no way that evolution could leave this world so sparse."
"Unless there was a disaster."
"Exactly."
"Something that wiped out all but a handful of species that were able to adapt."
"Yes," said Ela. "You see? And I have proof. The cabras have a huddling behavior pattern. When you come up on them, when they smell you, they circle with the adults facing inward, so they can kick out at the intruder and protect the young."
"Lots of herd animals do that."
"Protect them from what? The piggies are completely sylvan - they never hunt on the prairie. Whatever the predator was that forced the cabra to develop that behavior pattern, it's gone. And only recently - in the last hundred thousand years, the last million years maybe."
"There's no evidence of any meteor falls more recent than twenty million years," said the Speaker.
"No. That kind of disaster would kill off all the big animals and plants and leave hundreds of small ones, or maybe kill all land life and leave only the sea. But land, sea, all the environments were stripped, and yet some big creatures survived. No, I think it was a disease. A disease that struck across all species boundaries, that could adapt itself to any living thing. Of course, we wouldn't notice that disease now because all the species left alive have adapted to it. It would be part of their regular life pattern. The only way we'd notice the disease - "
"Is if we caught it," said the Speaker. "The Descolada."
"You see? Everything comes back to the Descolada. My grandparents found a way to stop it from killing humans, but it took the best genetic manipulation. The cabra, the watersnakes, they also found ways to adapt, and