Witches and Goblins, Wild Horses and Climate Change

About this time last year we lay in the dark, listening to the violent cracking of still-leafy tree branches outside our windows. A weirdly out-of-season snow-and-ice storm was turning Halloween into a broken, droopy winter wonderland. This year, it looks as if folks around here will have to bring their pumpkins and outdoor goblins inside, for fear they might become flying missiles when the hurricane dubbed “Frankenstorm” (a.k.a. Sandy) makes landfall somewhere along the New Jersey coast late tomorrow night. Already the outer bands of this gigantic storm that can’t quite decide if it’s a tropical cyclone or a winter nor’easter—because apparently it’s setting up to be both—have been buffeting the outer banks of North Carolina and moving in on Virginia and points north.

As I always do, I think of the wild creatures with no ability to board up windows and buy electric generators. It looks as if this time, the worst will pass to the north of Assateague Island, and the horses there will survive this storm as they have so many others. I’ll be thinking of them, and all the animals and people impacted by this historic weather event.

It does make me wonder, though. Is this crazy weather we’ve been having in recent years  a harbinger of global climate change? And how might man-made climate change affect both humans and the animals who share our planet in the future? So I was glad to find a study, published late last year, that addresses that very question. An international group of scientists collaborated in an effort to answer a nagging question: What caused the mysterious disappearance of many large mammals in North America some 10,000 years ago? Was it climate change, or human activity? (You can read a lot more about these mysterious extinctions in Wild Horse Scientists soon. November 6!)

Using genetic, archeological, and climatic data together to figure out what happened to Ice-Age mammals including the wild horse, these scientists concluded that the answer to the question, humans vs. climate change, is. . . both.

You can read more about the study here. Bottom line? The researchers concluded that there was likely no single cause for extinctions of the six large herbivores studied—the wooly rhinoceros, wooly mammoth, reindeer, bison, musk ox, and wild horse. Instead, says the study, “the relative impacts of climate change and human encroachment on species extinctions really depend on which species we’re looking at.”

During the entire Pleistocene Epoch, which lasted from about 2 million to 12,000 years ago, North America experienced many climatic ups and downs, and these mammals that had evolved during colder periods did suffer population losses during the warm intervals. But they always managed to find places where the climate was just right for them and survive, even in reduced numbers. When cooling came again, their numbers rebounded. But then, after the peak of the last ice age around 20,000 years ago, something changed.

What was that something?

Humans.

Our ancestors moved into the same places where the large Ice Age mammals had once thrived; they developed agricuture and hunting, and in so doing changed the landscape so dramatically that these animals were cut off from what they needed to survive. It’s an ancient drama being replayed today in passionate controversies over the place of wild horses in the remaining open lands of our American West.

One faction says that horses are not native to North America, but rather are an exotic, invasive species that can claim no natural rights to protection, while other voices argue just as forcefully that the horse evolved here in North America and nowhere else on earth. To them, wild horses have a right to exist on the lands where they evolved. Well, this and other studies lend compelling, scientific support to the second argument. Both fossil evidence and sophisticated genetic analysis support the claim that native horses driven from North America by climate change and human encroachment 10,000 years ago are biologically identical to the so-called “feral” horses we call wild today.

Says Beth Shapiro, biology professor at Penn State University and one of the study’s authors, “There are many more humans today, and we have changed and are continuing to change the planet in even more important ways.”  What will be the fate of populations threatened by climate change and habitat alteration happening in our time? Maybe this truly awesome storm—the Halloween Frankenstorm of 2012— will prompt more of us to ponder this question.