Martha, the last passenger pigeon. The species was hunted from several billion to zero in about a century.

The latest word in environmentalism is “de-extinction”: resurrecting species that have gone extinct by cloning them (or occasionally by selective breeding, such as recreating the wild aurochs from domestic cattle).

While there are a handful of species we might actually want to get rid of, like Anopheles gambiae, the malaria-carrying mosquito, we generally don’t like it when species go extinct, especially when it was due to irresponsible practices like over-hunting that are now frowned upon. So why not clone some of these extinct animals if we have their DNA and bring them back from the dead?

Actually, this has already been done. The Pyrenean ibex, which went extinct in 2000, was successfully cloned in 2009. Unfortunately, the single newborn ibex kid died shortly after birth due to lung defects. Cloning still has a long way to go before it can work on the species scale.

But that isn’t stopping some geneticists who have already started projects to resurrect the passenger pigeon and the gastric-brooding frog. Plenty of other species are being investigated, too, some of which were hunted to extinction by humans, while others, like the wooly mammoth, were only maybe wiped out by humans.

Of course, the idea of de-extinction is not without its detractors. This article, for example, points out a number of concerns. These concerns are real and merit serious consideration, but I don’t believe they should deter us from a responsible pursuit of de-extinction.

The de-extinction movement, the claim goes, ignores the largest driver of extinctions today, which is habitat loss. It won’t do much good to recreate extinct animals and not have anywhere to put them. Worse, it could distract from conservation efforts aimed at preventing extinction in the first place. Land use is a complicated economic issue that is beyond the scope of this post, but trying to prevent future mistakes should not stop us from doing what we can to fix the mistakes of the past, or vice versa. We would do best to address both problems.

The other area of concern is for the welfare of the animals themselves. Cloning is expensive, difficult, and has a low success rate. And even if cloning is perfected, we would likely be able to clone only a few individuals of any given species, resulting in a dangerously low level of genetic diversity. Yet these ethical concerns are not new. Cloning has these problems whether the cloned species is extinct or not, and we do it anywau. And as for genetic diversity, the California Condor is being repopulated from a low point of just 22 birds. Some may decry the high cost-benefit ratios of these efforts, or the high valuation of the more photogenic animals, but clearly, we are not shy about protecting the species we care about.

It all sounds very Jurassic Park, but I think that de-extinction is really leading us someplace far more profound. Where is that? Well…

We have the Neanderthal genome. All it needs is a reliable human cloning technique, and that is almost certainly coming. It may be in 5 years, or it may be in 50, but it is coming. That will bring a whole new raft of ethical problems, but none, I suspect, are insurmountable. After all, most of us are 3% Neanderthal ourselves, so it wouldn’t be anything entirely new. We may see our ancient cousins walking the Earth again sooner than you think.