On the evolution of skin color.

On the evolution of skin color.

Our criminal justice system ensnares people from all walks of life.  Occasionally we’ll hear about the arrest of a wealthy sociopath with a penchant for child abuse, like Jared Fogel or Jeffrey Epstein.

But, let’s face it.  Justice in this country isn’t applied fairly.  If you’re wealthy, your behavior has to be a lot more egregious for you to reap the same punishments as a poor person.  If you look white, your behavior has to a lot more egregious for you to reap the same punishments as a black person.

There’s abundant statistical evidence to back up these claims.  But the Supreme Court won’t allow any particular individual to petition for reduced punishment based on the statistical evidence.  After all, prosecutors, judges, and juries ostensibly came to their decisions based on the unique details of each individual case.  Just because people who resemble you are often treated unfairly doesn’t mean that you were treated unfairly, too. 

Or so ruled our Supreme Court.

Because we apply punishment so inequitably, our jails and prisons are full of people who’ve been treated poorly by the world.  Compared to the average citizen, people in prison grew up with less money, received less education, experienced more trauma.  And, no matter what people’s earlier lives were like, if they’re in prison, they’re not being treated well now.

So they have a lot of justifiable grievances against the dominant political, cultural, and religious beliefs of our country.  Punished unfairly by their fellow Christians, people sour on Christianity.  Inside walls where the demographics make it blatantly obvious that our laws are enforced in a malignantly racist way, racial tensions boil.

At Pages to Prisoners, an organization that sends free books to people inside, we get requests for stuff about Norse mythology, Odinism, and Asatru.  Lots of folks ask for material to learn foreign languages – people want to feel like they’ve accomplished something during their time in prison – but I always feel skeptical when somebody wants help learning Icelandic.

Not that there’s anything wrong with Icelandic.  And Norse mythology is cool!  Unfortunately, a gaggle of violent white supremacists decided that Norse mythology should be the basis for their religion.  Starting in the 1970s, a right-wing racist from Florida began sending “Odinist” publications into prisons.

A photograph showing a book page in Icelandic.

During the thirteenth century, Christian scholars transcribed many of the old Norse myths so that they could better understand the literary allusions of old Icelandic poetry.  But they didn’t record anything about ancient religious practice.  We barely have any information about most ancient pagan beliefs.  Anyone who wants to adopt a pre-Christian European religion now – whether it’s Wicca, Druidism, Odinism, or Celtic polytheism – is basically forced to make things up.

I have nothing against religious invention.  All religions were made by human beings – there’s no a priori reason why a religion created long ago, by people who understood much less about the world than we do now, would be better than something you invent today.  Sure, ancient religions have been tested by time, suggesting that they possess virtues that their practitioners found helpful over the years, but most ancient religions have their problems, too.  Inaccurate cosmologies, scattered hateful passages in their texts, that sort of thing.

So I like the idea of neo-paganism.  You want to find a clearing in the woods and do some moonlit dancing?  You’d rather worship a feminine generative force than a norm-enforcing patriarchal deity?  You want to exalt nature as a hearth to be protected rather than a resource to be exploited?  Go right ahead!  All of that sounds pretty great to me.

A Wiccan-style gathering of artifacts including a statue of a seated green goddess, her pregnant belly painted as the earth; mums; a chalice; a string of green beads; a stoppered rectangular prism bottle; and a candleholder appearing to be carved of wood, again of a pregnant woman with hands holding her belly.

Unfortunately, neo-paganism as it’s currently practiced in prison tends to be pretty hateful.

That’s why I’ve been working on a set of anti-racist pamphlets about Norse mythology.  Currently, when people ask for The Poetic Edda or whatever, we send a friendly letter saying that we don’t have it, and also that we generally don’t stock that sort of thing because it runs afoul of our anti-hate policy. 

But the Norse myths are certainly no more hateful than Biblical myths, and we send plenty of those.  The main difference is that centuries of continued Christian practice have created a scaffolding of gentler beliefs around the stories in the Bible. 

The text of Psalm 137 states that “Happy shall he be, that taketh and dasheth thy little ones against the stones.”  But the text is a tool, not the entirety of the religion.  The practice of Christianity frowns upon the murder of any human infant.  Whether you like the kid’s parents or not.

A sun-dappled photograph of a page of the Bible.

We’d be better off if Pages to Prisoners could send warm-hearted material about Norse mythology to people.  Sure, you can interpret the Norse myths as endorsing a war-mongering death cult.  You can interpret the Old Testament that way, too.  But you can also interpret the Norse myths as environmentalist.  Feminist.  Supporting the pursuit of knowledge.  Judging strangers based upon their merits, not their appearance.

Because contemporary Odinism is so entangled with white supremacy, though, our pamphlet will have to address skin color and genetic heritage directly.  It’s a fraught topic.  Lots of people in the U.S. don’t like any discussion of evolution.  Some people feel squigged out when they learn that contemporary birds evolved from the same set of common ancestors as the dinosaurs.  And that’s far less emotionally charged than a description of human evolution. 

A photograph of a model dinosaur, complete with feathers.

Plus, skin color still has huge implications for how people are treated in the United States.  Consider, um, those prison demographics I cited above. And so discussions about the evolution of epidermal melanin concentrations are especially tense.  Although the underlying biology is simple – some places have more sunlight than others! – because people think it matters, it does.

I’ve found that these conversations are actually a decent way to get people interested in the study of archeology and biology, though.  After we’ve discussed this in jail, people have asked me to bring research papers and textbooks so that they could learn more.

Whenever two groups of an organism stop mating with each other, they’ll slowly drift apart.  This rift might occur because the groups became physically separated from each other.  Maybe one group migrated to an island.  In contemporary times, maybe the groups were separated when humans built a new highway bisecting a habitat. Maybe two sets of similar-looking insects mate apart because they’re eating fruits that ripen at different times.

Or the groups might stop mating with each other because a chance mutation caused members of one group to want their sexual partners to smell a certain way.  Various species of stickleback are able to interbreed – they identify other members of their kind based on smell.  But water pollution has overwhelmed the fishes’s senses, leading the fish to mate indiscriminately.

A photograph of a three-spined stickleback fish.

If humans hadn’t polluted their waters, though, these sticklebacks would have drifted farther and farther apart until it became impossible for them to interbreed.  No matter how many sense-suppressing chemicals we dumped.

We don’t know what caused the initial rift between our ancestors and the ancestors of contemporary chimpanzees.  About 4 million years ago, though, these groups stopped having children together.  By 2 millions years ago (at least 100,000 generations later), these groups looked quite different from each other.  Although it’s possible that these organisms could have still mated with each other and raised viable progeny, they rarely did.

One group of these creatures, which included our ancestors, had a tucked pelvis and mostly upright posture.  This allowed for a good vantage while scavenging and, eventually, hunting.  The other group, which includes chimpanzees’ ancestors, mostly moved on all fours.  This body plan results in fewer mothers dying during childbirth.  As ever, there are trade-offs to be made.

Image shows the upright skeletal postures of gibbons, humans, chimpanzees, gorillas, and orangutans.

Up until about 2 million years ago, all our ancestors lived in Africa.  But then they began to migrate.  Over the next million years, they explored much of the globe.  By about 500,000 years ago, half a dozen different types of humans lived in Africa, Europe, and Asia.  The difference between one population to the next was not like the racial differences among contemporary humans, but more like the difference between lions and tigers, or between polar bears and brown bears.  Scientists describe them as distinct species.  Although they were similar enough that they could have sex and raise children together, they rarely did – they lived in distinct parts of the world and had begun to evolve adaptations to their specific environments.

Evolution isn’t easy.  Nor is it quick.  Just because a certain trait would be advantageous doesn’t mean that creatures will acquire it.  In the desert, it would help to have adaptations for water retention like camels, or long ears like jackrabbits to cool the blood.  But a trait can only spread after a random mutation creates it.  And, even if a trait is very helpful, if only one individual is born with the adaptation, there’s no guarantee that it will have enough children for the benefit to spread through the population. 

Once a beneficial trait has a good toe-hold – present in perhaps 1% to 10% of the population – then we can expect it to flourish.  But below that amount, even great adaptations might die off due to bad luck.  That’s why it takes so many generations – tens of thousands, or hundreds of thousands – before you see organisms become drastically better suited for the environment.  Even when scientists do directed evolution experiments in the lab, it takes about this many generations for a population of bacteria to evolve ways to consume a new food source, for instance.

By 500,000 years ago, the various species of humans were recognizably different.  Denisovans lived in the mountains, and their hemoglobin genes allowed them to avoid altitude sickness.  Their blood was less likely to clot and cause strokes, and they could extract more oxygen from the thin air.  These are incredibly beneficial traits.  Even though the Denisovans went extinct about 40,000 years ago, about 40% of people currently living in Tibet have copies of the Denisovan hemoglobin gene.

Our ancestors migrated east to the Denisovans’ homeland just before the Denisovans went extinct.  To be perfectly honest, we probably killed them.  But before or during this genocide, a few of our ancestors must have had sex with the locals.  And then the bi-racial children of these Homo sapiens / Denisovan couplings must have been significantly better off for the gene to spread so widely.

The Neanderthal lived at high latitude.  Over many generations, their average skin color became paler.  In part, this was probably due to the lack of selective pressure.  Think about a dodo – there was no advantage for these birds to lose their fear of humans.  But, because the dodos were living on an island that no humans traveled to, there was also no harm in the birds becoming fearless.

A sculpture of a dodo.

Dodos lost a beneficial trait – fear – because their fear wasn’t actively needed.  It’s kind of like the airbags in an old car.  If your car’s engine goes bad, you’ll notice right away.  Turn the key, hear it sputter.  You use the engine every time you drive.  But your airbags could get worse without you noticing … and then, in the moment when they’re needed, they won’t deploy.

Humans living near the equator need epidermal melanin.  If you don’t have enough melanin, you’ll get sunburns, which exacerbate the risk of infection and dehydration; you’ll suffer radiation-induced DNA damage, which leads to skin cancer; and you’ll lose folate, which means that pregnant women will have more birth defects.

The most recent ancestors that humans and chimpanzees shared in common had pale skin.  Contemporary chimpanzees are still pale.  They can afford to be – their fur protects them from the sun.  But our ancestors lost their fur, probably so that they didn’t overheat while running, and this led to the evolution of dark skin.

High concentrations of epidermal melanin distinguished humans from the other apes.

As humans migrated to higher latitudes, though, they gradually lost this indicator of their humanity.  Because the sunlight was less intense, there was less selective pressure.  Humans could lose their epidermal melanin in the same way that dodos lost their fear – not because it was helpful to go without it, but because the trait went untested in their day to day lives.  They had no way to “realize” how important it was. 

Your airbags aren’t helpful until you crash.  And then they’ll either deploy and save you, or they won’t.

Now, it’s possible that the Neanderthal also experienced some positive selective pressure on their skin color as they migrated north.  Over thousands of generations, the Neanderthals may have benefited from paler skin because it increased their production of vitamin D.  We don’t know for certain that the Neanderthal felt any evolutionary pressure to have more vitamin D – after all, contemporary Inuit people live at very high latitudes but still have a lot of epidermal melanin – but it’s true that vitamin D deficiency is a big risk among people with crummy diets.

In the past, hunter / gatherers typically ate much healthier, more varied diets than farmers.  When humans began to farm, they would mostly eat the one type of plant that they cultivated, rather than the wide mix of plants that could be found growing wild.  And when Homo sapiens farmers migrated to northern Europe, their diets were so poor that they even developed loss-of-function mutations in a cholesterol synthesis gene, probably so that they’d have higher concentrations of vitamin D precursors.  Among these people, pale skin was probably a big advantage.  They’d be ready for the cloudless days when their homeland’s feeble sunlight was enough to make some vitamin D.

Pieter Bruegel the Elder’s The Harvesters.

Around 40,000 years ago, our planet’s most recent ice age ended.  The world began to warm, and glaciers retreated from Europe.  By then, a group of humans living in Africa were recognizably Homo sapiens.  These were our ancestors.  Every human alive today – no matter what you look like or where your family is from – is descended from this group of people from Africa.  They lived in tribes of twenty to a hundred people, had darkly pigmented skin, made art, and spoke complex languages.

As the world warmed, some of these Homo sapiens began to migrate.  These journeys occurred over many generations.  Some tribes stayed in Africa; some tribes ventured north into Europe; others moved east toward Asia.  As they traveled, they encountered the humans who already lived in those places.  As I’ve mentioned, the newcomers occasionally had sex and raised children with the natives.  They probably also killed a lot of them.  Unfortunately, we Homo sapiens don’t have the best reputation for treating strangers well. 

Interbreeding happened rarely enough that most people living today have about 99% Homo sapiens DNA.  Some people, especially if their families are from Africa, have essentially 100% Homo sapiens DNA.  At other extreme, even people whose families are from Europe have 96% or more Homo sapiens DNA.

Among people living in Tibet, the Denisovan hemoglobin gene is common, but most other Denisovan genes are gone.

Everyone living today is human.  We are all Homo sapiens, all the same species.  But some of us do carry vestiges of the other human populations whom our ancestors killed.

Like the Neanderthal before them, the Homo sapiens who ventured north into Europe began to lose their epidermal melanin.  People who hunted and fished probably became paler simply because there was less risk of sun damage.  Remember, this didn’t happen all at once.  Average skin color would change only over the course of hundreds or even thousands of generations, not during the course of a single journeying Homo sapiens’s lifetime. 

Our ancestors spent almost all their time outdoors, which is why even dark-skinned people could probably synthesize plenty of vitamin D.  Among contemporary humans, vitamin D deficiency is such a big problem because we spend too much time inside.  As I type this, I’m sitting at a table in the YMCA snack room, lit up by flickering fluorescent bulbs.  This low-quality light won’t help me make vitamin D.

Instead, I take a daily supplement.  But that doesn’t come near matching the health and psychological benefits of time outdoors.

Perhaps it’s worth mentioning that people in jail – places not known for providing a rich, high-quality, varied diet – typically get to go outside no more often than once a week.  At our local jail, their hour of “outdoor rec” occurs in a little courtyard at the top of the jail, a cement space covered with a chain-linked fence.  Outdoor rec often happened at night – a friend who was recently released told me that “This was still nice.  You could see some stars.  And there’s that restaurant, Little Zagrib, down the street?  Sometimes we’d smell foods from their kitchen.”

Treating people that way is unlikely to help them get better.

Blue sky and white cirrus clouds as viewed through coiled razor wire atop a barbed-wire fence.

But back to our migrants!  Descendants of these pale-skinned Homo sapiens continued to explore new territories.  Some reached North America about 12,000 years ago, and some of their descendants continued farther, all the way to South America. 

As people traveled – journeys that lasted many generations – they continued to evolve.  Indeed, skin color was a trait that came repeatedly under selective pressure.  As people migrated south into the Americas, they were living progressively closer and closer to the equator.  Compared to their grandparents, they were bombarded by more intense sunlight.  They needed more epidermal melanin.

This is a process that takes a long time.  A family might have six kids; maybe the two palest kids get sunburned, which makes it more likely that they’ll develop skin infections and die before they have children of their own.  If this happens again and again, among many different families, then eventually the whole population will wind up with slightly darker skin.

A prediction for the distribution of human skin colors based on the intensity of ultraviolet light present at each latitude. Figure from Nina Jablonski & George Chaplin, “The Evolution of Human Skin Color,” in Journal of Human Evolution, 2000.
This figure depicts the (limited) data we have on the distribution of human skin colors before the modern era’s horrific set of forced migrations. In this image, white-colored regions indicate an absence of data, not low concentrations of epidermal melanin among a region’s prehistoric population. Figure from Nina Jablonski & George Chaplin, “The Evolution of Human Skin Color,” in Journal of Human Evolution, 2000.

Because human skin color has changed during each of the many prehistoric migrations, it isn’t correlated with other traits.  As we entered the modern era, people’s skin color was lighter or darker based on how close to the equator their recent ancestors lived.  But human populations migrated so often that there were many different groups, each with unique cultural and genetic heritages, living at every latitude.  Because skin color is so closely linked to latitude, this means many different groups shared similar concentrations of epidermal melanin.  And there’s no evolutionary pressure linking a trait that protects skin to brain size or intelligence.

As it happens, there are major events known to have caused a decrease in human brain size (and probably intelligence).  After all, human brains are costly.  Even though there’s a benefit to being clever, there’s also been constant evolutionary pressure against large brains.

Large brains kill mothers.  Because humans walk upright, childbirth is riskier for human mothers than for other primates.  Our posture constrains the width of our hips – both male and female – but a baby’s whole head has to pass through that narrow passageway.

Having children is so risky that we evolved to give birth about 3 months prematurely.  Human gestation takes about a year, but most mothers give birth after only 9 months.  This allows a baby’s head to continue to grow outside the mother’s body, but human babies are totally helpless at birth.  We have to be very devoted parents to keep them alive.

Also, our brains require a lot of fuel.  Human evolution occurred over such a long, long time that our ancestors lived through many droughts and calamities.  During the hard years, our ancestors would struggle to get enough to eat, and a large brain makes that struggle harder. 

A person with a smaller brain requires fewer calories, making that person less likely to starve in lean times.  And, again, it’s worth remembering that evolution happens over so many generations, among so many families, that even small changes can add up.  If mothers who have small-headed children can survive a dozen pregnancies, but mothers with large-headed children die after only a few, then the trend will be to have people with smaller brains.  Intelligence has to be extremely beneficial to overcome this sort of evolutionary pressure.

Similarly, if people with small brains are more likely to survive and raise children during droughts, then, after hundreds of generations of people who have survived dozens of extended droughts, you’d expect to see more people with small brains.

Many of us have the bad habit of reflexively thinking about evolution as the gradual development of more and more complexity.  But that’s not what it is.  Evolution is the process by which things that are better suited for their environment become more abundant.  If the environment is a hard place to live in, then evolution tends to push for more and more simplicity.  When it’s hard to get enough calories, why waste calories on anything that you don’t really need?

Starfish are descended from organisms that had brains.  But starfish are brainless.  The ancestral starfish that weren’t wasting energy thinking were more likely to survive.

Which should make you feel pretty good about your own brain, actually.  Your ability to think is so fabulous that your ancestors evolved larger and larger brains … even though these brains were sometimes causing us to starve to death, or kill our mothers.

That’s a valuable thing you’ve got inside your skull.  It cost our ancestors so much for you to be able to have it.

But, right.  Because the cost was so high, human brains did shrink sometimes.  Like when we first domesticated dogs.  Our ancestors began living with dogs about 30,000 years ago.  Dogs were willing to do some thinking for us – they’d sniff out prey and listen for predators at night.  Based on the behavior of my family’s dogs, I bet that they licked the faces of screaming children.  Maybe that doesn’t seem essential for survival, but I certainly appreciate every time our dogs calm the kids down.

Because we could slough off a few mental tasks – I don’t need to be so observant if the dog will help me hunt – our brains could shrink, making childbirth less deadly and reducing the caloric cost of maintaining our minds each day.

Pottery shard depicting a boar hunt in ancient Greece.

When humans switched from hunting and gathering to agriculture, our brains shrunk further.  A hunter / gatherer has to know so much about every plant and animal living nearby; the work asks more of a person’s brain than farming.  This evolutionary trend was exacerbated by the fact that people’s diets became way worse when they began to farm.  Instead of getting nutrition from a wide variety of different plants and animals, a farmer might eat meals consisting mostly of a single type of grain. 

There’s nothing we can do now about these evolutionary trends.  Dogs and farming swayed our ancestors’ evolution toward smaller brains, but it’s not as though you can get those neurons back by deciding to take up hunting, or never living with a pet.

But, honestly, our brains are so plastic that our genetic heritage matters less than how we choose to spend our time.  By nature, neither gorillas nor parrots will speak human language.  But individuals from both these species have been able to learn to communicate with us after we taught them.

Nobody is born with an innate understanding of mythology, religion, science, or mathematics.  None of that can be encoded in your genes.  If you want to understand this stuff, you’ll have to make an effort to learn it.

Neuron count only suggests a brain’s potential.  You could do incredible things with a low number – consider, by ways of analogy, the feats that 1960s NASA accomplished using computers much smaller than a contemporary telephone.  And, conversely, sensory deprivation will make it much harder to get things done, no matter what your innate potential.

That’s why I volunteer with Pages to Prisoners.  Our brains are capable of wonders.  At any age, we can learn and grow.  And yet, we lock people into prisons that seem designed to make them worse.

On neural plasticity.

On neural plasticity.

After discussing several forms of parasitic mind control during our poetry class in the local jail, somebody asked – somebody always asks – whether there’s some sort of parasite that makes people want to use drugs.

A few guys looked down at the table and nodded.  People are in there for a variety of reasons – domestic violence, burglary, DWIs, dealing or possession – but no matter the charge, many of the guys in jail were dealing with substance use that got out of hand.

I gave the same answer as always.

“Drugs do it on their own.  Chemicals can remodel your brain to make you want them again.  Like cocaine, it’s a dopamine re-uptake inhibitor, so if something makes you happy after coke, it’ll make you more happy than it would’ve … but your body responds by down-regulating the receptors, and then you’re stuck feeling less happy all the time unless you take it again.”


But it’s not all bleak.  Drug addiction takes hold because the brain is plastic – our minds change and we want that rush again, potentially to the exclusion of all else – but neural plasticity allows people to recover, too.  Dopamine receptor levels fall during periods of excessive drug use, but they’ll rebound during sobriety … and this rebound should attenuate the desire to use again.

Repeated exposure to drugs depletes the brain’s dopamine receptors, which are critical for one’s ability to experience pleasure and reward. From Wikimedia Commons.

(Unfortunately, the lecturers in our area’s court-mandated rehab courses have been telling people that, “After you take methamphetamines, it takes eight years of sobriety before your dopamine receptor levels come back.”  This sounds wrong to me – I don’t know the half-life of dopamine receptors, but the timing of sensitization and de-sensitization in conditions like bipolar disorder and antidepressant-induced mania suggests that it’s on the order of a month or so, not years – and it’s definitely unhelpful to say.  If you’re trying to help someone quit taking drugs, you want their goals to be feasible.

A former co-teacher tattooed “Day By Day” on his arm because quitting forever seemed impossible, but getting through one more day without drugs sounded like something he could do.  He’s now weathered five years of single days.  But if I felt like garbage and an instructor told me, “You’ll only feel like this for eight more years!”, I’d give up immediately.)

I don’t really understand Scientology – all my current knowledge comes from a single episode of South Park and a few minutes spent skimming through the Wikipedia article – but I was intrigued by the practice of using “E-meters” to measure a person’s cognitive development in the faith.  It made me wonder whether the sort of person who was interested in biofeedback and numerical metrics – somebody who tracks steps with a Fitbit or the gasoline saved on a Prius console – could use self-administered polygraphs for cognitive behavioral therapy.

An E-meter.

It’s well-known that polygraphs are fallible – you can fail them when you’re telling the truth, and you can learn to pass them while lying – but I imagine that the easiest ways to pass a polygraph is to convince yourself that whatever you’re saying is true.  There many physiological correlates to dishonesty – skin voltage, electroencephalogram patterns, eye movement, vocal tones – and by convincing yourself to earnestly believe whatever you happen to be saying, you could pass any of them.

Because you can cheat, U.S. courts generally don’t trust the results of lie detector tests.  In the pursuit of justice, cheating would be bad.  But as self-administered therapy, cheating is the whole point.  You cheat at lying until the lie becomes the truth.

“I like myself and I am worthy of love and self-respect.”

Rig up your polygraph and say something like that until the machine stops dinging you.  Do it daily.  Your brain is plastic, designed to learn and change.  Your words will become true.

On fish (and their similarities to us).

On fish (and their similarities to us).

I had a pet leopard gecko when I was growing up – he lived with me from fourth grade until I graduated from high school.  After that, my father took care of him, but I’d visit several times a year.  He would sit on my chest, occasionally skittering up to hide between my chin & neck, or buried in my underarm, while I lay on my back reading a book.

In all his glory (circa 2002).

He was a good friend to me, Mr. Lizard was (it took me almost an entire year to name him, and this was the name all that cogitation produced).  We had similar interests, mostly involving lying down in warm places to think.  I assume he was thinking.  But I have no idea what he was thinking about.  He rarely spoke – only twice that I remember – and, when he did, he made an irate chirping sound.  We didn’t have a great way to communicate.

But we, as humans, are moving closer to being able to understand some of the thoughts of other animals.  With some species, this is manageable for laypeople.  Dogs, for instance, co-evolved with humans (during which time both their & our brains shrunk as we sloughed certain tasks off onto the others).  Most humans are pretty good at guessing what a dog is thinking, especially when the dog’s thoughts involve wanting the human to scoop kibble or go on a walk.

fishFish, though?  I find fish inscrutable.  Mr. Lizard ate crickets, and the cricket bin at the local pet store was kept in the middle of the fish room, so I spent a lot of time peering into the various aquaria while their inhabitants blurbled lackadaisically about.  I always liked seeing the velvety black goldfish with eyes telescoped outward like hammerhead sharks.  I even bought a few to put into the pond in our backyard, but they swim slowly.  Within a week the raccoons had caught them all.

fishknowsJonathan Balcombe thinks I’ve been unfair, ignoring the thoughts of fish.  In What a Fish Knows, he combs through many decades of research into fish cognition in order to give blithely naive readers like myself some insight into their world.

It would be remiss of me to proceed with this essay without mentioning that, for many years, numerous scientists have argued that fish lack consciousness.  The crux of this argument is that fish brains are very different from human brains.  Indeed, fish lack the brain region that most humans use to process the experience of pain.  But that’s okay – recent animal cognition research has found that very different brain regions can be used for the same tasks in different species, as with parrots learning to sing and human children learning to speak.  And we’ve recently learned that blind humans, who use the brain regions most of us devote to sight for other purposes, are able to rewire their minds if suddenly granted vision.  Thank you Project Prakash.

So I’m not convinced by most of the arguments against fish feeling pain.  Throughout history, we’ve argued over and over again that perceived others don’t feel the way we do.  Descartes claimed that animals were nothing but automata.  White people in the United States often think that black people feel less pain.  That last sentence – I’m not just writing about the horrific way African Americans were treated long ago.  This is about how black people in the U.S. are treated today by highly-educated medical doctors.  Belief in bizarre racial stereotypes is widespread, and one consequence is that doctors offer less treatment for black people in pain than they would for equivalent white patients.

So I’m suspicious of any claims that the way we think, or feel, or suffer, is special.  As is Jonathan Balcombe.  In his words:

Thanks to breakthroughs in ethology, sociobiology, neurobiology, and ecology, we can now better understand what the world looks like to a fish, how they perceive, feel, and experience the world.

What this book explores is a simple possibility with a profound implication.  The simple possibility is that fishes are individual beings whose lives have intrinsic value — that is, value to themselves quite apart from any utilitarian value they might have to us, for example as a source of profit, or of entertainment.  The profound implication is that this would qualify them for inclusion in our circle of moral concern.

Not only is scientific consensus squarely behind consciousness and pain in fishes, consciousness probably evolved first in fishes.  Why?  Because fishes were the first vertebrates, because they had been evolving for well over 100 million years before the ancestors of today’s mammals and birds set foot on land, and because those ancestors would have greatly benefited from having some modicum of wherewithal by the time they started colonizing such dramatically new terrain.

Despite claiming that fish are extremely different from us, scientists have used fish to study human mental conditions for many years.  Since the 1950s, researchers have tried dosing fish with LSD, finding that, like humans, most fish seem to enjoy low doses of psychedelic drugs but are terrified by high doses.  Even today, antisocial cave fish are being investigated as a model to test drugs for autism and schizophrenia.  It is illogical to simultaneously claim that fish may be useful models to understand our own brains and that their brains are so different from ours that they cannot feel pain.

Of course, there probably are very significant differences between our minds and those of fish.  I’ve discussed some of these ideas in two prior speculative essays on octopus literature.  I stumbled across another lovely insight into fish brains in Sean Carroll’s The Big Picture.  He suggests, quite reasonably, that fish brains probably operate faster than our own, with less tendency toward meditative rumination.  His argument is based on the behavior of light in water versus air; in his words:

bigpictureAs far as stimulating new avenues of thought is concerned, the most important feature of their new environment was simply the ability to see a lot farther.  If you’ve spent much time swimming or diving, you know that you can’t see as far underwater as you can in air.  The attenuation length – the distance past which light is mostly absorbed by the medium you are looking through – is tens of meters through clear water, while in air it’s practically infinite. (We have no trouble seeing the moon, or distant objects on our horizon.)

What you see has a dramatic effect on how you think.  If you’re a fish, you move through the water at a meter or two per second, and you see some tens of meters in front of you.  Every few seconds you are entering a new perceptual environment.  As something new looms into your view, you have only a very brief amount of time in which to evaluate how to react to it.  Is it friendly, fearsome, or foodlike?

Under these conditions, there is enormous evolutionary pressure to think fast.  See something, respond almost immediately.  A fish brain is going to be optimized to do just that.  Quick reaction, not leisurely contemplation, is the name of the game.

Now imagine you’ve climbed up onto land.  Suddenly your sensory horizon expands enormously.  Surrounded by clear air, you can see for kilometers – much farther than you can travel in a couple of seconds.  At first, there wasn’t much to see, since there weren’t any other animals up there with you.  But there is food of different varieties, obstacles like rocks and trees, not to mention the occasional geological eruption.  And before you know it, you are joined by other kinds of locomotive creatures.  Some friendly, some tasty, some simply to be avoided.

Now the selection pressures have shifted dramatically.  Being simple-minded and reactive might be okay in some circumstances, but it’s not the best strategy on land.  When you can see what’s coming long before you are forced to react, you have the time to contemplate different possible actions, and weigh the pros and cons of each.  You can even be ingenious, putting some of your cognitive resources into inventing plans of action other than those that are immediately obvious.

Out in the clear air, it pays to use your imagination.

(An aside, added later, not about fish: dolphin sonar & whale songs often travel farther in water than visible light does near the Earth’s surface, perhaps inclining whales & dolphins to be more imaginative and introspective than land animals.  I neglected this thought when I first posted the essay because it’s hard to avoid favoring our own forms of perception.)

Human brains are amazing.  I think that goes without saying, especially because my ability to type the words “I think that goes without saying” is already a dramatic demonstration of our mental capacity.  As is your ability to read those words and understand roughly what I meant.

And yet.  Our brains are sufficiently remarkable that I think there’s no need to denigrate the cognitive abilities of other animals.  They can feel.  They can think.  They almost certainly have their own wants and desires.

Recognizing their value shouldn’t make us feel bad about our own minds, though.

We’ve come a long way.  We still have more, as a species, to do.  That’s glaringly obvious to anyone who so much as glances at the news.  Still, I’d like to think that the average person is doing a better job of recognizing the concerns of others than was common in our past.  There is dramatically less (but non-zero) slavery in the modern world than in the past.  And we treat non-human animals far more kindly than we used to.

From Frans de Waal’s Are We Smart Enough to Know How Smart Animals Are?:

smartenoughDesmond Morris once told me an amusing story to drive this point home.  At the time Desmond was working at the London Zoo, which still held tea parties in the ape house with the public looking on.  Gathered on chairs around a table, the apes had been trained to use bowls, spoons, cups, and a teapot.  Naturally, this equipment posed no problem for these tool-using animals.  Unfortunately, over time the apes became too polished and their performance too perfect for the English public, for whom high tea constitutes the peak of civilization.  When the public tea parties began to threaten the human ego, something had to be done.  The apes were retrained to spill the tea, throw food around, drink from the teapot’s spout, and pop the cups into the bowl as soon as the keeper turned his back.  The public loved it!  The apes were wild and naughty, as they were supposed to be.