Thorn Trees, Avocados, and VLS's (Very Large Sloths)

Photo by Greg Hume, Wikimedia Commons

This weekend I went for a walk with two of my friends through a swamp outside New Orleans. We saw plenty of waterbirds, three young alligators, some burly swamp rabbits, and a total of seven snakes. But what impressed my companions most was a honey locust tree we came across. Those are fairly common where I'm from in Arkansas, but they aren't common here, and they had never seen one before. Hearing them talk about it, I started seeing it with new eyes. The honey locust really is a stunning tree, with its clusters of icepick-sized thorns along its limbs and trunk. It's clearly not a tree to be trifled with.

Then my friends asked a question that I had never thought to ask: why does need such huge thorns? What assailant is it protecting itself from? Is it just paranoid?

None of us had any ideas, so we kept walking and forgot about it. But the next night, in one of those weird little jolts of serendipity, I stumbled across a possible answer. I was leafing through a picture book about natural history, and saw the following passage in the section on plants: "Species with fleshy fruits use animals to disperse their seeds: many of them are swallowed whole and then scattered by birds. In prehistoric times, wild avocados may have been dispersed by giant ground sloths."

That's right, giant ground sloths. They really existed. One of the most jaw-dropping things I have ever seen is a skeleton of one of these in the Smithsonian. I had seen the dinosaurs and pterodactyls skeletons and been duly impressed, but then, in the Ice Age hall, I came across the towering skeleton of Eremotherium; one of the largest of the ground sloths. The thing is just gigantic--as big as an elephant standing on its hind legs. You could build a small tree house between its pelvis and its ribcage...and it's a sloth. I stood there and stared at it like I was three years old.

Photo by Postdlf, Wikimedia Commons

Ground sloths were superficially built like long-armed bears, and like bears, they could stand on their hind legs. Some of them could reach nearly 20 feet into the trees to browse on buds, leaves, and fruit. And some of these fruits may have co-evolved with ground sloths and other big ice age mammals, as a way to disperse their seeds.

Plants can do many things, but what they can't usually do is get up and move around. That means they have to find ways to reproduce while being stuck in the same spot all their lives. They have to get their pollen to each other somehow, and then they have to scatter their seeds so that their offspring won't grow up right on top of them. Pollen is mostly spread by the wind, or by bribing or tricking flying animals like insects, hummingbirds, and bats.

Plants scatter their seeds in equally inventive ways. Dandelions and cottonwoods send them aloft on little cottony parachutes. Maple and sycamore seeds whirl like helicopter blades as the wind catches them, and the Javan cucumber's seed has wings like a hang glider. The seeds we call burs hitch rides on animals, and on our pant legs. Coconuts disperse by floating in the sea, sometimes drifting hundreds of miles from their parent plant. Some fruits dry up and explode. Impatiens are a familiar example--their fruit may burst if you touch it, which is why they are also called Touch-Me-Nots. But even more impressive is the Sandbox Tree, AKA the Dynamite Tree. Its fruits explode with a deafening blast, launching seeds over 150 feet away.

Of course, many fruits have evolved to entice animals to eat them. Plants don't put all that energy into producing sweet, tasty fruit because they have benevolent spirits. They do it to spread their seeds. Some seeds can't even germinate unless they've been through the gut of an animal. This often weakens their tough coating, and as a bonus, the seeds end their intestinal journey in a little dollop of fertilizer on the ground.

And that brings us back to avocados. Avocado seeds are too big for most modern creatures to swallow regularly, but huge prehistoric creatures like ground sloths might have gulped them down without even thinking about it, and then deposited them later in their poop, the way birds deposit blackberry seeds. Today, the ground sloths are gone, and avocados might have dwindled away too if people hadn't come along and started cultivating them. Perhaps that's only fair, since we may be what killed off the ground sloths in the first place, along with a host of other Pleistocene creatures of the Americas, including giant bison, mammoths, mastodons, and four-tusked gompotheres; as well as the predators who relied on them--massive dire wolves, sabertoothed cats, and 1800-pound short-faced bears. The fauna of the Americas was as impressive as the African savanna until a few thousand years ago--right around the time the first humans seem to have arrived. Of course, the climate got a lot warmer at the same time, so the jury hasn't declared humans guilty beyond a reasonable doubt. But they're eyeing us pretty suspiciously.

Anyway, it may be that avocados weren't the only plants left without partners by the extinction of the big mammals. Another tree I grew up around, the Osage orange, may have co-evolved with mammoths, mastodons, and their relatives. These trees once had a wide range across North America, but today they are confined mostly to Texas, Oklahoma, and Arkansas. Some biologists think this may be because their giant dispersers disappeared. In most places, Osage orange fruits simply pile up and rot under the tree. Most modern native animals ignore them, but horses eat and distribute them now. That has a certain symmetry, since Osage oranges would have evolved with native horses of the Americas, which went extinct at the end of the ice age. The reintroduction of horses from Europe may have reintroduced two old friends.

And what about the honey locust, with its menacing spikes? It's another tree that may have co-evolved with giant mammals. As prickly as it is, it's called the honey locust for good reason--its seed pods are filled with a sweet-tasting pulp that probably evolved to attract large animals, who would eat the seeds along with the pulp. If the seed pods aren't eaten, they just fall to the ground, and the seeds inside will be destroyed by insects. But if they get eaten by a large herbivore, they will pass through its gut unharmed. This is actually what happens with relatives of the honey locusts in Africa, the acacias. Elephants help disperse some acacia seeds by eating the pods. The insects attacking the seeds are killed, but the seeds do just fine; and are actually much more likely to germinate if they've made a trip through pachyderm innards. But elephants and other large mammals can be hard on acacias, too--stripping their bark, pushing them over, and browsing too many of their leaves. That's why acacias have thorns--to deter this sort of thing. Their cousins, honey locusts, have even bigger thorns. And maybe that's the answer to my friends' question. Why does that tree we looked at just this weekend have such huge thorns? Maybe it's still trying to protect itself from giant creatures that disappeared thousands of years ago. Those great beasts may seem almost mythical to us, but they were very real, and museums are full of the bones to prove it. They were certainly real to the honey locust, and it still has its thorny daggers ready, in case they ever return.

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Anachronistic Fruits and the Ghosts Who Haunt Them / Connie Barlowe

The Trees that Miss the Mammoths / Whit Bronaugh

Saving the Seeds (David Attenborough clip on acacias and elephants)

Endless Forms Most Wonderful

It's time, as the old song says, to accentuate the positive. My last couple of posts took a pretty jaundiced view of the living world, focusing on some of its more ghastly creatures. They're out there, but I don't want to dwell on them too much. Nature has produced plenty of wonder and beauty, too. What's most wondrous to me is the diversity of life--the amazing variety of ways to be a living organism. There are nine-pound crabs that climb trees but can't swim, and spiders that live their whole lives under water, wearing a web-bubble full of air. Bacteria flourish under Antarctic ice, and algae turn snowfields pink high in the mountains. In 1995, scientists found a creature that lives only on the mouth bristles of lobsters. I'm convinced you could study life on Earth for a thousand years and and never run out of surprises.

Life has been evolving for at least 3.5 billion years, creating millions of different species, each with its own unique--and often completely astounding--way of getting by in the world. The best estimates put the number of species on Earth today at around 8.7 million, and the ones living today are just a small percentage of all the species that have ever lived. The earth has seen entire dynasties of living organisms rise, diversify for tens of millions of years, and finally go extinct.

Our species, then, is a single living branch on an ancient tree; one of mllions of other branches. Before I talk about some of the weirder branches, it's worth mentioning a couple of things about the tree's major limbs, because our understanding of those has changed a lot in the last 50 years or so. There's still a lot of misunderstanding out there--lots of people still think you can classify every living thing as a plant, an animal, or a microbe. It's not that simple.

Early taxonomists like Linnaeus classified the natural world into three kingdoms: animal, vegetable, and mineral. Linnaeus classified living things using a hierarchy of categories (kingdom, phylum, class, etc.). One kingdom includes multiple phyla, which themselves include multiple classes, and so on. This system can be represented as a branching tree, but Linnaeus lived before Darwin, so he thought of it more as an organizational chart than a genealogical tree. In the mid-1800's, though, scientists started thinking of living things changing and diversifying over time, and Darwin explained the basic mechanism by which that happened. The tree of life turned out to be a true family tree.

The more biologists learned about the tree of life, the more complex it got. Microscopic organisms were given their own kingdom, Protista, as in this 1866 diagram by Ernst Haeckel. Then people realized that life has even broader divisions than kingdoms. Two of the deepest branches in its tree are between prokaryotes--simple cells with no nucleus, like bacteria--and eukaryotes, whose cells are more complex, and nucleated. Then prokaryotes themselves were found to contain two distinct groups: bacteria, and another kind of microscopic organism called archaea. Fungi turned out not to be a kind of plant, but an entirely separate kingdom, more closely related to animals. 

Today, most biologists divide the tree of life into three domains: Bacteria, Archaea, and Eukaryotes, as in the tree below. Each of these domains has deep divisions that correpond to kingdoms. Animals, plants, and fungi are still considered kingdoms within the eukaryotes, but so are other groups of eukaryotes. Single-celled eukaryotes like amoebas, giardia, and euglena are informally referred to as protists, but that's just a term of convenience, not a real biological group. Some non-animal/plant/fungi eukaryotes, like kelp, are multicellular and big enough to form underwater forests.

From Wikipedia

Now let's get into the fun stuff--the amazing diversity of lifestyles in nature. As animals, we get our energy and basic building blocks (organic molecules) by eating other organisms. Plants, of course, make their living in a totally different way. They get energy from the sun, and then use it to assemble their own organic molecules from scratch. Most people figure that since plants grow out of the dirt, they must be made of dirt. But they aren't. Soil just provides minerals and other nutrients. If you weigh the soil in a pot, then grow a five pound plant in it, and then weigh the soil again, you won't find much difference before and after. Plants literally build themselves out of air and water, using sunlight. Carbon dioxide in the air provides the carbon that forms the backbone of organic molecules. This trick, of course, is called photosynthesis, and it makes life possible for most living things--even the ones, like us, who can't do it. But plants didn't invent photosynthesis. Bacteria learned it long before plants existed, and so did many single-celled protists (some of which hedge their bets and eat other organisms too). 

Some bacteria and archaea get by in more exotic ways. Many can build their own organic molecules without light, using energy from chemicals like sulfur, iron, and even ammonia. Some of these weird organisms support ecosystems that grow in total darkness, around boiling volcanic vents at the bottom of the sea. There they form symbiotic relationships with seven foot tubeworms, who shelter them inside their bodies. Not how I would want to live, but it works for them.

Unexpected symbioses like that are common. Lichens are a symbiotic amalgam of algae and fungus. Termites and cows rely on bacteria in their guts to digest cellulose. Figs need tiny wasps inside their fruits in order to reproduce, which is why some vegans and squeamish biology majors won't eat figs. The bobtail squid of Hawaii harbors symbiotic bacteria that allow it to glow in the dark. Kudzu, soybeans, and alders develop nodules on their roots to house bacteria that help them use nitrogren. 

In plants and protists, photosynthesis itself is based on an ancient symbiosis. Chloroplasts, the photosynthetic cellular organs inside their cells, originated as bacteria that took up residence inside other organisms. Sometimes this process happened twice. For example, red agae is a kind of seaweed that isn't related to plants. Once upon a time, a single-celled ancestor of red algae engulfed photosynthetic bacteria and gained the ability to photosynthesize. Later, other eukaryotes called chromealveolates engulfed the red algae cells, creating a double-layer of internal symbiosis. They went on to form a major lineage of eukaryotes, which include several kinds of algae, as well as kelp, diatoms, and the parasites that cause malaria. It's a family with diverse interests. The red algae, meanwhile, formed several multicellular lineages, some of which get hardened with calcium and build reefs alongside corals (which are colonial animals).

It's a strange, unexpected world out there. Think of the amazing variety just among the plants. There are plants in the desert called living stones that avoid herbivores by looking like rocks. Here in Louisiana I see resurrection ferns along the limbs of live oak trees. They get their name because they look stone dead when it's dry, but then they have a green resurrection as soon as it rains. The titan arum of Sumatra produces a flower that can be ten feet tall. It's pollinated by flesh flies and carrion beatles, which is why it smells like something crawled into it and died. 

Plants have been co-evolving with insects for millions of years, forming some truly astounding relationships. Bee orchids get pollinated by tricking bees into trying to have sex with their flowers. Spider orchids trick wasps into stinging them. Darwin's orchid, like many flowering plants, bribes insects with nectar. But it keeps it at the bottom of a tube that can be over ten inches long. When Darwin saw it, he predicted that a moth would be found with a 10-inch proboscis, long enough to reach the nectar. The moth was discovered years later, after Darwin was dead.

The organisms that most capture the human imagination are our fellow animals. They're a stunningly diverse bunch, from lowly sponges and hideous tapeworms to lions, tigers, and bears. Animals have some strange lifestyles and behaviors themselves. There are male jumping spiders that flare their backsides like peacocks and wave their arms in the air to woo females. Scallops, which look like flattened clams, can swim away from predators by flapping the two halves of their shell together. Water beetles breathe through their rear ends (and some turtles can do the same thing). The boxer crab, also known as the pom-pom crab, is so-named because it holds a tiny, stinging sea anemone in each of its pincers. When threatened, it gives its opponent an anemone sandwich. Sometimes nature is dowright hilarious.

Our own group of animals, the vertebrates, is also full of surprises. Consider the world of fish. The first surprising thing about them is that they aren't a coherent biological category. Cartilaginous fish like sharks and rays are very different from bony fish like catfish or bass, and those, in turn, are different from lobe-finned fish like coelacanths (famous "living fossils") or lungfish. Lobe-finned fish were the ancestors of four-legged vertebrates, which means a lungfish is more closely related to us than it is to a shark. 

Fish have been around long enough to evolve into some truly weird forms. The gulper eel is basically a giant set of jaws with a tail, and it can swallow things much larger than itself. The tip of its tail glows, too, in case it wasn't freaky enough already. The eyelight fish, one of several kinds of flashlight fish, has bioluminescent lights under each eye. The barreleye has eyes on barrel-shaped stalks, enclosed inside a transparent dome on its head. The deep sea anglerfish is famous for the glowing lure that hangs from its forehead, and for being butt ugly. But the weirdest thing about it is its sex life. Male anglerfish are tiny, and when they find a female they attach themselves to her permanently, and then sort of dissolve on the inside, basically becoming a bag of gonads. Some females have five or six of these dangling off of them. Who says romance is dead?  

Then there's the flying fish, famous for leaping out of the water and gliding for hundreds of feet on wing-like fins. This is so well-known it's easy to forget how odd it is--this is a fish we're talking about here. But gliding isn't unusual among vertebrates. It's evolved several times. Wallace's flying frog flares out its fingers and toes and glides on the membranes in between. Flying lizards flare out their ribcages as wings. Flying snakes flatten their bodies, launch themselves out of trees, and glide by slithering through the air. Among the mammals are the flying lemurs and flying squirrels. They both glide with flaps of skin between their front and back legs, but they aren't closely related, which means their abilities evolved separately. Gliding must be a handy trick.

Gliding is just one of many weird, wonderful traits among animals. Possibly the most amazing of all, for my money, is this: baleen whales--the largest animals that ever lived--have an expandable mouth, like a pelican. They can hold more than their weight in water in their mouth...and some of them weigh nearly 200 tons. They take in all that water, strain krill out of it, and spit it out again. These behemoths are out there doing that right now, in oceans around the world. 

That kind of fact boggles my mind. But it's just one of many such facts about animals. And animals are just a part of a huge, diverse tree of life, and even life is just one aspect of the natural world. It's easy to get carried away talking about all the wonders of nature, and that's just what I've done in this long, rambling post. I can't help it. It's an astonishing world out there.

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The frog and tree pictures above are both by the German biologist Ernst Haeckel. If you haven't seen his natural history illustations, I urge you to check them out. 

The Lord God Made Them...All?

Peaceable Kingdom, Edward Hicks 1834

I've always loved James Herriot's books about his life as a Yorkshire veterinarian. That was pretty much inevitable, since I'm the son of an English teacher and a rural veterinarian. The books are full of comical but kind-hearted stories about eccentric creatures and their even more eccentric owners, and they're pretty much delightful all the way through. If you find yourself in a bad mood, Dr. Herriot offers good medicine.

The title of one of his books, which is often used as the title of the whole set, is All Creatures Great and Small. This comes from the second line of an Anglican hymn called Maker of Heaven and Earth, written by Ms. Cecil Frances Alexander in the 1840's. Its first verse goes:

All things bright and beautiful,
All creatures great and small,
All things wise and wonderful,
The Lord God made them all.

Once Herriot had used the second line, it was a no-brainer to use the other three for the titles of later books. I always liked those four lines. They really do fit the books perfectly, with their unabashed innocence and reverence. They don't match the more cynical, ironic aesthetic you find these days at all, but that's fine with me. 

But the rest of the hymn, it turns out, isn't as charming. Besides getting a bit too cutesy, it also includes this uncomfortable little verse: 

The rich man in his castle,
The poor man at his gate,
God made them high and lowly,
And ordered their estate.

Yikes.

That's not the only part of the hymn I can't agree with, though. As much as I like the first verse, I don't think the Lord God really made them all, any more than I think he made the 19th century English class system. Science has made it clear that all the animals on earth, as well as all the plants, fungi, diatoms, bacteria, etc, were shaped by evolution, not God. If there is a God, maybe he set the whole thing in motion, but even if the theory of evolution had never been formulated, I still wouldn't believe God could have crafted each of the living things on earth himself. Not if God is good, as most theists think he is.

Because the thing is, all things aren't bright and beautiful, much less wise and wonderful. Some creatures are really just horrid. I learned this at an early age, because as I said, my dad is a veterinarian. For as long as I can remember, he's had a jar in his office with a dog's heart in formaldehyde. The dog was killed by the heartworms that are still packed into its heart like a fistfull of vermicelli. Dad brings it out to show people why they need to get their dog on heartworm prevention medicine. It works. He's also got a jar of sheep bot fly larvae, and the less said about their life cycle, the better. Suffice it say you don't want to be a sheep.

When people wax eloquent about how God crafted all creatures great and small, they don't usually have heartworms or bot flies in mind. They talk about lambs, or hummingbirds, or whales...the beautiful people of the animal kingdom. But really, those who believe there's a God, and that he is good, might want to think twice about crediting him with some of the other creatures. Did God create the heartworm as well as the lamb? Did he create the bot fly that lays its eggs in that lamb's nose (sorry, TMI). Did he create the brain-eating amoeba and the bubonic plague...or the fleas that carried it...or the rats that carried them? Did he devise the lifecycle of the parasitic wasps I discussed in my last post? Did he teach the little cuckoos, laid in another bird's nest, to hatch early and push the rightful eggs over the edge? Do we really want to chalk those things up to God? 

The irreverent geniuses of Monty Python made the same point, lampooning Ms. Alexander's optimistic little hymn with their version; All Things Dull and Ugly, which begins:

All things dull and ugly
All creatures short and squat
All things rude and nasty
The Lord God made the lot 

Each little snake that poisons
Each little wasp that stings
He made their brutish venom
He made their horrid wings

Now, some may think I'm doing a sort of reverse cherry-picking, by choosing some especially yucky creatures to talk about. Surely those are in the minority? Well, no. Most people think parasites are on the yucky side of creation, and if you include bacteria and viruses in the definition of "parasite", then parasites may outnumber "free-living species" four to one. Parasites strike us as especially uncalled for, but they aren't the only source of nastiness in the living world. Male ducks, for example, practice something euphemistically known as "forced copulation". Among mammals, infanticide is rampant. There are snakes that lie in wait in nests, and welcome hatching babies into the world by eating them. They've been doing this since the hatchlings were dinosaurs. Most species on earth either eat, or are eaten by, other species. Many do both, of course (though they tend to have the second experience only once). 

If God is good, and God made the natural world--designing each organism in its turn--why is there so much pain and strife in nature? If you're going to credit a supernatural creator, Satan seems like a better candidate than God for some of what goes on out there. Doesn't Old Scratch seem more likely, for example, to have arranged for baby sharks to eat each other in the womb? That has his stamp all over it. As Darwin himself said, "What a book a devil's chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel work of nature!"

You can believe that God is good, or you can believe that He created every species personally, but I don't see how you can believe both at the same time. This leads to a surprising thought. If you want to keep believing God is good, it actually makes more sense to believe living species were created by a blind, amoral process of natural selection than individually by God. Natural selection is where all the evidence points, anyway, and it doesn't put us in the position of trying to explain why God made the liver fluke and the Guinea worm. Or, for that matter, why Satan did. The idea that those things evolved by blind natural processes may not be especially uplifting, but it's not as depressing as thinking they were created by a vengeful God or the evil king of the underworld.

But enough about the nastiness of the living world. It is an undeniable fact, but there's a lot more to nature than that. As shocked as Darwin was by waste and cruelty in nature, he also found nature awe-inspiring. This is apparent in these beautiful and oft-quoted concluding lines of The Origin of Species: 

Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

In later editions of the book, Darwin actually changed the text to say "breathed by the Creator." I'm not sure whether he believed this, or if it was meant to make the idea more palatable to the public. Darwin himself seems to have been an agnostic later in life. Whatever the implications of his theory for religion, Darwin was right about evolution, and I think he was also right about nature's grandeur. It really is full of "endless forms most beautiful and most wonderful". Nature may be amoral, but it's astonishingly creative; inventive beyond all human imagining. Some of those creations are beautiful, and some are awful, but all of them are amazing in one way or another.

From salt-loving bacteria in boiling volcanic pools, to horned narwals navigating though arctic ice, the variety of life is stunning. This world has seen dragonflies the size of crows and giant ground sloths the size of elephants. There are fish that fly and birds that swim; flowers that mimic insects and insects that mimic flowers. In the Rocky Mountains there are aspen groves--single organisms connected at the roots--covering dozens of acres and living for tens of thousands of years. You could study the living world all your life and never run out of wonders to marvel at. The Lord God didn't make them all (and that should be good news for people of faith), but that doesn't mean the world can't be bright and beautiful.

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Do Parasites Rule the World? / Carl Zimmer

I discovered Monty Python's version of the hymn, and Darwin's remarks about a devil's chaplain, in Richard Dawkins' excellent book The Greatest Show On Earth.

Rough Beasts

I have an odd habit. I'm always watching for interesting flowers and insects, taking pictures of them, and posting them on Facebook--as if everybody thought they were just as fascinating as I do. And sometimes they do. The other day, a friend (who, unlike me, actually makes a living as a writer) suggested I write about some of the weird bugs I see. It seemed like a good suggestion. I've let myself get too preachy on this blog anyway, and besides, she's a professional and I should probably listen to her.

The only problem, though, is that if you look closely at the world of insects, what you see tends to be kind of horrifying. As Annie Dillard put it, "Fish gotta swim, birds gotta fly; insects, it seems, gotta do one horrible thing after another."

It's true. Insect behavior can remind nature lovers like me not to romanticize the natural world too much. Nature can be achingly beautiful, but it's also for the most part amoral. It's not cruel--cruelty requires consciousness--it's just blind to things like hope, pleasure and pain. In the poem The Second Coming, Yeats talked about a "rough beast...its gaze blank and pitiless as the sun." Most of the time, nature is just such a beast.

Sometimes it seems the like littler nature's beasts are, the rougher they get. For example, the other day I spotted this little drama on a blade of grass. A katydid was in the grip of Sphex nudus, the Katydid Wasp. In the picture it looks like the katydid is about the become the wasp's dinner, but actually...it's worse than that. Digger wasps like Sphex nudus sting their prey to paralyze them, and then bring them back to their nests, which are burrows in the ground. Then they deposit them in one section of the nest, lay an egg, and seal the chamber up. When the egg hatches, the larva will feed on its living larder. The wasps are parasites (parasitoids, technically, but we won't get into that).

This katydid may have escaped that fate, because the wasp got alarmed by my camera and dropped it. I like to think the katydid hadn't been stung yet, and that the wasp didn't come back. But I don't know. I also like to think katydids are absolute automatons, as incapable of conscious experiences like pain and fear as a wind-up toy robot. At least I hope that's true of the ones that run into Katydid Wasps. But I don't know that either, and I suspect it's not entirely true. And evolution doesn't care either way. If evolution is blind to pleasure and pain, then behaviors like this will evolve whether or not the victims are conscious of what's happening to them.

And evolve they do, over and over again. Among the Katydid Wasp's cousins are the similarly thread-waisted Mud Daubers. We called these Dirt Daubers where I grew up in Arkansas, and in my family they were considered the good guys of waspdom, because they almost never sting. Well, they almost never sting people. They do sting spiders, for the same reason Katydid Wasps sting katydids. Mud daubers build their little adobe nests and give each larva its own compartment, well-stocked with several paralyzed spiders for it to dine on. The Blue Mud Dauber's young mostly eat Black Widows. How's that for tough?

I discovered the "good guy" mud dauber's dark secret for myself as a kid, when my mom had me knocking old mud dauber nests off the ceiling of our porch. I broke one open out of curiousity, and dead spiders cascaded down my arm, as I did lively little dance of terror. Maybe is was the Tarantella.

Whatever their secrets, mud daubers have enemies of their own, and some of them are other wasps. I encountered one of these a couple of years ago. I heard a constant buzzing sound at my back door, and when I went outside to look, I found a mud dauber nest on the screen. On it was a little iridescent wasp, so pretty it could have been made by Carl Fabergé, busily chewing its way inside. That seemed a little odd to me, so I went back inside and looked it up. It turned out to be a Cuckoo Wasp, and like its avian namesake, it's a brood parasite--it lays its eggs in the nests of others. When the Cuckoo Wasp larva hatches it proceeds to eat the Mud Dauber larva, as well as its paralyzed guests. Naturally, the mother Mud Dauber doesn't appreciate that, and it will attack the Cuckoo Wasp if it catches it. But the Cuckoo Wasp is ready. Its jewel-like exoskeleton is armored, and it just rolls itself up into a defensive ball like an armadillo. The proprietor of the nest usually can't do much but pick it and bounce it from the nest. Whereupon it simply unrolls and tries again. The Cuckoo Wasp is a tiny little reflection of nature itself: gorgeous and amoral.

Life isn't easy, even for wasps tough enough to feed their babies paralyzed spiders. Sometimes it's downright embarrassing (or would be if wasps had the brains to be embarrassed). Like many insects, spider-hunting wasps can be fooled by an organism with no brain at all--an orchid. Most people have heard how some orchids mimic female bees or wasps. The haplessly horny males try to mate with the orchid, and end up with packets of pollen stuck to their bodies. But they don't learn from their mistake, so they deposit the pollen on the next orchid they try to get cozy with. It's probably a good thing orchid flowers aren't as big as humans, because some guys would probably pollinate them, and just imagine what those flowers would look like.

Moving on...Spider Orchids of the genus Brassia use a slightly different tactic. They really do look like spiders, at least enough to fool certain wasps. The wasps land on the flowers and start stinging them, trying to paralyze the "spider". The only result is that they get a bit of pollen attached to their heads, which they will deposit on the next "spider". The orchids get pollinated, and the wasps get nothing.

But not all plants are so hard on the parasitic wasps. The cabbage plant, for example, is their ally. The caterpillars of the Cabbage White Butterfly, as their name implies, like to eat cabbage. But the cabbage doesn't like--in an unconscious evolutionary sense--to be eaten. When it starts to get munched it releases a chemical that attracts parasitic wasps which attack the caterpillar. But they don't take it back to their nest. Instead, they lay their eggs inside the caterpillar, which goes about its business. The wasp larvae hatch and begin to grow inside it, feeding on its fluids but avoiding its vital organs. Finally, they tunnel out of the caterpillar's side and start spinning cocoons for themselves.

And then, as if this tale weren't perverse enough, things start to really get crazy. The caterpillar's brain has been altered by its ordeal, and it actually helps encase the wasp larvae in a mass cocoon, using its own silk. And then, then it becomes their guard caterpillar. The wasp larvae are vulnerable to attack by other parasitic wasps, which lay their eggs in them. The addled caterpillar lashes out at them when they try, but it's understandably weak by now, and soon dies. Many of its wasp attackers get parasitized themselves by smaller wasps. And get this--those smaller parasites may become the hosts for yet another species of parasitic wasp. This is called hyperparasitism--the parasite gets parasitized. Sometimes this can keep going, for four, five, or more levels, all the way down to bacteria that are attacked by bacteriophage virues. It's like a horror story version of Johnathon Swift's poem:

"So nat'ralists observe, a flea
Hath smaller fleas that on him prey;
And these have smaller fleas to bite 'em.
And so proceeds ad infinitum."

Ah, the web of life..it's not all peace and harmony. In fact, it can be pretty dreadful. After all, that famously disturbing scene in the movie Alien was inspired by parasitic wasps. Of the living things that can't make their own food, like plants do, parasites may be the most abundant.

But maybe things aren't as bad as they seem. Maybe none of the players in these little dramas are actually conscious, and they only appear to feel things like pain, fear, or anger. Maybe. But we can be pretty sure that other animals, like birds and mammals, do experience those sensations, and they (and we) can do some pretty awful things to each other, too.

And the thing is, nature doesn't care. It's gorgeous and complex and awe-inspiring, but it doesn't care.

That's where we, and maybe a few other animals, part ways with the rest of nature. That's the silver lining in all this. We can realize that others--both human and animal--have sensations and preferences, and we can alter our behavior to avoid to avoid causing unnecessary pain. Unlike nature, our eyes are not blank and we don't have to be as pitiless as the sun...or a wasp.

In the movie The African Queen, a drunk Humphrey Bogart tells a prim Katherine Hepburn, "A man takes a drop too much every once in a while. It's human nature." She replies, "Nature...is what we are put in this world to rise above." I don't know what we were put in this world for, if anything, and I think she could give nature a good bit more credit. But she's still got a point. As amazing as nature is, when it comes to things like compassion and ethics, we actually can rise above it.

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Enter the Hyperparasite

National Geographic video about the White Cabbabe Butterfly being parasitized. Watch at own risk. No, seriously--it can't be unseen.

Pilgrim at Tinker Creek / Annie Dillard (possibly the most brilliant book I've ever read)

The Cuckoo Wasp: A Gorgeous Parasite

National Geographic Article Mentioning Spider Orchids

The Dragons in my Back Yard

When I lived in Colorado, I was always looking out in the distance. I paid attention to big things there--geological formations, clouds deflecting off peaks, mountain ranges visible from eighty miles away.  Even the animals I watched tended to be big and showy, like elk, bighorn sheep, and the occasional black bear.  Now I live in Louisiana, where you don't see wide, craggy vistas or herds of elk.  So I've adjusted my focus downward, paying attention to small things--to tiny little swamp flowers, the geckos on my porch ceiling; the brawling, sex-crazed house sparrows that live under my eaves.  These things may not seem as dramatic as a snow-capped mountain range, but the difference in majesty is really more in our heads than out there in the world.  Compared to the gulf that separates the smallest subatomic particles from clusters of galaxies--each big enough that human history is not long enough for light to cross it--a sparrow and a mountain range are practically the same size.  Besides, while a mountain may have many moods, depending on the angle of light and the season, it doesn't behave.  It doesn't stand up and meet life head-on, the way the most miniscule insect does.  Small things have their own majesty, and we're all surrounded by their tiny, life-and-death dramas.

The other day, for example, I stepped out my back door and saw a green anole lizard (Anolis carolinensis) creeping across a windowsill.  It was hunting, moving its head back and forth to focus on something in a leafy vine about a foot away.  Then it leapt into the leaves, narrowly missing a wasp, which flew away hurriedly.  The anole missed that wasp, but I've seen them munch down others like popcorn.  I'm duly impressed.  A full-grown green anole is only about 7 inches long, tail and all, which means leaping a foot to catch a wasp is equivalent to me leaping ten feet to pounce on a rattlesnake.  Anoles are formidable beasts, I don't care how big they are.

Little Orphan Annie liked to exclaim, "Leaping lizards!" but I didn't actually know lizards leaped until I moved to Louisiana.  Arkansas has plenty of skinks and fence lizards, and while they can scamper away like a rifle shot, I don't ever remember them launching themselves through the air.  I was amazed the first time I saw an anole do it.  I was also amazed, sitting on my porch swing in Baton Rouge, to see a bright green anole climb out of some leaves onto a brown limb, and then fade into the limb by changing color.  Until then, I had assumed the brown ones and the green ones were two different species.

Some people call anoles chameleons, but the two aren't closely related. Both are predators who live in trees and bushes, but they have very different styles of hunting.  True chameleons creep along as motionlessly as they can, moving mainly their eyes--one eye scanning one direction, while the other goes its own way, as if it's connected to a different brain.  Anoles, by contrast, are stalkers. They move like cats, creeping sinuously down limbs and up walls.  True chameleons always have a look of  half-deranged melancholy on their faces, their eyes rolling like they're about to crack under life's pressures.  Anoles, by contrast, look focused, with a gaze that seems intelligent (though they're probably not terribly bright creatures). If you get close and watch them, they'll watch you back, fixing you with a look that seems to say, "I see you, primate--don't try anything."

Sometimes, in the spring, they'll position themselves in a prominent spot and unfurl the dewlap under their chin, trying to impress the opposite sex. The females have white dewlaps, but the males have striking pink ones, specked with little white spots.  Male anoles are tough guys, who guard their territories like prospectors watching for claim jumpers. When two males meet, it's on: they raise an otherwise-invisible crest down their neck and back, puff out their throats, and gape at each other like tiny alligators.  This transforms them into bigger, more formidable creatures; like little dragons, with patches of black warpaint appearing behind each eye.  They circle each other, turning sideways to look as big as possible, pausing to do little pushups of machismo.  As with many other territorial animals, they're better off settling disputes by bluffing and posturing, rather than fighting and risking injury.  So, some of these encounters end when the combatants decide they've established the boundaries of their territory, or when one decides it had better back down. But the scars on their noses shows that real fights do happen, and they can be vicious.  They lock jaws and try to wrench each other's heads around, while their sides heave with the effort.  Eventually, the loser retreats, and the winner expands his territory a across a little more of the yard.



Big or small, it's a rough world.  Back in Colorado, I would go camping in the fall and listen to the elk bugle at each other all night.  At first I was shocked at how primal--how mortal--the sound is.  Here are animals weighing well over a thousand pounds, bellowing at each other across the darkness, just like they did when my ancestors were stalking mammoths across some glacial plain. Those elk have never known anything but wilderness, and they're not playing around. At first I thought of that sound as otherworldly, because it's so foreign and eerie.  But that's wrong. It's very much of this world--the real world out there in the wilderness, a world without police or laws.  Our world is the more artificial one.  While I'm all for that contrived layer of law and safety we've built for ourselves, living in it can make you go a little numb.  It's good to look back into that wilderness.  It's good to feel, at least secondhand, the real weight of that fierce, ancient world.

Now, you may be thinking, "Wait, weren't we talking about lizards here?"  Well, sure, it does seem a little silly to use such language to describe a backyard lizard rumble, but for them the stakes are every bit as high as for those elk in the mountains.  The distinction is a matter of my perspective, not theirs.  To them, my backyard is the wilderness.  Even in the most urban settings, if you shift your focus down to the small things, you realize you're surrounded by wild country.  If you don't see its majesty, that's just human bias--a sort of bigotry of scale. You can find natural grandeur anywhere, if you look close enough.

Prisoner's Dilemma: The Challenge of Cooperation

I called this blog "Ramblebrain", because that's exactly what my brain tends to do.  I never know where it's going to wander off to.  Recently, I spent a few weeks reading and writing about the foundations of ethics.  Then I got interested in a group of guys in New Orleans who dress as skeletons and wake people up on Mardi Gras morning.  In a couple of weeks, I'll probably be fascinated by something else. But I'm going to try to rein myself in here, and come back to the ethics topic.  All things considered, it's probably more important than some of the other things that strike my fancy.

In my last post on ethics, I talked about the idea that selfish genes can encourage altruistic behavior (self-sacrifice for the good of another) among related individuals, because related individuals carry the same genes.  This is why many organisms give preferential treatment to their relatives.  This preferential treatment can be quite selfless (at the organism level, if not the gene level).  Many animals work themselves nearly to death caring for their young.  Some even sacrifice themselves to protect others.  If you've ever been stung by a bee, and it left its stinger behind, you've been the victim of a suicide attack.  The bees in a hive are all quite closely related, which is why bees are willing to die defending their hive.

Humans also tend to be very altruistic toward their kin.  How we treat other people is obviously a big question in ethics, so the evolution of altruism is clearly important for understanding people's moral sense.  However, the idea of kin selection only explains altruistic behavior among related organisms.  It doesn't offer any reason for being nice to unrelated animals.  As we might expect, many unrelated animals--even of the same species--are pretty nasty to each other.  Large alligators see small, unrelated alligators as just another potential meal.  If a band of chimpanzees comes upon a lone male chimpanzee from another group, they will probably try to kill it.

However, cooperation is also pretty common among unrelated animals.  Crows, even unrelated ones, will cooperate to mob an owl or hawk, "encouraging" it to hunt somewhere else. Sometimes bluejays and other birds will join in, and they certainly aren't related to the crows (except in a more distant, evolutionary sense).  Mobbing an owl clearly carries some risk, since an owl is quite capable of killing an individual crow or bluejay.  Why do mobbing birds cooperate like this?

The likely answer is that each bird gains more by cooperating to drive away the owl than it loses in risk to itself.  Mobbing owls is a win-win situation for them.  Each one gains by joining in, because the more join in, the more likely they are to chase away the owl.  This kind of situation can be modeled mathematically using the branch of mathematics called game theory.  Game theorists refer to a win-win situation as a non-zero-sum game.  We tend to think of games as competitions where one side wins and the other loses.  These are called zero-sum games because we can think of a win as +1 and a loss as -1.  The sum is zero.  A lot of interactions that can be modeled with game theory are non-zero-sum, win-win affairs.  It's advantageous to both parties, so natural selection favors it.  Natural selection isn't always about being nasty to others, because oftentimes being nasty isn't adaptive.

Occasionally, though, unrelated organisms have interactions where one voluntarily sacrifices to help another.  A commonly-cited example of such benevolence occurs in, oddly enough, the vampire bat.  Vampire bats fly out every night in search of food.  When they find a large animal, they creep up on it, bite a sliver of skin away, and lap up its blood.  Oftentimes the victim doesn't notice, because the bat has an anesthetic in its saliva.  But many of them do notice, and shake the bat off. The bat may return to its cave hungry.  Because its metabolism is so high, it can starve to death after just a couple of hungry nights.  So, it will beg another bat in the cave to regurgitate some of its blood, to get it though the night.  Generally, they can find a bat willing to do so.

This is different from a clearly win-win interaction, because the donor bat gets nothing in return.  If it is unrelated, why does it do it?  One possible answer is that it can expect the other bat to donate on another night, when it comes home hungry.  I'll barf up blood for you, if you'll barf up blood for me.  Evolutionary biologists call this reciprocal altruism, although this is really a misnomer, since the donor bat is only sacrificing in the short term.  I'll use the term delayed reciprocity, to avoid the suggestion of true altruism.  It's a win-win situation (ideally), but the win for one party is delayed.

And that's why delayed reciprocity is rare in nature.  It's vulnerable to cheaters who don't return favors.  It's true that a bat who receives blood from another, and then gives blood on another occasion, is better off than it would be if it didn't cooperate.  But it would be even better off if it made a habit of accepting blood, but never giving any back.  In a large population of reciprocating animals, it's only a matter of time until a mutant appears that will exploit its more trusting brethren.  It will be better nourished than the others, and better able to survive and reproduce.  The "cheater" genes will spread through the population, until it becomes a population of cheaters and reciprocity vanishes.  Sure, the group as a whole will do worse, but as I explained in another post, evolution (probably) doesn't happen at the group level.

The only way delayed reciprocity can be stable in a population is for its members to learn to avoid cheaters.  This generally means they are smart enough to recognize individuals, and to remember whether that individual has cooperated with them in the past.  This means delayed reciprocity is only feasible among relatively smart animals, living in stable social groups small enough that most members are recognizable.  It also means that reciprocators can't be too forgiving.  They have to be willing to cooperate with animals that cooperate with them, but not with animals that don't.  They may even punish cheaters.  Let's say a monkey asks another monkey, which it has groomed in the past, to return the favor.  If the other monkey refuses, the first monkey is likely to scream and even attack the cheater.  Monkeys, and many other intelligent animals, have a sense of fair play, and get very indignant when others don't play nice.  In a population of monkeys that mostly groom each other when asked, but refuse to groom those that have refused to groom them, delayed reciprocity can be stable.

Economists and evolutionary biologists have used game theory to model this this kind of reciprocity.  This stuff can get pretty abstract, but it has some extremely important implications.  In game theoretic terms, a delayed reciprocity situation resembles what's known as a prisoner's dilemma.  This is a situation where it pays to cooperate, but there is a temptation not to.  It gets its name because it is commonly formulated as a situation faced by two prisoners accused of committing a crime together.  They are put in separate cells, and each one is given the following options.  "If you confess, and implicate your partner, you'll go free and he will get five years in prison.  If he confesses, and implicates you, he'll go free and you'll get five years.  If you both confess, you'll both get two years.  If neither of you confess, we'll hold you for a few months, but we'll have to release you for lack of evidence."

Each prisoner--let's call them Shorty and Biggy--sits in his cell and ponders his situation.  Shorty thinks, "If we cooperate, and we both refuse to talk, we'll both get out after a few months.  But if Biggy talks, and I don't, I'll get five years, and he'll walk.  If I talk, and he doesn't, I'll walk and he'll get five years.  I don't want to stay in here six months, much less five years.  I'm gonna talk".  Of course, Biggy will go through the same thought processes, and he will probably decide to squeal, too.  So they'll both talk, and both get two years.  Both of them would have been better off if they had cooperated, but they were both too tempted to defect, so they both suffer for their lack of cooperation.

Of course, in real life Shorty and Biggy would also be considering the fact that they will probably meet again.  Shorty thinks "I'd love to rat out Biggy and walk, but in five years, he'll get out and come after me".  Of course, Biggy will do that because he's a product of evolution, wired to punish cheaters.  Most of us are, at least to some extent.  So, they are more likely to cooperate if they think they will meet again.

What happens in real life is that prisoner's dilemma type situations are played over and over again.  This is known as an iterated prisoner's dilemma.  In the early 1980's, a political scientist named Robert Axelrod decided to run computer simulations of an iterated prisoner's dilemma involving multiple players.  He turned it into a contest, inviting people to send in programs that used a particular strategy.  When two programs met, each would choose to cooperate or defect, and was awarded a certain number of points depending on the outcome.  The biggest payoff for each one happened when it defected and the other program didn't.  But it was better for both to cooperate than for both to defect. 

People sent in programs with all kinds of different strategies.  Some were simple, some complex.  There were "nice" programs, that always cooperated, and "nasty" ones, which never did.  The simulation was run, and each program played against the other several times.  At the end, the scores were tallied.  The most successful one was called "Tit for Tat".  This program's strategy was to cooperate initially, and then, whenever it met another program for a second time, do whatever that program had done the last time.  If it had cooperated, Tit for Tat would cooperate.  If it had defected, Tit for Tat would defect.  So, Tit for Tat was "nice" by default, but not a pushover.  It wouldn't cooperate with a program that had cheated it in the past.  But it was forgiving.  It would start cooperating again with a cheater as soon as that cheater decided to cooperate.

Over many tournaments, Tit for Tat kept on beating other programs.  The only time it didn't win was when most of the programs submitted were "nasty" ones, that rarely cooperated.  In this environment, Tit for Tat proved to be too "nice", and could never get a foothold.  The average score for all the programs was lower when the population was dominated by "nasty" programs than when it was dominated by "nice" ones.  At the individual level, it turns out that it pays to be nice, but only if you're not willing to be a sucker, and only if you're not in a completely nasty environment.  At the group level, the group average is always better if the population is composed of cooperators.  While an individual may do best in a nasty environment by being nasty, he would be better off as a cooperator in a nice environment.

When evolutionary biologists use game theory to simulate organisms in a population, the ones who get the most points become more common in the population.  Whole populations can oscillate back and forth, as one strategy, and then another, gets more common.  In most populations, organisms with a Tit for Tat strategy come to dominate.  Cooperation prevails, and cheaters can't get a foothold.  However, if the population is too uncooperative in the first place, then cheaters do better, and soon the population is nothing but cheaters. Now everybody does poorly, but cooperation can't get a foothold, so that's the way it stays.  Another possibility is that in a population of Tit for Tat strategists, even "nicer" strategies can appear in the population.  Let's call these Saints. Saints always cooperate, and never retaliate against cheaters.  They do fine in a Tit for Tat environment.  But when the first mutant cheater appears, they are robbed blind.  The cheaters do well in this environment, because of the population of Saints that don't retaliate.  In this way, the cheaters can get a foothold.  The population swings back toward cheating, and everybody suffers.

So, what does all this have to do with human ethics and behavior?  A lot, in my opinion.  For one thing, it seems very likely to me that humans have a natural moral sense constructed by evolution.  Just as our urge to caring for certain others may have its roots in kin selection, perhaps our tendency to cooperate comes from the fact that we are social animals, who can often do better by cooperating than by fighting or going it alone.  Like many animals, we cooperate with non-relatives to take advantage of win-win situations where everybody gets an immediate payoff.  There's nothing particularly altruistic about this.  Both parties cooperate because it is too their advantage.  Adam Smith, the founder of modern economics, made this point beautifully: "It is not from the benevolence of the butcher, the brewer or the baker, that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love, and never talk to them of our own necessities but of their advantages."  Trade is cooperation based self-interest, not altruism. 

We humans also seem to be unusually good at delayed reciprocity, where we cooperate with others in the expectation of getting rewards later.  Among other animals, clear evidence of delayed reciprocity (AKA reciprocal altruism) is pretty scarce.  Even among vampire bats, it's been argued that the bats that feed each other are likely to be related, which would mean they're practicing kin altruism, not reciprocal altruism.

People are able to reap the benefits of delayed reciprocity, because we are smart enough to recognize a large number of people, and remember how they have treated us in the past.  This may be why we form friendships with unrelated people, and why we get so indignant when we think someone isn't treating us fairly.  In fact, some biologists think one reason we became so smart is that big brains helped us to reap the benefits of cooperation, while remembering those that cheated us.  This may even help explain language.  Humans spend a lot of time talking about each other.  We're tireless gossipers.  While gossip is often frowned upon, gossip may have allowed us to expand the circle of people that we can safely cooperate with. Maybe we learned to talk so we could gossip more effectively.  An animal deciding whether to cooperate with another has to just try it, and see what happens.  People, on the other hand, can ask around.  "I'm thinking about taking Zog mammoth hunting.  Does he pull his weight on a hunt?"  With our big brains, and our ability to talk about the reputation of others, we were able to combine into much larger, more cooperative groups than most other animals.

Of course, I don't mean to suggest that we should only make friends and cooperate with unrelated people when we can benefit from it.  I do think our cooperative instincts evolved because they were beneficial, but there's no reason we can't go beyond the dictates of biology.  Besides, most of us don't go around calculating the benefits we'll receive from making friends and being nice.  We just feel drawn to people we like and think we can trust.

Besides, cooperation and delayed reciprocity can't explain everything about human behavior, because people can be altruistic toward complete strangers they will never meet again.  A common example is that most people tip servers at restaurants, even if they are traveling, and will probably never meet that person again.  Some people are extremely altruistic toward people they've never met, for example, by sending aid money to people in other countries. Of course, a lot of people aren't very nice to anyone.  Still, it's clear that humans have found a way to expand the scale of cooperation far beyond what most animals are capable of.  We are able to do so partly because of our biology, which gave us our big brains and our ability to talk. But it is also cultural.  Over time, people have learned to live in larger and larger groups, and to engage in more and more complex types of cooperation.  We have developed cultural institutions like religions, governments, and laws that encourage us to cooperate, and to treat at least some non-relatives decently. 

Just how this cultural expansion of cooperation might have happened is a huge topic, and I'm certainly not going to tackle it now.  For now, I want to conclude by considering the lessons we can learn from biological ideas about win-win cooperation and delayed reciprocity.  As I look back over this post, I realize that my conclusions are more pragmatic than ethical.  I do think that cooperation between non-kin can tell us about human ethics, because it can tell us where our sense of friendship and fairness came from.  However, it really doesn't tell us that much about altruism.  At least in nature, true altruism (in the sense of self-sacrifice without expectation of future gain) is pretty rare.  But cooperation is common, and can be beneficial, even if it isn't altruistic. So, even though I admire altruism, my conclusions here will have more to do with applying lessons from game theory to encouraging mutually-beneficial cooperation, a much easier task than encouraging selfless altruism.

One thing we learn from the game theory models of reciprocity is that cheating is a big problem.  Any time there is a situation where people can take advantage of others, a few of them will.  Conservatives reading this may be nodding and saying, "See, we have to make sure people on welfare don't cheat the system."  That's true, we do, but we also have to make sure corporations don't cheat.  There are incentives to take advantage of others at all levels.  Liberals tend to have an overly rosy view of individual human nature, but conservatives tend to have an overly rosy view of "corporate nature".  When I hear people saying that oil companies will "police themselves", I think, "And they say liberals are the starry-eyed ones." 

In any competitive system, some of the players will always be tempted to play dirty.  That's why, at all levels, we have to make sure that there are rules to keep competition from getting too nasty.  That's why we have laws.  One of the most interesting results of computer simulations of the prisoner's dilemma is that there is no universally successful strategy.  What is a good strategy for dealing with others depends on the environment; on the strategies others are using.  In a big city, where most people are strangers to each other, people tend to be less trusting than in a small town, where most people know each other.  This makes perfect sense.  You have to be more careful when you're surrounded by strangers, even though many of them are perfectly trustworthy.  In the same way, if you grow up on the streets in a rough neighborhood, you may need to cultivate a reputation for toughness that you don't need if you grow up in the middle class suburbs. The tough guy approach may be a problem if you try to move into the middle class, but it may have been a necessity back on your block.

It seems to me that if people perceive that they are in a fair, safe environment, they will be more likely to be cooperative.  If people think they are in a dangerous, unfair environment, they will decide they have to play dirty to survive.  People are smart, and we adapt our behavior to suit our environment.  If we decide to have a dog-eat dog world, we shouldn't complain if we get bitten.  It seems to me that a major challenge for society is to establish ground rules that discourage cheating, and encourage fair play.  

I'm not advocating for pure top-down government control of everything here.  Some cooperative ventures can evolve on their own.  This includes free-market trade networks.  Lots of people think that countries have gone to war with each other less in the last fifty years because they trade with each other more.  As the psychologist Stephen Pinker puts it "The spread of trade and commerce has brought violence down, when it becomes cheaper to buy something than to steal it and more and more of the world becomes more valuable alive than dead."  Of course, competition is an essential part of market economies.  Companies that don't have to compete start making shoddy, overpriced goods.  The trick, with corporations as well as people, is to have ground rules to keep the competition from getting too nasty.  In basketball, it's OK to block your opponent's shot.  It's not OK to gouge him in the eye.  Competition can bring out amazing things in people and organizations, but it can also bring out a lot of nastiness, because it leads to incentives to play dirty.  We have to have competition within the framework of cooperation, where we agree to have rules to ensure that we play fairly, if not perfectly nicely.  We live in a competitive world, but we can choose what kind of competitive environment we want to have.  If we encourage everyone to play fair, everyone benefits.  If we let cheaters get too common, to the point it no longer pays to cooperate, everybody suffers.  The prisoner's dilemma turns into a losing game, even though it didn't have to be.

I'm not the sort to see much purpose in nature.  However, I can't help seeing the prisoner's dilemma as a challenge nature has handed us, even if only by chance.  It's as though nature is saying "You're a pretty smart species.  Are you smart enough to figure out the prisoner's dilemma, and how to win it?"  Well, are we?
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Recommended Reading:

Cooperation Between Non-Kin in Animal Societies / Tim Clutton-Brock

The Selfish Gene / Richard Dawkins

Nonzero:  The Logic of Human Destiny / Robert Wright

Prisoner's Dilemma:  John von Neuman, Game Theory, and the Puzzle of the Bomb / William Poundstone

Darwinian Family Values: From Selfish Genes to Altruism

It's a Saturday night in south Louisiana; the weekend before Mardi Gras.  There's going to be parading and debauchery from now through Fat Tuesday, and I intend to see some of it.  But tonight, the rain is pounding against my windows, and I just can't get that excited about going out in it.  So, I'll risk the wrath of Bacchus by staying in and continuing my recent ramblings about ethics.

In my last two posts, I've been considering whether ethical laws are an intrinsic part of nature.  I've concluded there are good reasons to be skeptical about the idea of natural law--the idea that there are clear ethical rules implicit in nature, and that we can use our reason to discover them.  If the natural world evolved through a combination of  basic physical processes and natural selection, then there's good reason to question the natural law idea that everything in nature has a purpose, and that learning our purpose can tell us what is good.  If humans are chance products of natural selection, then we may have no purpose at all.  It seems quite likely to me that we weren't put on earth for any reason.  We are here because we happened to evolve.  I don't mean to wring my hands and say life is meaningless.  I think human life can be incredibly meaningful.  We are smart, curious, social, and talkative creatures living in a world full of wonders.  There are plenty of ways to find rewards and meaning in life.  I just don't think we can assume that we are here to serve some cosmic purpose.

Another reason to be skeptical about natural law is the problem of the appeal to nature fallacy (or naturalistic fallacy), which reminds us that we can't automatically jump from descriptions about how things are to how things should be.  Evolution, for example, has made human males stronger and more aggressive (on average) than human females. In the past, and in some places and subcultures even today, being big and bad enough to outfight or intimidate other males was a successful strategy for having more offspring.  Does that mean men should fight more, since we are, in the mindless evolutionary sense, designed for it?  Certainly not.  The fact that belligerence was a successful strategy in the past doesn't mean it's the right way to act.  Is does not equal ought.

Nature only seems care about what works, not what's right.  However, this doesn't mean nature is irrelevant to morality.  We can't simply ignore the laws of nature, or the realities of human nature, when we decide how we should act.  We can't for example, decide that it's wrong to ever eat any part of another living thing.  We would starve to death. 

On a less drastic level, it's important to know as much as we can about human nature, to gain insight into why we have ethical preferences all.  Is our sense of morality a universal part of human nature, with deep roots in our evolutionary history?  Or are humans born a blank slate, learning the socially constructed rules of our particular culture?  In some circles, it's heresy to claim that human behavior has any intrinsic basis.  It smacks too much of old theories justifying racism, sexism, and the supposed superiority of western ways.  In the last few decades, though, it's been increasingly hard to deny that human nature has been influenced by evolution.  But it's a universal human nature, common to all people, regardless of race.  While our moral sense is obviously modified by the culture we grow up in, it was not created by that culture, at least not entirely.

If evolution is amoral and blind, how did it give us a sense of morality, a sense that some things are good or bad, right or wrong?  Let's focus one aspect of morality for now: altruism.  Altruism occurs when one animal (human or otherwise) does something to help another, at a cost to itself.  Most people feel an urge to help others, at least to some extent, especially if those others are their friends or family.  But we aren't the only animals capable of altruism. Vervet monkeys, for example, will give a loud call if they see a predator.  This warns the other members of the group to be careful, but it also increases the chance that the predator will zero in on it, and have that selfless monkey for dinner.  Wolves that have had a successful hunt will eat their fill, return to the pack, and regurgitate food for others who weren't part of the hunt.  This may be gross, but it's undeniably altruistic.

Now, we don't know if vervet monkeys and wolves feel some sense of obligation or empathy which spurs them to such selfless acts.  Both are fairly-large brained creatures, so it seems likely to me that they do.  In humans, a sense of obligation or empathy is considered a moral sense.  While I don't know if I would say wolves and vervet monkeys are moral creatures, I would say their urges toward selfless behavior could be a precursor of our more sophisticated moral sense.

But the question remains--how did this kind of behavior evolve?  Lots of people figure that animals are altruistic because it helps the group or species survive. After all, evolution is about the survival of the fittest species, right?  Well, not really.  Evolution doesn't seem to happen at the group level, except possibly in very special cases.  Here's why:  let's say you have a group of extremely altruistic monkeys, whose members always share food and help care for each others' offspring.  They always help each other, and because of that, they are a very successful group.  But there is always some variation within any group of organisms.  Occasionally, one will arise within the group that doesn't have "helpful genes".  They never help, and they take advantage of the altruism of the others.  This they will survive better, at the expense of the others.  It also means they have more offspring, who inherit their tendency to take advantage of others.  Very quickly, these non-altruistic monkeys will get more and more common in the population, until the group is no longer composed mostly of altruists.  To the extent that acting for the good of the group is not conducive to survival and reproduction of the individual, it is not--to use the evolutionary biologist's term--an evolutionarily stable strategy.

Actually, what matters most in evolution is not the even success of the individual, but of particular genes.  Individual living things are ephemeral--most only live a few years at best. An individual's particular combination of genes are also ephemeral.  In sexually reproducing organisms, each one has a unique genome, a mix of the genomes of their parents.  If they reproduce, they will pass 50 % of their genes on to each of their offspring, and each of them will have their own unique combination of genes.  What lasts across generations are individual genes.  For the last few billion years, genes that happen to be good at getting themselves replicated have increased at the expense of genes that weren't as good at replicating.  Over time, the world has come to be populated by organisms whose genes are good at replicating themselves.  As Richard Dawkins explains in The Selfish Gene, whole organisms are vehicles designed by genes for the purpose of replicating those genes.  Of course, neither the organism or the gene is conscious of this.  A gene has no consciousness at all, and an organism that acts in a way that spreads its genes isn't conscious of why it's doing so.  A mother alligator cares for her babies because her brain and hormones tell her to, not because she's thinking about how best to spread her genes.  This is true for people, too.  We care for our children because we feel an intense love for them, rarely considering that this love has anything to do with our genes.

Caring for children is so automatic for most people that it doesn't even seem like altruism.  It's just what you do.  But it is altruism in the sense that the parent is making sacrifices for the child.  Often big sacrifices.  Once I had a dog that had puppies.  She was a wonderful mother, and nursed them all the time.  Before long, her hair started falling out, because her puppies were getting nutrients she needed for herself.  She was sacrificing her health (albeit unconsciously) for the sake of other creatures--her puppies.  The immediate reason she did this is because she felt (and I'm convinced she had feelings) an overwhelming urge to do so.  But the ultimate, evolutionary reason she felt that way is that each one of those eight puppies held copies of her genes.  I say copies because genes can't pass themselves on.  They can only pass copies of themselves on.  This means it doesn't matter, in terms of the gene's success, that those copies are in another organism.  In fact, it works out well, because one organism can have many offspring, producing multiple copies of many of its genes (multiple copies of all of them, if it reproduces asexually, but that's a different topic). 

Today, this "gene's eye" view of evolution is often known as the "selfish gene" theory, because it was explained in the brilliant book of the same name by Richard Dawkins.  Other scientists, especially W.D. Hamilton, George Williams, John Maynard Smith, and Robert Trivers, came up with the basic idea of looking at evolution at the level of the genes.  As Richard Dawkins would readily admit, he was just explaining it.  As he would also admit, the title of the book has caused a lot of misunderstanding.  He called the book The Selfish Gene because genes tend to do whatever it takes to get themselves replicated, whether or not this is good for the individual organism.  A male preying mantis has an intense urge to mate with a female preying mantis, even though she is quite likely to bite his head off in the midst of their passion.  It's a risk worth taking, as far as his genes are concerned, because he is getting them reproduced.  As long as more genes are replicated in the long run, the misfortunes of Mr. Mantis are irrelevant to evolution.   This is the sense in which genes are selfish.  The mistake is to conclude that selfish genes always create selfish organisms.  Genes do whatever it takes to get themselves replicated.  Sometimes selfish organisms do this most effectively, but oftentimes, altruism works just as well.

We've already seen one way this is true: with parental care of offspring.  But altruism in nature goes beyond that.  If all genes become widespread by making copies of themselves, those copies don't have to be in direct offspring.  An organism's offspring, as I mentioned, have copies of 50% of its genes.  But so do its parents and siblings.  This means that if it doesn't have offspring, but helps two of its siblings survive and reproduce, the effect is the same in terms of gene replication.  This means natural selection will tend to produce organisms that act altruistically toward their relatives.  The closer the relation, on average, the more altruism.  While siblings share 50% of their genes, cousins only share 25% of them (on average, as always).  If we look at how the world works, that's exactly what tends to happen.  Some animals do take care of their siblings' offspring, but they don't spend as much time with them as their own offspring.  My aunts and uncles were all very kind and generous to me, but they didn't raise me.  They raised their own children.  That's how evolution made us.

Selection for altruism toward relatives is known as kin selection, and it accounts for most of the altruism in nature.  But it only goes so far.  It doesn't lead to absolute altruism, even toward ones children or siblings.  If there are two siblings, and only enough food for one of them to survive, kin selection theory predicts each will try take the food for itself.  Yes, if one of them lets it's sibling have the food, and then dies, 50% of its genes would have survived.  But if it takes the food itself, 100% of its genes have survived.  So, even close relatives don't share the exact same interests, genetically speaking, unless they are identical twins.  This means there's a lot of conflict in nature, even among members of immediate families.  In some cases, when an individual can spread its genes more effectively by surviving at the expense of its family members, kin altruism is selected against.  This is apparently the case in the Sand Tiger shark.  This shark gives birth to live young, but only two of them.  The shark has a double uterus, and in each branch, the shark embryos eat each other, until only one remains.  Evolution doesn't always encourage niceness, even among brothers and sisters.
 
This unsettling image brings up an extremely important point.  I want be perfectly clear that, while I do think evolution created most of our moral impulses, such as our urge to treat relatives well, I don't think these impulses are the best we can do morally.  As I discussed in the last post, nature is amoral.  Evolution encourages altruism when altruism is useful for spreading the most genes.  When it isn't useful, it isn't encouraged.  Our genes, in their mindless quest to replicate themselves, gave us large brains, capable of reflecting on our impulses, and (with a good bit of willpower) choosing which ones to follow, and which ones to resist.  And some of our natural impulses should definitely be resisted.

In any case, it seems likely to me that altruism between related individuals gave rise to some of our basic, morally-laden emotions, including love, the urge to nurture and protect, and our sense of loyalty to family.  In human societies, we are constantly using family metaphors to encourage bonding, cooperation, and loyalty among unrelated people.  Students in fraternities and sororities call each other brothers and sisters.  Catholic priests are called "Father".  Americans talk about our Founding Fathers, while Russian's talk about Mother Russia.  Confucius saw society as a large family, and believed that the kind of loyalty and hierarchy that made a good family (as he saw it) would also make a good society.  This extension of the family metaphor into larger groups has been a mixed blessing, of course.  On the one hand, it's built cooperative groups capable of accomplishing far more than they would have if they hadn't cooperated.  On the other hand, it can be used by tyrants to justify their power (Big Brother is watching you), and it can lead to a nasty kind of tribalism, where people abuse those that aren't part of their societal "families".

I don't want to get caught up in how the family metaphor is extended to unrelated people, at least not now.  My main point in this post is that the moral impulses humans feel have an evolutionary history that began long before humans did.  But it isn't common to all animals.  Many animals feel no impulse at all to treat other members of their species well.  If parental care isn't adaptive, they don't even feel the need to treat their own babies well. Many frogs simply leave their eggs in a pond, and then go about their business.  It's probably safe to say that this frog doesn't have any particular sense of good will or fair play toward other frogs.  However, animals that practice parental care--even solitary ones such as bears--do seem to feel an obligation to protect and care for other bears--if those bears are their own offspring.  In social animals, individuals may feel an urge to care for the rest of their family, not just their own offspring.  In many small groups of animals, most individuals are related, so they may feel a general altruism toward all their fellows (though they are likely to feel more of it towards immediate kin).

Of course, there's a lot more to human morality than altruism between relatives. We also have a sense of the sacred, of fairness, of loyalty, and of moral outrage when we think these things are being violated.  If I'm going to consider the origins of these impulses, then I have a lot more work to do.  However, I think it makes sense to start by looking at how some animals began to have the sense that they should be benevolent or cooperative to certain other animals (instead of ignoring them, chasing them away, or killing them).  One way this happened is though kin altruism.  But it's not the only way.  Unrelated animals do cooperate in nature, and some may even form friendships, develop a rudimentary sense of fairness and empathy, and trade favors.  This kind of cooperation isn't as strong as kin altruism, though, and it's prone to shifting alliances and exploitation by cheaters.  This is where social life among animals turns into a real soap opera.  But this post is long enough, so I'll talk about that in the next episode.

The Selfish Gene - Richard Dawkins

The Expanding Circle:  Ethics and Sociobiology - Peter Singer

Meerkat image © goldencolt - Fotolia.com