The selective advantage of consicousness in humans? Understanding each other.

Sam Harris recently interviewed his wife, Annaka, on his "Making Sense"podcast to discuss her new book on consciousness. One interesting exchange concerned the idea of "panpsychism," the view that consciousness is somehow inherent to matter itself. Both parties expressed a certain sympathy to the panpsychic view in light of a perceived inability to show a selective advantage to consciousness that would cause natural selection to produce and develop it. I'd like to argue here that the Harrises have missed a plausible and profound Darwinian advantage to consciousness, as well as the intuitions of free will, self, and agency; namely, the ability to predict what other human beings will do.

Humans (Homo sapiens and our hominid ancestors) have been part of relatively large and sophisticated social groups for millions of years. These groups have been both complex and remarkably effective; the culture of tool use alone, passed on without the aid of genetics from generation to generation for at least 2.6 million years, shows how important social groups have been for humans. Of course, as soon as one is part of a social group, there is a decided advantage in predicting how other members of that group will behave. It's easy to imagine how predicting the reaction of another human to one's aggression, consoling, or flirting would boost an individual up the social hierarchy and contribute to the number and fitness of that individual's offspring, thus enhancing that person's inclusive fitness. So traits that enhance the ability to predict the behavior of other humans would almost certainly confer a selective advantage.

The way we, as conscious people, regard other humans is shot through with the intuitions discussed by the Harrises - we see others as individual agents that make choices based on internal drives and desires. While those intuitions may not match up with our 20th century understanding of physics and neuroscience, they are nonetheless really useful models of other humans and their behavior. We may be far from perfect from predicting the reactions of others, but modeling them as agents still makes sophisticated and powerful predictions of what they will do (perhaps this ability reaches its zenith in the modern kindergarten teacher near the end of the school year). Those intuitions are also quite efficient; modern neuroscience has shown us just how much complexity underlies our simplistic ideas of how others behave, and therefore just how much computational effort we avoid by using the simpler model of others as decision-making agents. Further, the conscious post-hoc narratives we construct about others generally improve our predictions of what others will do (hence the difference between a beginning-of-year kindergarten teacher and the same teacher at the end of the year). So while our intuitions about others may not be strictly correct, they are still a vast improvement over a  reaction of merely fear or disgust, and we should not be surprised at the widespread adoption of those intuitions across humanity.

Given the practical utility of seeing others as agents with free will, it is not that surprising we might turn the model upon ourselves. Understanding our own behavior as agents that make choices based on drives or desires can help us better interact with our fellow humans. Telling ourselves stories about  why we make the choices we make - and what goals we believe motivate us - both helps us control our own reactions to others and plan our social strategies in much more nuanced ways that simple emotion can. Having the patience to wait for an opportune moment to challenge a rival or seek out an ally relies on the kind of ongoing narrative that consciousness provides. Even if consciousness is a post-hoc story we tell ourselves (as tantalizing results from the past few decades suggest) the potential to refine our future actions to better serve our interests is immense.

In case the reader is not yet convinced of the practical value of a conscious perception of other humans, a somewhat recent review of the selective advantage of various steps on the way to human consciousness (including the social advantages) by Michael Gratziano may be helpful.

One might object along the lines of "zombie" thought experiments that all this modeling of agency and narrative could be unconscious and still effective; why would it be necessary for the "lights" of awareness to be on to make good predictions about what we and others would do in social situations? We must concede that we really don't know what that possibility looks like; perhaps some future unconscious social genius AI will show us. Or perhaps a mental model sophisticated enough to effectively model our social interactions through a narrative of independent agents just equates to consciousness. Or maybe once that mental model is constructed, generating awareness is a low-cost adjustment that permits even more sophisticated predictions based on conscious reflection in memory.  Judging from our position as conscious beings, it's just hard to evaluate the other possibilities.

It is also important to point out that our intuitions about consciousness in other species generally correlates with social sophistication (the blog does have "empiricist" in the name). Whales and dolphins; dogs; other primates; birds like crows or parrots; even prairie dogs; all these social species are ones we intuitively suspect may have the "lights" of consciousness on, given their apparent ability to perceive and react to the emotional states of their peers and even us. Even the counterexample of social insects is instructive; we don't generally ascribe consciousness to, say, ants or honeybees, because the individuals in those societies behave in quite programmed and stereotypical ways to each other (as well as being bound by inclusive fitness). Further, the behavior of hives or colonies of social insects is not particularly sophisticated with regards to other hives or colonies; the typical interaction between ant colonies, for example, is ruthless (perhaps mindless) all-out conflict.

So far from being selectively neutral, the intuitive models contained in our conscious awareness are profoundly useful in navigating the complexity of even hunter-gatherer human societies. Indeed, they have likely been useful for millions of years, and perhaps across many different groups of social animals. While we do not know whether our particular self-aware version of these models is the only way to gain that predictive utility, it is not hard to see the adaptive value of a conscious representation of the world for a social animal. There is no need to conjure a panpsychic conscious property of matter itself, just as there was ultimately no need to define a "vital" force animating matter into living things. We have sufficient reason to predict that consciousness would be selected for as animals began living together in groups that were large enough for its mental models to matter.

Does Eric Metaxas really have comprehensive imagination?

Recently an opinion piece by Eric Metaxas, "Science Increasingly Makes the Case for God," caused a bit of a storm after the Wall Street Journal ran it on Christmas Day. The argument it makes - that the physical world is fine-tuned to match the needs of living things - is nothing new; similar claims from authors such as Michael Behe, William Dembski, and Michael Denton were part of founding the Intelligent Design movement in the early 1990s. The fact that Metaxas can still get publicity from his claims suggests a serious examination is in order.

The foundation of Metaxas's argument is the striking correlation between the physical conditions of the Earth and the needs of organisms that live on that Earth. As he puts it:

Today there are more than 200 known parameters necessary for a planet to support life—every single one of which must be perfectly met, or the whole thing falls apart.

This correlation is something any knowledgeable observer should accept; the match between organisms and their environments is quite striking. Given that correlation, we naturally want to understand the cause, and that is where Metaxas's views differ so radically from those of most scientists.

There are really two possibilities. The first explanation argues that life is picky, fragile, and static, and that the universe must have been adjusted to the particular needs of living things. This is where Metaxas's description, that "every single [parameter] must be perfectly met" comes from. If the universe needed adjusting (often called "fine-tuning" when describing the constants of physics), then there must have been an intelligent being doing the adjusting - hence "the Case for God."

The other possibility is that the conditions of the universe are relatively static and not "adjusted" to benefit life, but that living things are capable of evolving so that they can tolerate those conditions (at least in a few places like Earth). Either explanation could produce the striking correlation; how do we choose between them?

Each explanation makes strong demands on our understanding. One particularly strong demand for the fine-tuning explanation, often unstated or ignored, is a complete understanding of the possible ways living things could exist. Arguing that the universe has to be adjusted to the requirements of Earth life includes the implicit assumption that the Earth includes the complete sweep of potential living things. If you want to argue that Metaxas's "200 parameters" have to be the way they are, you have to argue that the only way living things could possibly exist is pretty much just the way they do here on Earth.

As an example, if you insist that life absolutely requires liquid water, having planets with liquid water on their surface seems like a reasonable demand of the universe. Can you be sure of that assumption when the only examples of living things you know of all come from a planet with oceans? It's rather like insisting that all mammals deliver well-developed live young, completely ignorant of the marsupial branch of the mammal family tree. Time has not been kind to this assumption of "comprehensive imagination." That living things could survive in deep oceanic hydrothermal vents (way too deep to get energy from the sun), at the near-boiling temperatures of hot springs,  or in extremely acidic conditions were all hardly conceived (not even taken seriously enough to be considered impossible) until the organisms living in those environments were discovered. Claiming to imagine every possible way of being alive seems both remarkably arrogant and extremely unlikely. To borrow from Daniel Kahneman's remarkable book, this explanation suffers from the "WYSIATI" fallacy: What You See Is All There Is.

But what about the other explanation - that life has evolved to match the conditions in which it finds itself? That lineages of organisms can change over time was once considered an extraordinary idea, and one might rightfully demand some pretty strong evidence of its reality. After over 150 years with the idea of natural selection, the evolutionary biologist can point to a range of different types of evidence, from change in fossil lineages, to the hierarchical pattern of diversity of living things, to the underlying biochemical similarity of all living things. One can observe the evolutionary process in the lab with organisms whose generation times are conveniently short, as well as in decades-long studies of wild populations. We even know that life on Earth has adjusted to huge shifts in the composition of its atmosphere caused by living things themselves! In short, that lineages of living things on Earth can change over time is a well-documented fact. That other forms of life could evolve does not seem far-fetched, since there is no apparent reason the conditions for evolution (reproduction, a genetic system, and differential survival) could not be fulfilled in radically different forms of life.

So in understanding the strong correlation between environment and living things, we can either claim that life is inherently dependent on the conditions here on Earth (again, a claim of comprehensive imagination for which we cannot have any real basis) or claim that life can adapt to at least some of the environments available (for which we have abundant evidence, at least for Earth-life). If we are really honest about the limitations of our examples of life - and the limits of our imaginations - we should see the absurdity of the assumptions necessary to claim proof of supernatural fine-tuning. The far more plausible explanation is the evolutionary one, and it is the only one with sound empirical evidence.

(note: not long after I wrote this post, the AAAS hosted a session on what a "shadow biosphere" (i.e. not based on DNA/protein) might be like. There's an account of the session here, if you're curious.)

What would an Intelligent Design theory look like?

When I first read about the "hypothesis" of Intelligent Design, I figured it would go away soon enough. Clearly, I underestimated the degree to which a vocal segment of society will prioritize their personal beliefs in a Designer over all the evidence that suggests there is no design in nature (and yes, I know people talk about natural "designs" all the time in a casual way, just like we use the term natural "selection," when both are mere metaphors that save a lot of verbiage). Advocates of "ID" are constantly claiming it is science (it helps justify putting it in a public school science classroom), so I'm going to take the intelligent design argument seriously enough to put it in scientific terms. What would a theory of Intelligent Design look like, and what testable predictions would it make?

1. If natural structures are the result of a design process rather than undirected evolution, they should be consistently optimal. An entity intelligent enough to design any of the complex creatures we see around us (and powerful enough to put those designs into use) would be expected to do a good job, and the designs should be really good. As a corollary, we shouldn't see a lot of designs that mere humans like us could easily improve.

2. Good designs should not be limited to one taxonomic group. If it's a good design - one that solves a problem well - it should be widely used.

3. We shouldn't see a lot of history in an intelligently designed world. There's no reason a designer would need to provide continuity between the organisms it designed, especially if the intermediate forms between current organisms (what we call common ancestors in evolution) did not perform as well as the ones we see today. (If you like, you could call this prediction a more general version of #2).

4. An intelligent designer would try to make its different designs compatible. In other words, an designer with any intelligence would never design parasites. Why would such a creative and intelligent entity go to all the trouble to design an fancy multicellular creature, then toss in some single-celled bacteria (or even viruses) that could take that creature down?

Now I'm sure some of the folks on the ID side of things will find fault with these predictions; they may say that I'm limiting the mystery of how a Designer would have worked, or its purpose in creating living things, etc. But I'm trying to do science here, and if ID is to be a scientific hypothesis, it has to have specific testable predictions, just like all the great scientific explanations.

So how well does the evidence from nature match these predictions? Not very well. Starting with prediction #1 (designs should be consistently optimal), there's lots of non-optimal design out there. Using our own bodies as an example, humans have this terrible design in our throat, where we cross swallowed food with inhaled air and occasionally choke to death because of it. We also have chronic back difficulties from standing on two legs with a spine that works just fine for animals on four. Childbirth in humans is much more difficult than other mammals, because moms push our babies' big, brainy heads through a small opening in the pelvis (caesarian sections work in difficult deliveries because removing a baby through the big abdominal opening is far easier than the natural route for birth). And finally, anyone who has studied the hormonal mechanism for regulating blood pressure ends up with a big facepalm; the kidneys respond to an decrease in blood pressure by modifying a hormone made by the liver, which is then modified again in the lungs and kidneys, which then both goes back to the adrenal glands to make another hormone which tells the kidneys to increase salt retention in the urine, while all the while the third version of the liver hormone goes to the brain, which makes another hormone to tell the kidneys to absorb more water from the urine. In simpler terms, the kidneys use the liver, lungs, brain, and adrenal glands as intermediaries in the process of the kidney telling itself to absorb more salt and water from the urine. NOBODY would call that a good design. In each case, I'd say we humble humans could have done much better. And those are just a few examples from one species (us).

So how about prediction #2 (good designs should be used all over the place)? There are a lot of species out there that could really benefit from some traits from other groups. Gliding snakes and squirrels are pretty cool for snakes and squirrels, but they are awful compared to true fliers like birds or bats (feathers would be helpful). We mammals would be much better at long aerobic efforts if we had the flow-through lungs that birds do. Those birds would benefit from better recognition of their chicks than just "it hatched in my nest" (you did know that cuckoos are nest parasites, right)? And there are the marine mammals, which do remarkably well given the fact that they have to routinely return to the ocean's surface to breathe ("I could sure use some gills, Shamu!"). Examples of good "designs" limited to one group of organisms abound here.

Now for prediction #3 (we should not see history). I'll just come out and say it: history pervades the record of life on Earth. Extinction has eliminated most of the intermediate ancestors between the species we see today, but we know they were there from fossils. It seems very strange that a designer would respect the ancestry of its various groups so carefully ("no nursing for you - you're a bird!" or "yes, whale, I know you have fins, but they still have to have all the fingers inside"). It also seems strange that a designer would put out an Archaeopteryx - a stepping-stone species between dinosaurs and birds that could never compete against a modern bird, but could make it without any true birds around yet. Why design a cobbled-together intermediate when you could just do real birds?

I can imagine someone arguing that a designer was learning as it went, and that the various groups of organisms were somehow the "rough drafts" along the way (no doubt arguing that we humans are the polished final draft). But that means that this intelligent designer didn't just publish the best designs, but all the "rough drafts." Does that make any sense?

And finally, prediction #4 (different designs should be compatible). I'll leave predators and prey aside, and just point out that there are roughly four species of parasite on earth for every non-parasite species (and plants may justly feel that most of those animals are also parasites as well - at least the ones that aren't helping them with pollination). While parasites certainly have ecological roles and big effects, it's hard to see those roles as necessary ones. Ultimately, why would any intelligent designer handicap its designs with so many effective parasites?

So there you have it. Some realistic and rational predictions from intelligent design, none of which match the actual world we have. I'm sure that ID advocates will argue that I'm setting up a straw man, and trot out their own prediction that they see "complex specified information" or "irreducible complexity" as predictions of the model. You should realize, however, that ID is not the only theory that predicts "CSI" (evolution would do the same), so it hardly qualifies as a prediction that discriminates ID from other explanations. As for "irreducible complexity," every time the ID folks argue something is "irreducibly complex," patient biologists point out the "reducibility" to simpler forms, at which point the ID movement abandons the case and picks out something else. Camera eyes, bacterial flagellae...it's like a big game of evidentiary whack-a-mole. I'm just going to ask you to judge my predictions on their own merits, and remind you that there's this other theory that would predict that organisms would often be bolted together in funny ways, that ancestry would be central to what features those organisms would have, and that struggling to survive would put organisms at cross-purposes all the time. I bet you've even heard of it...

The Agency problem

I recently heard an interesting podcast on "memes" and the extent of their similarity to genes. One of the hosts (and many online commentators) had trouble with the idea that memes (units of information transmitted among humans) could replicate themselves - after all, a song or phrase doesn't copy itself, does it? This was contrasted with genes, which we were assured could self-replicate, and thus the meme idea was dismissed. We can choose whether or not to pass along a pithy phrase, so it doesn't have the status that a gene does.

Of course, to anyone who understands genetics, the idea that a gene "self-replicates" is pretty silly. Aside from a few special sequences of RNA (and damn if those aren't interesting) DNA is just a molecular encoding of information - not fundamentally that different from a long string of text. Genes are particular stretches of DNA that code for useful proteins, but they are still just information. It takes a bunch of molecular machinery inside a cell to copy that information (or, for that matter, to convert it in to a protein). While it's true that the individual enzymes that copy, transcribe, and translate the information are produced from genetic information, it takes a collection of genes working in concert to duplicate any of the individual genes. For the gene to become more common in the world, it has to be in an organism that survives and reproduces. Genes replicate, proliferate, and disappear in cells in organisms (even if those organisms are unicellular), and genes can't "do" anything on their own.

So why does everybody just assume genes are doing their thing replicating and proliferating? Well, the fact that Richard Dawkins's groundbreaking book was called "The Selfish Gene" may have something to do with it. Dawkins pointed out that from the point of view of a gene, an organism is a "survival machine." Genes don't really "care" about individual organisms beyond their ability to promulgate genes. To bolster this view, Dawkins (correctly) pointed out that individual organisms (and even species) are incredibly short-lived compared to genes; hemoglobin genes, for example, are something like 500 million years old, and the genes for enzymes like DNA polymerase are presumably as old as DNA-based life itself - which is the only kind we know (and yes, RNA viruses are still DNA-based; they require the use of plenty of proteins from their hosts' DNA to reproduce). Most folks seem to accept some sort of independent drive for genes since Dawkins published the book - hence the idea that they are "self-replicating" - and the way Dawkins pointed out that evolution was not just about the survival and reproduction of organisms was a big step forward in understanding. Nonetheless, the idea that emerged ("it's all about the genes") is just plain mistaken.

The problem here is that we humans are used to the idea of agency. That is, changes come from agents which are capable of action in the world. In human political and social systems, agency is a basic assumption; if something happens, somebody must have done it. It's a great concept for explaining a market or a legislature. In understanding an evolutionary process, however, agency is basically useless, because changes occur at so many levels (gene, organism, population) at the same time that one just can't ascribe evolution to a single agent. Genes don't evolve on their own; neither do organisms. Populations evolve (change genetically over time) only to the degree that individuals in the populations are more or less successful at surviving and reproducing, but the change is at a genetic level (usually described as a change in gene frequencies). So who is the agent?

Really thinking deeply about this is hard when you're raised on agency; hell, even evolutionary biologists use Darwin's term "natural selection," as if some agent ("Nature") was carefully deciding who deserves to survive. That, of course, is not just nonsense, but unnecessary; organisms just survive and reproduce, passing on genes that determine part of the likelihood of survival of those organisms. In that situation, there is no agent that has to "select"; instead, better-surviving libraries of genes emerge in the surviving organisms, period. Evolution is literally the most natural thing to happen to reproducing organisms with some sort of genetic system, no agent required.

Back to memes. We have information (words, phrases, ideas, music) that sits around on its own, but tends to get passed around when you have people talking to each other. We (people) use information, share it, find it helpful, tell our kids. Nobody has to go out and force us all to put "ROFL" in our social media posts, but it works, and it spreads. That's a meme, and it deserves the same sort of respect as a concept in social informatics that a gene does in biochemistry. OK, I made up the phrase "social informatics," but you get the point. Genes and memes spread, or they don't; one is biological evolution, the other social evolution, but in any case, there's no point to trying to find the Agent of Evolution behind it all. In a situation where genes or memes can be copied, it just happens.

Seeing the forest *in* the trees

I previously posted on the human bias toward seeing patterns and causation everywhere, even when the pattern doesn't hold up. There are, however, cases where we fail to really notice a pattern that is all around us. A great example to an evolutionary biologist like me is the hierarchical pattern manifest in all the animals and plants we see in the world around us.

"Get OFF my lawn!"

I often ask my students "Wouldn't it be cool if you found a squirrel with a crab claw?" They usually chuckle at the apparent absurdity of the question - of course you would never find that. Mammals don't come with crustacean parts. They're right, of course - but is it so absurd to ask?



Here is a pattern that we're so accustomed to that we don't often bother to ponder it. The diversity of the natural world is divided up quite distinctly; you have conifers and angiosperms in plants, mammals, birds, lizards, fish, and amphibians among animals with backbones, insects, crustaceans, and arachnids among invertebrate animals, etc. We are so accustomed to this pattern that it would be really surprising to see a pine tree with a dogwood flower or an oak tree with a pine cone, or to find a bird giving birth to live young. In simple terms, birds are birds, fish are fish, and insects are insects - the names correspond to a suite of characteristics that are, quite literally, synonymous with the group.

This pattern gets interesting when you move to more or less-inclusive groups of species. For instance, within mammals, you can find species that give live birth to well-developed offspring (placental mammals - including us humans), species that give birth to live young that must latch on and nurse their mom for a long period of time (marsupials - think kangaroos with their cute pouches) and species that actually lay eggs (monotremes like the duck-billed platypus). In other words, there are subgroups within mammals that are clearly mammals, yet they differ in pretty fundamental ways. Those subgroups are also really distinct; it's tough to confuse a marsupial mammal with a therian mammal if you look carefully. That's why opossums seem so weird to North Americans - it's basically the only marsupial we ever encounter in our backyards.

Going in the other direction, we find that while birds and mammals are not at all hard to tell apart, they have lots of characteristics in common, from the bones in our skeletons to lots of details of our physiology and development. In other words, birds and mammals are distinct, but not nearly as distinct as birds and insects, or birds and flowering plants.

What's so interesting about this pattern is that there is no a priori reason for it. Why should diversity be divided up hierarchically? Why can't we have a squirrel with a crab claw? In the world of human-created things, there is lots of sharing around between designs (think, for example, about how much computer technology has infiltrated your car; I doubt carmakers were thinking about that in the days of ENIAC!).

Carl Linnaeus noticed the hierarchical pattern of characteristics way back in the 18th century and built a system of naming species on it (the one we have all seen that calls us Homo sapiens). What produced the pattern wasn't really worked out until the 19th century, when various theories of evolution from common ancestors suggested that the hierarchical pattern reflected the degree of shared ancestry among groups of species. For the vertebrate animals, the hierarchy looks like this:

image credit: University of California Museum of Paleontology's Understanding Evolution, http://evolution.berkeley.edu

In other words, the hierarchy of characteristics is the product of a hierarchy of ancestry of animal and plant species. The things we think of as "mammalian" are the vestiges of the common ancestor of what we call mammals (and for most people, that's the ancestor of marsupial and placental mammals). The things we think of as defining birds owe their origins to the ancestor of that particular lineage of sauropods. The pattern of diversity is the product of the evolutionary process.

Often when the theory of evolution is attacked, one will see it defended with documented artificial selection among laboratory bacteria, or observed small-scale adaptation in Darwin's finches. Those are fine examples, but they pale compared to the way the whole grand tapestry of species screams out "I'm the product of evolution from common ancestors!" The hierarchical pattern is ubiquitous and incredibly exhaustive (I leave it to the reader to work out the interesting example of whales and dolphins, and the ways in which they are quite distinct from their fishy marine colleagues) because the evolutionary process is likewise ubiquitous.

So the next time someone wonders if evolution really happens, explain to them that there are a lot of bats out there that could really use some feathers. And send me some gills if you can.