Pepin's clothes are covered with animals. Her books are about animals. Her toys are animals. Her room is wallpapered with animals. Her crib is printed with animals. Awake and asleep, she lives in a menagerie, as though all humans start out among the other species, only to join ours once they become interested in Legos.

I'd forgotten how closely childhood is linked with animals until I went to a baby store. It could have been a zoo gift shop, except for an unfortunate take on the hipster taxidermy trend (a stuffed Babar is one thing, an elephant's head on the wall is a mixed message at best). Pepin is embedded among the same animals I marveled at in Ranger Rick magazine and every Sunday on Mutual of Omaha's Wild Kingdom. Except now, in real life, they're quickly disappearing.

The polar bears on her pajamas: mostly gone by 2050 — when she'll be 35 — due to melting habitat. The elephants on her onesies, her crib, and her bookshelf: extinct in the wild in 10 to 20 years — when she'll be boxing up her stuffed animals — due to poachers hacking off their tusks for Asian knick-knacks. Rhinos: extinct even before she has booted Nosey, her mother's favorite stuffed animal, from her bed.

In Pepin's lifetime, all the creatures she's enchanted by will likely be gone or nearly so, one way or another (except for the patchwork crocodile snake with Disney eyes thing — that will probably be on the increase). It's the Sixth Extinction, if you're keeping score at home, and it's happening now, the fifth being the one that killed off the dinosaurs and the first being caused by cyanobacteria, another creature whose population spiked (and made our existence possible by boosting oxygen levels; we're not the only species to have radically altered our atmosphere).

This one is being caused by us. When I was growing up, it was less obvious; we could get away with thinking that we had our habitat and everything else had its own. But billions of people and many megatons of carbon later, it's clear we're the carp in the pond, the cyanobacteria. And the cognitive dissonance of watching Pepin romp among doomed animals is some days like a ringing in my ears, a tinnitus of the conscience.

There are no unselfish reasons for having children, which may be the best evidence that the urge is largely biological. We're selfish creatures — like all the others. And to open someone's eyes onto this big blue-and-green balloon — even with all the air we've let out of it, the wonders we're sapping with our strength — well, there's no better place we know of to bring humans into existence.

Pepin is predictably unfazed so far, and perhaps she will remain so. She may yet have a chance to see these creatures in the wild, and if they disappear before she does she may see them the way we see dinosaurs, as unfraught about their fate as we are awe-inspired. She may be into robots, finding her own wonders in answer to the question of her existence. She's unlikely to hold it against me.