It's a Jungle in There: How Competition and Cooperation in the Brain Shape the Mind (5 page)

The fact that sex feels good motivates organisms to do what they do to complete sex acts, thereby generating next generations. Sex also spreads genes. If a guy has one set of genes and a gal has another, their offspring get a mélange of ma and pa chromosomes. The genes the kids pick up may be good ones from dad and bad ones from mom, or vice versa. It’s impossible to tell in advance all the genes that will have positive or negative effects.

“Good” and “bad” are relative terms, defined
a posterior
rather than
a priori
. Beth may have married Bud despite his dandruff, but the genes that caused Bud’s flakes may later, when expressed in Bud’s and Beth’s baby, bestow on that kid immunity to some disease. Bud may have married Beth because of her freckles, but the genes for those winsome flecks may later predispose Beth’s and Bud’s kid to get some illness no one would wish on a friend. The good or bad consequences of a gene, then, are a matter of chance. Accordingly, sex, in Darwin’s theory, has the statistical consequence of quickening chance effects. Were there no sex (or were there sex with only oneself) the opportunity for genetic diversity would be low.

Sex or, more specifically, competition for mating provides a forum to show off features that, as far as the participants can tell, bode well for survival.
⁸
In humans, clear skin may signal resistance to infection, a firm butt may signal strength, and a capacity for cool dance moves may signal agility. It’s rare for physical or behavioral features that prospective mates find appealing to be obviously
bad
for survival. They may not be especially
good
for survival once history runs its course except insofar as they are useful for attracting mates. Peacock plumes are the paradigmatic example of sexual attractants with an advantage other than attracting mates. Basso voices in human males may be another.
⁹
Breasts in human females may also serve that function, for lactation in other mammals comes without swollen mammaries.
¹⁰

The Darwinian drama of individuals finding themselves more or less able to spawn offspring is a drama whose future direction no one knows or needs to know. The reason is that it can run its course without a prior plan. Indeed, there may be no plan at all.

This last point is of inestimable importance for the theory of cognition to come, especially because cognition is so much about predicting and planning.
¹¹
Later in this book I will suggest that what we take to be plans are just activities of neural populations shaped in basically the same way as other biological populations. Believing that we have plans need not imply that plans
per se
exist in our minds. Plans could be internal responses to situations (stimuli) we encounter that in turn trigger behaviors we call voluntary, intentional, or, indeed, planned.

Returning to evolutionary biology, scholars in that area of study have said much more about natural selection than I have here. My aim has just been to give the flavor of the Darwinian process in simple and, at times, fanciful terms.

Speaking fancifully is not meant to diminish the sophistication of the tools used by evolutionary biologists and their colleagues to explore the dynamics of natural selection. Those tools include studying fossils, counting organisms with different features in different environmental niches, and developing mathematical models of real and artificial life forms. With such methods, it has been possible to confirm Darwin’s theory or, saying this another way, to show that Darwin’s theory can withstand efforts to disconfirm it.
¹²
Darwin’s theory has gained so much credibility that it is possible to say it is no more speculative than Newton’s theory of gravitation.
¹³

Evolutionary biologists have also uncovered some phenomena of special interest for what’s to come in this book. I will discuss three of them here: (1) the founder effect, (2) punctuated equilibrium, and (3) niche opportunities.

The
founder effect
is the tendency of initial, successful occupants of a niche to have an exceptionally strong effect on succeeding generations. The effect holds when the rate of interbreeding among first settlers and their seed exceeds the rate of breeding with newcomers.
¹⁴

One illustration of the founder effect concerns the Amish, who live in Central Pennsylvania, where I happen to reside. The Amish live in insular communities. They mainly keep to themselves and mainly marry in-county. As a result, they enjoy less genetic variation than other, more open communities. As a further result, they have unusual traits. Due to a recessive allele shared by two members of the founders of this colony in the mid-1700s, a disproportionately large number of Amish have Ellis-van Creveld syndrome.
¹⁵
Individuals with this syndrome are shorter than usual, have unusually broad hands and faces, and have malformed wrists and an extra finger—a syndrome known as
polydactyly
. Ellis-van Creveld syndrome is traceable to two of the small number of individuals who first settled in the area that the Amish now inhabit.

The founder effect has psychological analogues. One is imprinting. Here, in the case of ducklings, the sight of a figure that may plausibly pass for Mama Duck is latched onto by recent hatchlings. They follow this figure even if she, he, or it is not their parent, provided it’s the first reasonable facsimile of a parental figure they encounter. This phenomenon was made famous by the Austrian ethologist Konrad Lorenz, who, it happens, worked with greylag geese rather than ducklings, though the phenomenon works with either
species.
¹⁶
Imprinting is analogous to the founder effect in that primary experience has extraordinary impact.

Two other psychological analogues of the founder effect can be mentioned. One is the tendency of words that are learned first to be read aloud at exceptionally high speeds—much higher than would be expected based solely on how often they are repeated. This has been shown both in tasks that require reading of printed words and in tasks that require naming of pictured objects.
¹⁷

The other psychological analogue of the founder effect is speaking a language with an accent reflecting the dialect spoken where you were raised. In my case, I was raised in Philadelphia, so I speak with a Philly accent. When I say “noodle,” I can’t help but say “neeodle.” When I say “legal,” I can’t help but say “liggle.” I can try very hard to say these words without my Philly twang, but it’s nearly impossible for me to do so. The same phenomenon occurs for people who speak English with a Russian accent, for people who speak Hebrew with a German accent, and so on. The fact that accents are so hard to shed—extensive voice coaching is usually required—attests to the founder effect for speech.
¹⁸

Besides the founder effect, another phenomenon of special interest from evolutionary biology is punctuated equilibrium. This is a relatively sudden change in the rate of evolutionary change. The term
punctuated equilibrium
refers to the fact that fossil records have shown that, in evolution, there have been periods of relative stasis or equilibrium punctuated by periods of very rapid change.
¹⁹

Punctuated equilibrium is important here because in mental development there are similar surges. One occurs around the age of 18 months, when in healthy human toddlers there is an explosion of language. From 18 months to 24 months, toddlers roughly double their vocabularies, from about 1,000 words to about 2,000 words.
²⁰

On a faster time scale, mental states also tend to change quickly after periods of seeming quiescence. You don’t
gradually
see a shape, and you don’t
gradually
learn a fact. As is true of evolutionary states, mental states are punctuated. Minds jump from state to state, from not understanding to understanding, from not seeing a solution to seeing one. If there is a stream of consciousness, as William James suggested, the stream doesn’t flow continuously.
²¹
Rather, what you think of from moment to moment is a series of discrete realizations.

The third phenomenon of evolutionary biology of interest here is the existence of
niche opportunities
. When niche opportunities arise, a species occupies a new habitat and survives within it with a low population density for a long time. Then, if conditions become more hospitable, the species proliferates.
²²

I mention niche opportunities because an analogous phenomenon may be recognized in individual experience. If you once learned to ride a bicycle, you will always be able to do so, provided you suffer no disabling physical change. Being away from a bike for years doesn’t prevent you from knowing what to do once you recycle. The knowledge you have for bike riding is there all along and can be reawakened. Likewise for other skills.
²³

The ability to re-engage skills that have lain dormant for years seems at first to be inconsistent with a prediction that might be made by applying the theory of natural selection to individual brains. That prediction is captured by the familiar phrase “use it or lose it.” If mental representations are untapped for long periods, the Darwinian account would seem to suggest that they should die. The phenomenon of niche opportunities shows, however, that, in the wild, species may “bide their time” if conditions for their survival are not too unfavorable. So too may neural ensembles that support long unpracticed skills, like long-ago biking or erstwhile skiing. As long as the neural ensembles supporting such skills are not crowded out by other competing elements, they can remain viable.

A last point about evolutionary theory that’s central for what’s to come can be called the “no-stone-goes-unturned” principle. This is not a phrase used by evolutionary biologists to capture a core principle in their field, as far as I know, but it’s one that, for me, captures the essential idea that nature is virtually perfectly efficient and that, by implication given the analogy I’m pursuing here, what’s good for the global goose (species) is good for the individual gander (the individual mind).

What I mean is that no potentially habitable niche goes unoccupied. Wherever living things can possibly live, they do so—under stones, under eaves, atop mountains, in the hottest deserts, in the coldest coves. Even in places where you’d least expect life to flourish, life can be found. The most salient example I know of are hydrothermal vents unfathomably deep in the sea, where there is scarcely a photon from the sun. Hydrothermal vent worms
live there, comprising a life form no one knew about until its recent discovery by a deep-diving sub. So hardy are the life forms on Earth that pains are taken by NASA to ensure that no bacterium goes along for the ride to other worlds, lest extraterrestrial neighborhoods get infected by terrestrial bugs.

There’s a tie-in between the no-stone-goes-unturned principle and brain use. A claim in the popular press is that we use only 1/8 of our brains, or some such fraction. Admittedly, some people act like they use less brain power than they should. But that’s different from saying parts of their brains lie idle. Wherever neuroscientists have looked, they’ve found brain regions that are busy. As long as healthy neurons are present in an area of the brain, neurons studied there have been shown to be active. Finding a healthy region of the brain that’s completely dormant is as likely as looking under a stone and not finding a weevil, worm, or wily bacterium. The trillions of living things on Earth find places to live in every nook and cranny. If a “Vacancy” sign appears anywhere in the outer jungle, it doesn’t stay up for long. Vacancies are filled in the blink of an eye. The brain, too, provides a welcome environment for opportunistic bands of neural gnomes to flourish, as long as the living conditions aren’t too difficult. Given the hospitable environment of the brain, a wondrous diversity of neural, and then mental, life can spring up.

If it’s a jungle in there and you’re curious how the jungle works, you’d better screw up your courage, put on our hiking boots, and grab your walking stick. Brace yourself for the scenes to come. You might see mice munched by minks, goats gulped by gators, doves downed by dogs. If your nerves jangle at such sights, the jungle might not be the place for you.

Of course, I’m speaking only metaphorically here, stretching the jungle metaphor to the point of silliness. But if you come along with me in pursuit of the metaphor, you’ll recall that jungles aren’t the only kind of ecosystem. Others are deserts, tundra, swamps, forests, cliffs, and plains. All these niches afford different perils and potentials. A bluff is a good place for beasts that fly. A cove is a good place for beasts that swim. Species that thrive in different niches are well adapted for them. Those that aren’t tend to die.

Recognizing that different places afford different adaptations can help you approach the functioning of the brain with positive expectations. You can expect the internal environment of the brain to have different ecosystems, with different cranial creatures thriving within it. In the brain, as in the outer world, different functions flourish depending on the niches they occupy.

This chapter is about the brain. A wonderful aphorism about the brain by a cognitive neuroscientist at the University of Toronto captures a profound truth about how the brain is organized. According to this cognitive neuroscientist, Geoffrey Hinton, “The brain is locally global and globally local.” What did he mean?
¹

The first part of the sentence, “The brain is locally global,” means that on a local scale, the components of the brain are alike. If you look at the brain with a microscope, figuratively or literally, you can see the elements all doing the same thing more or less: sucking up nutrients, expending energy, and so on. The second part of the sentence, “The brain is…globally local,” means that on a larger scale, the components of the brain do
different
things; they have their own special
local
features. Different regions act differently. One
area leans toward language, another veers toward vision, another heads toward hearing, and so on. In general, the farther apart two areas of the brain happen to be, the less similar their functions. This isn’t because some brain supervisor declares that there should be a language zone, a vision zone, and a hearing zone. Rather, different regions tend to have different functional properties because of where they happen to reside or, more importantly, with whom they happen to interact most closely. The structuring of mental function follows this fellowship.