Such scenes would be great for tourists. Ecotourism has that potential even in North America to raise substantial funds that could benefit the parks that protect these animals as wells as the surrounding communities. About 1.5 million people annually visit the San Diego Zoo’s Wild Animal Park in California to see large animals. By contrast, only twelve US national parks receive that many visitors.
Rewilding might fill the excitement gap of public and private parks in the US. The reintroduction of wolves to Yellowstone National Park has generated an additional $6 million to $9 million annually at costs of $500,000 to $900,000 to the park. If the chance of seeing a wolf in the wild has generated that much support, how much support might come from the chance to see a cheetah or an elephant?
The California condor thrived throughout North America until the end of the last ice age. They roamed over the Grand Canyon ten thousand years ago, scavenging on large animals that are now extinct. Today, California condors once again soar over the Grand Canyon, but the captive breeding program that promotes this must feed these animals with cattle carcasses. If Pleistocene megafauna were returned to the American West, these scavengers might again flourish.
Today, deer populations in the Northeastern woods of the United States are at historically high levels; so are disease-bearing pests, as we’ve seen with black-legged ticks. The presence of disease is associated with ticks, white-footed mice, and white-tailed deer. Gray wolves once caused deer to avoid heavily wooded areas, where they were more vulnerable to attack. But without gray wolves, white-tailed deer frequent the wooded forests, where ticks and Lyme disease reach their highest incidence. If wolves were to return, a lessening of disease risk, including Lyme disease, hantavirus, monkey pox, typhus, bubonic plague, and hemorrhagic fever might result from a better-balanced ecosystem.
These megafauna proxies proposed for rewilding are not exactly the same species that existed at the time of the Pleistocene extinction, but they could fulfill similar roles, as did the reintroduced birds in the North American peregrine falcon program. That program attempted to restore to North America peregrine falcons, whose eggs had become too brittle for hatching due to the use of DDT, a commonly used pesticide that was banned in 1972 but persisted in the environment for years afterward. The program used large numbers of captive-bred birds of different subspecies to bolster American falcon populations. In the end, these birds adapted to fulfill the niche left by the Midwestern peregrine population, which disappeared in the 1960s.
Biologists with cautious controls would carefully monitor a Pleistocene rewilding program while staying as true to the fossil record as possible. Private lands would hold the most immediate potential. More than seventy-seven thousand large Asian and African mammals now occupy Texas ranches. Larger tracts of public lands in the Southwestern United States could be brought on board to expand the program.
Bolson tortoises and exotic species of horses might be the first logical step, since they so recently occupied similar lands in North America. Camels and llamas might follow, since these animals could help control invasive plants. The final introductions might be elephants and African lions. The benefit of having elephants and camels for the control of woody vegetation has already been explained. But the benefit of African lions is more controversial. The African lion was once the widest-ranging land mammal of all time. The Asiatic lion is critically endangered, with a single population in India’s Gujarat State. Yet lions have been introduced and managed in African and Indian reserves that are a similar size to some contiguous and private lands in the US.
Establishing a predator population would be a necessity. The central issue, of course, is that lions sometimes attack humans. Such a reality has been growing in acceptance with mountain lions in the US. Attacks don’t precipitate large kills of lions anymore. But African lions would be an upgrade in size and predator status. The African lion is the apex predator of Africa.
The African and Indian reserves that have reintroduced lions have been successful in reestablishing normal behavior and population controls in their prey. But momentous questions would have to be answered before the reintroduction of cheetahs and lions could begin in the US.
Wolves were introduced in the 1990s to Yellowstone National Park and they have contained burgeoning elk populations there sufficiently to allow a resurgence of the forest. They have also started to take coyotes, not just as prey, but as competitors, which reduces the coyotes’ take of pronghorn antelope fawns and other smaller predators, like raccoons and beavers. Wolves also reduce or scare off hoofed mammals that trample streamside vegetation, and this enhances nesting habitat for migrant birds.
Before man migrated to North America, there were many more predators and prey in considerably grander and better-balanced ecosystems. The situation that exists now is diminished, impoverished, and unnatural. We have fewer birds, animals, reptiles, and amphibians—fewer of almost everything. “But we are incredibly adaptive, which means we don’t remember the past well,” says UC Berkeley paleobiologist Charles Marshall. “Where I grew up in Australia, the area was just packed with wildlife and all sorts of natural noises. In comparison America is much more impoverished. It has far fewer natural sounds. But I’ve adapted. I don’t notice the relatively silent days anymore. But I sure noticed it when I got here.”
Scientists tell us that Southeast Asian jungles used to be raucous forests with abundant wild noises. But these jungles have become the key supplier of the international wildlife market, providing animals for food, traditional medicine, pets, trophies, and decorations. The demand is fueled by the region’s economic growth, increased personal wealth, and the rising popularity of traditional Chinese medicine, both in China and abroad.
According to Liz Bennett, vice president of species conservation at the Wildlife Conservation Society in New York, poaching is pervasive across Southeast Asia, creating “silent forests,” empty of wildlife, throughout the region. She experienced this most starkly at Kubah National Park in Malaysia, on the island of Borneo. “It’s a beautiful forest, all the trees are intact, there are insect noises, but you don’t hear gibbons in the morning, you don’t hear birds singing, you don’t even see squirrels.”
Rewilding might be an exotic concept to Americans, but not to the Dutch. Flevoland, a province of central Netherlands, formerly resided at the bottom of an inlet of the North Sea. An enormous drainage project lifted Flevoland from the muck of its former seafloor in the 1950s. Today, Flevoland houses Oostvaardersplassen, a wilderness erected from what was formerly mud. Biologists have now stocked these fifteen thousand acres (six thousand hectares) with animal types that would have occupied the mainland and Flevoland—if it hadn’t been underwater. Most of the original animals have gone extinct, so biologists looked for surrogates. Instead of aurochs, large and now extinct bovines, they brought in Heck cattle, red deer, and Konik horses (a primitive breed native to Poland), which live in wild herds in a natural manner. They also added white-tailed eagles, ravens, foxes, egrets, geese, and other creatures. Now herds of large animals roam over this Dutch park, which looks from a distance like the Serengeti. Visitors pay up to forty-five dollars to take a safari-like tour of the place.
Such is the success of the Dutch experiment that it has inspired Southern Europe’s own rewilding movement. Every year thousands of acres of marginal farmland is taken out of production, some of it to counter climate change, and those have been suggested as future parks. The Fundación Naturaleza y Hombre (Nature and Man Foundation) recently released a herd of twenty-four Retuerta horses, one of the oldest horse breeds in Europe, in the Reserva Biológica Campanarios de Azaba in Spain. With large-scale land abandonment now happening in many parts of Europe, it provides an opportunity for nature. The creation of this new population of Retuerta horses will help to guarantee the survival of this rare breed in an area with black vultures and black storks. Rewilders are also working on the Reserva da Faia Brava in Portugal, which hopes to mix Portuguese horses with Bonelli’s eagl
es, golden eagles, griffon vultures, Egyptian vultures, and eagle owls.
The idea behind rewilding is noble, but the question is: Will the sixth mass extinction leave the world intact, or will man bulldoze or burn the last of earth’s open spaces before he turns the light off? The causes of mass extinctions past—whether they were volcanoes, asteroids, or man—have left devastated landscapes from which it took a long while to recover. If rewilding leaves no legacy and man should exit stage left, then where will the fauna and floral of the future emerge from?
University of Washington paleontologist Peter Ward writes in Future Evolution: An Illuminated History of Life to Come that domestic and urban species are the best candidates for a future laid waste by man. He believes that domestic animals and plants will be the dominant members of what he calls the recovery fauna and flora (animals and plants), those species that follow a mass extinction. He claims that domestic species are already taking the functional place of extinct or endangered life.
Domesticated plants would have problems, says Scott Carroll, the director of the Institute for Contemporary Evolution, in Davis, California. “They are really like pets. We’re basically watering, fertilizing, and tending them like house plants.” A few adaptive plants like date palms might persist and grow as weeds, but he’s not optimistic about corn or any of the major domestic grains.
The most successful domestic animal species display rapid maturity, the ability to breed in captivity, a reluctance to panic when startled, and, perhaps most of all, an amenable disposition. If domestic species exhibited these traits, they survived. If they didn’t, man killed them. For this reason, domestic animals are basically dumber than their ancestors. Dogs are dumber than wolves, cats are dumber than lions, and cattle are dumber than bison. Carroll thinks domestic horses might persist. “Horses are bred to run, which would give them a chance against wolves and mountain lions. Cattle, on the other hand, are not so good at running,” he says.
Sure, these animals have taken the place of the megafauna on the grasslands of the world, but could sheep, goats, or cattle exist without human guardians? It’s hard to imagine domestic animals taking over the wild—or whatever wild that man leaves intact.
To understand what might have been the ultimate wild, I visited the La Brea Tar Pits, which surround the Page Museum on Wilshire Boulevard. On an overcast day in Los Angeles, Caitlin Brown and Mairin Balisi, two graduate students at UCLA, took me on a tour of the museum and its famous tar pits. We visited Pit 91, the centerpiece of one of the richest pockets of Ice Age fossils in the world. The walls of the pit have been shored up with railroad ties, and the entire excavation is surrounded with glass. The pit is an actual tar seep from underground oil deposits of the Salt Lake Oil Field about a thousand feet below the surface of a section of Los Angeles called Hancock Park. Pit 91 is seven miles west of downtown Los Angeles and three miles south of Hollywood.
Early Los Angelenos came here in the 1800s to collect asphalt for road building and other purposes. Early bones found here were dismissed as domestic animals until 1875, when William Denton, a geologist, visited the tar pits and identified the canine tooth of a saber-toothed cat. Still, people didn’t realize what a treasure the pits were until 1901, when another geologist identified the bones as having come from extinct species. A paleontological gold rush ensued until, panicked at the prospect that the place would be overrun, George Allan Hancock, the owner of the land, granted the Natural History Museum of Los Angeles County exclusive rights to excavate the pits from 1913 to 1915.
The museum unearthed nearly a million bones from approximately a hundred sites at the pits. Those bones included saber-toothed cats, dire wolves, American lions, and short-faced bears—all bigger than their modern-day equivalents. The North American giant short-faced bear weighed up to 2,500 pounds (1,134 kilograms). Its cousin, the South American prehistoric giant short-faced bear, tipped the scales at up to 3,500 pounds (1,600 kilograms), perhaps the largest carnivore of its day. The pit also gave up the remains of camels, ground sloths, and mastodons.
During the summer months, the asphalt at the surface turned into a thick, sticky mess, quickly acquiring a deceptive surface of dust and leaves, making these pits an efficient animal trap. If a ground sloth, camel, or mammoth ventured out on the surface, it would take only about an inch or two of tar to totally entrap it, leaving the animal open to starvation and predator attack.
In winter, the asphalt would turn hard again, slowly interring the bones captured in the warmer seasons. One of the most interesting findings at the La Brea Tar Pits is that carnivores outnumber herbivores by almost nine to one. Even birds caught in the tar were predominantly birds of prey. The noise of the mired herbivores may have served as bait for predators that then also became mired. Once these bones were covered with tar, they endured little weathering, as tar is a good preservative.
Because pits would open at different times, they presented unique windows into our world from twenty-seven thousand to forty thousand years ago. The George C. Page Museum was built at the La Brea Tar Pits in 1977 and the bone collection transferred to it. Pit 91 was reopened and is currently under excavation. The museum staff, UCLA academics, and assorted volunteers are currently emphasizing smaller prey, carnivores, birds, and plants in the hope of understanding the ecosystem that existed back when the giant animals roamed the earth.
I met with UCLA paleontologist Blaire Van Valkenburgh, who heads up the school’s contribution to the excavation, at her office later that spring day. She claimed that the La Brea Tar Pits provide an accurate window into life and the ecosystems surrounding it prior to the Pleistocene extinctions and the rise of man. Her research has been focused on large predatory animals. Modern species evolved with larger and much more complex predators, and one of her goals is to understand how those animals affected the ones today.
The Page Museum has a mechanical statue of a saber-toothed cat on the back of a giant ground sloth, which was one of nature’s largest beasts in the Pleistocene. The mechanical cat sinks its enormous canines into the neck of the ground sloth over and over, but this is a mischaracterization. “In reality, a saber-toothed cat wouldn’t have been able to bite into the animal’s back,” Van Valkenburgh pointed out to me. “Ground sloths are related to armadillos and have small nodules of bone, which formed in the skin, under the fur. Saber-toothed cats wouldn’t have been able to penetrate that. The cat would have had to go for the neck of the sloth, and the ground sloth could have crushed the saber-toothed cat in its arms. Ground sloths were very powerful.”
A more typical encounter at the pits thirty-six thousand years ago would have involved a pack of dire wolves quickly dispatching a camel. They might be challenged by large condors circling overhead while large coyotes hovered nearby, eager to feast on the scraps, but only the saber-toothed tiger, which had twice the mass of the wolves, could have moved the wolves off their kill. Says Van Valkenburgh, “By the following day, little evidence would have been left of the camel’s death, and over time their bones would have been entombed in the tar. It is the fossils of just such scenarios that we study today.”
According to Van Valkenburgh, the biggest change between life thirty-six thousand years ago and today is the diversity of large animals that inhabited North America until the end of the last ice age, about ten thousand years ago. About thirty-six thousand years ago there were fifty-six species of hoofed mammals the size of a wild pig or larger. Today, there are only eleven. Fifteen carnivores the size of a coyote or larger preyed upon mastodons, mammoths, bison, horses, and camels. Now only the coyote comes near this part of Los Angeles.
In the Pleistocene, this city was a wide floodplain with lush vegetation and multiple streams and rivers rushing down from the tall mountains that surround the basin. The climate was cooler, wetter, and greener than it is today, more like the Big Sur area, which is three hundred miles north and famously forested. These were coastal lands that attracted migratory animals that followed the coastline with the s
easons, feeding on the plants and animals along the way.
This scenario, then, is what life would have been like without us: a paradise of green lands and wild creatures and birds next to blue oceans equally rich in fish, whales, and marine animals. Though the view afforded by the scientists who work at the La Brea Tar Pits is a bit gruesome, it was not always that way.
Multiple predators ganging up on single prey wasn’t the norm. In fact, scientists speculate that only one of those scenarios in a decade would have been enough to produce the fossils found at La Brea. There were plenty of green plants, shrubs, and trees around. Predators in Los Angeles thirty-six thousand years ago would have kept the animal herds stronger and the vegetation greener.
This area now surrounded by tall buildings used to be a wilderness paradise filled with creatures the likes of which we can hardly imagine. But the only way it could presently return to that idyllic scenario is without man.
So what are the chances? Could man survive a mass extinction? Is there an escape—a way out?
13
INVADERS TO MARS?
IF WE SPOIL THE EARTH, should we try another planet? Interplanetary travel could be a major force for human change. Other planets could have different atmospheres, dissimilar amounts of cosmic radiation, varying periods of night and day, wildly divergent temperatures, and drastically disparate amounts of gravity. All of these are strong evolutionary forces that could over time change man into something quite different from what he is here on Earth. The change in gravity alone could make the difference. In discussions about such travel, Mars is often mentioned.
Giovanni Schiaparelli, director of the Brera Astronomical Observatory in Milan, Italy, first seriously investigated Mars in the late 1800s when, through the observatory’s telescope, he counted more than sixty crisscross marks on the face of the planet. Schiaparelli referred to them by the names of famous earthbound rivers, identifying the markings as a system of canali—the Italian word for channels. But it was the descriptions by Percival Lowell, a wealthy New Englander, author, and astronomer, whose book Mars and Its Canals (1906) identified those canals as a planet-wide system of irrigation—the work of intelligent inhabitants of a dying Mars, who had constructed them to utilize water from the polar ice caps—which really fired the public’s imagination. Lowell’s astronomy showed that colonizing Mars might not be the answer, since somebody was already up there.
The Next Species: The Future of Evolution in the Aftermath of Man Page 22
