Chapter 6 Chapter 6 The African Paradox

origin Fortunately, in a world without humans, not all large mammals would go extinct.The entire continent of Africa is a museum, with amazing collections.Why are they all over the earth after we are gone?Could they replace animals we've wiped out elsewhere, or evolve to be exactly like those lost? But the first question is: if humans came from Africa, why are elephants, giraffes, rhinos and hippos there too?Why weren't they all killed off, and why didn't they end up with 94% of Australia's large animals (most of which are large marsupials), or the species that paleontologists in the Americas mourn?

Oroqsari is the site of a Paleolithic tool-making site discovered by Louise and Mary Leakey in 1944.It is a dry, yellow basin in the Great Rift Valley, 1,145 miles from Nairobi.Much of the basin is buried in chalk of diatomaceous earth deposits (the same material used in our pool filters and cat litter), consisting of the fossilized exoskeletons of freshwater plankton. Louis Leakey and Mary Leakey discovered that a lake had filled the depression of Ologsari many times in prehistoric times, appearing in the rainy season and disappearing in the dry season.The animals came to drink, and so did the toolmakers who hunted them.Excavation work now confirms that early humans lived near the lake between 992,000 and 493,000 years ago.The remains of hominids were not found until 2003: a small skull was discovered by archaeologists from the Smithsonian Institution and the National Museum of Kenya.This may have come from Homo erectus, our closest ancestors.

What we found were thousands of stone hand axes and cutting knives.The latest types of tools are used for throwing purposes: one end is round, the other end has an eyelet or a reversible sharp edge.The Olduvai Canyon is similar to that of the Australopithecus bumping two stones, making one of them thinner and sharper. By this time, the stone hand ax and the cutting knife have been sliced ​​into thin slices with certain skills, and can be cut piece by piece. copy.Every formation here contains these sharp stone tools, which means that humans have captured and slaughtered prey in Orogeseli for at least half a million years.

From the dawn of civilization to the present day, recorded history is only a hundredth of the time our ancestors lived in this land, uprooting plants and holding sharp stone tools at animals.With the awakening of human technology, there must be a lot of prey here to meet the needs of more and more predators.Femurs, tibias or bone marrow were intermingled at the Oroqsari site, many crushed.The sheer number of stone tools found around the massive remains of an elephant, a hippopotamus, and a troop of baboons suggests that entire tribes of hominids relied on collective action to kill prey, which was then dismembered and shared.

If humans really slaughtered so many large animals in the Pleistocene of America in just a thousand years, how did they do it?Of course, Africa has more people and has been around for longer.If so, why is Africa still such a well-known large wildlife community?Thinly sliced ​​basalt, obsidian and quartz rock blades at Ologsari suggest that within a million years hominids were capable of cutting through the thick hides of elephants and hippopotamuses.So why didn't Africa's large mammals go extinct? Because here, humans evolved together with large animals.Unlike the herbivores of the Americas, Australia, Polynesia, and the Caribbean, who were unsuspecting and unaware of the dangers of the sudden arrival of humans, animals in Africa adjusted to the increase in human numbers.Animals that accompany predators know how to stay vigilant and have evolved to avoid being hunted.In the company of many hungry neighbors, animals in Africa have learned how to pack together, making it difficult for predators to isolate and capture a single animal; responsibilities.A zebra's stripes can dazzle a lion, creating an optical illusion of chaos.Zebra, wildebeest and ostrich form a trinity united front on the vast prairie. The former's excellent hearing, the middle's keen sense of smell and the latter's sharp vision are combined together.

Of course, if this defense worked every time, the predator would be doomed.It's a balance: In a sprint race, the cheetah can catch the gazelle; in a long-distance race, the cheetah is no match for the gazelle.The trick to survival is to buy enough time to reproduce by avoiding being someone else's dinner, or to ensure that some of the offspring always survive by breeding frequently.In view of this, the old, weak, sick and disabled are always the ones that predators such as lions can catch.Early humans did that, too; or, we started out like coyotes, doing something simpler: cleaning up the carrion left over by more skilled hunters.

However, when something changes, this balance can be disturbed.The developing brains of modern humans have come up with inventions that challenge the defense strategies of herbivores: close-knit groups of animals, for example, actually increase the chances of a hatchet-throwing hit.In fact, many of the now extinct species found at the Ologsari site include horned giraffes, large baboons, elephants with downward-curving tusks, and a species of hippopotamus that was much larger than today's hippos to appear stronger.However, we don't know if humans drove them to extinction. This was, after all, the middle of the Pleistocene.During this period, glacial periods and interglacial periods alternated 17 times. The global temperature fluctuated up and down, and the land without ice was either deep or hot.The crust sometimes shrinks and sometimes relaxes under the changing weight of glaciers.The Great Rift Valley widened and volcanoes erupted, one of which periodically erupted and buried Orogoseri in ash.After two years of research into the Orogeseli Formation, Smithsonian Institution archaeologist Rick Poots discovered that some typical plants and animals survived climate and geological upheavals.

We humans are one of them.Lake Turkana is a rift valley lake on the Kenya-Ethiopia border.As Rick Pouts documented the remains of a large number of ancestors, he realized that whenever climatic and environmental conditions became capricious, the number of early modern humans increased, eventually replacing earlier hominids.Adaptability determines who is best suited to survive, and the extinction of one species is often accompanied by the evolution of another.In Africa, large animals, like us, have had the good fortune to evolve their own better-adapted species. This is fortunate for us, because to map out the world before us—a basis for our understanding of how the world will change after we are gone—Africa is our most complete, living gene pool, of which Entire families of certain species and animals taken elsewhere are also included.Some animals have indeed migrated from other regions: in the Serengeti National Park, when North Americans toured under the open sunroofs of tourist jeeps, dazzled by huge herds of zebras, what they saw was exactly Descendants of American zebras that migrated from Asia and the Greenland-European land bridge, but are now no longer seen on their own continent. (Columbus did not reintroduce Equus until 12,500 years after the mass extinction; before then, the horses that thrived on the American continent were probably striped.)

If animals in Africa evolved to avoid human predators, how could this balance be upset by the disappearance of humans?In a world without us, might some large animals be so well adapted to our presence that some underlying dependency or symbiosis disappears with us gone? The high, cold Aberdare Swamp in central Kenya was daunting to human settlers, though people must have traveled far to get here.Here are the sources of four rivers, which flow in four directions, along basalt cliffs and deep ravines, and provide irrigation to the African land below.Gula Falls winds its way through nearly a thousand feet of mountains, lost in mist and tree-like ferns.

In this land of megafauna, this is an alpine swamp of megaflora.Except for some dwarf rosewoods, the rest are above the tree line. Two 13,000-foot peaks form the eastern wall of the rift south of the equator, and vegetation covers the valley between the two peaks.There were no trees here, but huge heathers, growing sixty feet high, dropped curtains of moss.The groundweed of the lobelia grows in columns eighty feet high, and even the sessica (which is usually no more than a weed) reaches thirty feet high, tipped with cabbage shoots, which grow in dense in the grass. The descendants of early modern humans who climbed out of the rift eventually became the Kikuyu tribe of the Kenyan highlands.No wonder they think this is the residence of "Nai" (god).Except for the rustle of the wind blowing sedges and wagtails waving their tails, the place is as quiet as a sanctuary.The stream dotted with asters on both sides flows silently through the soft hill grass, and the abundant rain makes the stream seem to float.Africa's largest antelope, the seven-foot-tall, 1,500-pound eland, with spiraling horns a yard long, is dwindling by the day.They seek refuge in these frigid highlands.The marshes are too high for most animals, but waterbucks live here, as well as lions, who hide near water sources in fern forests, waiting for an opportunity to ambush waterbuck.

Elephants appear from time to time, and baby elephants follow behind.The mother elephant tramples through purple clover and crushes tall hypericum bushes in search of her 400 pounds of daily forage.Fifty miles east of Aberdare, across a flat valley, elephant herds scatter near the snowline on the 17,000-foot peak of Mount Kenya.African elephants are much more adaptable than their woolly mammoth relatives, and through their feces we find their tracks stretching from Mount Kenya or the frigid Aberdare down to the Samburo desert in Kenya up to two miles.Today, the hustle and bustle of human civilization has cut off the passage between the three places.Elephant herds living in Aberdare, Mount Kenya and the Samburo Desert have not seen each other for decades. Below the swamp, a thousand-foot bamboo forest encloses the Aberdare Hills, a sanctuary for the bongo, another endangered species whose stripes provide cover.Thick bamboo forests keep coyotes and pythons at bay, and the spiral-horned bongo's only natural predator is an animal unique to Aberdare: the rare black panther.The lush rainforest of Aberdare is also home to black servals and a black African golden cat. This is one of the most pristine areas left in Kenya, lush with camphor trees, cedars, variegated wood, vines and orchids, where a 12,000-pound elephant could easily hide.The most endangered African species, the black rhino, is also here. In 1970, there were 20,000 black rhinos in Kenya, but now there are only about 400 left, and the others are poached to death—the so-called medicinal effects make their horns sell for $25,000 each in eastern countries; in Yemen , Horns were made into dagger handles used in ceremonies.An estimated seventy in the Aberdare region is the number of black rhinos left in the wild. Humans are also hiding here.During colonial times, the water-rich slopes of the Aberdare Volcano belonged to English tea and coffee growers who raised cattle and sheep on their plantations.Farming Kikuyu were forced to become tenant farmers on small plots of land, working the occupied land. In 1953, under the cover of Aberdare Forest, they organized themselves.Kikuyu guerrilla groups lived on wild figs and brown-spotted salmon that the British farmed in the Aberdare River, terrorizing and attacking white landowners—the historic Mau Mau uprising.The Queen brought troops from England and bombed Aberdare and Mount Kenya.Thousands of Kenyans died.Only 100 Britons were killed, and by 1963 a truce was negotiated that led to the majority decision that would become Kenya's independence. Today, Aberdare is a national park - a non-binding agreement between humans and nature.It is a haven of refuge for the rare giant forest hog, the smallest antelope (the island antelope the size of a jackrabbit), golden-winged sunbird, silver-cheeked hornbill, red-crowned and blue turaguars.The black and white bearded monkey looks like a Buddhist monk, and it inhabits this virgin forest.The forest spread down and covered the entire slope of Abadry... …until people pull up a wire fence.Today, 200 kilometers of galvanized, 600-volt galvanized wires enclose Kenya's largest water storage area.The grid is buried three feet below ground and up to seven feet above ground, and electric heating columns keep baboons, vervet monkeys and ring-tailed civets out.An electrified arch would allow vehicles to pass through, but an elephant the size of a vehicle wouldn't be able to get through dangling wires. This is a fence that separates people from animals.The two sides of the fence have the most fertile soil in Africa, with tropical rainforest above and corn, soybeans, leeks, cabbage, tobacco and tea planted below.Over the years, both sides of the fence have been attacked by intruders.At night, elephants, rhinos and monkeys sneak in and uproot the crops.The Kikuyu are growing in numbers, creeping into the higher mountains and cutting down three-hundred-year-old cedars and conifers.By 2000, a third of Aberdare had been leveled.To keep the trees in place, to circulate enough water through the transpiration of the leaves into the Aberdare River, to keep the water flowing through a hungry city like Nairobi, to keep the hydroelectric turbines turning, and to keep the Rift Valley Lake from disappearing, we Something has to be done. Hence the world's longest live circuit barrier.But at that time, Aberdare National Park had other water problems.In the 1990s, Kenya surpassed Israel to become Europe's largest supplier of cut flowers, and even surpassed coffee as its main export income, so a new drainage ditch was built around the Aberdare National Park, and roses and Carnations are grown here.But even if the flower lover is no more, this fragrant wealth will continue to multiply. Like humans, flowers are two-thirds water.So, a typical flower exporter ships to Europe the amount of water a year equal to the water needs of a town of 20,000 people.In the dry season, flower factories with production indicators siphon into Lake Naivasha-this is located in the lower reaches of Aberdare, and the banks are covered with papyrus, which is the habitat of freshwater birds and hippos.In addition to lake water, they also sucked up an entire generation of fish eggs.It is the chemicals that are poured into the lake that keep the roses from wilting on the way to Paris. But Lake Naivasha doesn't look too pretty.The water hyacinth that consumes dissolved oxygen grows overwhelmingly in the nutrients of phosphate fertilizer and palladium nitrate leached from the greenhouse.Water hyacinth is a perennial herb in South America, introduced to Africa as a potted plant.As the water level of the lake dropped, the water hyacinth grew to the shore and took over the living space of the papyrus.The carrion of a hippopotamus reveals the secret of a beautiful flower: DDT12 and dieldrin (forty times more poisonous than DDT) - pesticides banned from markets in some countries made Kenya the largest rose in the world export country.The fairly stable man-made molecules contained in dieldrin will remain long after humans and even animals and roses are gone. No fence can contain animals in Aberdare, not even a 600-volt electrified fence.They either multiply, break down barriers, or die out as the gene pool declines until a single virus consumes the entire population.But if humans were the first to go extinct, then electrified fences would no longer work.Baboons and elephants feast on grains and vegetables on nearby Kikuyu arable land.Only coffee has a sliver of hope; wild animals are not much interested in caffeine, and the coffee species from Ethiopia are well adapted to the volcanic ash of central Kenya and are completely native. The wind can tear the polyethylene covering of the greenhouse, and the polymer molecules become very fragile under the irradiation of equatorial ultraviolet rays.Methyl bromide, the most commonly used fumigant in the UV and flower industry, is the biggest killer of the ozone layer.Chemically adapted roses and carnations will no longer survive, but water hyacinths will have the last laugh.The Aberdare Forest will flood the unprotected fences, reclaim the arable land, and spill over the old colonial remnant below, the Aberdare Country Club, whose lawns are currently manned by the warthogs that live there.From Mount Kenya to the Samburo desert, the only forest obstacle on the way is the ghost of the British Empire - the eucalyptus forest. Among the myriad creatures that have been freed to proliferate, the eucalyptus, ailanthus, and kudzu will be the ones that devour the land when we're gone.To propel their steam locomotives, the British often imported fast-growing eucalyptus from their Australian colonies to replace slow-growing tropical hardwood forests.Eucalyptus oil, the aromatic compound we use to make cough medicines and disinfect surfaces on furniture, is antiseptic in large part because of its toxicity, which can also be detrimental to other plants.Few insects live near the eucalyptus; since there is nothing to eat, few birds nest there. Eucalyptus need a lot of water, so they live close to water sources, such as along the narrow irrigation canals of cultivated land, where they form a tall shrubby hedge.Without humans, they had to move to barren places where the wind would scatter their seeds downhill.The end result will be that the elephants, the loggers of African nature, will carve a passage back to Mount Kenya, driving the last of Britain's ghosts from the land for good. africa after us In an Africa without humans, elephant herds roaming the equator, through the Samburo, and across the sahelian steppe13, may have discovered that the Sahara desert is retreating north, as the goats, the advance party that caused the desertification problem, have fallen. prey for lions.It is also possible that they will face the Sahara Desert head-on, because rising temperatures are a scourge left by humans, and rising carbon content in the atmosphere will accelerate the process of desertification.The reason why the Sahara Desert has recently expanded at an alarming rate (2-3 miles per year in some areas) can be attributed to the timing of the weather. The largest non-polar desert in the world today was a green savannah six thousand years ago.Crocodiles and hippos play in the Sahara rivers.Then the Earth's orbit undergoes a periodic adjustment.The Earth's axis is tilted half a degree from vertical, which reduces rain clouds on Earth.This is not enough to turn a meadow into a dune.Coincidentally, at this climatic stage, when humans developed, the dry scrubland was also destroyed.Over the past two millennia, Homo sapiens in North America have evolved from hunting with spears to growing Middle Eastern grains and raising livestock.They took their possessions and rode camels, the tame offspring of the American ungulates.Their brethren went extinct in the massacre of large animals in their homeland, but luckily they had relocated before then. Camels eat grass; grass needs water.The cultivation of crops brings human prosperity, but they also need water.More people need more livestock, pastures, fields and water - but all at a bad time.No one knew that the position of the rain cloud had changed.Thinking that the climate would return to what it was and everything would grow back, humans and their livestock went even further, leading to overgrazing. But in fact, the climate has not been restored.The more they consume, the less water is transpired into the sky, and the less rain falls.The result was the Sahara we see today.Only it was smaller then.Over the course of the twentieth century, the number of humans and livestock in Africa has increased year by year, as has the temperature.This puts the sub-Saharan Sahel countries at risk of desertification. Further south, Africans in the equatorial region have grazed for thousands of years and hunted even longer, but in fact there is a reciprocal relationship between humans and wild animals: when herders like the Maasai of Kenya While grazing in grasslands and pools, their spears keep lions at bay, and antelopes follow for protection from human predators.Zebras also followed the antelopes.Nomads no longer eat so much meat, but carefully bled and stanched the jugular veins of cattle, and learned to live on the milk and blood of their livestock.Only when drought strikes and livestock feed dwindles do they start hunting again, or exchanging game with bush-dwelling tribes. Then humans themselves became prey—or, rather, commodities—and the balance between humans, flora, and fauna shifted.Like our fellow chimpanzees, we often engage in bloody battles over territory and mates.But with the rise of slavery, we were reduced to something for export. Today, we can still see the traces of slavery in Africa in a bushy countryside in southeastern Kenya known as "Ci Buddha".It's an eerie place where lava flows, black locusts, myrrh trees and baobabs grow.Because the tsetse flies of Cefo are not suitable for humans to herd cattle and sheep, this place has become a hunting ground for the Vaata jungle people.Their prey include elephants, giraffes, buffaloes, various gazelles, kamala, and another striped antelope, the kudu, whose horns resemble corkscrews and are as long as six foot. The destination of East African black slaves was not America, but the Arabian Peninsula.In the mid-nineteenth century, Mombasa Island off the coast of Kenya was a shipping terminal for human trafficking and a transit point for the "commodities" captured by Arab slave traders from villages in Central Africa by gunfire.Groups of slaves walked barefoot down the mountain from the rift, escorted by slave traders riding on donkeys and carrying weapons.When they came to Ce Buddha, the temperature rose and tsetse flies swarmed.The surviving slavers, shooters and slaves headed towards a small oasis called "Zima Spring District".There are artesian springs where terrapins and hippos live; 50 million gallons of water a day rise from a volcanic belt thirty miles away to keep the pools clean.Slave convoys would stay here for days, buying supplies from Vaata's bow hunters.They escorted the slaves all the way and shot the elephants they encountered.As demand for ivory grew, its price surpassed that of slaves, whose main value shifted to ivory handling. In the vicinity of the Zima Spring area, the water once again exposed to the surface, forming the Cefo River leading to the sea.Lined in the shady shade of cinchona and palm trees, the road has an irresistible appeal, but the price it pays is often malaria.Jackals and coyotes trailed behind the procession, and the lions of the Buddha were also known to devour dying slaves who fell behind. Until the end of the nineteenth century when the British stopped the slave trade, thousands of people and elephants died on the "Ivory-Slave Road" connecting the Central Plains to the Mombasa auction market.After the road was closed, a railway was built between Mombasa Island and Lake Victoria (a source of the Nile), which was crucial to British colonial rule.The hungry lion would sometimes jump on a train and trap railroad workers, eventually becoming world famous for his cannibalism.Their appetites are the stuff of legends and movies, but it is rarely mentioned that the reason for their hunger is the scarcity of prey, which has been killed for thousands of years to feed the slave army. With the abolition of slavery and the completion of the railway construction, Cefo became a deserted and empty countryside.Without humans, wild animals slowly came back.But it didn't take long for people to come here again with weapons.Britain and Germany originally agreed to carve up most of Africa, but between 1914 and 1918, the two countries went to war in Africa for darker and dirtier reasons than the two countries fought in Europe.German colonial troops from Lake Tanganyika bombed the railway from Mombasa to Lake Victoria several times.The two sides fought in the palm and cinchona woods on the banks of the River Ceve, lived on the flesh of jungle animals, and killed as many soldiers from malaria as from the guns, but the bullets killed the wild animals. . As a result, the book Buddha became empty again.After humans left, Cefo once again became a habitat for animals.Sandpaper trees with yellow fruit cover World War I battlefields and are home to families of baboons. In 1948, the Queen declared that the Buddha has no use value for human beings, and this busiest trade route in human history was declared a protected area.Twenty years later, the number of elephants in the Cefo area reached 45,000, making it the largest elephant sanctuary in Africa.It won't be for long, though. As the white plane slowly takes off, the most incongruous landscape in the world is presented under the wings.The vast savannah below is Nairobi National Park, where eland, Thomson's gazelle, South African buffalo, hartebeest, ostrich, white-bellied bustard, giraffe and lion live huddled together, behind the thick walls of tall buildings .Behind this gray urbanized building lies the largest and poorest slum in the world.Nairobi has been around as long as the railway, which was originally built as a supply station between the island of Mombasa and Victoria.It's one of the youngest cities in the world, and it's likely to be the first to disappear, because even new buildings here quickly crack.Nairobi National Park is at the other end of the city without fences.The plane crossed the park's unmarked boundaries, across gray plains dotted with morning glory trees.As long as they pass through here, antelopes, zebras and rhinos can migrate with rain along a channel.These days cornfields, flower farms, eucalyptus plantations and tall homes with fences and private wells have narrowed the passage.All of this could turn Kenya's oldest national park into a wildlife island.The passage is unprotected; homes on the outskirts of Nairobi National Park have become so hot that, in the opinion of pilot David Weston, the smartest option is for the government to foot the bill for residents to agree to keep animals on their property walk through.He also participated in the negotiations, but without hope.Everyone is terrified that elephants will trample their gardens, or worse. Counting elephants is David Weston's task today - a job he has been doing for nearly three decades.He grew up in Tanzania, the son of a well-known British hunter, and as a child would often hike for days with his gun-toting father without seeing anyone else.He'd shot an animal in his life; the look of a dying warthog drowned out all passion for the hunt.His father died under the ivory, and the mother moved with her children to the relative safety of London.David studied zoology at university and returned to Africa. An hour's flight southeast of Nairobi, Mount Kilimanjaro looms, its melting snowcap like cream dripping from a scorching sun.In front of the mountain, verdant swamps suddenly appear in an alkaline basin, fed by springs flowing down the slopes of the volcano.Here is Amboseli, one of Africa's smallest and most species-rich parks, a must-see for those looking to photograph elephant herds silhouetted in front of Mount Kilimanjaro.Previously, this was only seen during the dry season, when wild animals flock to Amboseli's swampy oasis to feed on cattails and sedges.But now, they stay here all year round. “Elephants are not supposed to be sedentary animals,” Westen murmured as he passed dozens of them.Not far away is a pool of hippos covered in mud. From above, the plains that surround the park look as though they have a megasporial infection.This is actually an ethnic cultural village in Kenya: these ring-shaped huts piled up with mud and excrement belonged to the herdsmen of Maasai, some are still in use, and some have been abandoned and returned to the soil.The grassy patch of land in the center of each yard is where the nomadic Maasai keep their livestock at night to avoid predators before they move to the next pasture with their families. As the Maasai left, the elephant herds came.After the drought in the Sahara, humans first brought livestock down from the North African plateau and developed a dance to represent elephants and livestock.After the cattle and sheep gnawed out the savannah, the bushes invaded here.It didn't take long for them to grow quite large and become a delicacy for elephants - they ate the bark from the trees with their tusks, knocked down the trees to eat the tender leaves, and after razing this, the new growth will It is a meadow. David Weston was a graduate student at the time. He was sitting on the top of a hill in Amboseli, counting the cattle brought to graze by the Maasai herdsmen. At this time, the elephant herd was plodding from the other direction. eat grass.Although he went on to serve as director of Amboseli National Park, head of the Kenya Wildlife Service and founder of the non-profit African Animal Conservation Centre, his work on counting cattle, elephants and people has never been interrupted.The work of African Animal Conservation Centers is to protect wildlife and flora and fauna by integrating humans into them, rather than isolating them from them; we humans once lived in them. After descending 300 feet, he began a clockwise circle, making a 30-degree banked turn.He notes a ring of dung and plaster huts—one for each wife: some wealthy Maasai can have as many as ten.He calculated the approximate resident population, marking 77 cattle on his vegetation map.From an airplane, the Maasai herdsmen look like a drop of blood on the green plains: tall, natural, dark-skinned, they wear traditional red plaid shawls – speaking of traditions, which go back at least to the nineteenth century , where Scottish missionaries at the time distributed tartan blankets, Maasai herders found the material to be very warm and lightweight to carry on the road during the weeks they were grazing. "Nomads," Westen said over the voice of an airplane engine, "have become synonymous with migratory species. Their behavior and habits are very similar to antelope." Grassy prairie, bring them back to the pool after the rainy season stops.On average, the Maasai of Abboseli change residences eight times a year.Westen is convinced that such human actions theoretically benefit wildlife in Kenya and Tanzania. "They grazed the cattle and left the woodlands for the elephants. And in time the elephants cleared the grasslands. You can always have a combination of grasslands, forests, and shrublands. That's the whole secret to the diversity of the savannah. If you only have A forest or a grassland may only support species that are suitable for the forest or organisms that are suitable for the grassland." In 1999, Weston drove across southern Arizona to examine sites where the Clovis people wiped out the local mammoth 13,000 years ago.En route, he described the phenomenon to Paul Martin, a paleoecologist and founder of the Pleistocene "overshooting" theory.Since that time, the American Southwest has been free of large herbivores.Humans have always burned pea bushes."Do you think elephants can live here?" Martin asked, pointing to the haphazard peas growing on the land leased by the farmer. Then David Westen laughed.But Martin went on: "How do African elephants survive in this desert? Can they climb the rugged granite mountains in search of water? Asian elephants are more closely related to mammoths. Would they be better off?" Some?" "It's certainly better now than bulldozers and herbicides to clear pea bushes," Wisten agrees: "It's much cheaper and easier to have elephant herds do it, and their droppings are as good as they get." It is conducive to the growth of grass seeds." "That's right," Martin said. "That's what mammoths and mastodons do." “是啊，”威斯腾回答说：“如果原先的物种消失了，为什么不用后继的物种来取代呢？”从那时起，保罗·马丁就一直在劝说人们让象群回归北美洲。 然而与马阿塞人不同的是，美国的农场主并非游牧民族，它们不会定期腾出地方给象群栖息。不过马阿塞人和它们的牲畜也变得越来越倾向于定居。安博塞利国家公园外围一圈圈过度放牧造成的贫瘠土地证实了这个结果。大卫·威斯腾浅色头发、皮肤白皙，当他用斯瓦希里语与七英尺高、皮肤黝黑的马阿塞人交谈的时候，人种间的差异在长期起来形成的互敬互重中消解。土地的划分是他们一直以来的共同敌人。随着开发商和竞争关系的部落移民竖起围栏和标界的时候，马阿塞人没有任何选择了，他们只能寻找一块自己的地盘，定居下来。威斯腾说，人类消失之后，人类重塑非洲的格局不会那么容易就被抹去。 “这是个极端化的情况。如果你把象群赶入公园内，你在园外放牧，那么就会产生两种截然不同的环境。里面，所有的树木都会消失，草地会长出来；外面呢，会变成浓密的灌木丛。” 二十世纪七八十年代，象群学会了如何呆在安全的地方。不知不觉中，它们竟步入一场全球范围内的贫富碰撞中：一方是越发贫穷的非洲，肯尼亚的出生率达到全球第一；另一方是亚洲经济的腾飞，刺激了对远东奢侈品的无限渴求。这其中也包括象牙，人们对它的强烈贪欲甚至超过了几世纪以来对奴隶的渴求。 随着原先20美元/千克的价格增长了10倍，象牙偷猎者涌入册佛这样的地方，于是满山遍野都是拔走了象牙的大象尸体。到了二十世纪八十年代，非洲130万头大象已有超过半数死亡。肯尼亚境内现在还有19000头，它们栖息在安博塞利国家公园等保护区内。国际象牙禁令和“格杀勿论”的命令让偷猎者有所收敛，但对动物的屠杀从未根除，尤其是保护区外借着保护庄稼和人的幌子残杀大象的行为。 如今，安博塞利沼泽地边上的金鸡纳刺槐消失不见了，河马和犀牛之类的厚皮动物把它们吞食一空。随着公园慢慢变成没有树木的平原，瞪羚和长角羚羊这样的沙漠生物取代了长颈鹿、捻角羚和薮羚等食草动物。这种极度的干旱是人类一手造成的，冰川时期的非洲也是这样——居住地缩小了，生物纷纷躲进绿洲中避难。非洲的大型动物逃过了那场劫难，但大卫·威斯腾害怕它们这次难逃一劫——它们被困在孤岛般的保护区中，在庞大的人类居住区、划成小块的土地、枯竭的草原、工厂和农场上艰难求生。几千年来，迁移的人们与它们如影随形：游牧民族和他们的牲畜取其所需，继续前行，新长出来的植物比从前更为茂盛。但是现在，人类的迁移要永远结束了。定居人轻轻跃过了这个环节。现在，食物自己朝人类跑来，与此相同的还有人类历史上从未出现过的奢侈品和其它消费品。 除了无人居住的南极洲，只有非洲未曾遭受大范围的野生动物灭绝。“但是不断发展的农业和人口数量，”威斯腾对此表示担忧，说道：“意味着我们或许将看到这种灭绝的场面。”在非洲，人类与野生动物之间形成的平衡已经遭到破坏，我们无法再进行控制：太多的人口，太多的牲畜，太多的大象被太多的偷猎者赶入到太狭小的空间中。大卫·威斯腾得知非洲还有一些地区仍保持着从前的模样，在人类统治它们之前，大象完全能在这些地区繁衍生息。这是大卫唯一的精神安慰了。 他认为，在没有人类的世界中，非洲这个最古老的人类发源地，也许将回归最纯洁的原始状态。因为如此之多的野生动物靠草为生，因此非洲是外来植物未能逃出远郊公园而在野外泛滥的唯一大陆。不过，没有了人类的非洲会经历一些重大的变化。 从前，北非的牛群是野生的。“但是和人类生活了几千年之后，”威斯腾说：“它们的胃进化得像个巨大的发酵池，白天要吃下不计其数的草料，因为它们没法在夜间进食。所以现在，它们并不敏捷。如果放任不管，它们便会遭到攻击，沦为上等的牛肉。” 它们数量众多。现在，牛群占据了非洲热带草原生态系统的大半壁江山。没有马阿塞人的长矛来保护它们，它们便会成为狮子和土狼的饕餮大餐。它们消失后，草原的数量至少会翻两番。威斯腾用手遮住阳光，倚在吉普车上，考虑着新的数量意味着什么。“150万头羚羊吃草的速度和牛群相当。你会看到，羚羊和大象之间的遭遇会越来越频繁。马阿塞人说，'牛群植树，象群种草。'它们会扮演起这样的角色。” 至于没有人类的象群会怎样，“达尔文估计非洲有1000万头大象。事实上，这个数字与人类展开象牙贸易之前的大象数量十分接近。”他转而注视着安博塞利沼泽地中玩水的母象说：“现在，我们只剩下50万头了。” 人类消失后，大象的数量将增加二十倍，无可争议地成为植被种类丰富的非洲大地上的主要物种。与此形成对比的是，在南美和北美，13000年以来，只有昆虫才会啃食树皮和灌木。猛犸灭绝之后，若不是农场主的铲地，牧场主的焚烧，农民砍树作燃料，或开发商的威胁，这里本该能长成一片巨大的森林。没有了人类，美洲的森林将成长壮大，等待着大型食草动物来享用它们的营养。 3.危险的碑文 帕托亚斯·欧莱·桑提安随着父亲养的牛群在安博塞利西面漫游，他在成长的过程中经常听到这个故事。卡西·库奈是个头发灰白的老人，他和三个妻子住在马阿塞玛拉的民族文化村，桑提安现在在那里工作。库奈又把这个故事讲了一遍，也桑提安则怀着崇敬之心侧耳聆听。 “刚开始的时候，神灵赐予我们狩猎者。但后来动物迁居到了遥远的地方，没法再狩猎了。于是马阿塞人向神灵祈祷一种不会迁居的动物，神灵说要等七天。” 库奈拿出一条兽皮绑带，一端朝向天空，摆出从上而下的天梯的模样。“牛群从天而降，每个人都在说'快看呐！我们的神灵实在仁慈，他赐予我们如此美丽的动物。它有奶水、漂亮的牛角和斑斓的色彩。不像羚羊和水牛，浑身上下只有一种颜色。'” 就在这时，故事发生了转折，变得不令人愉快起来。马阿塞人宣布所有的牛群都属于他们，将丛林的狩猎者驱逐出了住所。当他们向神灵祈求他们自己的牛群时，神灵拒绝了，不过赐给他们弓和箭，“这就是为什么他们现在依然在森林中狩猎，而不像我们马阿塞牧人的原因了。” 库奈笑了，露出牙齿，他细长的眼睛在午后的烈日下微微发红。锥形的青铜耳坠在阳光下闪闪发光，使他的耳垂微微下坠。他解释说，马阿塞人发现了如何焚烧树木，来为他们的牲畜开辟出草原，同时也能消灭带有疟疾病菌的蚊子。桑提安沉浸在自己的思绪中：如果人类只是猎杀动物和采集果实，与其它动物就没有太大的区别。我们被神灵选中成为牧人，对动物享有神圣的支配权，神的恩赐也与日俱增。 但是桑提安也知道，问题在于马阿塞人并未维持现状。 即便是白人殖民者夺取了那么多的牧地，游牧的生活也照样能继续。但马阿塞的男人至少娶三个妻子，每个妻子生五六个孩子，她大致需要100头牛才能维持生计。这个数字还在增长。桑提安年轻时，他目睹了圆圆的文化村住宅变成了锁孔形，因为马阿塞人添加了小麦和玉米的种植区，开始定居下来照顾作物。一旦他们成为农业民族，一切都将改变。 帕托亚斯·欧莱·桑提安是马阿塞人实现现代生活方式后的一代人，他有机会进行学习，精通科学，懂得法语和英语，是个博物学者。26岁时，他获得了肯尼亚野生动物园专业导游协会的银质证书，这是最高级别的证书，获此证书的非洲人不过十来个而已。坦桑尼亚塞伦盖提平原在肯尼亚的延伸叫做马阿塞玛拉公园，公园里不仅有动物专门的保护区，也有动植物混合保护区，马阿塞人、他们的牲畜和野生动物可以像以前一样在这里一起生活。桑提安在这儿找到了工作，居住下来。长满红色野燕麦的马阿塞玛拉平原上点缀着沙漠枣椰子树和平顶刺槐，和非洲其它热带草原一样繁茂。不过，这里最多的食草动物是家畜牛。 桑提安经常把皮靴系在他长长的腿上，爬上玛拉地区最高的山峰——基尔列奥尼山。这里依然保持着原始风味，猎豹把黑斑羚的尸体悬挂在树枝上，以备饿时享用。从山顶俯视，桑提安能望见六十英里以南的坦桑尼亚，还有塞伦盖提辽阔的绿色海洋。六月，低鸣的羚羊群绕着圈子奔跑，不久之后，它们便集合起来进行大迁徙，如洪水一般向北涌过边境。它们得趟水过河，而蠢蠢欲动的鳄鱼则在水里安心等待着它们的年度大餐，狮子和在金合欢树中打盹的猎豹只要翻个身就能大开杀界。 塞伦盖提草原长期以来一直都是马阿塞人的伤疤处：1951年，方圆50万平方公里被夷为平地，因为这里要兴建一个智人主题公园，来迎合看着好莱坞电影长大的游客们认为非洲是原始荒野的谬见。但是现在，桑提安这样的马阿塞博物学者却为此感到欣慰：塞伦盖提拥有肥沃的火山灰，利于草原的生长，是世界上最大的哺乳动物基因库。如果道路顺畅，这里的物种有朝一日可能会散布到世界其它区域。尽管塞伦盖提草原广袤无垠，但博物学者还是担忧，如果它成为围栏圈住的农场，会不会无法养育数量惊人的瞪羚，更不用说大象了。 这里没有足够的降雨将热带草原变成可以耕作的农田。可这并没能停止马阿塞人的繁衍。帕托亚斯·欧莱·桑提安目前只娶了一名妻子，他不想再娶了。他刚结束传统的武士训练就娶了努克夸，她是他孩童时代的女友。她或许将成为这段婚姻关系中的唯一妻子，而没有其他女伴的陪伴——对此她感到惊愕。 “我是个博物学者，”他向她解释说：“如果所有的野生环境都消失，我就不得不开始种田。”马阿塞人认为农耕比起放牧牛群来并不那么高贵，因为他们是被神灵选出进行放牧生活的人。他们甚至不愿意为埋藏尸体而破开草皮。 努克夸能理解这点。但她毕竟还是个马阿塞的女人。最后他俩妥协，娶两个妻子。但她还是想要六个孩子。他希望只要四个，因为第二个妻子肯定也要生孩子的。 库奈自言自语地说，只有一件让人想都不敢想的事或许会在动物灭绝之前减缓人类繁衍的速度。他称之为“世界末日”。“只要时机到来，艾滋病将消灭人类。动物会重新夺回大地的统治权。” 艾滋病对于定居的部落而言是个噩梦，马阿塞人暂时还未面临这个问题，但桑提安认为不久之后噩梦便会开始。从前，马阿塞人带着牲畜、握着长矛步行穿过热带草原。现在，有些族人到了镇上，和娼妓发生关系，回来时便开始传播艾滋病。更糟糕的是卡车司机，他们一周出现两次，为马阿塞人购买的敞蓬小货车、小轮摩托车和拖拉机运输汽油。甚至是年轻的女孩也受到了感染。 马阿塞人的地盘以外，比如在海拔较高的维多利亚湖，塞伦盖提的动物每年都迁徙，咖啡种植者因患上艾滋病再没力气精心照料它们，于是改种易于照料的作物，比如香蕉，或者就砍树制造木炭。咖啡树现在成了野生植物，高达15英尺。桑提安听人们说，因为艾滋病无药可治，他们现在再也不去管它，还是照样生孩子。所以孤儿们携带着病毒，住在没有成人的村庄里。 没有人居住的住宅倒塌下来。泥巴为身、粪便为顶的棚屋正在融化，剩下的只是砖块和混凝土浇铸了一半的房屋——商人用开货车做运输生意挣来的钱建造这样的房屋。之后他们就染了病，把钱财给了草药医生和他们的女人。没有人恢复健康，因此半拉子工程也再也没能接着做下去。草药医生拿了所有的钱财，然后也患了这病。最终，商人、他们的女人和医生都相继死去，钱财灰飞烟灭，剩下的只是没有屋顶的房屋，刺槐从中生长出来，受到感染的孩子为了活命而卖身，最终也难逃夭折的命运。 “艾滋病正在杀死整整一代的未来领导者，”桑提安在那个下午这样回答库奈，但是老人觉得，如果动物将成为大地的主人，有没有未来领导者都无关紧要了。 太阳沿着塞伦盖提草原东升西落，将天空染得一片绚烂。太阳落下地平线之后，深蓝的暮色笼罩在这片热带草原上。这天的余温还在基尔列奥尼山的这头飘摇，渐渐湮没于黄昏之中。随之而来的寒冷气流夹杂着狒狒的锐声尖叫。桑提安把他红黄相间的大方格披肩裹得更紧了。 难道艾滋病是动物最后的复仇吗？如果真是这样，黑猩猩——我们中非洞穴中的同胞，便是人类毁灭的共犯。能感染大多数人的人类免疫缺陷病毒与黑猩猩携带的猿免疫缺损病毒息息相关，但它不会使黑猩猩得病。（不太常见的HIV-II病毒与坦桑尼亚极为罕见的白眉猴身上携带的一种病毒极为相似。）人类或许是因为食用丛林动物而得到传染。我们与最近的灵长类亲戚只有百分之四的基因有所不同，传播到我们身上之后，这种病毒发生了变异，能够致人于死地。 难道说迁居草原使我们在生理上变得脆弱了吗？桑提安能识别出这个生态系统中所有的哺乳动物、鸟类、爬虫、树木、蜘蛛、大多数的花、肉眼能看见的昆虫和药用植物，但他没法知道遗传学上的细微差异——所有人都在寻求艾滋病的疫苗。答案或许在我们的大脑中，因为脑容量是人类与黑猩猩、倭黑猩猩最大的区别所在。 突然，从下面飘来另一声狒狒的尖叫。它们可能是在骚扰把黑斑羚尸体挂在树上的猎豹。有趣的是，雄性狒狒懂得如何在合力驱逐猎豹之前就中止争夺首把交椅的争斗。狒狒的大脑是智人之后的所有灵长类动物中最大的，也是除人类以外唯一能够在森林面积缩小之后适应草原生活的灵长类动物。 如果热带草原上数量最多的有蹄类动物——牛消失的话，羚羊便会取而代之。如果人类消失了，狒狒会取代我们的位置吗？难道说因为我们抢先一步离开了树林，使它们大脑机能的发展在全新世时期受到了压抑？如果我们不再挡着它们发展的道路，它们的智力潜能会不会突然释放，于是突飞猛进地进化，最终占据这个空旷世界的每一条缝隙呢？ 桑提安站起来，伸展了一下腰肢。一轮新月从赤道的地平线上缓缓升起，两端弯弯翘起，等着银色的金星在其中停留。南十字星座、银河和麦哲伦星云呈现在夜空中。空气中弥漫着紫罗兰的气息。桑提安听见上方传来林鸮的叫声，这和他童年时听到的声音一模一样，直到后来围绕文化村住宅的森林被改造为小麦的种植地后，这个声音才渐渐消失。假如人类的作物能回复成林地和草地，假如狒狒取代了我们的位置，它们会甘心生活在纯粹的自然美景中吗？ 或者，因为力量的不断膨胀，它们会不会产生好奇心和自我陶醉，最终也将它们自身和这个星球置于毁灭的边缘呢？