Friday, August 16, 2019

Wild Free and Happy Sample 21


[Note: This is the twenty-first sample from my rough draft of a far from finished new book, Wild, Free, & Happy.  I don’t plan on reviewing more books for a while.  My blog is home to reviews of 201 books, and you are very welcome to explore them.  The Search field on the right side will find words in the full contents of all rants and reviews, if you are interested in specific authors, titles, or subjects.] 

Perfection of Hunting

Human pioneers continued their colonization of new regions.  Along the way, they kept learning new hunting strategies, and inventing more and better tools.  They became masters at killing big critters, and bringing home lots of meat.  But the more skillful they got, the greater the risk of unintentional overhunting.  Not only did many large herbivores gradually go extinct, but so did many of the carnivore predators that specialized in hunting them. 

For example, several large cat species had long upper canine teeth or fangs.  These cats were specialized for killing huge herbivores with very thick hides — including elephant-like species.  Big, strong, saber-tooth and scimitar-tooth cats evolved in Africa several million years ago, and eventually expanded across Eurasia and the Americas — and so did elephant-like species.  As hominin hunters gained skill, elephant-like species declined, as did the cats that killed them.  Baz Edmeades suspected that as the number of jumbo critters with thick hides declined, the cats’ long fangs may have become a handicap for hunting other types of prey. 

Evolution provided large herbivores with different self-defense strategies.  One was jumbo size and thick hides.  Another was the ability to flee at high speed.  As evolution gradually made the prey a bit faster, it also sped up the carnivores a bit, too.  Ecosystem health required that the two teams stay relative balance.  If carnivores got too fast, they would deplete their prey and starve.  If herbivores got too good at escape, they would overgraze the land and starve.  In some regions today, speedy lions, leopards, and cheetahs have managed to survive, along with a variety of fast moving herbivores.

When the sacred dance of eater and eaten drifted out of balance, trouble ensued.  Aldo Leopold wrote a famous parable that delivered a powerful ecological lesson.  The sun feeds the grass, the grass feeds the deer, the deer feeds the wolf, the wolf feeds the soil, and the soil feeds the grass.  In the family of life, we all feed each other.  The U.S. government’s predator eradication program has nearly driven wolves to extinction, much to the delight of livestock ranchers.  Leopold explained that when wolves are scarce, deer numbers soar, vegetation gets stripped off the mountain, the soil washes away, and rivers carry the future off to the sea.  The deer lived in fear of wolves, and the mountain lived in fear of deer.

Over the course of four million years, hominin hunters slowly gained some advantages via genetic evolution.  But it was cultural evolution that enabled them to begin a long journey down a powerful and dangerous path.  More and better tools and strategies amplified their ability to hunt and eat a wider variety of animals.  Their growing toolbox included gizmos specialized for killing animals of every size and shape — megafauna, small game, birds, fish, and so on.  

Saber-tooth cats were doomed by hyper specialization.  Human survival is not highly dependent on a narrow variety of food sources.  We are omnivores.  We can digest deer, rodents, eels, shellfish, locusts, worms, maggots, grass seeds, nuts, berries, roots, and so on.  Dietary flexibility, tool making, and cooking technology are important reasons why humans haven’t joined the saber-tooth cats in megafauna Valhalla.

Of course, in the good old days, the preferred prey was megafauna.  For the time and energy invested, they provided generous servings of high quality nutrients — far more than bunnies or maggots.  Of course, large game was not an infinite resource for skilled hunters.  Populations of some megafauna gradually declined, and eventually went extinct.  Plan B for human survival was to adapt to changing conditions, not be a fussy eater, and dine on whatever delicacies were handy.

In the good old days, there were no hunting licenses, regulations, or game wardens.  Hunters were free to do things that are restricted today.  In different regions, herds were sometimes driven into traps, where the killing was indiscriminate, and excess meat was left behind to be recycled by wolves, ravens, microbes, and other scavengers.  Nothing was wasted, but more animals were killed than the hunters needed.  This could weaken the herd.

In Europe, several sites indicate that hunters had focused on nursery herds, consisting of mothers and their offspring.  It was much less dangerous to kill a young mammoth than to attack its huge and powerful daddy, who could easily splatter you into a puddle of bloody mush. 

Edmeades noted that scimitar-tooth cats also preferred to dine on youngsters.  In the Friesenhahn Cave in Bexar County, Texas, excavations revealed the remains of 33 cats, and 300 to 400 young mammoths, mostly two year olds.  He added that the human youngsters in ice age Europe were similarly vulnerable.  Their homeland did not sound like traffic and sirens, it sounded like moaning lions and whooping hyenas.  Wandering away from the camp at night was dangerous and dumb.  Babies instinctively cry when left alone too long.  Even our chimp and baboon cousins have been known to snatch and devour helpless infants.

Evolution continuously learns new tricks via ongoing trial and error.  This is why every species produces surplus offspring, because they are insurance policies.  If each mating pair only had two offspring, they would be in the fast lane to extinction.  Bunnies produce many surplus offspring, and megafauna produce some extras.  This worked brilliantly for millions of years — until tropical primates acquired deadly superpowers via cultural evolution.  These dangerously clever critters developed new and unusual abilities far faster than the genes of other critters could evolve new adaptations to counteract them.  Oh-oh!

Fernando Fernandez noted that, on every continent that humans colonized, the process of driving species extinct often took at least several thousand years.  Abundant populations of megafauna could tolerate centuries of folks who sometimes hunted a bit too hard.  Over the passage of many generations, it would have been normal for the hunters to remain unaware of the gradual long-term decline in game — until the arrival of hunger times, when they slammed hard into the stone wall of resource limits.

In the good old days of abundant megafauna and simple weaponry, some bands of hunters reportedly had no sense of limits at all.  Dan Flores wrote that the Cree tribe believed that buffalo numbers were essentially infinite, and that the animals they killed in no way diminished their abundance.  Shepard Krech wrote that the Powhatan tribe hunted throughout the year, and killed animals regardless of their age, sex, or breeding state.  The Cherokee believed that every deer they killed was reanimated, each would be replaced.  Eventually, unpleasant experiences of scarcity revealed the existence of limits, which inspired a shift toward a more conservation-oriented approach.

Farley Mowat told stories about the Ihalmiut people who lived in the region around Hudson Bay in northern Canada.  When traders moved in, the natives learned that they could trade fox furs for cool stuff like guns and ammunition.  These made it far easier to kill deer, so their traditional mode of low tech hunting was abandoned.  Prior to firearms, it had never occurred to anyone that it was possible to kill too many deer.  Until then, the availability of deer was as reliable as the dance of the sun and moon.

Two factors were in play here.  (1) When each generation of hunters experienced adequate game, the sense of abundance could mask their gradual decline for centuries.  (2) Times of abundance could also absorb some growth among the hunting clans.  Dan Flores noted that the average size of coyote litters is 5.7 pups, but when food is abundant, or their numbers are dwindling, they have larger litters.  As I write today, the thundering herd of 7.7 billion humans demonstrates that, like coyotes, our numbers also grow when food resources increase.

Ronald Wallace noted that in times of abundance, intensification of hunting was normal.  When caribou herds were migrating, folks killed as many as they could, because winters were long, dark, and cold.  They could enjoy a stable (but temporary) way of life, for as long as intensification didn’t eliminate abundance.  Of course, the shadow of intensification was population growth, which had a tendency to hasten the end of easy living.  Scarcity inspired the nerds to innovate new hunting gizmos, like the leister, fish hook, net, snare, and bow and arrow.  Over time, as megafauna became scarcer, the menu expanded.  Red deer, elk, roe deer, wild pig, fish, shellfish, and waterfowl were eaten at the Maglemose site in Denmark 10,000 years ago.

Another star in this snow country soap opera was climate change.  When warmer eras moved in, ice sheets melted and retreated.  Ice was replaced by tundra, then steppe, then forest.  Much of Europe was covered with dense forest by 9,500 years ago.  Megafauna that live in herds thrive on steppe grasslands.  Forests were home to lower numbers of more solitary large game — elk, aurochs, deer, wild pigs.  Expanding forests encouraged some folks to migrate to coastlines, lake shores, wetlands, rivers, and streams.  Locations with abundant marine food resources sometimes developed into sedentary communities — like coastal tribes in the U.S. Pacific Northwest.

Some cultures understood the notion of limits, and the risks of living too hard.  Some made efforts to live more conservatively, with greater emphasis on foresight and self-restraint.  Some developed traditions and taboos intended to reduce the risks of overhunting and overbreeding. 

Other cultures became less cautious, and pursued riskier paths.  Today, it’s clear that the risk-takers have overwhelmed the cautious, careful, and conservative.  Cultures that mindfully limit their numbers often become road kill for cultures that don’t.  Sadly, the world outside your window is a monster child of the risk fiends, for whom Growth is the god word — growth by any means necessary.

Anyway, Ronald Wright wrote that maybe 12,000 years ago, hunters in some regions had become too clever, too successful, and too numerous.  It was becoming apparent that their traditional lifestyle was approaching its expiration date.  Cave painters put down their brushes and became rabbit hunters.  Wild megafauna was not an infinite resource. 

Wright called this transition “the perfection of hunting,” and he declared it to be humankind’s first progress trap.  Progress traps are the unintended consequences of brilliant innovations that permit clever folks to survive by shifting to a new and improved way of life.  Unfortunately, they also tend to burn the bridges behind them as they advance.   Returning to the good old days is no longer possible. 

For example, our transition to fossil energy has fueled explosive population growth, which makes a quick and easy return to a muscle-powered way of life impossible.  It’s like we’re helpless passengers on the Titanic.  Despite our legendary big brains, our capacity for foresight is often abominable.  Over and over we fail to anticipate what the unintended consequences of our ingenious inventions might be — agriculture, automobiles, nuclear weapons, etc.  The list is endless.

Wright concluded that the perfection of hunting put the forks to an ancient tradition, forcing humans to explore dangerous paths, like herding and farming.  Hunter-gatherer cultures mostly blinked out over time.  A few have managed to survive into modern times.  He expected that the fossil record left behind by the Anthropocene will resemble the effects of an asteroid strike.

Mark Nathan Cohen lamented the shift to plant and animal domestication.  Hominins had been hunters for four million years.  He wrote that hunting “has been the most successful and persistent adaptation man has ever achieved.”  Around 10,000 years ago, almost everyone lived on wild foods.  By 2,000 years ago, most of humankind depended on food produced on farms. 

The early days of hunting megafauna was a luxurious life.  Gradually increasing population pressure was what drove the downward spiral to surviving on domesticated crops.  These foods were less nutritious and far more labor intensive to produce.  The engines of this decline were cultural evolution and technological innovation.  These forces were highly contagious, and spread around the world. 

Wright noted that in 1492, the culture of the Old World washed up on the shores of the New World.  The two cultures had been separated for 15,000 years or more.  The similarities between the two are striking.  Both had roads, cities, palaces, schools, kings, priests, temples, armies, peasants, merchants, sports, theater, art, books, music, and so on.

Diana Muir wrote a fascinating sketch about the early human experience in New England.  After the glaciers retreated, the land became home to animals including horses, musk oxen, wolves, saber-tooth cats, bison, giant bears, giant beavers, and four species of mammoths.  By 10,000 years ago, a number of the megafauna species had gone extinct.  The menu then featured deer, bear, beaver, moose, waterfowl, turkeys, heath hens, salmon, shad, alewives, shellfish, berries, acorns, and so on.  This was a land of abundance, and the human population grew and grew.

Oysters and clams had once been famine food.  By 2,000 years ago, they became a dietary staple.  Digging them up was tedious backbreaking work, and a grown man needed to eat 100 every day.  Many thousands more were smoked and dried for winter dining.  Empty shells were dumped in huge piles.  At the lowest, oldest layers, the oyster shells were 10 to 20 inches wide (25 to 50 cm), indicating 40 year old animals.  In newer layers, the shells were much smaller.

By 800 years ago, agriculture was producing half of their food.  Staples included corn, beans, and squash.  Their slash and burn farming required tedious backbreaking work.  It also depleted the fertility of the thin, rocky soils.  The good old days had passed.

Thursday, August 1, 2019

Wild Free and Happy Sample 20


[Note: This is the twentieth sample from my rough draft of a far from finished new book, Wild, Free, & Happy.  I don’t plan on reviewing more books for a while.  My blog is home to reviews of 201 books, and you are very welcome to explore them.  The Search field on the right side will find words in the full contents of all rants and reviews, if you are interested in specific authors, titles, or subjects.] 

Imperceptible Overkill

It’s easy to become perplexed when contemplating the megafauna extinctions.  Paul Martin described the process in North America as a blitzkrieg, an ecological catastrophe that was largely accomplished in a mere thousand years or so — far faster than the earlier extinction spasms in the Old World.

Obviously, the North American spasm was only lightning fast in an evolutionary timeframe.  From the perspective of living humans, a thousand years is quite a while.  I expect that some of my readers are younger than 200.  A much earlier spasm in Africa took place over hundreds of thousands of years.  These hominin ancestors were apparently still cadets in their ability to hunt slightly too hard.

All animals pay careful attention to the here and now, in the immediate vicinity.  Few, if any, think about tomorrow or next year.  Wild ecosystems, and the weather, exist in a state of constant change.  It’s impossible to predict what living conditions will be like a year from now, or in two months.  What game will be plentiful?  What will be scarce? 

Small isolated bands of people were living in a vast wilderness, unaware of current conditions in every surrounding hill and valley.  There was no way they could accurately monitor the populations of game animals.  When hunting was bad, they couldn’t know why.  Was the herd declining, or had they wandered elsewhere to visit relatives?  An ecosystem is not an enclosed laboratory where everything can be precisely measured and controlled.  Hunting is a game of chance.

Anthropologists have reported that some hunter-gatherer cultures, who survived into recent times, understood the risks of overhunting.  They developed rituals and taboos for avoiding it.  Richard Nelson wrote that when deer numbers declined, the Koyukon people stopped hunting them for several years, and ate other critters instead.  Also, when game was abundant, they would stop hunting in a portion of their domain, creating a refuge where game could get a break from hunting, and recharge their numbers.  Sometimes mindful efforts at conservation worked well.  Sometimes folks starved.  Humans were not in full control.

Two important factors in megafauna extinctions were shifting baseline syndrome, and the low reproductive rates of large game animals.  Shifting baseline syndrome describes the fact that our conception of “normal” is continuously changing.  Kids in school today can’t imagine a world without smart phones, video games, and access to unlimited sources of entertainment.  When I was born in 1952, there were five billion fewer humans on Earth.  In my childhood, the only glowing screen was a small black and white TV with four boring channels that shut down out at 11:00 P.M.  In those days, we kids regularly played together outdoors all the time, and communicated by actually speaking to each other, face to face.

“Normal” in 1960 was far different from normal in 1990, or 2020.  My perception of normal fishing is far more modest than my father’s, my grandfather’s, and so on.  Each generation experiences fewer and smaller fish, yet each considers the reality they experience to be the normal state.  Pleistocene hunters did not know how abundant game was in their grandfather’s days, or 500 years earlier.  Nobody probably noticed if the number of mammoths was gradually declining.

Fernando Fernandez concluded that the primary factor in megafauna extinctions was the fact that the jumbo-sized walking meatballs that hunters eagerly desired did not reproduce like bunnies or cockroaches.  Killing them just slightly above their fertility rate could wipe them out over the passage of centuries.  It wasn’t so much about the intensity of the hunting as the fragility of the hunted.  Over a thousand years, and many generations of hunters, extinctions may have been essentially invisible.

Elizabeth Kolbert noted that modern elephants do not reach sexual maturity until their late teens, each pregnancy takes 22 months, and there are never twins.  Because they reproduce so slowly, mammoths could have been driven to extinction by nothing more than modest levels of hunting.  Doug Peacock estimated that taking only 4 or 5 percent of a slow breeding species could put them on a gradual path to extinction.  Peter Ward estimated that if hunters had regularly taken just two percent of the mammoths each year, the extinction process would have taken 400 years — too slow for each generation of hunters to notice.  Hunting alone could have wiped them out.

Kolbert wondered how Neanderthals had lived in Europe for more than 100,000 years without causing weird disturbances.  She suspected that if humans had never arrived, the good old days of abundant megafauna would have never ended.  Prior to the arrival of skilled teams of human hunters, jumbo size provided a survival advantage.  Megafauna thrived in Eurasia and the Americas 50,000 years ago, before trouble rumbled in — at which point being huge and slow became a serious vulnerability.  Kolbert was not sure if there was ever a time when humans lived in ecological harmony.

Pita Kelekna wrote that large herds of wild horses were once common in the river valleys of western and central Europe.  By about 8,000 years ago, they were nearly eliminated by overhunting in most of the continent, except in a few small pockets.  Several writers concluded that domestication probably spared horses from extinction.  Folks learned that horses were more valuable for transportation, and as beasts of burden.  There were many other delicious critters to feast on.

Australasia

The Australian extinctions probably occurred between 50,000 and 40,000 years ago, following the arrival of humans.  Tim Flannery described how ecosystems went through a number of substantial changes, as the early Aborigines learned how to survive in an unusual land, via trial and error.  He believes that they finally learned how to live in relative balance by around 12,000 years ago. 

Australia was blessed with having ancient worn-out soils, and a bipolar climate.  Severe droughts could last years, which might suddenly end with terrific deluges.  Thus, Australia was a lousy location for the emergence of agriculture and civilization.  Aborigines retained a Stone Age way of life until 1788, when British colonists arrived, and attempted to transplant an English way of life to a land for which it was not ideal.

Humans arrived in New Zealand between 800 and 1,000 years ago, and by 400 years ago the moas were extinct.  Moas were ostrich-like birds that could grow to 10 feet (3 m) tall, and weigh 550 pounds (250 kg).  Many collections of moa bones have been found, some containing the remains of up to 90,000 birds.  Evidence suggests that a third of the meat was tossed away to rot.  Obviously, the birds were super-abundant and super-easy to kill.

In the global eco-catastrophe that we are experiencing today, Australasia did not historically play a leading role.  The planet-thrashing juggernaut, which was born in Africa, gained a lot of strength and momentum when humans migrated into snow country, where a challenging climate inspired a surge in techno innovation.

Europe

In Europe, the era of megafauna extinctions corresponded to the arrival of human colonists.  Most of the extinctions occurred in two spasms — from 45,000 to 20,000 years ago in the warmer south, and from 14,000 to 9,000 years ago in the cooler north.  The process was much faster than the earlier extinctions in Africa.  Two million years ago in Africa, our pre-human ancestors were smaller, and still learning the basics of big game hunting.  The humans who later colonized Europe were bigger, stronger, and better equipped for hunting.

Paul Martin had an intriguing notion.  In the tropics of Africa and Asia, the warm climate favored the existence of infectious diseases and parasites that tropical primates were vulnerable to, like sleeping sickness and malaria.  Maybe these pathogens limited the size of hominin populations, thereby boosting the survival of large game.  In the cooler climate of Europe, the pathogens that could harm humans were fewer in number or less virulent.  In snow country, maybe healthier humans lived longer and hunted more. 

Below is a sampler of some of the species that blinked out in Europe.  Most had been around for more than a million years, and had survived multiple ice ages.  This list is far from complete, and highly oversimplified.  These species had survived for a very long time, but their luck ran out following the arrival of humans.

Irish “elk” were actually a species of large deer (not elk).  They existed for several million years, including 400,000 years in Europe.  The last ones died 7,700 years ago in the Ural Mountains.  They lived throughout Europe, east to Siberia and China, and south to northern Africa.

Straight-tusked elephants were in Europe by around 780,000 years ago, and vanished 30,000 years ago.

Cave hyenas were gone by 13,000 years ago, after 3.5 million years.  They dined primarily on horses, steppe wisent, and woolly rhinoceros.  Large hyenas could weigh up to 225 pounds (102 kg).  They inhabited northern Africa, the Middle East, and much of Europe, and Asia.

Cave bears emerged about 1.2 million years ago, and vanished 29,500 years ago.  They ranged from Britain and Spain, east across much of Europe, and into Russia and Iran.

European cave lions were quite similar to the lions still alive in Africa.  The two lines diverged about 1.9 million years ago, and the European cats went extinct 13,000 years ago.  They ranged in a wide belt from Spain and southern England, to Siberia, Alaska, and the Yukon.

European hippopotamus ranged across Europe, from Spain to Britain to Greece.  They emerged 1.8 million years ago, and went extinct 24,000 years ago.

Woolly Mammoths emerged 400,000 years ago in Eurasia, and went extinct in Europe 10,000 years ago.

Woolly rhinoceroses were living on the Tibetan Plateau 3.6 million years ago.  They were common throughout Europe and northern Asia, from Spain to China.  They survived until 10,000 years ago.

Americas

Paul Martin created much controversy with his theory that many of the extinctions in North America took place within a thousand years.  Among his critics were Native Americans, who were offended by the implication that their ancient ancestors foolishly hunted too hard.  For them, Martin’s ideas had the stinky aroma of racism.  The dating of the fossil specimens found so far does not rubbish his theory.  He did acknowledge that the extinctions seem to have ended about 12,000 years ago, but by this time, all the remaining large species had probably learned, the hard way, that primates were dangerous predators.

In an attempt to sidestep accusations of racism, a number of experts have tried to shift the primary blame to climate change, but that theory does not hold up as well to scrutiny.  Efforts to place the blame on epidemic animal diseases have yet to discover supporting evidence.  In the last 50,000 years, there is a clear pattern that megafauna extinctions routinely followed the arrival of humans into new continents — not the ups and downs of glaciation cycles.

As humans crossed into North America from Siberia, hunting began in northwest Canada, and spread south and east like a wild fire.  Peter Ward wrote that within one to two thousand years, at least 33 genera (50 species) of large mammals went extinct — far more than in the preceding three million years, which included numerous glaciation cycles.  Many of those that disappeared had lived in America for tens of millions of years. 

To put the North American extinctions in context, let’s take a peek at some of the evidence. 

Elephant family species immigrated into America from 1 to 15 million years ago.  There were at least seven varieties (mammoths, mastodons, etc.).  They survived until 12,000 years ago.

Horses originated in North America about 4 million years ago, and later spread into South America, Asia, Europe, and Africa.  They were extinct in North and South America by 8,000 years ago.  The Equus genus includes horses, asses, and zebras. 

Saber-tooth cats emerged in Africa 12 million years ago.  Some types could grow up to 620 pounds (280 kg).  They have been found in North America, South America, Eurasia, and Africa.  They went extinct in Africa 1.4 million years ago.  In North America they vanished 10,000 years ago.

Scimitar-tooth cats emerged in Africa about 4 million years ago.  They vanished from Africa 1.5 million years ago, from Eurasia about 28,000 years ago, and from America about 12,000 years ago.

American lions originated in Africa over a million years ago, and migrated into North America, as far south as Central America.  They went extinct around 11,300 years ago.

Camels originated in North America maybe 40 million years ago.  By 2 to 5 million years ago, some had crossed into Asia, and spread into Africa.  In North America, they went extinct 10,000 years ago.  They still survive in the Old World.

Short-faced bears were among the largest land dwelling mammalian carnivores on Earth, and they were abundant in California.  The species emerged about 1.8 million years ago, and went extinct about 11,000 years ago.

Giant armadillos were mammals that originated in South America 5.3 million years ago, migrated into North America, and went extinct about 12,000 years ago.

Ground sloths could grow as large as elephants.  They emerged in North and South America about 4.9 million years ago, and went extinct 11,000 years ago.

Giant beavers were the largest North American rodent.  They emerged about 2.6 million years ago, and went extinct about 11,700 years ago.

Tapirs could grow up to 4.6 feet (1.4 m) long, and weigh up to 496 pounds (225 kg).  They emerged 20 to 30 million years ago in North America, and went extinct about 11,000 years ago in America.  In China, some survived until 4,000 years ago.

Woodland musk ox could grow to 934 pounds (423 kg).  They lived from Alaska to California, and east to New Jersey.  They emerged about 2 million years ago, and went extinct about 11,000 years ago.

Dire wolves lived in North and South America from 125,000 to 9,440 years ago.  The average wolf weighed about 150 pounds (68 kg).  Their prey included camels, bison, mastodons, ground sloths, and horses.

Monday, July 15, 2019

Wild Free and Happy Sample 19


[Note: This is the nineteenth sample from my rough draft of a far from finished new book, Wild, Free, & Happy.  I don’t plan on reviewing more books for a while.  My blog is home to reviews of 201 books, and you are very welcome to explore them.  The Search field on the right side will find words in the full contents of all rants and reviews, if you are interested in specific authors, titles, or subjects.] 

Climate Shifts?

So, what caused megafauna extinctions?  The two primary suspects in this mystery are hominin hunters and climate change.  After numerous rowdy fistfights at scholarly conferences, the overhunting theory has become the most widely accepted.  Quite a few still believe climate change was a secondary factor, because the swings between hot eras and frosty ones could cause substantial shifts in a habitat’s vegetation.  When tundra became forest, mammoths no longer lived in paradise.  Their numbers likely declined, and their groups could have become more isolated.

When the climate warmed, hippos and monkeys migrated into Europe, joining the woodland rhinos, elephants, boars, and deer.  Tundra became boreal forest, and the cold adapted critters no longer enjoyed optimal conditions.  This could have weakened them, and made them more vulnerable to hungry hominin hunters. 

Then, when temperatures dropped, ice sheets advanced again, and the good old days ended for the warmth loving critters.  Woodlands were displaced by tundra and taiga — good habitat for lemmings, arctic foxes, reindeer, woolly mammoths, and woolly rhinos. 

Peter Ungar discussed research in Greenland, where scientists bored deep into the thick 150,000 year old ice sheet.  In the ice core samples, the annual layers of ice buildup contained details about climate trends.  Patterns could remain stable for thousands of years, and then suddenly change.  The emergence of agriculture and civilization only became possible with the arrival of the current, unusually long warming trend, which began about 11,600 years ago.  It followed a 1,200 year stretch of intense cold.  The transition from intense cold to the modern warm trend occurred during one lifetime.  A lass who was born in an arid tundra would see the land transform into a young forest by the time her hair was gray.

Now, gaze at the globe on your desk.  As Earth makes its annual joyride around the sun, its axis tips.  When the northern hemisphere tips closer to the sun, it’s summer time.  Six months later, summer begins in the southern hemisphere, and winter arrives up north.  The regions close to the equator consistently receive the most solar energy throughout the year, so they are Earth’s warmest — the tropics.  Both the North Pole and the South Pole get the least solar energy, so they are icy year-round. 

On your globe, note that most dry land regions on the planet are north of the equator.  Also, at the top of the world, the northern edges of North America, Europe, and Asia extend into the Arctic Circle.  Consequently, the northern hemisphere has experienced a number of intense glaciation cycles.

The southern hemisphere has far less dry land, and far more ocean area.  The surrounding oceans retain heat, and encourage a more moderate climate.  In the southern hemisphere, the bottom edges of South America, Africa, and Australasia do not come close to the Antarctic Circle.  For these reasons, glaciation events have been less extensive.

The Last Glacial Maximum (LGM) was the frigid peak of the most recent glacial cycle.  Ice sheets began growing about 33,000 years ago.  Glaciation peaked between 26,500 and 19,000 years ago.  Large regions of northern Europe, Asia, and North America were buried under ice sheets up to one mile (1.6 km) thick.  During the LGM, climate conditions were similar across these northern regions.  Glaciers retained so much frozen water that sea levels were 410 feet (125 m) lower than today.  A lass could walk from Ireland to Scandinavia or France without getting her feet wet. 

Bernardo Araujo’s team studied up-to-date climate models for the last 122,500 years.  For 19 regions, they compared the dates when humans arrived, with the dates when megafauna species went extinct.  They found that humans were entering Europe and Central Russia about 45,000 years ago.  In the colonized regions of Eurasia, extinction dates began about 40,000 years ago, and continued until about 10,000 years ago — the longest of the megafauna extinction cycles outside of Africa.

Araujo emphasized that our colonization of Eurasia was a significant turning point in the human colonization of the planet.  It was the first time that our fully tropical species was moving into regions that were colder than the conditions for which evolution had fine-tuned us.  It was far more challenging for humans to survive in snow country.

Fernando Fernandez also found no connection between climate patterns and extinctions.  He wrote that there were essentially two pulses of extinctions in Eurasia.  The first pulse was from 45,000 to 20,000 years ago, across the southern latitudes.  The second pulse was from 14,000 to 9,000 years ago, in the northern latitudes.

In North America, Fernandez reported a much quicker extinction spasm.  It mostly occurred between 13,500 and 11,000 years ago.  Experts still disagree when humans arrived on the continent, suggesting dates ranging from 20,000 to 13,000 years ago.  By the time humans entered North America, they had developed effective tools and strategies for succeeding in snow country, making a faster dispersal possible.  South American extinctions were mostly between 13,000 and 7,800 years ago.

Fernandez presented a list of arguments why climate change was not the primary cause of megafauna extinctions.  Climate swings affected the whole planet, but the extinction spasms occurred at widely different times, in different places — not everywhere at the same time.  The timing of extinctions does not closely correspond to the timing of glacial cycles.  Preceding the megafauna extinction spasms were 31 earlier glacial cycles which wiped out few if any species. 

Extinctions occurred first on continental mainlands, while species on isolated islands in the same region, with the same climate, survived much longer.  When extinctions took place in a region, there is no evidence that plant species were zapped by temperature swings at the same time.  It was the large animals that blinked out (the preferred game of hunters).  Small animals did not vanish in the same era (like they might have during a climate shift).  He did say that glacial cycles could have stressed ecosystems, making some species less resilient.

Baz Edmeades noted that most of Africa lies between the Tropic of Cancer and the Tropic of Capricorn, the equatorial belt.  When there were extinction spasms in the equatorial belt, there was no rise of extinctions in regions where hominins had not yet arrived.  The extinctions were limited to Africa and southern Asia — tropical regions where hominins resided.

OK!  So, based on what I know today, I am convinced that climate change was not the primary cause of megafauna extinctions.  I am also thoroughly convinced that the pattern of extinction spasms was closely related to the early emergence of advanced hominins in Africa, and to the later pattern of world colonization by humans.

I remain befuddled by one mystery.  During the North America extinction spasm, most of the megafauna species that survived were not indigenous. They were immigrants from the Old World, like moose, bison, caribou, elk, deer, grizzly bears, black bears.  Indigenous megafauna got hammered.  Super-speedy pronghorn antelope were among the few to escape extinction.  The implication here is that the Old World megafauna immigrants had arrived at about the same time as the Siberian hunters, and these foreigners were fully aware that humans were dangerous murderers — run!  I was not able to find information confirming that “about the same time” is true.

William Stolzenberg presented a different twist.  He shared a fascinating story about Joel Berger.  Early in the twenty-first century, when Berger was working near the Teton Range of Wyoming, wolves from Yellowstone began wandering back into the region.  They had been absent for 50 years, victims of a predator eradication project.  For 50 years, moose and elk had not been bothered by serious predators.  Berger freaked out.  He tried scaring the moose with wolf calls and scents.  No response.  They had completely forgotten their natural fear of wolves.  So, the wolves casually walked past the clueless moose mothers, and hauled away their calves.  Eventually moose learned that wolves were dangerous.

Global Serengeti

Baz Edmeades grew up in South Africa, where he enjoyed observing the remnants of African megafauna at Kruger National Park.  His deep interest in archaeology and evolution led him to read Björn Kurtén’s book on Pleistocene Europe.  He was shocked to discover that 15,000 years ago, hyenas, leopards, and lions roamed Europe, and they closely resembled the animals he watched in Africa.  Woolly rhinos and mammoths had cousins at Kruger.  Not that long ago, large animals were incredibly abundant.  Grassland regions of Europe were once a wildlife wonderland, like Africa’s Serengeti.

North and South America also had Serengeti-like grassland regions.  Dan Flores wrote that the Great Plains used to be home to many species of large mammals, none of which had evolved adaptations for living near packs of aggressive bloodthirsty tropical primates with spears, dogs, and fire.  Many blinked out.  Five hundred years ago, when European colonists began arriving in great numbers, with highly advanced technology, life on the American Serengeti got blindsided with astonishing speed and efficiency.

Today, many documentaries and nature programs present images of the African megafauna that still survive in protected areas, like the Serengeti.  These images of lions, zebras, giraffes, and baboons inspire astonishment among the wretched mobs trapped in sprawling, grungy, concrete landfills like New York City or London.  But, compared to the Serengeti of 2 million years ago, the twenty-first century Serengeti is much diminished.

Two million years ago, all the other continents were also astonishing Serengetis.  Earth was one big wonderful celebration of abundant life.  The critters of every ecosystem had coevolved with each other, resulting in functional relationships between the eaters and the eaten.  Loose cannon critters were not yet molesting the sacred dance.  Today, of course, a hurricane of swarming tropical primates has reduced Planet Serengeti to Planet Train Wreck.

It’s heartbreaking to comprehend that this staggering tragedy was driven by the innocent unintended consequences of thousands of years of gradually accumulating more and more clever innovations.  Today, the rate of extinctions is in the stratosphere.  Innovation and technology have given us the ability to thoroughly obliterate healthy ecosystems faster than ever before.  We call this “progress,” one of our god words.  Another one is “growth.”

In North America, when humans arrived, there were at least nine species of big cats, and seven species of elephants.  The biodiversity was incredible — beavers as big as bears, two-ton buffaloes, armadillos the size of VW Beetles

Mammoths emerged in South Africa about five million years ago.  By 2.6 million years ago, they had spread across Eurasia and North America.  Around 190,000 years ago, all mammoths in Europe had evolved the woolly look.  Until 14,000 years ago, mammoth country ranged from Western Europe to Siberia to New England to Mexico.  The last mammoths survived until about 3,700 years ago, on Wrangel Island, off the coast of Siberia.

Aurochs once ranged from England to Korea, and south to India and North Africa.  Rhinos once ranged from Africa to Europe to Sumatra.  Leopard country spanned from southern Africa to England, to Java.  Short-faced hyenas were as big as lions, and their addresses included India, China, Transvaal, and Europe.  And on and on….

Tim Flannery mentioned Neanderthals, who had significantly larger brains than humans.  They were long-time residents of Eurasia that had coevolved with the other large animals.  For hundreds of thousands of years, they coexisted with mammoths, straight-tusked woodland elephants, and two species of woodland rhinoceros.  Scholars tend to regard Neanderthals as dullards.  Ecological stability is not a sign of pathological intelligence.

Mother Africa

Around 5 million years ago, the climate in Africa was getting cooler and dryer, forest area was being displaced by expanding savannah.  The ancestors of hominins learned ways to survive in the changing conditions.  Our hominin ancestors were bipedal at least 3.6 million years ago.  Somewhere around 2.5 million years ago, the climate in Africa once again entered a cooler and dryer pattern. 

By this time, our hominin ancestors were getting better adapted to savannah living.  They were bigger and smarter, using stone tools.  They may have been cooking with domesticated fire, but we’ll never know when the first fire was kindled.  As previously mentioned, hominin evolution was influenced by having the ability to regularly dine on cooked food, which significantly tweaked the design of our teeth and digestive tracts.  This implies that domesticated fire appeared early in the game.

The series of megafauna extinctions that occurred during the hominin era began in Mother Africa.  Lars Werdelin, an expert on ancient carnivores, wrote that beginning around 2 million years ago, large carnivore species began to gradually decline.  Hominins were becoming regular hunters, and they were eating more meat.  Carnivore extinctions accelerated around 1.5 million years ago.  Coincidentally, Homo erectus emerged around 1.5 million years ago.   Erectus was the first advanced hominin, having a brain larger than average for its body size.  This era corresponds to the oldest known evidence of domesticated fire.  Today, only two percent of the original African large carnivore species still survive.

Werdelin assumed that hominins were not deliberately hunting large carnivores, which would have been insanely dangerous.  The extinctions were likely due to a decline in herbivores — the prey that carnivores depended on.  Was climate change reducing the forage that herbivores required for survival?  Small carnivores were not in decline, which would have been the case if ecosystems were being walloped by a climate shift.  Werdelin believes that hominins had become successful competitors for the traditional carnivores, both of whom were eager to dine on the same prey. 

Baz Edmeades noted that the African continent was loaded with megafauna 1.8 million years ago, but many were gone by 1.4 million years ago.  In the good old days, Africa had nine species of big cats (three today), up to nine species of elephants (one today), and at least four types of hippos (one today).  There were giant antelopes, giant hyenas, giant pigs, giant monkeys, giant baboons, and many others — all gone.  Over the course of many thousands of years, the consequences of hunting just a bit too hard accumulated. 

Some species that disappeared in Africa continued to survive on other continents.  Edmeades emphasized that during the African wave of extinctions, there were no corresponding extinction blips in Siberia, Europe, Australia, or the Americas.  In these other regions, most megafauna species thrived for another million years.  A jury would not convict climate change for the extinctions in Africa.

Sunday, June 30, 2019

Wild Free and Happy Sample 18


[Note: This is the eighteenth sample from my rough draft of a far from finished new book, Wild, Free, & Happy.  I don’t plan on reviewing more books for a while.  My blog is home to reviews of 201 books, and you are very welcome to explore them.  The Search field on the right side will find words in the full contents of all rants and reviews, if you are interested in specific authors, titles, or subjects.] 

Megafauna Pioneers

Every continent has regions of grasslands — savannahs, steppes, prairies, and so on.  Grasslands provide the nutritious greenery that can nourish herds of large herbivores.  Forest or desert ecosystems are far less ideal for grazing animals.  Meat provides nutrients that are essential for good health — nutrients much harder to acquire from wild grassland vegetation.  Hunters prefer to kill a large animal, rather than numerous rodents, grubs, worms, and so on.

Naturally, the existence of large herbivores needs to be kept in balance by the existence of hungry carnivores.  Too many grass eaters can turn grasslands into barren wastelands.  Large herbivores and large carnivores are both megafauna.  Megafauna are animals weighing more than 100 pounds (45 kg).  (Outside of America, more than 50 kg.)

Many families of megafauna species have expanded across five continents: Africa, Europe, Asia, North America, and South America.  During glacial cycles, some regions currently separated by water became connected by dry land, as sea levels dropped.  Land bridges allowed megafauna on both sides to cross over into new habitats.  Australia has mostly been isolated from the other five continents.  It has its own unique story of herbivores, carnivores, and megafauna extinction spasms.

Buried under downtown London, construction crews have discovered the remains of hippos, elephants, Irish elk, aurochs, and lions.  North America was the original homeland for the ancestors of horses, bears, rhinos, camels, and others.  Horses and bears spread across the five continents.  Camels expanded into Asia and Africa.  Rhinos vanished from America five million years ago.

Mother Africa was the homeland for the saber-tooth cat group, which later expanded across Eurasia, and then to North America and South America.  Africa was also where the elephant-like family began, which eventually colonized the five continents, diversifying into many forms over millions of years, including mammoths and mastodons.  Until 13,000 years ago, mammoth country ranged from Western Europe, across Siberia, and down into Mexico.  In the Americas, before hunters from Siberia arrived, there were seven elephant-like species.

On nutrient rich grasslands, a major trend in evolution was to encourage herbivores to gradually expand to jumbo-sized proportions, a trait that increased their odds for survival.  Bigger was better — thicker hide, stronger, and more dangerous.  Size mattered.  For example:

Giant beavers could grow to 7.6 feet (2.3 m) long, and weigh up to 276 pounds (125 kg) — about the size of a black bear.

Giant ground sloths could grow as large as elephants.  They could stand erect up to 20 feet (6 m) tall, and weigh 2,204 pounds (1,000 kg).

Giant armadillos were mammals that had an armor of bony plates.  Some weighed more than 1,000 pounds (454 kg).

Short-faced bears were among the largest land dwelling mammalian carnivores.  They could weigh over 1,500 pounds (680 kg).

Irish elk were giant deer that could weigh more than 2,500 pounds (1,133 kg).  Their enormous antlers weighed more than the animal’s skeleton.  They could spread up to 13 feet (4 m) across.

Of course, the rise of jumbo herbivores encouraged evolution to also select for larger carnivores.  Grasslands were home to a continuous evolutionary arms race, the ancient sacred dance of eaters and eaten.

Later, when skilled teams of hominin hunters became prominent, jumbo size eventually became a huge liability.  (Jumbo herbivores became as vulnerable as whales did when primates began harpooning them from boats.)  Jumbo herbivores were easy to see, and they did not excel at high speed getaways.  To hungry hunters, they were slow moving giant meatballs.

In 1961, Colin Turnbull noted that a Mbuti pygmy hunter could singlehandedly kill an elephant with a short handled spear.  This deadly spear technology was available to African hunters two million years ago.

Overkill?

Paul Martin stimulated much controversy in the study of megafauna extinctions.  In the 1960s, he was surprised to discover that in Africa, about 1.4 million years ago, a cluster of megafauna species went extinct.  The number of elephant-like species dropped from twelve to eight.  Three species of sabertooth cats, adapted for preying on large animals like the elephant family, also vanished from Africa.  These cats had two long upper teeth that were useful for stabbing through the very thick hides of elephants.  When the elephants declined, the huge incisors became a fatal handicap.

Baz Edmeades notes that this time period corresponds to when hominin hunters developed the larger and more complex Acheulean class of tools.  Apparently, hominins were getting better at competing against the sabertooths for jumbo-sized prey.  As the prey populations declined, so did the cats that ate them.  Hominins can survive on a far wider variety of foods.  When elephants are scarce, they can feast on eggs, grubs, or lizards.

The notion of hominin-caused extinctions 1.4 million years ago did not sit well with those who proposed the Great Leap Forward theory.  While Jared Diamond accepted the notion of the more recent overkill in North America 13,000 years ago, the far earlier date clashed with his belief that humans were essentially cute chimp-class primates until 40,000 years ago, when the miracle of turbocharged cognitive abilities arrived.  (This date also corresponds to the start of the human migration into snow country.)

Later, Martin grated even more nerves when he presented his research on the megafauna extinctions in North America.  He framed them as a rapid thousand year “blitzkrieg” (lightning war) of overkill.  Following World War II, there was a golden age of anthropology, when scholars visited many lands, and learned that most wild folks were not stupid, fiendish, bloody savages.  In fact, they had many admirable traits.  In fact, in many ways their lives were far healthier and saner than those of the anxious stressed out consumers of industrial civilization.

It became trendy to issue shining halos to wild people, because they were clearly not relentless maniacal planet thrashers.  Indeed, compared to modern consumers, their eco-impacts can seem close to insignificant.  But, as centuries pass, even modest impacts can gradually snowball into embarrassing blunders that hurl numerous species off the stage.

In hindsight, it’s easy to see that most or all techno-innovations have unintended consequences (even fire drills and wooden spears).  These consequences can often outweigh the benefits.  Also, the combined consequences of numerous innovations can swirl into bad juju hurricanes that can sharply impact the stability of entire ecosystems, even the planet’s atmosphere and climate systems.

It’s important to put these impacts into proper perspective.  Compared to modern consumers, whose whirlwind lives have staggering eco-impact, the lives of those Pleistocene ancestors were much closer to ecologically sustainable.  Walter Youngquist reported that in just the last few hundred years, highly educated civilized people have dug up and burned 500 million years of safely sequestered carbon, most of it during the lifetime of the baby boomer generation — me and my peers.  Look, it took 1,400,000 years to finally drive all sabertooth cats extinct on five continents.  It took just 40 years for greed-crazed American yahoos, with their rifles and railroads, to exterminate something like 60 million buffalo, and waste most of their meat.  Technology matters.

At the same time, paying careful attention to reality leads to far less cognitive dissonance than indulging in magical thinking.  Dan Flores prodded the romantics.  If the Paleolithic was such a long wonderful era of harmony, why did our ancestors abandon it?  Why, in the last 50,000 years, did they fan out across the world?  Why does the pattern of megafauna extinction spasms correspond to the geographical pattern of human expansion?

It’s always embarrassing to compare the human saga to our ancestral baseline.  Chimps and bonobos have continued to live sustainably, in the same way, in the same place, for several million years, without swerving off to dangerous experiments in technological innovation.  We seem to be the one and only living species that has wandered off the traditional path.  Many cultures have foolishly succeeded at monopolizing the exploitation of resources in their territories — a perfectly insane joyride of ecological self-destruction that will not have a happy ending.

Now, I must confess that I find it a bit difficult to effortlessly believe the overkill theory without a doubt.  I mean, how could a modest population of hunters, travelling on foot, armed with spears, exterminate all of the horses in all of North America, over the course of a dozen centuries or so, while the bison and others survived?  Many readers who have hunted wild horses with spears will find this idea hard to swallow.  To get a deeper understanding of this extinction tragedy, it’s time to pull on our waders, slog down bloody Megafauna Lane, and take a bunch of selfies.

Trail of Tears

Hominins have been around for maybe 2.8 million years.  During our visit on Earth, there have been several spasms of megafauna extinctions.  The spasms during the hominin era began in Africa about two million years ago, when the hominin predecessors of Homo sapiens were romping around on the savannah. 

Our species emerged maybe 300,000 years ago, and eventually expanded eastward, across tropical Asia.  Around 50,000 years ago, folks arrived in Australasia, setting off a wave of large animal extinctions.  Over the course of several thousand years, 17 out of 18 genera of megafauna blinked out.

What’s a genera?  It’s the plural of genus.  A genus is a category of closely related species.  For example, the Homo genus includes the species Homo sapiens, Homo neanderthalensis, Homo erectus, and so on.

Around 40,000 years ago, humans wandered into Europe, where the extinctions were less extreme because the local megafauna had already been living with dangerous armed primates (Neanderthals and others) for maybe 500,000 years.  The megafauna had learned the hard way that primates were not their good little buddies.  In the European spasm, 21 of 37 genera vanished.

Eventually folks expanded across northern Asia (Siberia), and crossed into the Americas, where the extinction spasm was rapid and intense.  Asia lost 24 of 46 genera, North America lost 45 of 61, and South America got hammered hard, with 58 of 71.

Finally, on many isolated islands, extinctions happened much later, when humans arrived.  For example, 4,700 years ago in Cuba, 1,500 years ago in Madagascar, 500 years ago in New Zealand, and so on.

Attentive readers will perceive that this series of extinction spasms clearly corresponds to the expansion of humans into new regions.  [Martin’s chart]  It is also absolutely clear that the pattern of extinctions does not correspond to patterns in climate history.  Most or all of the genera that blinked out had been in existence for at least several million years, and had survived numerous glacial cycles.

Fernando Fernandez summed up the extinctions more broadly.  Between 50,000 years ago, and A.D. 1500, about two thirds of the world’s megafauna species went extinct.  In this process, of the 150 genera of large mammals, at least 97 went extinct.  This statistic does not include the extinctions in Africa prior to 50,000 years ago.  When we take a moment to reverently sniff reality’s butt, it’s easy to see that, in the long run, innovation is not a good little buddy of the family of life.  Our magnificent standard of living has mindlessly created a global gas chamber.