Of course anyone who truly loves books buys more of them than he or she can hope to read in one fleeting lifetime. A good book, resting unopened in its slot on a shelf, full of majestic potentiality, is the most comforting sort of intellectual wallpaper.
—  David Quammen

“Life is short, but snakes are long” - David Quammen


Reticulated Python - Python reticulatus

The reticulated python is the longest snake in the world, reaching up to 6 meters (~20 ft) long. Most reticulated pythons are shorter than this (around 5m), but on average, they are still the longest of any known species.

However, in the wild, they’re not the heaviest. That record is held by the green anaconda (Eunectes murinus). While a wild adult reticulated python can reach around 170 lbs, the adult green anaconda can weigh over 200 lbs. They’re much wider creatures, as they’re primarily aquatic (the reticulated is primarily terrestrial), and a 4.5m anaconda would likely weigh the equivalent of a 7.5m reticulated python.

Brehms Tierleben, Allgemeine Kunde des Tierreichs. Prof. Dr. Otto zur Strassen, 1913.

Collectie Tropenmuseum. Date unknown, pre-1916.

Are Humans an Outbreak?

Grist Magazine interviewed science writer David Quammen about his new book Spillover. The overall message of this great interview is that we had better prepare for the worst because animal viruses that spillover to humans (think Ebola, AIDS, SARS, avian flu) can’t stop, won’t stop. But here’s where the interview kicked it into high gear: 

Grist: In the last section of the book, you arrive at the unavoidable question: Are we ourselves an outbreak, like a disease?

David Quammen: As I say in the book, outbreaks are an ecological phenomenon. They’re not unnatural in that sense. Certain kinds of species have a propensity for these huge rises followed by these crashes. And so what I call The Analogy essentially is a question that I have put to some of the experts, including the people who study outbreaks in tent caterpillars and forest Lepidoptera: Is it reasonable to think of us humans as an outbreak population? And generally they say yes.

There has never been any large-bodied vertebrate before us on this planet that was anywhere near as abundant. There have never been 7 billion apes of any species. There have never been 7 billion water buffalo or deer of any species. There has never been anything like what we are now. And in that sense we’re an outbreak population … and the thing about outbreaks is, they end.


This April 10th through 12th, the Southwest Collection hosts the Sowell Collection Conference. The Sowell Family Collection in Literature, Community, and the Natural World contains the personal papers of some of the country’s most prominent writers who are dedicated to documenting the ways in which we interact with our world, and creating new ways of examining our world and our place within it.

David Quammen, another Collection author, is known for writing concise and highly accessible articles on scientific topics. His book, The Song of the Dodo (Scribner, 1996), in which he investigates the rate of species extinction in island ecosystems, won the John Burroughs Medal for nature writing and several other awards. In The Kiwi’s Egg (above) Quammen uses the personal letters and notebooks of Charles Darwin to explore the revolutionary scientist’s life, focusing on the tangled relationship he had with his most famous theory.

We’ve written a little more about the Sowell Collection here.


These days, wilderness is found where the weeds are. This is because cityscapes, nature reserves, fisheries - ecosystems generally - are increasingly being managed (farmed?) for the benefit of humans. Wikipedia says that “a weed is a plant in an undesired place”. But who judges desirability? Basically weeds are “unwanted plants in human-controlled settings” that grow and reproduce aggressively. Is there anywhere on the planet that is not human controlled? In his discussion of  how satellites end ‘nature’, McLuhan says no. Nature reserves and national parks are human controlled because they usually involve management of invasive species and predators.

What will happen when people stop weeding out the weeds? Humans don’t have a snowball’s chance of managing a global ecosystem of rampant invasive speciation. The world’s ecosystems have been  permanently altered on a large scale since the introduction of farming about 8,000 years ago, and particularly rapid change has occurred since the industrial revolution in the last couple of centuries. The genie is out of the bottle. Global ecosystems are now on a different trajectory, charting new territory. 

David Quammen has written an awesome article about this called Planet of Weeds. Here is a summary - which states:

“There have been five major extinctions in earth’s history and it appears that we are currently entering a sixth. The difference between the current mass extinction and those that preceeded it is that this one is human-caused; the five major threats to biodiversity being habitat destruction, habitat fragmentation, overharvesting, invasive species, and cascading secondary effects resulting from disruption of ecological connections. At the root of these problems is human population expansion, a problem which is itself complicated by the widening wealth gap between the developed and the developing nations. The biological consequence of this extinction is very likely to be that we will live in a world populated by weedy species. Loss of biodiversity and proliferation of weedy species will degrade ecosystem services and eliminate biological resources; in combination with population pressures, this will result in a far less pleasant, more stressful, and uglier world.”

The struggle between wilderness (uncontrollable nature) and management (appropriation of resources for human use) is leading to a wilderness of weeds. This is the outcome of attempting to dominate 'nature’ (or wilderness) for 8,000 or so years, because domination has lead to the eradication of what is not wanted, generating a mass extinction which leaves ecosystems incomplete and weak, providing plenty of opportunities for invasive species to spread. We’d better get used to weeds, they will be our bread and butter in the future.

External image

Gorse in Aotearoa / New Zealand

The summary of Planet of Weeds omits Quammen’s wonderful way with words as he draws readers into his grim tale. There is a lot in the article, so a number of standout sections have been cut from the original article and pasted below to generate an extended summary of sorts. The idea is that these paragraphs are here, waiting to be discussed further some other day…

“Hope is a duty from which paleontologists are exempt… they’re the coroners of biology”

“Some people will tell you that we as a species, Homo sapiens, the savvy ape, all 5.9 billion of us in our collective impact, are destroying the world. Me, I won’t tell you that, because "the world” is so vague, whereas what we are or aren’t destroying is quite specific.“

"Some people say that the environment will be the paramount political and social concern of the twenty-first century, but what they mean by "the environment” is anyone’s guess. Polluted air? Polluted water? Acid rain? A frayed skein of ozone over Antarctica? Greenhouse gases emitted by smokestacks and cars? Toxic wastes? None of these concerns is the big one, paleontological in scope, though some are more closely entangled with it than others.“

[I love what Quammen says here about 'the environment’. It is a particular bugbear of mine that people in advertising often say that if you buy a particular product you will be 'helping the environment’. What does that mean? Does 'the environment’ need help? I don’t think so - it is people that need help.]

"How many protected areas will there be? The present worldwide total is about 9,800, encompassing 6.3 percent of the planet’s land area. Will those parks and reserves retain their full biological diversity? No. Species with large territorial needs will be unable to maintain viable population levels within small reserves, and as those species die away their absence will affect others. The disappearance of big predators, for instance, can release limits on medium-size predators and scavengers, whose overabundance can drive still other species (such as ground-nesting birds) to extinction. This has already happened in some habitat fragments, such as Panama’s Barro Colorado Island, and been well documented in the literature of island biogeography. The lesson of fragmented habitats is Yeatsian: Things fall apart.”

“We shouldn’t take comfort in assuming that at least Yellowstone National Park will still harbor grizzly bears in the year 2150, that at least Royal Chitwan in Nepal will still harbor tigers, that at least Serengeti in Tanzania and Gir in India will still harbor lions. Those predator populations, and other species down the cascade, are likely to disappear. "Wildness” will be a word applicable only to urban turmoil. Lions, tigers, and bears will exist in zoos, period. Nature won’t come to and end, but it will look very different.“

"What do fire ants, zebra mussels, Asian gypsy moths, tamarisk trees, maleleuca trees, kudzu, Mediterranean fruit flies, boll weevils and water hyacinths have in common with crab-eating macaques or Nile perch? Answer: They’re weedy species, in the sense that animals as well as plants can be weedy. What that implies is a constellation of characteristics: They reproduce quickly, disperse widely when given a chance, tolerate a fairly broad range of habitat conditions, take hold in strange places, succeed especially in disturbed ecosystems, and resist eradication once they’re established. They are scrappers, generalists, opportunists. They tend to thrive in human-dominated terrain because in crucial ways they resemble Homo sapiens: aggressive, versatile, prolific, and ready to travel. The city pigeon, a cosmopolitan creature derived from wild ancestry as a Eurasian rock dove (Columba livia) by way of centuries of pigeon fanciers whose coop-bred birds occasionally went AWOL, is a weed… In gardening usage the word "weed” may be utterly subjective, indicating any plant you don’t happen to like, but in ecological usage it has these firmer meanings. Biologists frequently talk of weedy species, meaning animals as well as plants.“

"Do you see Homo sapiens as a likely survivor, I ask him or as a casualty? "Oh, we’ve got to be one of the most bomb-proof species on the planet,” he says. “We’re geographically widespread, we have a pretty remarkable reproductive rate, we’re incredibly good at co-opting and monopolizing resources. I think it would take really serious, concerted effort to wipe out the human species.” The point he’s making is one that has probably already dawned on you: Homo sapiens itself is the consummate weed. Why shouldn’t we survive, then, on the Planet of Weeds? But there’s a wide range of possible circumstances, Jablonski reminds me, between the extinction of our species and the continued growth of human population, consumption, and comfort. “I think we’ll be one of the survivors,” he says, “sort of picking through the rubble.” Besides losing all the pharmaceutical and genetic resources that lay hidden within those extinguished species, and all the spiritual and aesthetic values they offered, he foresees unpredictable levels of loss in many physical and biochemical functions that ordinarily come as benefits from diverse, robust ecosystems–functions such as cleaning and recirculating air and water, mitigating droughts and floods, decomposing wastes, controlling erosion, creating new soil, pollinating crops, capturing and transporting nutrients, damping short-term temperature extremes and longer-term fluctuations of climate, restraining outbreaks of pestiferous species, and shielding Earth’s surface from the full brunt of ultraviolet radiation. Strip away the ecosystems that perform those services, Jablonski says, and you can expect grievous detriment to the reality we inhabit.“

"Still, evolution never rests. It’s happening right now, in weed patches all over the planet. I’m not presuming to alert you to the end of the world, the end of evolution, or the end of nature. What I’ve tried to describe here is not an absolute end but a very deep dip, a repeat point within a long, violent cycle. Species die, species arise. The relative pace of those two processes is what matters. Even rats and cockroaches are capable–given the requisite conditions; namely, habitat diversity and time–of speciation. And speciation brings new diversity. So we might reasonably imagine an Earth upon which, 10 million years after the extinction (or, alteratively, the drastic transformation) of Homo sapiens, wondrous forests are again filled with wondrous beasts. That’s the good news.”

E.O. Wilson calculated that the current rate of extinction for all animals was 10,000 times greater than the background rate, a loss of biodiversity that is helping to create what the nature writer David Quammen memorably described as a ‘planet of weeds’: a simple world where 'weedy’ animals - pigeons, rats, squirrels - thrive and little else remains.
—  Mitchell, LRB, 8 May 2014, page 16.
This is for all of you spider murderers.

The Face of the Spider

David Quammen

One evening a few years ago I walked back into my office after dinner and found roughly a hundred black widow spiders frolicking on my desk. I am not speaking metaphorically and I am not making this up: a hundred black widows. It was a vision of ghastly, breathtaking beauty, and it brought on me a wave of nausea. It also brought on a small moral crisis—one that I dealt with briskly, maybe rashly, in the dizziness of the moment, and that I’ve been turning back over in my mind ever since. I won’t say I’m haunted by those hundred black widows, but I do remember them vividly. To me, they stand for something. They stand, in their small synecdochical way, for a large and important question.

The question is: How should a human behave toward the members of other living species?

A hundred black widows probably sounds like a lot. It is—even for Tucson, Arizona, where I was living then, a habitat in which black widows breed like rabbits and prosper like cockroaches, the females of the species growing plump as huckleberries and stringing their ragged webs in every free comer of every old shed and basement window. In Tucson, during the height of the season, a person can always on short notice round up eight or ten big, robust black widows, if that’s what a person wants to do. But a hundred in one room? So all right,yes, there was a catch: These in my office were newborn babies.

A hundred scuttering bambinos, each one no bigger thin a poppy seed. Too small still for red hourglasses, too small even for red egg timers. They had the aesthetic virtue of being so tiny that even a person of good eyesight and patient disposition could not make out their hideous little faces.

Their mother had sneaked in when the rains began and set up a web in the comer beside my desk. I knew she was there—I got a reminder every time I dropped a pencil and went groping for it, jerking my hand back at the first touch of that distinctive, dry, highstrength web. But I hadn’t made the necessary decision about dealing with her. I knew she would have to be either murdered or else captured adroitly in a pickle jar for relocation to the wild, and I didn't  especially want to do either. (I had already squashed scores of black widows during those Tucson years but by this time, I guess, I was going soft.) In the meantime, she had gotten pregnant. She had laid her eggs into a silken egg sac the size of a Milk Dud and then protected that sac vigilantly, keeping it warm, fending off any threats, as black widow mothers do. While she was waiting for the eggs to come to term, she would have been particularly edgy, particularly unforgiving, and my hand would have been in particular danger each time I reached for a fallen pencil. Then the great day arrived. The spiderlings hatched from their individual eggs, chewed their way out of the sac, and started crawling, brothers and sisters together, up toward the orange tensor lamp that was giving off heat and light on the desk of the nitwit who was their landlord.

By the time I stumbled in, fifty or sixty of them had reached the lampshade and rappelled back down on dainty silk lines, leaving a net of gossamer rigging between the lamp and the Darwin book (it happened to be an old edition of Insectivorous Plants, with marbled endpapers) that sat on the desk. Some dozen others had already managed dispersal flights, letting out strands of buoyant silk and ballooning away on rising air, as spiderlings do—in this case dispersing as far as the bookshelves. It was too late for one man to face one spider with just a pickle jar and an index card and his two shaky hands. By now I was proprietor of a highly successful black widow hatchery.

And the question was, How should a human behave toward the members of other living species?

The Jain religion of India has a strong teaching on that question. The Sanskrit word is ahimsa, generally rendered in English as “noninjury” or the imperative “do no harm.” Ahimsa is the ethical centerpiece of Jainism, an absolute stricture against the killing of living beings—any living beings—and it led the traditional Jains to some extreme forms of observance. A rigorously devout Jain would burn no candles or lights, for instance, if there was danger a moth might fly into them. The Jain would light no fire for heating or cooking, again because it might cause the death of insects. He would cover his mouth and nose with a cloth mask, so as not to inhale any gnats. He would refrain from cutting his hair, on grounds that the lice hiding in there might be gruesomely injured by the scissors. He could not plow a field, for fear of mutilating worms. He could not work as a carpenter or a mason, with all that dangerous sawing and crunching, nor could he engage in most types of industrial production. Consequently the traditional Jains formed a distinct socioeconomic class, composed almost entirely of monks and merchants. Their ethical canon was not without what you and I might take to be glaring contradictions (vegetarianism was sanctioned, plants as usual getting dismissive treatment in the matter of rights to life), but at least they took it seriously. They lived by it. They tried their best to do no harm.

And this in a country, remember, where 10,000 humans died every year from snakebite, almost a million more from malaria carried in the bites of mosquitoes. The black widow spider, compared to those fellow creatures, seems a harmless and innocent beast.

But personally I hold no brief for ahimsa, because I don’t delude myself that it’s even theoretically (let alone practically) possible. The basic processes of animal life, human or otherwise, do necessarily entail a fair bit of ruthless squashing and gobbling. Plants can sustain themselves on no more than sunlight and beauty and a hydroponic diet—but not we animals. I’ve only mentioned this Jainist ideal to suggest the range of possible viewpoints.

Modem philosophers of the “animal liberation” movement, most notably Peter Singer and Tom Regan, have proposed some other interesting answers to the same question. So have writers like Barry Lopez and Eugene Linden, and (by their example, as well as by their work) scientists like Jane Goodall and John Lilly and Dian Fossey. Most of the attention of each of these thinkers, though, has been devoted to what is popularly (but not necessarily by the thinkers themselves) considered the “upper” end of the “ladder” of life. To my mind, the question of appropriate relations is more tricky and intriguing—also more crucial in the long run, since this group accounts for most of the planet’s species—as applied to the “lower” end, down there among the mosquitoes and worms and black widow spiders.

These are the extreme test cases. These are the alien species who experience human malice, or indifference, or tolerance, at its most automatic and elemental. To squash or not to squash? Mohandas Gandhi, whose own ethic of nonviolence owed much to ahimsa, was once asked about the propriety of an antimalaria campaign that involved killing mosquitoes with DDT, and he was careful to give no simple, presumptuous answer. These are the creatures whose treatment, by each of us, illuminates not just the strength of emotional affinity but the strength, if any, of principle.

But what is the principle? Pure ahimsa, as even Gandhi admitted, is unworkable. Vegetarianism is invidious. Anthropocentrism, conscious or otherwise, is smug and ruinously myopic. What else? Well, I have my own little notion of one measure that might usefully be applied in our relations with other species, and I offer it here seriously despite the fact that it will probably sound godawful stupid.

Eye contact.

Make eye contact with the beast, the Other, before you decide upon action. No kidding, now, I mean get down on your hands and knees right there in the vegetable garden, and look that snail in the face. Lock eyes with that bull snake. Trade stares with, the carp. Gaze for a moment into the manyfaceted eyes—the windows to its soul—of the house fly, as it licks its way innocently across your kitchen counter. Look for signs of embarrassment or rancor or guilt. Repeat the following formula silently, like a mantra: “This is some mother’s darling, this is some mother’s child.” Then kill if you will, or if it seems you must.

I’ve been experimenting with the eyecontact approach for some time myself. I don’t claim that it has made me gentle or holy or put me in tune with the cosmic hum, but definitely it has been interesting. The hardest cases—and therefore I think the most telling—are the spiders.

The face of a spider is unlike anything else a human will ever see. The word “ugly” doesn’t even begin to serve. “Grotesque” and “menacing” are too mild. The only adequate way of communicating the effect of a spiderly countenance is to warn that it is “very different,” and then offer a photograph. This trick should not be pulled on loved ones just before bedtime or when trying to persuade them to accompany you to the Amazon.

The special repugnant power of the spider physiognomy derives, I think, from fangs and eyes. The former are too big and the latter are too many. But the fangs (actually the fangs are only terminal barbs on the chelicerae, as the real jaw limbs are called) need to be large, because all spiders are predators yet they have no pincers like a lobster or a scorpion, no talons like an eagle, no social behavior like a pack of wolves. Large clasping fangs armed with poison glands are just their required equipment for earning a living. And what about those eight eyes—big ones and little ones, arranged in two rows, all buggedout and pointing everywhichway? (My wife the biologist offers a theory here: “They have an eye for each leg, like us—so they don’t step in anything.”) Well, a predator does need good eyesight, binocular focus, peripheral vision. Sensory perception is crucial to any animal that lives by the hunt and, unlike insects, arachnids possess no antennae. Beyond that, I don’t know. I don’t know why a spider has eight eyes.

I only know that, when I make eye contact with one, I feel a deep physical shudder of revulsion, and of fear, and of fascination; and I am reminded that the human style of face is only one accidental pattern among many, some of the others being quite drastically different. I remember that we aren’t alone. I remember that we are the norm of goodness and comeliness ohly to ourselves. I wonder about how ugly I look to the spider.

The hundred baby black widows on my desk were too tiny for eye contact. They were too numerous, it seemed, to be gathered one by one into a pickle jar and carried to freedom in the backyard. I killed them all with a can of Raid. I confess to that slaughter with more resignation than shame, the jostling struggle for life and space being what it is. I can’t swear I would do differently today. But there is this lingering suspicion that I squandered an opportunity for some sort of moral growth.

I still keep their dead and dried mother, and their vacated egg sac, in a plastic vial on an office shelf. It is supposed to remind me of something or other.

And the question continues to puzzle me: How should a human behave toward the members of other living species?

Last week I tried to make eye contact with a tarantula. This was a huge specimen, all hairy and handsomely colored, with a body as big as a hamster and legs the size of Bic pens. I ogled it through a sheet of plate glass. I smiled and winked. But the animal hid its face in distrust. 

Let’s start by imagining a fine Persian carpet and a hunting knife. The carpet is twelve feet by eighteen, say. That gives us 216 square feet of continuous woven material. Is the knife razor-sharp? If not, we hone it. We set about cutting the carpet into thirty-six equal pieces, each one a rectangle, two feet by three. Never mind the hardwood floor. The severing fibers release small tweaky noises, like the muted yelps of outraged Persian weavers. Never mind the weavers. When we’re finished cutting, we measure the individual pieces, total them up – and find that, lo, there’s still nearly 216 square feet of recognizably carpetlike stuff. But what does it amount to? Have we got thirty-six nice Persian throw rugs? No. All we’re left with is three dozen ragged fragments, each one worthless and commencing to come apart…

An ecosystem is a tapestry of species and relationships. Chop away a section, isolate that section, and there arises the problem of unraveling.

An entomologist named Alan A. Berryman addressed it some years ago in a paper titled “The Theory and Classification of Outbreaks.” He began with basics: “From the ecological point of view an outbreak can be defined as an explosive increase in the abundance of a particular species that occurs over a relatively short period of time.” Then, in the same bland tone, he noted: “From this perspective, the most serious outbreak on the planet earth is that of the species Homo sapiens.” Berryman was alluding, of course, to the rate and the magnitude of human population growth, especially with the last couple centuries. He knew he was being provocative.

But the numbers support him. At the time Berryman wrote, in 1987, the world’s human population stood at 5 billion. We had multiplied by a factor of about 333 since the invention of agriculture. We had increased by a factor of 14 since just after the Black Death, by a factor of 5 since the birth of Charles Darwin, and by doubling within the lifetime of Alan Berryman himself. That growth curve, on a coordinate graph, looks like the southwest face of El Capitan. Another way to comprehend it is this: From the time of our beginning as a species (about 200,000 years ago) until the year 1804, human population rose to a billion; between 1804 and 1927, it rose by another billion; we reached 3 billion in 1960; and each net addition of a billion people, since then, has taken only about thirteen years. In October 2011, we came to the 7-billion mark and flashed past like it was a “Welcome to Kansas” sign on the highway. That amounts to a lot of people, and certainly qualified as an “explosive” increase withing Berryman’s “relatively short period of time.” The rate of growth has declined within recent decades, true, but it’s still above 1 percent, meaning we’re adding about 70 million people yearly. …

And here’s the thing about outbreaks: They end. In some cases they end after many years, in other cases they end rather soon. In some cases they end gradually, in other cases they end with a crash. In certain cases, even, they end and recur and end again, as though following a regular schedule. Populations of tent caterpillars and several other kinds of forest lepidopterans seem to rise steeply and fall sharply on a cycle of anywhere from five to eleven years. A population of tent caterpillars in British Columbia, for instance, has shown a cycle like that dating back to 1936. The crash endings are especially dramatic and for a long while they seemed mysterious. What could account for such sudden and recurrent collapses? One possible factor is infectious disease.  …

The Next Big One [pandemic] could very well be flu. Greg Dwyer knew this, which is why he mentioned it. I’m sure you don’t need reminding that the 1918-1919 flu killed about 50 million people; and there’s still no magical defense, no universal vaccine, no foolproof and widely available treatment, to guarantee that such death and misery don’t occur again. Even during an average year, seasonal flu causes at least 3 million cases and more than 250,000 fatalities worldwide. So influenza is hugely dangerous, at best. At worst, it would be apocalyptic. …

None of them [disease scientists] has disputed the premise, by the way, that if there IS a Next Big One it will be zoonotic. …

These scientists are on alert. They are our sentries. They watch the boundaries across which pathogens spill. And they are productively interconnected with one another. When the next novel virus makes its way from a chimpanzee, a bat, a mouse, a duck, or a macaque into a human, and maybe from that human into another human, and thereupon begins causing a small cluster of lethal illnesses, they will see it–we hope they will, anyway–and raise the alarm.

Whatever happens after that will depend on science, politics, social mores, public opinion, public will, and other forms of human behavior. It will depend on how we citizens respond.

So before we respond, either calmly or hysterically, either intelligently or doltishly, we should understand in some measure the basic outlines and dynamics of the situation. We should appreciate that these recent outbreaks of new zoonotic diseases, as well as the recurrence and spread of old ones, are part of a larger pattern, and that humanity is responsible for generating that pattern. We should recognize that they reflect things that we’re DOING, not just things that are HAPPENING to us. We should understand that, although some of the human-caused factors may seem virtually inexorable, others are within our control.

—  Spillover: Animal Infections and the Next Human Pandemic by David Quammen

Perhaps today you thought to yourself, I wonder what New York City booksellers recommend for fall. Well, friend, Capital has you covered–with recommendations from McNally Jackson, Housing Works, Greenlight, WORD, and BookCourt.

The redoubtable Jenn Northington–she of WORD–plugs David Quammen’s Spillover, about “the next human pandemic,” and as a special bonus, Capital also recommends Aman Sethi’s A Free Man: “Vivid and funny narrative nonfiction about an Indian day laborer—and about the slippery relationship between a journalist and his subject.”

Invasive Intelligent Species

In my previous post but one, The Native Range of Intelligent Species, I considered the problem of the range of an intelligent species in an ecological context. There is much more than could be said in elaboration of this perspective. 

The universal distribution of Homo sapiens (we require the use of machines to inhabit air and water, but, given these machines, we are the apex predator in every life zone of our planet) means that human beings are an invasive species, and it has been our unique status as the sole intelligent species that has made it possible for us to thrive in every ecosystem we have entered, effectively dictating the terms upon which other species are allowed to continue in existence. 

Humanity is the ultimate invasive species, forcing its way into non-native ecosystems and causing the extinction of endemic species. We are, in other words, a weedy species. David Quammen quotes a conversation to this effect that he had with paleontologist David Jablonski:

“Do you see Homo sapiens as a likely survivor, I ask him, or as a casualty?  ‘Oh, we’ve got to be one of the most bomb-proof species on the planet,’ he says. ‘We’re geographically widespread, we have a pretty remarkable reproductive rate, we’re incredibly good at co-opting and monopolizing resources. I think it would take a really serious, concerted effort to wipe out the human species.’ The point he’s making is one that has probably already dawned on you: Homo sapiens itself is the consummate weed.  Why shouldn’t we survive, then, on the Planet of Weeds?” (Natural Acts: A Sidelong View of Science and Nature, W.W. Norton, 2008)

It would be interesting to consider the counter-factual of an intelligent species that was not also an invasive species. An intelligent humanity that had not also been an invasive species might have remained endemic to East Africa. An endemic intelligent species would be at greater existential risk, as implied in the above quote, than an invasive intelligent species, which latter could easily survive regional extinctions. It is our invasive nature as much as our intelligent nature that has made us biologically successful to the degree we now enjoy.

If we extrapolate this beyond the geographical regions of a single planet and think of human ecology in planetary or interstellar terms (which, as I noted previously, may be the native range of an intelligence species), an invasive species that distributes itself widely is, again, tolerant to regional extinction. On a cosmological scale, a “regional” extinction might be extinction across an entire planet. But if an invasive intelligent species has entered into many different ecosystems on multiple worlds, a local or regional extinction on a single world would still leave the species intact elsewhere. However, the adaptive radiation that led an invasive species to many worlds would rapidly result in genetic drift and divergence from distinct selection pressures. Even a widely distributed species would rapidly become “endemic” to a single world.

Both the idea of the native range of an intelligent species and of an invasive intelligent species (in contradistinction to an intelligent species that was not invasive) are relevant to my previous posts on intelligence-rich biospheres. In an intelligence-rich biosphere one would expect to find a diversity of expressions of intelligence, so that different intelligent species would have different ranges, and while some intelligent species would be invasive, some would remain endemic, and perhaps as unique as the finches of the Galapagos islands. In an intelligence-rich biosphere one would expect to see the specialization of intelligence, and, with the specialization of intelligence, the narrow adaptation to a niche that would result in endemic species (or, at least, more endemic species, as we now have no endemic intelligent species on Earth). 

Because human beings have been the sole intelligent species on Earth, we have not developed an ecology of intelligence – partly because of our sense of human exceptionalism, and partly because of our lack of comparable species (much as we have no non-human civilizations with which to compare our civilization, we have no non-human intelligence with which to compare our intelligence). Given our sentience-rich biosphere, we could formulate an ecology of sentience, but I don’t think that this has been done in any kind of conscious or systematic way. We recognize that there is a distinctive ecology of mammals, most of which possess sentience to some degree, but we do not usually think of this as an ecology of sentience. We could think of it that way, but, typically, we do not.

More generally, we can imagine an ecology in an extended sense that takes account of a range of cognitive functions – a cognitive ecology, if you will, and a cognitive ecology might be considered in the context of cognitive astrobiology – all of which are emergent from consciousness (in its various grades), whether intelligence, or sentience, or any other quality of mind, and all of which profoundly affect behavioral adaptation and so figure prominently in the evolutionary history of our world (and presumably also on any other world).

Martin Johnson Heade, Cattleya Orchid and Three Hummingbirds, 1871, (detail), National Gallery of Art, Washington DC, Gift of the Morris and Gwendolyn Cafritz Foundation.