The Human Journey: Part 1

WHEN I WAS pursuing a Masters degree in anthropology in the mid 1980’s, the story of human evolution differed greatly from the present version. Back then, the list of early hominins (the group of primates that includes humans and their upright relatives) contained a mere handful of names. The most famed of the bunch was Australopithecus afarensis, a small, apish creature discovered in Ethiopia only a decade prior. Recovered from 3.7 million-year-old rocks, afarensis laid claim to the title of oldest known hominin [1] and made a plausible human ancestor. The best-preserved specimen, nicknamed Lucy, possessed a human-like thighbone and a diminutive cranium,
clear evidence that upright walking preceded big brains. Other bipeds placed on the evolutionary “main line” heading for humanity included a succession of bigger-bodied, larger-brained, smaller-faced forms, including Australopithecus africanus, Homo habilis, and Homo erectus. This sequence also represented a geologic series from oldest to youngest. Put a chimp at one end and a human at the other, and there before you was the classic conga-line progression from stooped-over ape to upright human, with the man (it was always a man) striding boldly into the future. To be fair, we students also learned about a few hominin offshoots from the main line—among them a pair of super-robust australopiths in Africa and the Neanderthals in Europe—but these creatures were clearly evolutionary dead-ends. The story’s central plot was simple and straightforward, heading in a bee-line for the pinnacle of creation. Ah, those were the days.

Back in the 80’s, you could have fit almost all known early hominin fossils from Africa onto a large table or two. But times have changed. Thanks to the dogged efforts of insightful scientists and keen fossil-finders, the past quarter century has witnessed a startling series of discoveries and insights in paleoanthropology. The bounty of recently unearthed fossils, coupled with revelations from the world of genetics, have dramatically fleshed out the human evolutionary story, and greatly complicated it as well. Umpteen new characters have been added to the dramatis personae, with the total number of hominin species now varying somewhere between 15 and 25, depending on whose counting. Key metaphors have been swapped out too. The traditional evolutionary ladder with Homo sapiens sitting on the uppermost rung has morphed into an arborescent family tree, each branch occupied by a different long lost cousin.

If we are to understand our relationship with nature, we must know something of the human journey, which is but one chapter in a much longer cosmic journey. How we conceive of humanity’s emerging cannot help but shape our views of the natural world. In a series of three posts, I will offer a synopsis of this 6 million year epic drama in three acts, each spanning roughly 2 million years. For the beginning of the story—your story—I have chosen a pivotal event that took place sometime between 5 million and 7 million years ago: the splitting of the human and chimpanzee lineages. One of these lines would culminate in the present day with relict populations totaling about 100,000 animals, all restricted to a few patches of West African forest. The other would wind up tracing the rise of a globally dominant species numbering more than 7 billion. Had you been present to witness this consequential parting of ways, it’s highly doubtful that you would have discerned any hint of such divergent futures. Those signs would come later, as evolution gradually molded the raw materials of our ancestors into a new kind of animal. So what happened? Given our shared heritage, why didn’t chimps take over the world instead of us? Answering that question is our critical task.

AS THE TIME machine sets us down in Act 1, we find ourselves immersed in a savannah-like scene in northeast Africa during the early Pliocene Epoch, about four and half million years ago. From the vantage of a circling eagle, we see a patchwork of grasslands and forest. A river with thickly wooded borders snakes lazily through the landscape, emptying into a nearby lake where catfish congregate in the depths, hippos and crocodiles lounge near the shore, and an impala herd pauses to drink. Zooming down for a closer look, we find a rhino mother and calf browsing a woodland margin. A startled family of guineafowl scurries into the underbrush. Not far off, a kudu male with august, spiraling horns plucks leafy foliage, keeping a watchful eye on his “harem,” while a giant tortoise plods along with his own reptilian concerns. Stepping into a forest patch, we enter another world, full of greenery, shadow, and birdsong. Sweltering grasslands are exchanged for a cool canopy of hackberry, palm, and fig trees. Colorful parrots and peafowl abound, accompanied by doves, lovebirds, swifts, and an occasional barn owl (minus the barn, of course). The litter of the forest floor hosts a profusion of dung beetles, snails, millipedes, and other creepy crawlies. You catch brief glimpses of lizards and rodents. A loud roaring overhead marks the arrival of a colobus monkey troop, evidently pleased to take a hiatus from leaf-eating to consume some sumptuous figs. A nearby squirrel, unhappy about the primate interlopers, chatters his objections. Although the vast majority of species here are distinct from those living today, the characters seem very familiar.

But then the rowdy colobus begin a new call, one that sounds more like an alarm. You look up to see the monkeys abruptly abandon their meal and make a rapid arboreal retreat. Moments later another hooting primate arrives. Instead of monkeys, these agile, ape-like creatures are much larger, about the size of chimpanzees yet distinctly different. Two adults move through the tree canopy on all fours, running along branches with grasping hands and feet. Four more individuals, among them a pair of juveniles, arrive on foot—two feet to be precise. They are walking upright, but with a strange gait, waddling side to side like John Wayne inflicted with serious saddle sores. Hanging by their sides are exceptionally long arms terminating in oversized, flexible hands. Now at the base of the fig tree, the animals climb with powerful, deliberate movements, more like tree sloths than colobus monkeys. Finally, the group gathers high in the canopy to feast on the ripe fruit. Watching them eat, you note that the largest individual, a male, lacks the long, dagger-like canines typical of chimps and gorillas. What is this creature?

Meet Ardipithecus ramidus—“Ardi” for short—by far the best known resident (for the moment) at the base of the hominin family tree [2]. Ardi was recovered in the Aramis region of Ethiopia, entombed within 4.4 million year-old rocks that predate Lucy by a million years. She is a marvelous, surprising amalgam of primitive and specialized features,

seemingly with one foot planted in the ape camp and the other in the human camp. In fact, Ardi’s foot is one of the best examples of this “split personality,” with the big toe directed sideways, able to grasp tree branches like an ape, and the remainder of the foot bones stiff and forward facing, well suited (at least to the eyes of some experts) to upright walking. The pelvis of Ardipithecus is similarly schizophrenic, with a flared upper portion adapted for two-legged walking and a deep lower portion suggestive of powerful climbing muscles. The brain was slightly larger than a chimp’s, and about 20% the size of a human brain. The size and shape of the teeth point to an omnivorous diet of plants, fruits, nuts, and tubers, perhaps supplemented by such delicacies as small mammals, bird eggs, and insects. Ardi’s fragmentary fossils have even been used to infer social behavior. Whereas chimp males use their oversized canines to compete aggressively for females, Ardipithecus males had small canines equivalent to those of females, suggesting to some investigators that males exhibited much less aggression toward one another. Perhaps, they argue, Ardipithecus couples formed long-term pair bonds, as humans do, an innovation that would have cascading effects down the hominin line.

At first glance, Ardi seems to be the perfect “missing link,” part ape and part human. But the notion of missing links turns out to be outdated, misguided, and, well, just plain wrong. First, and most trivially, animals like Ardipithecus clearly are not missing, but found. Second, such transitional animals are not links, a metaphor of progress closely allied with ladder rungs. Instead, such creatures are better regarded as mid-level branches that help us fill out the human family tree. Finally, although chimpanzees may be our closest living relatives, Ardi makes it clear that our last common ancestor with them differed markedly from Jane Goodall’s most beloved primate.

Gorillas and chimps both walk on the knuckles of their hands, so it’s long been thought that we humans must have passed through a knuckle-walking phase on our way to becoming bipedal. Yet Ardi lacks the stiffened hands seen in knuckle-walkers, and evidently walked on her substantial palms instead. Similarly, Ardipithecus doesn’t have the specialized arm and shoulder anatomy of our closest living ape cousins, suggesting that tree-swinging evolved in the chimp lineage sometime after the split with our ancestors. The feet too are informative. Chimpanzees are adept tree climbers in part because they lack a specialized foot bone, allowing their flexible feet to grasp branches when aloft. But that same flexibility hinders their ability to walk upright. Like us, Ardi possesses the key foot bone, suggesting that this element was lost in the chimp line sometime after the “great branching event.” In short, we didn’t evolve from chimpanzees. Far from being “primitive” or “backward,” our closest ape cousins, with whom we share more than 98% of our genes, have been on their own journey since we last parted ways in some ancient African forest.

In all, Ardi was a unique creature with a switch-hitting lifestyle, splitting her time between the ground and the trees, but likely more at home in the latter. Bipedalism, rather than offering views over tall grass or freeing the hands for tool use, may have evolved initially as a way to get around in a mixed habitat, walking upright on the ground and moving on all fours while up in the trees. As befits any arbor-loving species, Ardipithecus appears to have inhabited woodland settings, an ecological interpretation bolstered by the abundance of forest-living organisms found in the same sediments (a list that includes, by they way, all the plants and animals mentioned in our time-traveling scenario). Grasslands had been expanding in Africa for millions of years in response to a long-term trend toward drier, more seasonal climates. Yet plenty of forest patches persisted, more than enough to sustain Ardi and her kin [3].

Ardipithecus is not the only fossil representative from this earliest phase of hominin evolution. Recent discoveries of two other fossil forms, Sahelanthropus tchadensis from Chad and Orrorin tugenensis from Kenya, offer additional tantalizing clues of the chimp-human split [4]. But Ardi provides the only substantial illumination of the human journey’s first act. My strong hunch is that we’ll ultimately discover a diverse tribe of Ardipithecus-like hominins that lived between 7 million and 5 million years ago. Why? Because so little is known from this time interval and, as we shall see in the next post, experience gleaned from explorations into subsequent acts of this drama reveal an African continent populated by unexpected clans of upright cousins. Stay tuned.

Notes and References

1. The terminology applied to our nearest evolutionary relatives has changed over time. Back in the 1980’s, the word “hominid” referred only to humans and their bipedal relatives. More recently, the close genetic relationship that we share with chimpanzees and other apes has prompted a shift in terms. Today, the word “hominid” refers to the larger family of primates that includes all great apes and humans, together with their last common ancestor and all extinct members of this group. In its place, the word “hominin” is now commonly used to denote humans and other bipedal apes, including Ardipithecus, Australopithecus, Paranthropus, and extinct species of Homo.

2. White, T, D. Asfaw, B., Beyene, Y., Haile-Selassie, Y., Lovejoy, C. O., Suwa, G., WoldeGabriel, G. 2009. "Ardipithecus ramidus and the paleobiology of early hominids. Science, 326 (5949): 75–86. doi:10.1126/science.1175802

3. Not all investigators are convinced that Ardipithecus inhabited a forest setting. A study by Thure Cerling (University of Utah) and colleagues presents evidence that forests were largely limited to the banks of rivers and that grasslands were abundant even then. Tim White (University of California, Berkeley) and his team have responded by arguing, convincingly I believe, that, although grasslands were certainly present, the weight of evidence points to a forest habitat for Ardi. Cerling, T. E., Levin, N. E., Quade, J., Wynn, J. G., Fox, D. L., Kingston, J. D., Klein, R. G., and Brown, F. H. 2010. Comment on the paleoenvronment of Ardipithecus ramidus. Science, 328(1105): doi: 10.1126/science.1185274; White, T. D., Ambrose, S. H., Suwa, G. and WoldeGabriel, G. 2010. Response to comment on the paleoenvironment of Ardipithecus ramidus. Science, 328(1105: doi: 10.1126/science.1185466.

4. Brunet M. et al. 2002. A new hominid from the Upper Miocene of Chad, Central Africa. Nature, 418:145-151; Senut, B., Pickford, M., Gommery, D., Mein, P., Cheboi, K., Coppens, Y. 2001. First hominid from the Miocene (Lukeino Formation, Kenya). Comptes Rendus de l'Academie des Sciences, Series IIA - Earth and Planetary Science 332(2):137-144.

Image Sources (from top to bottom)

1. http://www.dailymail.co.uk

2. http://www.theosophy-nw.org/theosnw/evol/ev-ibel2.htm

3-5. http://www.news.sciencemag.org

6. http://www.news.sciencenews.org

Backyard Dinosaurs

“Can we go see the barn owls one more time? Pleeeeeeeeeeeeease?” That was my daughter Jade a couple of Saturdays ago. “Ok, ok,” I gave in. “Let’s go!” We found the owl couple perched in the rafters of the barn just as we’d left them an hour before, with the tan-and-speckled female wedged up against the snowy-white male. Only the male cracked open his eyes as we snuck back in for another peek. Through binoculars, their striking, heart-shaped faces appeared unreal, almost otherworldly.

It was International Migratory Bird Day, and a nearby park, Muir Woods National Monument, had organized a bird walk in celebration. Jade and I joined a group of about 15 other kids and adults. Most of us carried binoculars. Our intrepid lead birder, Dave Mackenzie, toted an even more powerful spotting scope mounted on a tripod. As we met him in the beach parking lot, he pointed at the scope and said, “Check out the Pacific Loons. We’ve seen hundreds fly by this morning heading north to their Arctic breeding grounds.” It took Jade a minute to get the hang of looking through the eyepiece, but then her eyes went wide with amazement as she watched the black-throated fish-eaters zoom past one after the other.

“Turkey vultures,” someone yelled, and all heads tilted skyward. Jade and I are accustomed to seeing “TVs,” as they are affectionately known. But today, surrounded by this group of bird-lovers, the two-toned undersides of those giant, soaring wings took on new meaning. Ravens, Bonaparte’s Gulls, and an Anna’s Hummingbird were quickly added to the list before we set off for the nearby marsh. A host of Red-Winged Blackbirds perched on cattails was there to greet us, flashing their brilliant red epaulets while their piercing metallic voices rang out. A Snowy Egret attempting merely to fly over the marsh was immediately attacked by three of the dive-bombing blackbirds. The kids were enamored with two families of Mallard Ducks, laughing as the yellow, waddling chicks did their level best to keep up. Meanwhile I was staring through the scope at a male Northern Flicker, completely absorbed by his red “mustache” and black-speckled body. A huge highlight for both of us was climbing a nearby hill to get a “bird’s eye” view into the nest of a Red-tailed Hawk. The large stick nest, nestled atop a Monterey Cypress tree, held two gangly white chicks, while one of the parents kept a steadfast watch nearby.

The surprising truth of the matter is that every single one of these winged wonders is a dinosaur, members of the same family as T. rex. All living birds are the direct descendants of small, feathered dinosaurs that lived more than 150 million years ago. Thus, in a very real sense, those raucous Red-Winged Blackbirds are backyard dinosaurs, offering a vibrant window into the distant past. In recent years, fossils of more than a dozen different varieties of feathered (nonavian) dinosaurs have been unearthed in China. So similar are many of these animals to birds that it’s difficult to tell one from the other; indeed the two are often confused. Dinosaurs aren’t extinct, then. With over 10,000 different living species, they far outnumber mammals (closer to 6,000 species). The Mesozoic Era is often called “The Age of Dinosaurs,” and the succeeding Cenozoic Era, in which we live, “The Age of Mammals.” But no, it seems that we still live in the Age of Dinosaurs. (To be fair, whether your metric is number of individuals, variation, or total biomass, the past four billion years are best regarded as the “Age of Bacteria,” but we macro-sized creatures tend to overlook the microbial world.)

In previous posts, I have bemoaned the recent startling transformation in children’s leisure time. A child growing up today is likely to spend 90% less time outdoors than a child born just one generation ago. How can we possibly build sustainable communities if people don’t care about the places they live. And how are we to care if we don’t spend any time experiencing our local natural communities? Robert Michael Pyle has referred to this frightening state of affairs as, “the extinction of experience.” [1]

I grew up playing outside and fascinated by all things nature-oriented. As a parent, I am very conscious of exposing my daughter to the nonhuman world around our home. However, I’ve found that taking her on hikes is not always welcomed. “My legs hurt daddy,” is what I hear after the first half mile—in spite of the fact that she can run around all day long with her friends. So I’ve learned to replace the word “hike” with “adventure,” a tip shared by another frustrated parent. Adults tend to be goal-oriented; when out hiking, this means reaching a particular destination. Kids are more interested in playing. By making the outing more about the moment, and less about the goal, I’ve found it much easier to keep Jade engaged and happy.

But, to retain your parental credibility, you still need to deliver on the “adventure.” This is where the magic of birds (i.e., dinosaurs) comes in. Most kids think trees and other plants are pretty ho-hum. And the majority of animals out there can be tough to find, unless you focus on the creepy-crawlies beneath your feet. But, in addition to being beautiful, active, and diverse, birds are nearly ubiquitous. A set of binoculars and an identification book (the Sibley field guides are the birding gold-standard) are all you need to get started, though feeders are an excellent way to attract birds literally into your backyard. In addition to making identifications, it’s fun to watch what birds do. (While I was out walking a few months back, a large raven flew toward me about 20 feet off the deck and inverted itself just as it passed overhead. I just stood there stunned, suddenly reminded of Tom Cruise executing the same show-off aerobatics in Top Gun.)

Now, added to all this is the T. rex angle. As I know from direct experience in my role as Dr. Scott the Paleontologist on Dinosaur Train, most kids love dinosaurs. So what better way to entice youngsters to go outside than to offer the carrot of seeing living, breathing dinosaurs?! In short, we desperately need to connect kids to local nature—both for their sake and that of the local nature—and backyard dinosaurs are arguably the most powerful tool to make these connections happen. In my recent book [2], I called for a “backyard dinosaur revolution.” So how about it? Are you in?

Jade and I have decided to get more serious about birding and begin keeping a “life list,” a logbook of bird identifications and observations. So now our “hikes” have become “treasure hunts” as we look to add more feathered neighbors to our respective tallies. Mom is excited to join in too. Just yesterday Jade asked, for the umpteenth time, “Daddy, when can we go back to see the barn owls?”

References

Pyle, R. M. 1998. The Thunder Tree: Lessons from an Urban Wildland. Lyons Press, Guilford, CT.

Sampson, S. D. 2009. Dinosaur Odyssey: Fossil Threads in the Web of Life. University of California Press, Berkeley.

All images derived from National Geographic: http://photography.nationalgeographic.com/photography/

Discovering Your Journey

Do you possess a meaningful sense of place, an emotional connection to the life and land around you? Or how about a strong sense of history, an affective connection to the deep time story of you? If you’re like most of us, your answer to both questions is no. A little reflection will reveal the immense depth of this problem. How can we ever hope to live sustainably if we don’t care about the places we live? As the late evolutionary biologist Stephen J. Gould once claimed [1], “We cannot win this battle to save species and environments without forging an emotional bond between ourselves and nature—for we will not fight to save what we do not love.”

Until very recently, virtually all cultures were rooted to their native places by origin stories—or cosmologies—that provided explanations for the origin and ordering of the world around them. Although present-day indigenous peoples and most followers of religious traditions have a cosmology, the bulk of us living in Western industrial societies don’t. Previously, I have written in this blog about the scientific Epic of Evolution, that astonishing and staggeringly beautiful account of our deep time evolutionary history that has emerged from within science over the past several decades. Following in the giant footsteps of Thomas Berry [2], I am convinced that this grand narrative, arguably science’s greatest contribution, has the potential to unite humanity and root us in both local places and deep time. Yet to date the evolutionary epic remains virtually absent from our culture. Why?

Some would point to the efforts of religious fundamentalists to suppress evolution. Others would underline Western culture’s myopic focus on the present day, with the implicit message that almost everything that came before is irrelevant. Still others would note that the deep scientific insights at the core of the cosmic story tend be highly counterintuitive; as I've said before, it’s not easy to grasp the notion that we are chunks of starstuff living on the side of a giant, spherical rock hurtling through space at thousands of miles an hour! While these factors and others are certainly involved, the single greatest obstacle preventing widespread dissemination of the Epic of Evolution may well be abstraction. To date, the evolutionary epic has been presented as a grand saga uniting all of humanity within a single cosmic unfolding. Yet absent has been a clear means of grounding this story in everyday experience, where it could assert its full emotional (as opposed to merely intellectual) impact.

At first glance it would seem that cosmic evolution has little in common with everyday experience in local places. After all, the former deals with the biggest scales of time and space, whereas the latter is concerned with the very intimate nearby. But imagine for a moment communicating the universe story entirely through reference to local characters and features. To give a few examples from my home, a forest-clad mountain might serve to tell of the origins of galaxies and stars (with all heavy elements in the rocks forged within stellar furnaces); a gurgling creek could become the vehicle for speaking of the birth of molecules (combining oxygen and hydrogen to become water); a majestic redwood could convey the story of life learning to harness the sun’s energy; a spawning salmon could become the entry point for telling of the first back-boned animals and their transition onto land; a raven flying overhead offers a fine protagonist for conveying the story of reptiles, dinosaurs, and birds; and the indigenous Miwok peoples offer a vibrant focus for telling of the birth of humans and their changing relationship to the land. The entire story might be conveyed outdoors in a natural setting, engaging the full range of listeners’ senses. The essential point here is that the key characters of the cosmic journey (galaxies, stars, landscapes, bacteria, plants, animals, culture, etc.) are all present today in one form or another in every place. So any place can be used to convey the full splendor of the cosmic saga.

This “cosmolocal approach” provides the opportunity for reciprocal illumination of place and story. On the one hand, the Epic of Evolution offers a wondrous narrative context that adds meaning to local place. On the other, local places provide the characters and direct experience that makes this evolutionary epic alive, immediate, and engaging. Each version of the story can be tailored not only to place, but also to the age and knowledge base of the audience, from children through adults. Importantly, these stories should not be presented as received ‘truths.’ After all, like science generally, the story of cosmic evolution, although well established in its fundamentals, is still provisional in some aspects, and will undoubtedly “evolve” itself. More importantly, the cosmolocal approach opens the door for each person to construct his/her own unique version of the Universe Story, selecting the most meaningful local characters with which to explore and convey this saga.

The beauty of the evolutionary epic is that it allows for an endless variety of interpretations, each one informed by specific historical, cultural, spiritual, and ecological contexts. Certainly the grand cosmic saga is not compatible with all religious beliefs,particularly fundamentalist notions of creation within the past 6,000 years. But just as the world’s spiritual traditions have adapted to the reality that the Earth does not exist at the center of the universe, so too must we now accept, indeed embrace, the fact that we live in a dynamic universe that has been unfolding for billions of years.

Ultimately, the cosmolocal approach has potential to simultaneously foster both a deep sense of place and history. This way of understanding the universe is not new, of course. Indigenous peoples have used it for many thousands of years to root their origin myths in intimate details of their homelands. It’s high time that we married this ancient wisdom with modern science to root ourselves in both local place and the greater cosmos.

In closing, I strongly recommend that you check out a spectacular, newly released documentary, Journey of the Universe, created by my very wise and talented friends, Brian Swimme and Mary Evelyn Tucker (together with a team of others). "JOTU," as the project is labeled, is the amazing culmination of many years work, offering a brief, jaw-dropping synopsis of the evolutionary epic. Go to: http://www.journeyoftheuniverse.org/

References

1. Gould, S. J. 1993. Unenchanted evening. Eight Little Piggies: Reflections in Natural History. Norton, New York. (p. 40)

2. Berry, T. 1990. The Dream of the Earth. Sierra Club Books, San Francisco.

All images derived from National Geographic: http://photography.nationalgeographic.com/photography/

The Nature of Love

Albert Einstein, that seemingly endless fount of quotations, once said, “gravitation is not responsible for people falling in love.” Ok, fair enough, but who or what is responsible? Why do we fall in love? Most of us think of love as an inspired feeling, but it turns out that our passions and attachments owe more to chemistry than to Cupid.

Of the theories I’ve seen on love, the one I find most compelling comes from anthropologist Helen Fisher [1]. Fisher speaks of three varieties of human bonding with the opposite sex, each mediated by a different neurochemical system. There’s the sex drive, linked in both males and females to that infamous hormone testosterone. Next comes romantic love, triggered by a brain chemical called dopamine. And finally there’s that deep, persistent feeling of attachment, governed by a pair of pituitary gland hormones: oxytocin and vasopressin. Think of this passionate trio as lust, love, and longing, respectively.

Why the three flavors of love? Fisher argues that the answer involves an evolutionary solution to the ancient problem of reproduction. Lust motivates us to seek sex with an assortment of partners. Love (of the romance variety) keeps us focused on just one partner at a time. And longing glues us to one partner long enough to raise a child through infancy. The three systems collaborate, . . . well, . . . shall we say, imperfectly, allowing us simultaneously to feel a deep sense of attachment for a spouse and a desire to romance another, while fighting off lustful thoughts of nameless others.

Of course, intersexual relationships are not the only kind of human bonding. There’s also mother-infant bonding as well as bonds with fathers, more distant kin, and nonkin, all of which appear to serve the function of bolstering infant survival rates. (Bonds between kin and nonkin can facilitate the formation of social networks as well). Looking beyond the human realm, we discover that chemically mediated bonding—particularly between mothers and infants, and between males and females—is rampant among birds and mammals, and for the same reasons: reproduction and survival. In the competition to pass one’s genes on to the next generation, evolution, it seems, leaves little to chance [2].

What I find especially fascinating is that some of the same chemicals are involved in these other forms of bonding. For example, oxytocin, the hormone linked to long-term attachment, shows up as a major player in the mother-infant bond. Mothers with higher levels of oxytocin in the first trimester of pregnancy tend to form stronger bonds with their infants postpartum than mothers with lower levels [3]. Oxytocin also turns out to be a primary ingredient of mother’s milk, helping baby bond with Momma. And what hormone is involved with bonding pets to their respective human counterparts? That’s right—oxytocin [4]. Although research into the chemical basis of love remains in its infancy [5], it’s no wonder that some folks call oxytocin “the love drug.”

Now, I am certainly no neurochemist. Indeed chemistry has never been one of my strong suits. (For some inexplicable reason, concepts like covalent bonding and oxidation states have always made my eyes glaze over and my brain turn to mush). Nevertheless, I’m going to make a prediction about the nature and neurochemistry of bonding. I predict that future research will reveal solid evidence of a human bond with (nonhuman) nature—what people have referred to as “biophilia” (see my previous post)—and that this bond will be facilitated by none other than our hormonal friend oxytocin.

Going further out on the limb of theory, I speculate that this effect will turn out to be strongest if strengthened by abundant childhood experience in local nature. In other words, I think that this human-nature bond will have a cultural component (plenty of time as a child exploring local natural environs) and a genetic component (neurochemical mediation by oxytocin). To my knowledge, no solid evidence exists to support any of this, but I’m sticking with it until proven otherwise.

Part of my reasoning relates to the bevy of studies that report the stress-reducing effects of being in nature, or even gazing at it out a window or on a screen [6,7]. I am suspicious that such feelings have a neurochemical basis related to human-nature bonding. But what eco-evolutionary function might such a bond serve? In other words, why on Earth would humans evolve an emotional attachment to the more-than-human world? Reproduction? Survival? Something else? The answer (or at least my current best answer) must await a future post. Thanks for staying tuned.

References

1. Fisher, H. 2004. Why We Love: The Nature and Chemistry of Romantic Love. Henry Holt, New York.

2. Broad, K. D., Curley, J. P., and Keverne, E. B. 2006. Mother-infant bonding and the evolution of mammalian social relationships. Phil. Trans. Roy. Soc. B., 361:2199-2214.

3. Feldman, R., Weller, A., Zagoory-Sharon, O., and Levine. A. 2007. Evidence for a neuroendocrinological foundation of human affiliation: plasma oxytocin levels across pregnancy and the postpartum period predict mother-infant bonding. Pscyhol. Sci., 18(11):965-70.

4. Odendaal, J. S. J. and Meintjes, R. A. 2003. Neurophysiological correlates of affiliative behaviour between humans and dogs. Veterinary Journal, 165:296−301.

5. Campbell, A. 2010. Oxytocin and human social behavior. Personality and Social Psychology Review, 14(3):281-295.

6. Ulrich, R. S. 1993. Biophilia, biophobia, and natural landscapes. Pp. 73-137 in S. R. Kellert, S. R. and E. O. Wilson (eds.), The Biophilia Hypothesis. Island Press, Washington, D.C.

7. Kahn, P. H., Jr. 1999. The Human Relationship with Nature: Development and Culture. MIT Press, Cambridge, MA.

All images derived from National Geographic: http://photography.nationalgeographic.com/photography/

Loving Life

About 4:30 am this morning, amidst a coastal downpour, my wife Toni and I awoke to the sound of two young raccoons having a WWF-style wrestling smackdown in the gathering pool of water on the skylight overhead. Smiling at the rambunctious pair going head to head, trying to toss each other “out of the ring,” I paused to wonder whether or not I really cared about raccoons—or any other “wild” animals for that matter.

So how about it? Do you love life? I’m not talking here about the concept of living; rather I refer to your emotional bond with other, nonhuman forms of life. Nothing kinky here folks. The question is whether or not you, and people generally, feel some sort of deep-felt connection to the more-than-human world.

The term “biophilia”—literally, a love of life—was first used by psychologist Erich Fromm [1] in 1964 to describe a particular psychological orientation—a vital attraction to nature, both human and nonhuman. Use of this term became much more widespread two decades later following publication of a thin volume from biologist E. O. Wilson [2]. Wilson’s “biophilia hypothesis” proposed that humans possess an instinctive tendency to affiliate with other life forms. According to this idea, biophilia is no less than a genetically mediated need resulting from numerous millennia of human evolution living in direct contact with the nonhuman world.

A diverse range of evidence has been cited in support of the biophilia hypothesis. One group of studies examined the health benefits of interacting with nature. To give an example, a group of patients who had just had gall bladder surgery were placed either into a room with windows looking out onto a natural setting or a room lacking windows [4]. By several measures—for example, pain medication needed and length of hospital stay—individuals in the former group fared significantly better than those in the latter. Health benefits following exposure to natural settings have also been reported for dental patients, prison inmates, and individuals recovering from stress [e.g., 4,5,6]. Similarly, a summary of more than 100 studies [4] reported benefits for individuals who have spent time in a wilderness area. In short, exposure to natural settings—whether through direct experience, looking out a window, or observing a photograph or video—appears to have measurable positive effects on health, both physiological and psychological.

A second group of studies looked at habitat preferences. Ecologist Gordon Orians [7] proposed that

humans have an innate tendency to prefer an “ideal” habitat with a particular trio of characteristics: 1) a savannah or park-like landscape with a mixture of forest and grasslands; 2) a body of water such as ocean or a lake; and 3) a prominence, offering a view of the surrounding terrain. In proposing the biophilia hypothesis, E. O. Wilson grabbed onto on this concept, claiming that our inherited preference for savannah settings cascades from our lengthy evolutionary heritage on the African savannah. Plenty of subsequent research [e.g., 5] has supported the existence of an innate landscape bias, although the idea has also had its detractors. For example, Jared Diamond [8] noted that humans have occupied a diverse range of habitats in the tens of thousands of years since we departed the African savannah, allowing plenty of time for inherited preferences to evolve in other landscapes. It is feasible, then, that we do not necessarily possess a genetic bias for savannah settings, but rather an innate preference for landscapes that, for much of our history, provided key elements for survival (i.e., prospect, refuge, food, and water).

Yet another group of studies has addressed the human propensity to affiliate with some animals and avoid others. As in the case of natural landscapes, exposure to animals—from fish in aquariums to birds, cats, and dogs—tends to promote physiological health and a sense of well being [e.g., 6]. Much research into so-called “human-animal bonds” has documented the great health benefits in

particular of companion animals [9].

Without doubt, the biophilia hypothesis has struck a chord with a range of environmentally minded people, from activists, educators, and conservationists to psychologists, architects, and landscape designers [e.g., 10.11,12]. Adherents have particularly embraced the implication that abundant, direct experience outdoors is an innate need, essential for a healthy childhood [e.g., 13,14]. E. O. Wilson himself [2,3] has suggested that biophilia might serve as no less than the foundational concept of a new conservation ethic. Unsurprisingly, the biophilia hypothesis has also garnered widespread support from within ecopsychology [15]. An innate propensity to affiliate with life has been seen as a framework for investigating the troubled human-nature relationship, and even a vehicle to redefine this relationship.

Yet biophilia has attracted its share of critics as well [e.g., 8,16,167], and, to be frank, has received minimal attention within scientific circles. Most telling of all is that biophilia—an evolutionary hypothesis pertaining to the human mind—has been all but ignored by the rapidly growing field of evolutionary psychology. A pair of recent books reviewing the latter discipline [18,19] lacks so much as an index listing for biophilia (although, to be fair, there are discussions of certain elements, such as habitat preferences).

Among the problems with Wilson’s hypothesis is the fact biophilia is continually defined as the human affinity for other organisms, despite the fact that people also affiliate and bond with nonliving aspects of nature. Indeed one of Wilson’s key examples of biophilia, the putative “ideal” savannah habitat, is based largely on physical elements of environment (e.g., topographic relief, water). Perhaps the most intractable problem for biophilia is its apparent lack of testability. Biophilia is generally regarded as an umbrella term designated to cover a diverse range of inherited behaviors involving our interactions with the nonhuman world. So it is difficult, if not impossible, to test the concept as a whole. One thing is clear. If we do possess an innate proclivity to affiliate with other life forms (and with nature more generally), cultural overprinting can prevent the development (or at least the persistence) of a bond with the living world. Evidence for this fact can be found in the rapidly increasing numbers of “biophobics” [10].

This debate over biophilia is not merely an intellectual exercise. Make no mistake; the stakes are high. As evolutionary biologist Stephen J. Gould [20] claimed, “We cannot win this battle to save species and environments without forging an emotional

bond between ourselves and nature as well—for we will not fight to save what we do not love.” In my view, the theoretical underpinnings of biophilia are not sufficiently robust to serve as the foundation for understanding the human bond with nature. In coming posts, I will propose an alternative hypothesis that addresses many of the key criticisms of biophilia and outlines a pathway for fostering emotional bonds with the more-than-human world.

Lying there in bed unable to get back to sleep after the big event, I decided that I really do care about raccoons, and the myriad other creatures with whom I share this place in northern California. Now if only I could figure out a way to stop those masked wrestlers from using their best moves on our garbage can!

References

1) Fromm, E. 1964. The Heart of Man. Harper & Row, New York.

2) Wilson, E. O. 1984. Biophilia: The Human Bond with other Species. Harvard University Press, Boston.

3) Wilson, E. O. 1993. Biophilia and the conservation ethic. Pp. 31-41 in S. R. Kellert, S. R. and E. O. Wilson (eds.), The Biophilia Hypothesis. Island Press, Washington, D.C.

4) Ulrich, R. S. 1993. Biophilia, biophobia, and natural landscapes. Pp. 73-137 in S. R. Kellert, S. R. and E. O. Wilson (eds.), The Biophilia Hypothesis. Island Press, Washington, D.C.

5) Heerwagen, J. H. and Orians, G. H. 1993. Pp. 138-172 in S. R. Kellert, S. R. and E. O. Wilson (eds.), The Biophilia Hypothesis. Island Press, Washington, D.C.

6) Kahn, P. H., Jr. 1999. The Human Relationship with Nature: Development and Culture. MIT Press, Cambridge, MA.

7) Orians, G. H. 1980. Habitat selection: General theory and applications to human behavior. In J. S. Lockard (ed.), The Evolution of Human Social Behavior. Elsevier, New York.

8) Diamond, J. 1993. New Guineans and their natural world. Pp. 251-271 in S. R. Kellert, S. R. and E. O. Wilson (eds.), The Biophilia Hypothesis. Island Press, Washington, D.C.

9) Walsh, F. 2009. Human-animal bonds I: The relational significance of companion animals. Family Process, 48:462-480.

10) Kellert, S. R. 1997. Kinship to Mastery: Biophilia in Human Evolution and Development. Island Press, Washington, D.C.

11) Orr, D. W. 1994. Earth in Mind: On Education, Environment, and the Human Prospect. Island Press, Washington, D.C.

12) Suzuki, D. 1997. The Sacred Balance: Rediscovering Our Place in Nature. Greystone Books, Vancouver.

13) Nabhan, G. P. and Trimble, S. A. 1995. The Geography of Childhood: Why Children Need Wild Places. Beacon Press, Boston.

14) Louv, R. 2006. Last Child in the Woods: Saving Our Children from Nature-Deficit Disorder. Algonquin Books, Chapel Hill, NC.

15) Roszak, T., Gomes, M.E. Kanner, A.D. 1995. (eds.). Ecopsychology: Restoring the Earth, Healing the Mind. Sierra Club Books, San Francisco.

16} Sagan, D. and Margulis, L. 1993. God, Gaia, and biophilia. Pp. 345-364 in S. R. Kellert, S. R. and E. O. Wilson (eds.), The Biophilia Hypothesis. Island Press, Washington, D.C.

17) Fischer, C. S. 1994. Widespread likings: Review of The Biophilia Hypothesis. Science, 263:1161–1162.

18) Buss, D. M. (ed.). 2006. The Handbook of Evolutionary Psychology. Wiley, New York.

19) Buss, D. M. 2008. Evolutionary Psychology: The New Science of the Mind, Third Edition. Pearson, New York.

20) Gould, S. J. 1993. Unenchanted evening. Eight Little Piggies: Reflections in Natural History. Norton, New York. Quotation from p. 40.

All images derived from National Geographic: http://photography.nationalgeographic.com/photography/

Interbeing

Author Note: Today, I offer a short essay posted a few days ago on Edge.org. It represents my answer to John Brockman's annual question, which this year is: What scientific concept would improve everybody's cognitive toolkit? Check out other people's answers to this question.

___________________________

Humanity’s cognitive toolkit would greatly benefit from adoption of “interbeing,” a concept that comes from Vietnamese Buddhist monk

Thich Nhat Hanh. In his words:

“If you are a poet, you will see clearly that there is a cloud floating in [a] sheet of paper. Without a cloud, there will be no rain; without rain, the trees cannot grow; and without trees, we cannot make paper. The cloud is essential for the paper to exist. If the cloud is not here, the sheet of paper cannot be here either . . . “Interbeing” is a word that is not in the dictionary yet, but if we combine the prefix “inter-” with the verb to be,” we have a new verb, inter-be. Without a cloud, we cannot have a paper, so we can say that the cloud and the sheet of paper inter-are. . . . “To be” is to inter-be. You cannot just be by yourself alone. You have to inter-be with every other thing. This sheet of paper is, because everything else is.”

Depending on your perspective, the above passage may sound like profound wisdom or New Age mumbo-jumbo. I would like to propose that interbeing is a robust scientific fact—at least insomuch as such things exist—and, further, that this concept is exceptionally critical and timely.

Arguably the most cherished and deeply ingrained notion in the Western mindset is the separateness of our skin-encapsulated selves—the belief that we can be likened to isolated, static machines. Having externalized the world beyond our bodies, we are consumed with thoughts of furthering our own ends and protecting ourselves. Yet this deeply rooted notion of isolation is illusory, as evidenced by our constant exchange of matter and energy with the “outside” world. At what point did your last breath of air, sip of water, or bite of food cease to be part of the outside world and become you? Precisely when did your exhalations and wastes cease being you? Our skin is as much permeable membrane as barrier, so much so that, like a whirlpool, it is difficult to discern where “you” end and the remainder of the world begins. Energized by sunlight, life converts inanimate rock into nutrients, which then pass through plants, herbivores, and carnivores before being decomposed and returned to the inanimate Earth, beginning the cycle anew. Our internal metabolisms are intimately interwoven with this Earthly metabolism; one result is the replacement of every atom in our bodies every seven years or so.You might counter with something like, “Ok, sure, everything changes over time.So what? At any given moment, you can still readily separate self from other.”

Not quite. It turns out that “you” are not one life form—that is, one self—but many. Your mouth alone contains more than 700 distinct kinds of bacteria. Your skin and eyelashes are equally laden with microbes and your gut houses a similar bevy of bacterial sidekicks. Although this still leaves several bacteria-free regions in a healthy body—for example, brain, spinal cord, and blood stream—current estimates indicate that your physical self possesses about a trillion human cells and about 10 trillion bacterial cells. In other words, at any given moment, your body is about 90% nonhuman, home to many more life forms than the number of people presently living on Earth; more even than the number of stars in the Milky Way Galaxy! To make things more interesting still, microbiological research demonstrates that we are utterly dependent on this ever-changing bacterial parade for all kinds of “services,” from keeping intruders at bay to converting food into useable nutrients.

So, if we continually exchange matter with the outside world, if our bodies are completely renewed every few years, and if each of us is a walking colony of trillions o f largely symbiotic life forms, exactly what is this self that we view as separate? You are not an isolated being. Metaphorically, to follow current bias and think of your body as a machine is not only inaccurate but destructive. Each of us is far more akin to a whirlpool, a brief, ever-shifting concentration of energy in a vast river that’s been flowing for billions of years. The dividing line between self and other is, in many respects, arbitrary; the “cut” can be made at many places, depending on the metaphor of self one adopts. We must learn to see ourselves not as isolated but as permeable and interwoven—selves within larger selves, including the species self (humanity) and the biospheric self (life). The interbeing perspective encourages us to view other life forms not as objects but subjects, fellow travelers in the current of this ancient river. On a still more profound level, it enables us to envision ourselves and other organisms not as static “things” at all, but as processes deeply and inextricably embedded in the background flow.

One of the greatest obstacles confronting science education is the fact that the bulk of the universe exists either at extremely large scales (e.g., planets, stars, and galaxies) or extremely small scales (e.g., atoms, genes, cells) well beyond the comprehension of our

(unaided) senses. We evolved to sense only the middle ground, or “mesoworld,” of animals, plants, and landscapes. Yet, just as we have learned to accept the non-intuitive, scientific insight that the Earth is not the center of the universe, so too must we now embrace the fact that we are not outside or above nature, but fully enmeshed within it. Interbeing, an expression of ancient wisdom backed by science, can help us comprehend this radical ecology, fostering a much-needed transformation in mindset.

Image Credits

All images courtesy of National Geographic: http://photography.nationalgeographic.com/photography/