By now I knew exactly where he was going. I felt cold.

“Mammals but not human,” I said heavily. “And humans make choices about how they live their lives, Peter. Rational and moral choices. We’re in control of ourselves, in a way no animal can be.”

“Are we? How about that traffic jam?”

“Peter—get to the point. Forget the mole rats. Talk about the Order.”

He nodded. “Then we have to talk about Regina, your great-great-greatest-grandmother. Because it all started with her.”

In those first few turbulent decades, for the band of women huddling in their pit under the Appian Way, it had been just as it was for a band of naked mole rats out on the savanna—or so Peter’s analysis went. With imperial Rome crumbling around them, it became a lot safer for daughters to stay home with their mothers, to extend the Crypt rather than to migrate.

“So you have just the same kind of resource and population pressures as in a mole rat colony.”

I frowned. “But Regina would never have made a choice about eusociality. In the fifth century she couldn’t even have formulated it.”

“But she had the right instinct. It’s all there, in her own words. Remember those three slogans, carved on the walls?”

“Sisters matter more than daughters. Ignorance is strength. Listen to your sisters.”

“Yes.” He called up another file on his handheld. “. . . Here we are.”

It was an extract from Regina’s biography. I read: “Regina asked her followers to consider the blood of Brica, her daughter, and that of Agrippina, her granddaughter. Agrippina’s blood is half the blood of Brica, half of her father, and so a quarter mine, said Regina. But if Agrippina were to have a baby her blood would mix with the father’s, and so the baby would be only an eighth mine. Suppose I have to choose between a baby of Agrippina’s, or another baby of Brica’s. I can only choose one, for there is no room for both. Which should I choose? And they said, You would choose for Brica to have another child. For sisters matter more than daughters . . .”

Peter looked at me. “Sisters matter more than daughters. Regina thought in terms of keeping her blood from being diluted. It doesn’t matter that the mechanics actually works with genes—her instinct was right. And once that is established, much else follows. The breeding rights of a few mothers, your mamme-nonne, are favored over everybody else’s rights, even over their own children’s. The drones’ only chance of passing on their own genes is to help their mothers, and their sisters . . .”

It was the first time he had used the word drones.