Cradle in the Tree of Life

Part II by Dr. Donald Perry

Dr. Perry welcomes your comments and questions. Please email him at canopy evolution at

The fruits of our creativity – music, dance, mathematics, technology, and our awareness of the universe – are the result of evolutionary events that occurred in the murky depths of humanity’s distant past. Where and why this creative mind came into existence is the ultimate question of philosophy, religion and science.  

Some theorists place human origins in the development of language, others in rock throwing, still others in our unique form of walking upright. However, all of these suggestions are highly speculative.

A sign post to when the mind started becoming human exists in the archeological record. It is a remarkable stone tool with a complexity of form that defied explanation by over a century of scientists. It was made around two million years ago and was humanity’s first technological invention. It was used for nearly that whole length of time, making it the most important and longest-lived invention ever made.

trees with no leaves, ropes set

So what kind of life inspired this invention? As I was exploring the origin of human intelligence I came across an interesting piece on Robert Goddard, in the book Dragons of Eden, by Carl Sagan. Goddard was the inventor of modern rocketry and as it turns out he got his brilliant idea for space travel while climbing into a tree as a youth. Although there is debate about this point, some have said Sir Issac Newton got his brilliant idea concerning the gravitational force from watching an apple fall from a tree.

The influence of trees therefore is associated with the Copernican Revolution and The Renaissance – changes in human thinking that ended the Dark Ages, kicked off the age of science, and have led to space exploration.  Long before ancient Greeks discovered the earth was a sphere suspended in space, trees inspired our understanding of the nature of the universe. The earliest myths of Egyptians and Northern Europeans had universe trees with kingdoms and limbs holding up the cosmos.  New Guineans imagined we slid down a rope from a kingdom in the sky to live on the ground.  Closer to home, Eden was said to be a garden of the earth’s fruiting trees. Myths show we have a deep and intimate respect for trees, but it seems to me myths are also telling us that a kingdom in the sky was a real place – once upon a time.

A naysayer would point out that forests have played an important role in the world’s habitats for hundreds of millions of years. Both North America and Eurasia were fully forested until humans burned and cut them down. (Not much love for trees evident there!) Grand organisms, like the Giant Sequoias whose life spans approach immortality, should and would be a focus of mysticism. They were here before us and probably will be here after we are gone too.  It would be really odd if huge old growth, impressive, humbling trees, did not play a dominant role in origin myths.  So the significance of vague myths from around the world of a lost aerial home in trees has been routinely ignored.  As a result myths of an aerial home as a safe haven from the ferocious predators of the ground have never played a role in scientific theories about our origins.

Yet one does not have to look far to find a well of empirical evidence – genetically-based programs – displayed by children and the way we behave that tells a complementary story to myths. Many adults still climb and so do most children. Alex Honnold is a climbing machine who can free climb high rock faces barehanded. He demonstrates that humans are one of the best climbing species on earth.  His fingers tell a story that recalls Neanderthal times.

fall foliage on large tree

This phenomenal climbing ability is written directly into Alex’s genes. Where did these genes come from? When we write evolutionary theories about a species it must always include the probable reason for possessing various traits. A turkey for example is a great runner that uses its sharp claws to dig up humus to find things to eat such as nuts and insects. While evolving to become a heavy bird of the ground (a bipedal ground species too), natural selection retained its ability to fly up to tree limbs to roost at night where it would be safe from predators. Finding food and escape from predation are essential elements driving the evolution of all species. An utterly absurd theory of turkey evolution would omit or ignore the role of flight.

And so the human evolutionary story is similar to that of the turkey in having two main branches – it, of course, must be about our upright walking and tool making, and also about our climbing. The story about our tool making and upright walking is found in all the libraries of the world. Yet oddly the stories on library shelves and documentaries are silent about what is the most important aspect of human nature – tree climbing! 

The following is the untold, most important half of the human evolutionary story. It is about a place where science and religion meet. The two walk, or should I say climb, hand in hand along a path lit by childhood nightmares of ferocious beasts, inexplicable instincts in infants, and bits of fossil evidence that lead to a new panorama of human origins. At path’s end, our compulsion to design temples that reach into the sky, cathedrals that mimic the look and feel of towering old-growth groves, our gazing from penthouses, and our drive to build forests of concrete and steel, emerge as leftover  sentiments from a recent tree climbing past. We arrive at the place where the mind was born.

Respected books on human evolution continue to be based on Darwin’s founding premise in his book The Descent of Man.  He claimed that the most important event in our origins was when we gave up climbing and left trees to begin living on the ground.  Activities on the ground, he said, stimulated the intellectual development of the mind.  While I do not doubt Darwin’s theory of biological evolution, I have a much different human evolutionary view.  

3 tree climbers against the sky

I am an evolutionary zoologist and an avid tree climber.  I pioneered the exploration of the canopy’s arboreal continent of hidden life for three decades.  This work gave me a bird’s eye view of how we became human.

If our mind and body evolved solely on the ground, which is now commonly believed, why do we rank among the best climbers to have ever evolved?  How is it possible for construction workers to walk along a skyscraper’s narrow steel girders at dizzying, terrifying heights?  No ape can climb a thousand-foot cliff barehanded, nor can they build a tree house in a towering treetop as do the Korowai people of New Guinea. Our ability to work and build in trees far outdistances those of apes, and we stand apart from all other primates due to our ability to construct.  

Articles in both popular magazines and scientific journals tell us that when we abandoned tree climbing to walk on the ground, our hands were then free to make tools.  Tool use on the ground triggered the development of an enlarged brain and an enhanced intelligence. (A rebuttal of the aquatic ape yarn must wait.) But there is a problem with this view. We possess a menagerie of odd adaptations that could never have evolved on the ground. There is overwhelming evidence that some of the amazing leaps in human evolution – primitive tool making, the development of language, construction – can be traced to the period when we were spending more time in trees.

tree climber headed up a rope

Strong evidence of an arboreal link is found in our children. They are born with an innate behavior known as the Moro reflex. This reflex is viewed as an oddity, but it is actually a network of precise neurological circuitry in the infant mind. While flaws in its expression help practitioners to determine the mental health of an infant’s brain, the evolutionary explanation of this hardwired reflex and how it once provided for the newborn’s safety remain undiscovered by the medical and anthropological professions.  Physicians activate the Moro reflex by placing a baby on a table covered with soft spongy material, supporting its head in cupped hands, then allowing the head to drop slightly but suddenly while still being held. (Do not attempt this.) The baby flings its arms out sideways, its whole body stiffens, and a few seconds later the baby relaxes and begins to cry loudly. This reflex disappears after a few months.

The Moro reflex can also be triggered by sudden nearby movements or a loud noise.  To create such an instinctive reflex, life-threatening movements and noises had to have occurred for tens of thousands to hundreds of thousands, of years.  Where might that have taken place?  

In the forest, booming thunder and limbs crashing down would have been familiar loud sounds that caused great alarm.  If our ancestors lived on platforms and the platform was struck by a falling limb, a sleeping infant could easily bounce off the platform’s edge. In such a case heavy selection would account for the sideways-extended arms of the Moro reflex, along with a stiffening body that minimized rolling and stabilized an infant. The startle reflex, as it is also called, makes little sense as an adaptation for life on the ground.  For this reason it has never been understood.

Additional reflexes and behaviors possessed by infants weave a neurological fabric helping us link the Moro reflex to a climbing past.  Soon after birth, and while still virtually helpless, infants have the incredible capability of bearing their entire body weight by a single hand.  Their ability to grip hair with an iron fist is amusing to some, but it was not amusing in our ancestor’s world.  Known as the grip-reflex, this feat of strength is often brushed aside as a vestige of pre-human evolution from a time when our infants, like other primates, needed a strong grip to cling to their mother’s fur as she clambered through the treetops.  Never is it pointed out that this reflex would provide safety to an infant clinging onto vines among high limbs.  Of course, few branches are found in cribs today, but cribs are ideal proving grounds for what infants really want to do.

A few months after birth children start climbing.  This occurs before they can walk and it becomes difficult to keep them safely in a crib.  The urge to climb is strong.  Is this urge leftover from an ancient time or is the infant’s escape from the crib telling a more timely message?  Could this be telling us how we lived just a few tens of thousand years ago?

The instincts of all newborn animals, like the get-up-and-run behavior of newborn gazelles, are imperative programming for survival in the habitat where that animal will spend its life.  Escape is essential on a savanna, and in many other habitats as well.  Newborn humans practice climbing soon after birth. Within a few years they can often be found clambering among tree limbs with exceptional skill.  Gymnastic instructors have told me that nearly all of our youth have fantastic climbing capabilities.  Of course these abilities are genetically based.  Zoologically and biologically these can not be considered vestigial instincts.  Our young are playing out a recently essential drama before our very eyes.  We are witnessing recordings of our ancestral past. 

When infant instincts and capabilities are so well developed for climbing, one evolutionary explanation exists: recent and stringent natural selection anchored these instincts in the infant mind.  Very recently we were spending much more time in trees.  

5 tree climbers - back to camera

This explains other instincts and physiology that are incongruous with life on the ground. Our young often screech at the top of their lungs to attract a parent’s attention, especially when the parent is out of sight.  This is not an adaptation for life on the ground.  While we can only speculate why such noise is needed in trees, it is definitely abhorrent for life on the ground.  There is a basic tenet followed by all terrestrial young – silence is golden.  Life on the ground mandates that young animals remain quietly huddled under the cover of grass and shrubs when parents or guardians are away. Only in dire circumstances would they cry out, because there is no sweeter music to a ground predator’s ear than a screaming, defenseless infant.

Oddly, anthropologists tell us that human intelligence and the invention of weapons evolved when we lived on savannas.  Yet savannas were incessant war zones of prehistoric times.  Before trudging out onto the savanna with its huge cats and other savage residents, it seems obvious we would have need of weapons.  So their invention must have come while we still inhabited forests.  Yet anthropological art portray our ancestors standing on the ground poised to attack a predator with rock or stick in hand.  A trip to grizzly bear country armed with only a rock would wake up any believer in that foolish anthropological myth.  The film Grizzly Man, a 2005 documentary film by German director Werner Herzog, ends with a disturbing story of people being eaten alive.  We can be confident our ancestor came fully armed during their invasion into the savannas.  

Other anthropologists think our ancestors slept on the ground. But exposure to roving packs of quadrupedal killers would quickly have spelled extinction for our species.  Why would we have not been like all apes, except the massively over-sized male gorilla, which build tree platforms to sleep out of reach of ground predators?  

Because no evidence of tree houses has been found in layers of fossiliferous clays, it is thought that our ancestors did not sleep in trees.  I believe the evidence is there.  However, if an absence of evidence confirms that we did not sleep in trees, then the absence of evidence confirms that we did not live in or frequent savannas either.  Before 40,000 years ago there is little evidence of protective shelters (there were not enough caves to house early human populations), effective weapons, or domesticated dogs, all of which would have been needed to dissuade the predators of the ground.

Anthropologists so desperately want us to sleep on the ground that they have pointed out to me that leopards are good climbers, so we would not have been safe in trees.  This, of course would mean that great apes and all the species that nest in trees find no protection by sleeping it trees?  It is established fact that predation is higher on the ground.   And shortly, I will show why leopards would have quickly learned to avoid any tree that smelled of humans, or have their head cleaved in two. 

young tree climbers at a park

In my work I have dealt with handling deadly poisonous snakes.  I would choose sleeping with those snakes hands down over the saber-toothed cats, hyenas and cave bear that roamed the ancient savanna.  Reason should direct theory.  So where would you rather have slept: on the ground with predators or in a tree-house?   

Anthropologists tell us that Homo habilis (Handy Man) lived on the ground when he developed the first tools.  He walked upright and had a significantly larger brain than Lucy (his presumptive tree climbing forebear).  He seemed to provide perfect evidence to support how the power of walking on the ground stimulated human intelligence.  It was also believed that Handy Man had given up climbing, but then someone examined the bones more carefully.  As it turns out, Handy Man was quite proficient at tree climbing.  Since Handy Man is the probable maker of the first tools, the empirical evidence shows that the first stone tools were made by tree climbers around two and a half million years ago.  Tree climbers!   

Tree climbing is linked with tool making, as the best tool makers in the zoological world are climbers.  And it is a well hidden, but fully supported fact of zoology that tree climbing holds a significant position in the evolution of large brains.  With the exception of some aquatic species (the reason for this is explained in my book manuscript, The Descent), in all of evolutionary history the relatively largest brains among mammals, birds, and dinosaurs are found in climbing species.  Those species that shunned forests and trees always earned relatively small brains.  Something about tree climbing can promote encephalization in many species, and something about life on the ground favors a small brain in nearly all species!    

Given that we are one of the best climbers on earth, the zoological conclusion is inescapable. Climbing must be involved with the evolution of our brain.  We must have been doing some smart activities in trees that apes never imagined doing.  What were those smart activities?   

The noose around the neck of Darwin’s ground theory is tightened by examining the origins of the use of the most important tool of early human evolution.  The “hand axe” first appeared around 1.7 million years ago and is the first tool with an elegant design.  This stone tool unquestionably marks our transition out of an apish realm, but understanding its function has been one of the greatest puzzles of human evolution.

The hand axe is a large, flattened, tear drop-shaped rock that weighs up to several pounds, sometimes much more.  The perimeter of this stone is sharpened all around.  Since earlier varieties were too heavy to be thrown effectively and much too large to be attached to a shaft as a spear point, the tool is called a “hand axe”.  (Early anthropologists produced art that placed the stone as a spear point, which now appears rather ludicrous.)  I would label the tool differently because it should be clear that striking prey with this tool would cause injury to the user.  On impact, its sharp-edged perimeter would slice into the hand that held it.  How the idea this stone was hand-held got on the blackboard is unfathomable, but get there it did, and it was generally accepted for decades.  

Puzzling over hand axe function has sparked a century of wild speculation.  The literature is full of ideas: it was used for digging, chopping, perhaps a discus.  Someone came up with “an ancient religious object.”   When something can’t be explained, religion is always there to lend a helping hand.

2 people climbing a tree posing for camera

Some have called it the Swiss Army knife of ancient times.  However, Swiss Army knives are characterized by having many known functions, not many unknown functions.  It’s all rather frustrating for anthropologists.  So some have reverted to calling the stone a “bi-face”, meaning it is a flattened rock with two sharp edges. But it is sharpened at the butt end too, giving it a heavy, cleaving, chisel end.  Take note of that end!

Our ancestors definitely had a function in mind.  Examining where these tools are found awakens an understanding of their use.  The typical deposition site is like Olorgesailie, Africa, where hundreds of hand axes lie together at the bottom of large mud holes in ancient stream beds.  In fact, most hand axes are found in ancient mud holes.  Safe storage areas some say, which is just one more unbelievable view that is inexplicably respected.

Our basic understanding of the activities that produced the human mind hinges upon the hand axe.  Therefore an analytical explanation of its function that fits the empirical evidence is needed, not guesses.

Here is what I see in the empirical evidence.  One essential clue to hand axe function is that some of them seem embedded, stuck, in the bottom muck of stream beds.  And another thing: mud holes in slow-running streams of ancient times would undoubtedly serve the same function as they do today.  They are excellent fishing/hunting locations.  

What is really exciting from a tree climber’s perspective is that the ancient streams where hand axes were found meandered through gallery forest.  These forests boast really magnificent, old-growth trees with beautiful crowns that can spread over 150 feet in diameter.  Large limbs would have grown over waterways, enclosing the stream in a tunnel of high overhanging limbs.  Let’s see.  Chimps carry rocks into treetops, don’t they?  So it stands to reason that humans did too!   

The fog is finally dissipating, and along with it goes the need for speculation.  The hand axe’s hydrodynamic fusiform shape screams out its purpose.  It was designed specifically to be dropped from high limbs, heavy chisel end down.  In contrast to Handy Man’s round stones, a hand axe could part the water with the killing force of a rifle bullet and cleave a brain case.  This is no exaggeration.  Rocks falling from those heights would be high powered projectiles.  Call it a gravity bullet.  Of course the mud holes have rounded stones in them too, telling us that any stone was better than none at all.  But the sharp perimeter of the hand axe would cut no matter what edge of the stone struck first.  It was the best possible design, a really smart design, to kill or maim surface-feeding fish and other prey that wandered in for a drink at a waterhole.  

I have given the tool its proper name: “drop-stone.”  The hunter would climb up and sit hidden on a high limb, motionless, the drop-stone held in position over the water.  He might then have released some bits of fruit to chum.  Then, with the first sign of rippling water, the fingers let go.  The hunter remained motionless until impact.  A child could do this.  The drop-stone was the first high-powered gun.

climbing pines 3 people

I can remember my step brother, cousin and I spending every free moment running around in the desert looking for lizards and ground squirrels.  We always brought them home. That is instinct.  When we went fishing, my father told us we had to eat everything we caught, to limit our take.  Without a doubt, ancestral children were provisioning the larder.  Occasionally, massive drop stones have been discovered that could kill large prey such as hippos.  While men would have likely used these stones, most of the stones could have been handled by everyone.  Youth would have played a significant role in the success of the family and tribe.  It is unfortunate that our children have lost this position in the clan.  It brought them both respect and responsibility.    

After the stones were dropped, some inevitably became lost in the mud.  Since large amphibious reptiles normally lurk about in fishing holes, it would often have been too dangerous to retrieve drop-stones.  These animals no doubt stole the kill at times.  Some of the stones could have been retrieved during dry spells, but we’ll never know the details for certain.      

Drop-stone function is the only explanation that has ever embraced all hand axe data including locations, sizes, shapes, deposition numbers, positions in mud and weight.  The rules that determine the acceptance of a theory are dictated by Occam’s Razor.  The most parsimonious theory is the correct theory.  A drop-stone function is an elegance of parsimony. 

The most important invention of human prehistory, the invention that shows when we crossed the threshold from ape to human, was an arboreal design.  

Before there could be an Einstein there was the first Einstein.  That tree climbing Einstein gave birth to humanity when he/she combined potential gravitational energy with the first technological invention  – a teardrop-shaped cutting edge that was the high powered rifle of antiquity.  It was the most enduring invention in human history.  Tree climbing is what made us human.  Geneticists tell us we share up to 98% of our genes with apes.  This drives home the point that our brain circuitry, bodies, hands, fingers nearly everything that we are, evolved primarily for analyzing and utilizing the arboreal world.  It is very difficult to find genes that can be attributed to life at the ground.  The parsimony of my climbing theory in explaining the empirical evidence establishes it as the leading explanation for the evolution of the human body and mind. 

My book The Descent blows away the cobwebs spun during a century and a half of anthropological thought.  It rests on the single simple premise that, not long ago, our ancestors were spending much more time in trees.  In the trees, we invented language, construction, rope, knots, stone throwing, drop-stones, spears, and more.  With these inventions we were able to challenge the beasts of the savanna.  

For over thirty million years of our evolution as primates we had a safe harbor in the trees from the predators of the land.  It was only around 50,000 years ago that we moved our homes out of  that aerial kingdom and began building them on the ground.  This was so recent that this period may well have filtered down into our myths.  No wonder we place deities in sky-high kingdoms and design cathedrals with an ambiance that mimics the high limbs of old-growth trees.  No wonder our children long for a tree house.    

When I climb into a high cradle of limbs I feel as if I am going home.  I have roots embedded in the arboreal sky. Is this feeling a memory from that time when the Arboreal Continent provided us safer harbor?  Perhaps.  But what is certain is the empirical evidence telling us that what made us human were the activities our ancestors did in trees.  

It was in a high cradle in that nearly forgotten kingdom in the sky safe from leopards that we first opened our eyes to gaze in wonder at the sparkling stars of the universe.  And now a neurological celestial tree having outstretched limbs reaching to the heavens seems to be lifting us toward the stars. 

Copyright © 2014 Donald R. Perry. Published in this Blog with Dr. Perry’s permission. Pictures courtesy of TCC.