Bloated with stuffing, their ruddy brown chests resemble a row of sweet potatoes. Slate-blue heads and thin white tails protrude in perfect alignment, except for one bird that cranes its neck to face its neighbor. A pea-sized bulge of white cotton sits where its eye should be. A slip of paper tied to its foot reads, “Ectopistes migratorius. Manitoba. 1884.” This is the passenger pigeon, once the most abundant bird in North America. When Europeans first landed on the continent, they encountered billions of the birds. By 1914 they were extinct.

That may be about to change. Today scientists are meeting in Washington, D.C. to discuss a plan to bring the passenger pigeon back from extinction. The technical challenges are immense, and the ethical questions are slippery. But as genetic technology races ahead, a scenario that’s hard to imagine is becoming harder to dismiss out of hand.