I nodded. “Which is why I felt breathless.”

“With low oxygen levels, you get a low metabolic rate, low body temperatures. A slow pulse, cold skin.” He rubbed his nose. “I’d like to get a look at any urine tests they do.”

“Why?”

“Because in animals, one way of getting rid of excess cee-oh-two is through your piss, in the form of flushed-out carbonates and bicarbonates. I wouldn’t be surprised if they’ve come up with some such adaptive mechanism.”

“Adaptive. You’re saying she’s adapted to the Crypt.” I thought it over. “Like her pale skin. Her eyes. Those thick sunglasses.”

“It does all fit together, sort of. And there’s more. With a low metabolic rate, you’d grow more slowly, mature later. Live longer, too.”

“Could that explain the sterility?”

“I don’t know. You know, those people must have been down that hole for a very, very long time.”

“Peter—what are we dealing with here?”

He glanced at Daniel, and beckoned. We moved a few seats away from the boy.

Peter unfolded his laptop and showed me some images, which I could barely make out for the glare from the big windows. “What do you know about orangutans?”

As far as Peter could tell the file Daniel had given him on Pina was genuine. When Pina went into hospital for her broken leg, the doctors who examined her had been concerned enough by her appearance to insist on giving her more extensive tests.

“George, I think the kid was right. Pina had an imperforate hymen, and quiescent ovaries.”

“Quiescent?”

He shrugged. “Not producing eggs. Never had produced eggs. There’s a brief note here, where one doctor speculates about the mechanism—”

I waved a hand. “I’m not going to understand any of that.”

“Anyhow they never did the conclusive tests before she was sprung. I’ve been onto the search engines and looked wider. The biologists call this ‘arrested development.’ It can happen for genetic reasons—for instance, a mutation in the receptor for a certain growth factor can cause a form of dwarfism. Or if food is short—say if you’re an anorexic—puberty can be delayed. It makes a certain evolutionary sense, because if you can’t feed yourself it makes no sense to waste calories on bone mass and fatty tissue for sexual characteristics until your body can be sure it will survive. It’s actually quite common among the animals. Sometimes subordinate males don’t develop sexual characteristics. Tree shrews. Mandrill monkeys. Elephants.”

“And orangutans—”

“Even orangutans, even apes.”

“Get back to Pina. You’re saying she has this ‘arrested development,’ too.”