Spring 2010

“When any one population exceeds the carrying capacity of its ecosystem, other populations suffer.”
– Sam Taylor, Director, Carnegie Museum of Natural History

Our Super-sized World

 A new exhibition at the Museum of Natural History explores one of the most pressing environmental issues of our time: how unchecked population growth has lasting consequences on natural systems, and how the choices we make today will shape our future.

By John Altdorfer

Sam Taylor isn’t worried about the fate of the Earth. In fact, the director of Carnegie Museum of Natural History believes the planet will do just fine, despite humans inadvertently doing their best—or worst—to wreck it. What he’s far more concerned about is the    day-to-day and long-term survival of humankind around the globe.

“The asteroid that wiped out the dinosaurs 60 million years ago also took with it at least 50 percent of all species on the planet, and the Earth recovered,” says Taylor. Yet he’s not so confident that the seven billion humans who now inhabit the world, as well as not-so future generations, will fare so well in the aftermath of a crisis of their own creation. Understanding the factors that might trigger that  scenario is the subject of Population Impact, on view in the museum’s third-floor alcove.

Using video, large-scale video graphics, specimens, and even satellite images, Population Impact explores the relationships between ecosystems and their various populations, with a sharp focus on how humans dominate—and control the fate of—nearly every ecosystem on Earth.

“Human beings have to play by the same rules as every other species on the planet,” says Taylor. “We need air to breathe. We need water. We need food. And we need room to live. But when  any one population exceeds the carrying capacity of its ecosystem, other populations suffer.”

Unlike other species, humans can and often do break the rules. “We are the only species that isn’t dependent on our immediate ecosystem to survive,” says Taylor. “We can live on ecosystems halfway around the world and trash those environments without the impact being felt in our immediate surroundings. But that will catch up with us. We are consuming resources in a way that is unsustainable.”

To illustrate the consequences of man overstepping his boundaries, Population Impact zeroes in on Las Vegas, Beijing, Dubai, and Santa Cruz, Bolivia, to show the drastic environmental impact of those cities’ seemingly endless demands for food and water, space, and natural and manmade resources to sustain standards of living that range from lavish to below marginal. Visitors discover the devastating results of burgeoning populations that have outgrown their regions’ ability to support them: unchecked urban sprawl and poverty, severe water shortages and drought, destruction of natural habitats, depletion of resources, and severe stresses on native flora and fauna.

While the conclusions are obvious, Taylor says Population Impact isn’t pushing a political or social agenda. The goal, instead, is to increase public awareness and provide a glimpse of how the work of museum scientists helps in the search for solutions to these problems.

“Much of the research we conduct at the museum generates new scientific knowledge that is exactly the kind of   information needed to address these issues,” he explains.

The research of several staff scientists forms a significant portion of the exhibition. Cynthia Morton, associate curator of botany, discovered an exceptionally low genetic diversity among several species of trees in Pittsburgh’s parks and along its streets. After considerable digging, she found that for each of these species, the vast majority of trees had been cloned from a small subset of plants. Though that process produces a tree that has desirable traits for the nurseryman, the lack of diversity dangerously increases the possibility that an infestation of pests or diseases could kill thousands of trees in a short period of time. Morton has undertaken efforts to increase the genetic diversity of trees without reducing their durability.

While Morton is searching for ways to  make the populations of all urban forests more resistant to bugs, John Rawlins, an entomologist and head of the museum’s invertebrate zoology section, studies populations of insects for clues that might help avert ecological
disasters waiting to happen.      

“We know that bugs in their enormity of diversity present a rainbow of information opportunities. Our studies are basically measuring change, good and bad, in the ecological system,” he says. “In terms of the environment, change is hard to assess from looking at historical records. But you can look at changes in 100 different species of moths in the northern United States over a period of time and know that something is occurring.”

One place where Rawlins and his colleagues are noting significant change is the island of Hispaniola, home of the Dominican Republic and Haiti. Long before the recent earthquake, human population pressure and related poverty were causing visible environmental stress. “If you look at Hispaniola on Google Earth you can actually see the border between Haiti and the Dominican Republic because Haiti has been completely deforested,” says Rawlins, also noting that if Haiti can recover from the ravages of mankind and nature, there’s hope for the rest of the planet as well.

Another important point the exhibition  drives home: You don’t have to be a scientist to notice the impact of overpopulation—sometimes in your own backyard. Once nearly extinct, white-tailed deer today roam freely throughout western Pennsylvania, even in inner-city neighborhoods. Without any natural predators to keep their numbers down they cause big headaches for area homeowners whose gardens and shrubbery provide an all-you-can-nibble buffet for hungry herds. As suburban sprawl claims vaster swaths of woodlands that once provided ample food and living space for deer, the exhibition opens a spirited debate as to whether they are victims of human overpopulation and trespass or simply a nuisance that needs to be better controlled.

Taylor believes the exhibition’s real success isn’t that it presents answers to the challenge of population, rather that it demonstrates how natural systems work. “Nature is the lens through which we can understand the human condition,” he says. “My real desire is that we stimulate viewers’ curiosity and imaginations about nature, so that they have more questions than they came in with. I also hope that they’ll go away thinking of the Museum of Natural History as a place they can turn to as a resource to gain a deeper understanding of today’s most pressing issues.”

Also in this issue:

I Just Want to Watch  ·  The Next 15  ·  Regenerative Medicine: A Growing Future  ·  Run, bounce, spin, climb— and learn!  ·  President's Note  ·  NewsWorthy  ·  Face Time: Heather White  ·  Artistic License  ·  About Town: Asking Andy  ·  The Big Picture