Cradle of Humankind



East Africa is called the Cradle of Humankind because it’s where our ancestors originated.  As noted in an earlier post, two to four million years ago, the region became cooler and dryer.  Forests shrank.  The ancestors of baboons and humans moved out of the forest and adapted to savannah ecosystems (grasslands with scattered trees).

In this new habitat, male baboons evolved large canine teeth, to better deflect predator attacks.  All baboons retained the physique for scampering up trees.  Baboons still live sustainably, as they have for millions of years, because they continue to live in the manner for which evolution fine-tuned them.  They adapted to their ecosystem without altering it.  They did not make weapons and hunt animals larger than they were but, on happy days, they could mob a leopard and disassemble it.

Our ancestors evolved into critters that stood on two legs (bipedal).  They became furless, sweaty, long distance runners who, in a hot climate, could chase animals until they collapsed from exhaustion.  Heavy sweating kept them cool whilst jogging for hours.  With these traits, evolution created a new mode of offense, but it was weirdly stingy about providing defensive assets like speed, strength, teeth, or claws.  These ancestors were less agile at zooming up trees.  Over the eons, many species of bipedal apes have evolved, but only one still survives.

In the early days, the ancestors acquired new abilities very slowly, via evolution.  At the same time, other species were also busy evolving new abilities for countering our advances, and maintaining the balance.  For large animals like apes, genetic evolution can take thousands of years to stabilize a new and improved trait.  Evolution does not always mean progress.  We’re discovering that big brains can be more trouble than they’re worth.

With our transition to tool making, we began gaining new abilities by inventing them, a much faster process.  Spears enabled our ancestors to impede the man-eating predators that had kept their populations neat and tidy.  This rubbished the laws of nature.  Imagine rabbits inventing tools that allowed them to overpower foxes.  With spears, we could also kill large game, acquire abundant meat, and feed more bambinos.

By becoming tool freaks, our ancestors stumbled into the dangerous juju of cultural evolution, a painful experiment that has achieved enormous momentum and speed.  There are now seven-point-something billion of us.  We are the best-educated generation ever, the most destructive, we know it, and don’t seem to care much.  There is an important lesson here, summed up by Orgel’s Second Rule: “Evolution is cleverer than you are.”

Here’s a happy idea.  Genetic evolution is the result of a process that constantly generates billions of random mutations in every species of flora and fauna.  Most mutations are maladaptive and promptly blink out.  When mutations survive and continue, we call this natural selection.  William E. Rees reminds us that cultural evolution is also subject to something like natural selection.  Maladaptive cultural mutations, like soil mining or forest mining, are unsustainable.  Natural selection has no mercy for cultures that refuse to learn the dope slap lessons of repeated mistakes.  In the long run, the family of life will always trump self-destructive cultures, in a messy and merciless manner.

Rainforests are a paradise for biodiversity, providing a pleasant home for huge numbers of species.  Savannahs support far less biodiversity, but provide excellent habitat for many large animal species.  A square mile of rainforest contains tons of biomass in its trees, far more biomass than a square mile of grassland, but grassland can produce more new biomass every year, primarily during the wet season.  This nutritious vegetation grows close to the ground, a convenient location for grazing animals.

The biological productivity of grasslands (savannahs, prairies, and steppes) enabled the emergence of large herbivores and their predators in Africa, Eurasia, Australia, and the Americas.  For grassland herbivores, size and speed are evolutionary assets, because they discourage predators.  Lions scatter when menaced by uppity elephants.  Elephants live longer than bunnies.  Size matters.  Bigger is better.

Some species use simple tools like sticks, stones, or blades of grass, but our ancestors took the fabrication and use of tools to new levels.  They learned how make blades, projectile tips, scrapers, and axes by chipping flakes off stones.  Confronted with an organized gang of hungry apes with spears, giant size lost its advantage, and became a serious handicap.  Cultural evolution trumped genetic evolution.

In addition to getting extremely clever with tools, our ancestors also learned how to make and use fire, an ability that helped keep man-eating predators at bay.  Fire allowed us to inhabit the entire planet, and disrupt the balance of ecosystems wherever we went.  Cooked foods were easier to digest, so we could extract more nutrients.  Cooking also enabled us to digest formerly inedible materials.  Thus, our food resources were greatly expanded.

Stephen Pyne is the world’s expert on fire history.  He described excavations at Swartkrans Cave in South Africa.  At the oldest layers, the pre-fire level, no charcoal is found.  There are complete skeletons of big cats, and the scattered gnawed bones of the critters they ate, including hominids — cats were the top predator.  Charcoal is found in newer layers, the fire age.  Here are found complete hominid skeletons, and the scattered bones of the critters they gnawed, including big cats — hominids had become the top predator in the cave.

Pyne concluded, “Without fire humanity sinks to a status of near helplessness, a plump chimp with a scraping stone and digging stick, hiding from the night’s terrors, crowding into minor biotic niches.”  Combined with fire, our ability to make spears, javelins, hammers, choppers, baskets, nets, and so on propelled our blastoff into outer space, far beyond Africa.  Maybe fire and tool making are the reason that evolution didn’t bother enhancing our defenses.

Baz Edmeades is a specialist in megafauna extinction, and he notes that our ancestors were not masters of sustainable living.  Africa was loaded with megafauna species at the dawn of the Pleistocene 1.8 million years ago, but many were gone by 1.4 million years ago.  At the Olduvai Gorge site in Tanzania, in 1.8 million year old deposits, they have found the butchered bones of rhinos, hippos, elephants, antelopes, and buffalo.  Elsewhere, evidence suggests that our ancestors were tending fires 1.6 million years ago.

In the good old days, Africa had nine species of big cats (three today), nine species of elephants (one today), and four hippos (one today).  There were giant antelopes, giant hyenas, giant pigs, giant monkeys, and giant baboons — all gone.  Primary suspects include an Australopithecus species and Homo erectus.  Homo sapiens emerged much later, maybe 100,000 years ago.

Edmeades emphasizes that during this wave of extinctions, there were not corresponding extinction blips in Siberia, Europe, Australia, or the Americas.  In these other regions, most megafauna species thrived for another million years — including many species that blinked out in Africa and South Asia.  If climate change was the primary cause of megafauna extinction, the northern hemisphere should have been hammered harder, because it was the region most affected by glaciation.

Lars Werdelin is a specialist in the evolution of mammalian carnivores.  He ponders the current efforts to designate a new era of geologic time, the Anthropocene, the period when humans began causing irreversible impacts.  When did it start?  Some think 1945, or the Industrial Revolution.  Others say the dawn of soil mining and animal enslavement.  Paleontologists like Werdelin observe reality from a perspective that embraces a much broader sweep of time.

He notes that between 3.5 million years ago, and 2 million years ago, the number of large carnivore species in Africa was reduced by half.  Today, only two percent of the African large carnivore species still survive.  This transition does not correspond to what is known about climate patterns — similar extinctions did not occur in other regions at this time.  A more likely suspect is the appearance of an early species in the Homo genus.  With regard to the kickoff date for the Anthropocene, Werdelin notes, “Humans have had the ability to affect ecosystems on a major scale for the past two million years.”

Björn Kurtén was an expert on the fauna of Pleistocene Europe.  The megafauna included varieties of mammoths, rhinos, horses, aurochs, reindeer, giant hippos, giant deer, giant musk ox, giant hyenas, giant bears, giant cheetahs, giant cave lions, saber-tooth cats, leopards, antelopes, goats, and many others.  Many of these species survived in Europe until the Late Pleistocene (which ended 10,000 years ago), but are now gone.

Kurtén concluded, “The mass death can hardly be ascribed to climatic causes alone, for there was no similar mass extinction in earlier interglacials.  It seems fairly certain that modern man has played a dominant role in the wiping out of many species, although perhaps by indirect influence as much as by actual hunting.”

Edmeades notes that, in Europe, warmth-loving megafauna species, like the straight-tusked elephant, hippos, and woodland rhinos, went extinct by 25,000 years ago, around the time of the last glaciation.  There were many glaciations during the Pleistocene, and some were more severe than the last one.  The last glaciation corresponds to the time when Homo sapiens colonized Eurasia.  Cold-tolerant mammoths and wooly rhinos survived in Western Europe until 12,000 years ago.

In North America, prior to human colonization, Edmeades says the ecosystem remained comparable to Africa 1.8 million years ago.  There were condor-like birds with 16-foot wingspans (4.8 m), mammoths, and mastodons.  In addition to cheetahs, “No less than five other kinds of big cat were living on an extravagant assortment of camel, llama, deer, horse, musk ox, bison, goat and sheep species.  With its giant bears, giant beavers, giant armadillo-like species, giant tortoises, and its giant ground-sloth species, North America was, without exaggeration, a super-Serengeti containing many more big-animal species than present-day Africa.”

“The population of every organism on Earth,” he writes, “is limited by collisions with the wall of limited resources.”  Baboon numbers are limited by the availability of nutrients they can acquire with their bare hands.  Specialized meat eaters like lions are limited by the availability of prey animals.  Both lions and baboons live as evolution fine-tuned them.  Food may be abundant one season, and scarce the next.  When abundant, populations increase.  Starvation is perfectly normal and natural.

Our ancestors had the added benefit of being omnivores.  When hunting was bad, they could dine on roots, nuts, and fruits.  This dietary safety net provided a huge strategic advantage over specialized meat eaters.  Of course, even omnivores can experience mass starvation.  All life requires nutrients, and all nutrients are finite.

The ancestors also benefitted by having cutting edge technology like fire, javelins, lances, harpoons, nets, snares, boats, and warm clothing.  Modern humans have blindsided the planet by converting many wild ecosystems into freaky food production plantations, dramatically increasing their nutrient resources — as long as the soil remains fertile, and pests, viruses, droughts, deluges, and frosts don’t nuke the plan.

Everyone agrees that, once upon a time, many species of megafauna inhabited every continent, and that most are now extinct.  Everyone agrees that the extinctions did not occur at the same time, around the world.  There were not major spasms of extinctions in places where our ancestors had not yet arrived.  The extinct species had previously survived multiple eras of global and local climate swings, which were sometimes sudden and severe.  Climate shifts do alter the flora and fauna of affected ecosystems, and this contributed to regional extinctions, like the hippos of London.

When it comes to success at long-term sustainability, the chimps, bonobos, baboons, and every other non-human species, get high scores.  When the food supply in their ecosystem declines, they starve and die.  Our lineage took a different path.  Instead of starving, they increased their food supply via innovation.  Wild and free chimps, without technology, would struggle to survive beyond their current habitat.  They live where evolution fine-tuned them to live.

The creature you see in the mirror has the body of a meat-eating hunter.  It is bipedal, designed to be a long-distance runner in a hot climate.  Its hands, arms, and shoulders are fine-tuned for hurling projectiles (killing from a distance), and making and using tools.  Our ancestors were hunters more than a million years before Homo sapiens appeared.

Daniel Quinn wrote Ishmael, a best-selling novel that defined two classes of human societies, Takers (naughty) and Leavers (nice).  The fall of humankind was the transition to agriculture and civilization.  The book torpedoed sacred cultural myths and blew my mind.  Hunter-gatherers certainly have far less impact than civilized folks, but the history of megafauna extinctions is important. 

So is the fact that plant and animal domestication emerged independently in several regions.  Some groups of hunter-gatherers chose to increase their food supply rather than rely completely on the fickle luck of the hunt — or become masterful at family planning.  They cleverly began displacing the wild ecosystem to produce plant and animal foods — a transition that had Earth-shaking unintended consequences.

Worse, by producing far more food, their population bloated.  There is strength in numbers.  For thousands of years, mobs of hungry dirty farmers and herders have been steamrolling wild societies, helpless deer in the headlights of progress.  This is a real pisser!  High impact societies routinely trump low impact ones.  Consumer culture has become a monster factory where students are entranced by dark juju sermons on Sustainable Development™.  This feels like the Mother of All Predicaments.

The good news is that Big Mama Nature will not allow this tragic game to continue forever.  Highly educated consumers are consuming nonrenewable resources at a growing rate, blissfully ignorant of the existence of limits — a wall that they will slam into.  At the same time, centuries of progress are destabilizing the climate that has enabled the existence of civilization.  Wildlife populations are severely depleted and plummeting.  We are getting very close to the peak of our batshit crazy joyride of turbocharged foolishness.  An era of healing is coming.

Meanwhile, on the rainforest sidelines, are the chimps and bonobos, our closest living relatives, who have lived in the same place for millions of years without leaving scars on the habitat.  Imagine that!  Humans are animals, an extremely embarrassing fact that most of us adamantly deny.  I have no brilliant solutions to offer today.  My humble suggestion is to think like an animal.  Thinking like a consumer is pushing us toward the coffin of humankind.  All the best!

Edmeades, Baz, Megafauna — First Victims of the Human-caused Extinction, 2013.  This fascinating manuscript has been withdrawn from its home location (megafauna.com) for updates.  An earlier version is available HERE.

Kurtén, Björn, Pleistocene Mammals of Europe, Aldine Publishing Company, Chicago, 1968.

Pyne, Stephen J., Fire: A Brief History, University of Washington Press, Seattle, 2001.

Rees, William E., Is Humanity Fatally Successful?, Vancouver Institute, British Columbia, 2003 (Download).

Werdelin, Lars, Hominids, Carnivores, and the Origin of the Anthropocene, Swedish Museum of Natural History, 2015 (50 min video).