In the movie Jurassic Park, a tree extinct for millions of years delights the paleobotanist. Then a sauropod eats its leaves. This movie later shows us how to re-create the dinosaur but not how to grow the tree, which at that size would be perhaps a hundred or more years old, or how to do so metaphorically overnight. To sustain even a single dinosaur, one would need thousands of trees, probably of many species, as well as their pollinators and perhaps their essential symbiotic fungi.

De-extinction intends to resurrect single, charismatic species, yet millions of species are at risk of extinction. De-extinction can only be an infinitesimal part of solving the crisis that now sees species of animals (some large but most tiny), plants, fungi, and microbes going extinct at a thousand times their natural rates. (Related: Photos of Nearly Extinct Species.)

"But wait"—claim de-extinction's proponents. "We want to resurrect passenger pigeons and Pyrenean ibex, not dinosaurs. Surely, the plants on which these animals depend still survive, so there is no need to resurrect them as well!" Indeed, botanic gardens worldwide have living collections of an impressively large fraction of the world's plants, some extinct in the wild, others soon to be so. Their absence from the wild is more easily fixed than the absence of animals, for which de-extinction is usually touted.

Perhaps so, but other practical problems abound: A resurrected Pyrenean ibex will need a safe home, not just its food plants. Those of us who attempt to reintroduce zoo-bred species that have gone extinct in the wild have one question at the top of our list: Where do we put them? Hunters ate this wild goat to extinction. Reintroduce a resurrected ibex to the area where it belongs and it will become the most expensive cabrito ever eaten. If this seems cynical, then consider the cautionary tale of the Arabian oryx, returned to Oman from a captive breeding program. Their numbers have declined so much that their home, designated as a UNESCO World Heritage site, was summarily removed from the register.