In 2014, Wisconsin and the rest of the nation will observe a sad anniversary — the 100th year of a world without passenger pigeons.
Preparations are already under way in the state to properly note the passing of a bird that once turned daylight to darkness with its numbers. From books and conferences to buffing and rededicating the famous memorial monument at Wyalusing State Park, it will be a year spent pondering the meaning of the loss.
But, as opposed to other such anniversaries since the bird’s passing, this one will be marked also by a curious and perhaps momentous new twist.
Why not, some are asking, bring the passenger pigeon back?
Once relegated to the realm of science fiction, the possibility of bringing back extinct species by using remnants of their DNA has suddenly become the subject of considerable discussion in mainstream science. If it is any indication of how serious scientists are about this, the practice now has a name — de-extinction. And among the vanished creatures at the top of scientists’ wish list are two with strong Wisconsin ties: the passenger pigeon and the woolly mammoth.
“It’s getting close to being predictable science,” said Stan Temple, an emeritus professor of wildlife ecology at UW-Madison who last month was one of the keynote speakers at a National Geographic meeting on de-extinction.
But the stir that is moving through genetic and conservation communities comes with an abundance of caution. Just because science may be on the verge of allowing us to bring back that which has been lost, should we? Where, after all, would we put woolly mammoths when we can hardly find places on a diminishing landscape for elephants?
Or, as Temple so aptly put it at the National Geographic session: “Think very carefully about this before the saber-toothed tiger is out of the bag.”
Two possible ways to
bring back the extinct
But it is such a tempting possibility, especially to those who have spent their careers studying creatures that no longer exist. Bill Mueller is an ornithologist who has long been active in the Wisconsin Society for Ornithology and is as wistful as any bird enthusiast when it comes to the passenger pigeon. He doesn’t hesitate when asked if he would mind seeing the species resurrected.
“Of course!” Mueller said. “Who would object to having the passenger pigeon back again?”
Even Aldo Leopold, long before there was even an inkling that such scientific miracles might become possible, lamented the loss of the passenger pigeon and longed for its physical presence again.
“There will always be pigeons in books and in museums, but these are effigies and images, dead to all hardships and delights,” Leopold said in a 1946 speech. “Book-pigeons cannot dive out of a cloud to make the deer run for cover, nor clap their wings in thunderous applause of mast-laden woods ... They know no urge of seasons; they feel no kiss of sun, no lash of wind and weather.”
At the time of that speech, the workings of DNA were still being unraveled. It wasn’t until 1953, for example, that Francis Crick, James Watson and Rosalind Franklin discovered the double helix structure of DNA.
Today, however, our understanding of DNA is so sophisticated that not one but two avenues are open to scientists seeking to revive a lost species, according to Temple. The first and most appealing option would be cloning. This would require a living cell from the lost creature. Cutting-edge cellular science would allow researchers to reprogram the cell to grow into an embryonic cell, which would then be implanted into a surrogate mother — an elephant, for example, in the case of the woolly mammoth.
A team of Spanish and French researchers have already done this with a recently extinct wild goat called the Pyrenean Ibex, or bucardo. But the difficulties they encountered show that the science remains full of peril.
The researchers implanted the DNA of a bucardo into goat eggs emptied of their own DNA and implanted the eggs into a surrogate goat. Out of 57 implantations, only seven animals became pregnant. Six of those pregnancies ended in miscarriages and the one surrogate that carried to term gave birth to a bucardo that died shortly thereafter from a malformed lung.
The other method is even dicier and would be necessary with long-extinct animals such as the woolly mammoth or the passenger pigeon. Because it is unlikely that field researchers will find an intact and living cell, complete with its complement of DNA, scientists would have to use whatever remnants of DNA they can find and fill in the missing pieces.
This is the plan with the passenger pigeon, according to Temple. A California lab is already sequencing remnants of the passenger pigeon genome, retrieved from museum specimens. Gaps will be filled in with DNA from the closest living relative, a band-tailed pigeon. Then the patched-together DNA will be implanted into a type of cell that will grow into sperm or eggs and injected into a surrogate such as a rock pigeon, which is easy to work with in the lab. The hope is that two such re-engineered birds could be bred to create a passenger pigeon.
How solid is the science? Temple is wary. “I would say they’re not that close,” he said. “But obviously, somebody is going to try ... If I had to predict, I don’t think anything really exciting is going to happen for years, perhaps decades.”
What do we do after we
bring species back?
Some who may have been skeptical in the past are now convinced that geneticists can pull this off. Archaeologist Dan Joyce is the curator of exhibits and collections at the Kenosha Public Museum, home to a couple of mammoths unearthed in Wisconsin.
Over 18 months in 1991, Joyce and a team of volunteers uncovered the nearly complete remains of the oldest known mammoth believed to have been butchered by humans with tools east of the Mississippi River. It’s now known as the Schaefer mammoth, named for the farmer on whose farm it was found.
Joyce finds himself almost irresistably drawn to the idea of seeing one of these great beasts alive again. So taken is he with the possibility that he took samples from the Schaefer mammoth and had them analyzed for traces of DNA. Examination turned up evidence of amino acids, the building blocks of proteins. It leads Schaefer to believe that sometime, perhaps in the near future, a buried mammoth will provide enough DNA to begin the process of reviving the species.
“I think it will eventually happen,” Joyce said. “But from a professional point of view, there are a lot of questions. What do we do with them when we bring them back?”
Curt Meine, Leopold’s biographer and a conservation biologist, wonders the same thing. He said he still wrestles with whether de-extinction is something we should pursue. Mostly, Meine worries that bringing back these vanished animals will become an easy excuse for not working harder to keep species from passing into extinction.
“Any of us who treasure biodiversity would be thrilled to see a passenger pigeon or a woolly mammoth,” Meine said. “But it is so much easier than the hard work of conservation. And, as a working conservationist, I don’t know if I consider it conservation, frankly. It’s a sideshow.
“You’re not going to see 5 million passenger pigeons in the sky over Wisconsin again because the world they lived in no longer exists. Resurrecting a species is different than conserving a species. If there is no place for these creatures anymore, if we’ve altered the world so profoundly that there is no place for them, maybe this would be the ultimate act of ignorance.”