January 20, 2014

Are big brains not for being smart, but for staying smart?

Another Edge essay on scientific ideas that should be retired:
Nicholas Humphrey 
Emeritus School Professor, The London School of Economics; Author, Soul Dust 
[Anti-] The Bigger An Animal's Brain, The Greater Its Intelligence 
The bigger an animal's brain, the greater its intelligence. You may think the connection is obvious. Just look at the evolutionary lineage of human beings: humans have bigger brains—and are cleverer—than chimpanzees, and chimpanzees have bigger brains—and are cleverer—than monkeys. Or, as an analogy, look at the history of computing machines in the 20th century. The bigger the machines, the greater their number-crunching powers. In the 1970's the new computer at my university department took up a whole room. 
From the phrenology of the 19th century, to the brain-scan sciences of the 21st, it has indeed been widely assumed that brain volume determines cognitive capacity. In particular, you'll find the idea repeated in every modern textbook that the brain size of different primate species is causally related to their social intelligence. I admit I'm partly responsible for this, having championed the idea back in the 1970's. Yet, for a good many years now, I've had a hunch that the idea is wrong. 
There are too many awkward facts that don't fit in. For a start, we know that modern humans can be born with only two thirds the normal volume of brain tissue, and show next to no cognitive deficit as adults.

"Next to no" <> "no"

The brain scan volume to IQ correlations found in recent years have been in the 0.3 to 0.4 range, which is approaching a "moderate" correlation for the social sciences. In other words, the glass is part-full as well as part-empty, but very few people know that. Far more assume Stephen Jay Gould had the last word on the subject.
We know that, during normal human brain development, the brain actually shrinks as cognitive performance improves (a notable example being changes in the "social brain" during adolescence, where the cortical grey matter decreases in volume by about 15% between age 10 and 20). And most surprising of all, we know that there are nonhuman animals, such as honey bees or parrots, that can emulate many feats of human intelligence with brains that are only a millionth (bee) or a thousandth (parrot) the size of a human's.  
The key, of course, is programming: What really matters to cognitive performance is not so much the brain's hardware as its onboard software. And smarter software certainly does not require a bigger hardware base (in fact, as the shrinkage of the cortex during adolescence shows, it may actually require a smaller—tidier—one).

But the history of computers suggests that while there are occasionally advances in software that allow the same work to be done by less powerful hardware, the more typical pattern is for software to elaborate over time so that the minimum processor size keeps going up: look at the "Requirements" small print on an old Word Perfect box, say, and marvel over the tiny amount of hardware capacity (as measured in transistors) once required to provide highly adequate word processing capability.

What has happened of course (Moore's Law) is that the number of transistors you can place on a square centimeter has doubled every year or two, but that seems to be somewhat different from what we see in the brains of animals.
It's true that programs to deliver superior performance may require a lot of designing, either by natural selection or learning. But the fact is that, once they've been invented, they will likely make less demands on hardware than the older versions. To take the special case of social intelligence, I'd say it's quite possible that the algorithm for solving "theory of mind" problems could be written on the back of a postcard and could be implemented on an iPhone. In which case, the widely touted suggestion that the human brain had to double in size for humans to be capable of "second-order mind-reading", makes little sense.

Okay, but our relatively large-brained primate relatives don't seem as well-programmed as honey bees to benefit from cooperation. I've spent maybe 20 hours in the Lincoln Park zoo Great Ape House, and the chimps struck me as jerks. So, considering our relatives, maybe primates have to cogitate their way to cooperating more than social insects have to?
Then why did the human brain double in size? Why is it much bigger than you might think it needs to be, to underpin our level of intelligence? There's no question that big brains are costly to build and maintain. So, if we are to retire the "obvious theory", what can we put in its place? The answer I'd suggest lies in the advantage of having a large amount of cognitive reserve. Big brains have spare capacity that can be called on if and when working-parts get damaged or wear out. From adulthood onwards humans—like other mammals—begin to lose a significant amount of brain tissue to accidents, haemorrhages and degeneration. But because humans can draw on this extra reserve, the loss doesn't have to show. This means humans can retain their mental powers into relative old age, long after their smaller brained ancestors would have become incapacitated. (And as a matter of fact the unfortunate individual born with an unusually small brain is much more likely to succumb to senile dementia in his forties).

Not wholly implausible. Has anybody studied it?
True, many of us die for other reasons with unused brain power to spare. But some of us live considerably longer than we might have done if our brains were half the size. So, what evolutionary advantage does longevity bring, even the post-reproductive longevity typical of humans? The answer surely is that humans can benefit—as no other species could do—from the presence of mentally-sound grandparents and great-grandparents, whose role in caretaking and teaching has been key to the success of human culture.

Or, say, that having a crafty old mother or grandmother to act as matchmaker and social arbiter increases your chance of marrying well? Some of the predicament of the five unmarried Bennett daughters in Pride and Prejudice is not only that their father hasn't provided them with dowries, but also that their mother isn't all that bright at manipulating the social whirl for them.

The basic brain size equals intelligence in old age theory seems quite testable. For example, Ian Deary continues to give IQ tests to Scots born in 1921 who were first given IQ tests in 1932. What are there hat sizes today? (Granted, hat sizes are pretty crude measures.)
    

45 comments:

Anonymous said...

"There are too many awkward facts that don't fit in. For a start, we know that modern humans can be born with only two thirds the normal volume of brain tissue, and show next to no cognitive deficit as adults."

Somehow I don't think that those individuals are going to master Whitehead and Russell's PRINCIPIA MATHEMATICA.....

Or, to phrase it in terms of statistics, I don't think that they will be found lurking in the far-right hand side of the IQ Bell curve.

Anonymous said...

What is really quite preposterous here is equating the brain--or rather consciousness, with its component of IQ--with computers hardware and software.

This is at best merely a metaphor.

Here another "cognitive scientist" indulging in pseudo-science.

These are rather tiresome speculation to be coming from a so-called scientist. It goes to show just how unsound neuroscience has become these dats.

Bill said...

I certainly hope that's how it works. If having an XXL sized head offsets some of what I've put my brain through, maybe I won't be a doddering idiot by 60 after all...

Dave Pinsen said...

The key metric about brain size and intelligence I remember from biology was the ratio of brain size to body surface area, though that kind of sounded like a ratio scientists backed into to explain why humans were more intelligent than animals such as whales or elephants.

Anonymous said...

and the chimps struck me as jerks.

I hate all apes, chimps, and monkees. They're like little retarded humans, who want to grab your ass and make fart noises when you walk by. Plus, they'd chew your face off given the chance.

Glossy said...

Human, pilot whale and elephant brains compared. So, yeah, there's more to it than size.

JayMan said...

Brain tissue is expensive to develop and costly to maintain. Humans wouldn't have bigger brains if it wasn't necessary for brains to be so. Sure, there is variations in the efficiency of brains, and indeed, human brain sizes have shrunk, but obviously brain size is important as we could conclude from simple evolutionary facts.

As for the idea that larger brains provide a reserve in later life, sure, perhaps this is at work. There is a distinct association between IQ and lifespan and resistance to cognitive decline with age (as discussed in my post IQ and Death, so maybe that's a part of it.

Anonymous said...

Okay, but our relatively large-brained primate relatives don't seem as well-programmed as honey bees to benefit from cooperation. I've spent maybe 20 hours in the Lincoln Park zoo Great Ape House, and the chimps struck me as jerks. So, considering our relatives, maybe primates have to cogitate their way to cooperating more than social insects have to?

Someone needs to factor in the "autistic" Neanderthals. They got along with each other quite well without either being jerks or robots. It may be possible that Neanderthals evolved from bonobos or heavily mutated common chimpanzees.

Anonymous said...

"If having an XXL sized head offsets some of what I've put my brain through, maybe I won't be a doddering idiot by 60 after all..."

By this logic Peyton Manning should have a better post-sports career than Tom Brady.

Anonymous said...

(And as a matter of fact the unfortunate individual born with an unusually small brain is much more likely to succumb to senile dementia in his forties).

Too bad for old Hard Hat Mac to perish this way after spreading his genes around in his teens and twenties. Stupidity is so sexy.

Anonymous said...

I hate all apes, chimps, and monkees. They're like little retarded humans, who want to grab your ass and make fart noises when you walk by. Plus, they'd chew your face off given the chance.

I do like gorillas and gibbons, though, when they interact with other gorillas and gibbons rather than humans.

Anonymous said...

Here's a good clip of chimps planning and coordinating a raiding attack in the jungle:

https://www.youtube.com/watch?v=A1WBs74W4ik

Dave Pinsen said...

"Not wholly implausible. Has anybody studied it?"

I don't remember the man's name, but the FT had an obituary within the last few years for a geriatrics researcher who had found that much of the mental and physical decline commonly associated with aging wasn't an inevitable consequence of aging but a consequence of neglect.

Anonymous said...

OT

http://www.csmonitor.com/World/Asia-Pacific/2014/0120/A-test-for-one-Chinese-province-How-to-educate-an-influx-of-US-born-children

Jennifer said...

Steve, have you noticed this crazy story?

http://grantland.com/features/a-mysterious-physicist-golf-club-dr-v/

It involves two of your favorite things: golf and World War T. The Twitter and Tumblr kids are going nuts over the outing of a trans woman who later committed suicide. To me it just reads like another manipulative fraud getting busted.

Auntie Analogue said...


Methinks Professor Humphrey overlooks that if we had small brains our heads would look really funny.

Anonymous said...

I hate all apes, chimps, and monkees. They're like little retarded humans, who want to grab your ass and make fart noises when you walk by. Plus, they'd chew your face off given the chance.

I've never heard of any problems with gorillas.

Anonymous said...

Rachel Caspari, Milford Wolpoff's wife, did some work on human longevity in prehistory and found that up until around 30K ago it was rare for humans to live past 30 years and yet the human brain was bigger 30K ago than it is now. It appears big brains preceded grandparenting, thus Nicholas Humphrey is likely wrong.

http://scicom.ucsc.edu/publications/QandA/2013/caspari.html

Anonymous said...

The facts seem to be quite indisputable; there is a consistent association with head size and IQ, and an even stronger one between MRI brain size and IQ.

This does not mean that there are not other factors accounting for differences in IQ; of course there are, because head size does not account for ("explain") all of the IQ variation. I am fairly sure that processing speed is one of them, and beyond a certain brain size, there might even be a trade off between processing speed (inter-neuronal connectivity) and brain size (neurons being further apart; energy requirements, cooling requirements excessive, etc).

If there was (and there certainly was) selection pressure for higher IQ in cold climates, then it makes sense that every genetic strategem for increasing IQ would be exploited to the extent possible, perhaps in subtly different ways depending on the particularities of the environment. None of this gainsays the brain-size IQ relationship.

Cold climate is not the only driver of IQ; individualistic and belligerent personality tendencies would also raise the survival value of IQ, whereas more compliant personality types might relax the requirement for astuteness in interpersonal relations, eg.

Doubtless we do not fully understand everything about this, or even most of it. But we do know that ceteris paribus, bigger brains = higher IQ, on average.

And average is what matters.

Anon.

Anonymous said...

Cold climate is not the only driver of IQ; individualistic and belligerent personality tendencies would also raise the survival value of IQ, whereas more compliant personality types might relax the requirement for astuteness in interpersonal relations, eg.

Why then are Northern Europeans so compliant/cooperative/team spirited?

Anonymous said...

Why then are Northern Europeans so compliant/cooperative/team spirited?

They are?

Anonymous said...

Why then are Northern Europeans so compliant/cooperative/team spirited?

They are?


They are without peer in cooperation and team spirit.

Anonymous said...

Interesting.

Personally, I have very little time for all thes triumphalist pieces, trumpetting the human brain as some sort of pinnacle of evolution and the most precious fruit of the universe. Perhaps it's a slightly different pont, but waht about the physical attributes and faculties of the golden eagle, for example?

Anyway, the one fact that renders me deeply, deeply cynical about the supposed supremacy of the human brain, (nevermind mathematical theory, quantum theory, space exploration etc), is the reality of immigration to the western world. I mean not even creatures without brains, eg nematode worms, are so dumb to advocate such utter, utter madness.

Anonymous said...

"Chimps are jerks", care to elaborate, Steve?

Anonymous said...

The key to understanding an animal is to understand how it survives and 'makes its living' in the natural world. Hence Victorian biologists and palaentologists were deeply concerned with an animals's teeth more than anything else - basically, an animal's teeth tell you more about the mode of life and characteristics of the animal than anything else.
In the case of humans, the jaw has been vastly reduced in size - the teeth are perfectly useless for any wild life - and there has been a corresponding swelling of the braincase - this accompanied by freeing of the hands and bipedalism. So, basically that's waht humans do from a zoological perspective - we are a form of ape that has specialized in forming strategems and plans in order to survive - the 'selected for' trend has gone in that direction. In other words, so-called 'human intelligence' is merely a by-product of that ape survival strategy that involved cunning and deductive reasoning.

Steve Sailer said...

http://www.isteve.com/chimps.htm

Anonymous said...

Am I the only person who has been consistently disappointed with the results from the annual "Edge" question?

It would stand to reason that posing a provocative question to a bunch of hyper-intelligent folks would result in a truly mind-bending array of different responses. Yet year after year, the results have always let me down. There are usually a handful of outside-the-box responses, but nearly everything else is dull boilerplate clothed in profundity.

Humility and basic self-awareness are always in depressingly short supply; there are always a discouraging number of responses that basically amount to: "Everything would be perfect if we would just let Scientists-with-a-capital-S run the whole world."

Respondents consistently show zero awareness that the dogma of the present ALWAYS becomes the butt of future jokes, and that this pattern has repeated itself since the dawn of recorded time. No, we're always the next-to-last generation, just a few short steps removed from the Final Answer. The possibility we could stumble upon another quantum mechanics is never considered.

The true threat, it seems, is always from those damn annoying dissidents and nonconformists, never from the self-satisfied champions of orthodoxy. We're So Close To The Truth Now that it's finally time to change the rules and close down any further comments from the skeptics and cynics.

Yes, I'm exaggerating, but only slightly. I have yet to read an Edge question response along the lines of, "man, when you really think about it, we don't know anything about anything, and at the end of the day, we'll never understand more than a tiny fraction of everything."

Instead, many of the responses I read each year tend to confirm my belief that it takes an incredibly smart person to be incredibly stupid. Slow-minded folks are always limited by the immediate experience of reality; smart people can reach untold depths of dumb because they are clever enough to argue away facts that are right in front of them.

Yeesh. I wish I could get Robert Heinlein's reaction to all this stuff. He had the number of people like this 60 years ago.

Anonymous said...

"I certainly hope that's how it works. If having an XXL sized head offsets some of what I've put my brain through, maybe I won't be a doddering idiot by 60 after all..."

The baseball cap labelled 'one size fits most': The garment industry's concession to the bell curve.

Gilbert P.

Anonymous said...

Germans (and Dutch who are genetically the same) are known for having big heads and have the highest IQ among Europeans.

Gottlieb said...

Highly intelligent people can quickly reach the obvious conclusion
We are ants in the midst of countless universes , it is as if all humanity fit a measly grain of sand.

Thinking thus , it is obvious that we will reach the final answer . But we do not live in other dimensions , to our knowledge , have no consistent and constant awareness that we do not have carnal consciousness that we are ants amid the immensity . We live on Earth , in a specific place and for us , the reality is that the ants is that look like grains of sand .
Many highly intelligent people have psychotic tendencies , as seems to have been found in the Nordic countries . Psychosis along with everything that it can offer , can make us alert about reality ( and become supporters hbd ) , can make us more creative and can become depressed and delusional about reality . Because we agree that insignificant ants , directly affects the ego , and we have a lot of ego to prevent egalitarian demagoguery . We love what we are, and we want more . We want to transcend everything, but when we came to the conclusion that we can not do this in the open to become pessimistic and nihilistic thought
We are ants , fuck the world.
Very intelligent people are affected by super-reality. When you arrive at the conclusion that continued animals are born only to procreate, we are sure that we will die, the worst kinds are the most successful in adapting and procreate ... you begin to think seriously about what to do to destroy the subjective reality that the masses believe.

Anonymous said...

jon haidt points out (he may be citing another scientist - i forget) that no chimp has ever been seen helping another chimp carry a log or big stick - i.e., chimps don't cooperate very well - whereas humans are notably bizarre for being able to cooperate with non-kin.

Anonymous said...

Anonymous said...
Rachel Caspari, Milford Wolpoff's wife, did some work on human longevity in prehistory and found that up until around 30K ago it was rare for humans to live past 30 years and yet the human brain was bigger 30K ago than it is now. It appears big brains preceded grandparenting, thus Nicholas Humphrey is likely wrong.

http://scicom.ucsc.edu/publications/QandA/2013/caspari.html


1/20/14, 6:53 PM

============


Before I decide whether or not to read it (what can I say? I'm just really lazy), can someone answer me this: Did they really all die in their twenties at the latest, or was infant and maternal mortality just that bad?

pat said...

The brain size of honey bees and parrots doesn't quite prove what you seem to think.

My ex-father in law was a bee keeper in Canada. On morning about this time of year we were up there visiting. It was a quiet clear but very cold January day. So I ventured a walk into the back yard. Californians don't have the clothes for Canada so I was usually house bound when we visited her parents.

But this day I walked out in the snow to one of the bee hives. There on the unbroken snow were dead bees about two feet from the hive.

It seems that the hive measures the outside temperature by sending a worker out every day or so. This was January so the explorer bee would freeze solid in mid air after a flight of about two feet. There was a little pile of frozen bees in the snow - they had never returned so the hive knew it wasn't spring yet.

A lot more bees were doomed to take that last flight before April or May (or whenever). The hive 'mind' regards individual bees about the way I regard my fingernail clippings.

I don't think it makes sense to make too much of the size of the brain of a bee.

The birds case is similar but different. Birds have weight efficient brains so they can be carried aloft. Similarly ocean mammals have weight inefficient brains because of water's buoyancy. People - creatures who are intermediate land borne animals - see the small efficient bird brains and think they're stupid and the large inefficient sea mammal brains and think they're smart.

Albertosauus

Bottledwater said...

It would stand to reason that posing a provocative question to a bunch of hyper-intelligent folks would result in a truly mind-bending array of different responses. Yet year after year, the results have always let me down. There are usually a handful of outside-the-box responses, but nearly everything else is dull boilerplate clothed in profundity.

Where's the evidence that they're hyper intelligent?

Bottledwater said...

The basic brain size equals intelligence in old age theory seems quite testable. For example, Ian Deary continues to give IQ tests to Scots born in 1921 who were first given IQ tests in 1932. What are there hat sizes today? (Granted, hat sizes are pretty crude measures.)

Well the whole theory of cognitive reserve originated with the discovery that big brained people who get Alzheimers (as measured by neuropathology at autopsy) tend not to become demented because they have enough reserve brain mass to compensate for the diseased tissue.

But brain size clearly correlates moderately with IQ at all ages so this whole theory is superfluous. Moreover, even in animals where the elderly don't pass on much wisdom (i.e. Dinosaurs, birds), there's been much selection for brain size.

I think brain size was rigorously selected in humans up until about 10,000 years ago. After 10,000 years ago, some other gene/allele probably appeared that allowed humans to get smarter without the metabolic and physical burden of too huge a head. This gene/allele probably originated in the middle east giving rise to mesopotamia, and then spread to adjacent areas, but not to the isolated peoples of Australia, the Americas, and Bushmen.

This explains why East Asians have IQ's about 1 SD higher than their arctic cousins even though the latter have slightly larger brains because they experienced the coldest and thus most cognitively demanding environment.

Bottledwater said...

humans have bigger brains—and are cleverer—than chimpanzees, and chimpanzees have bigger brains—and are cleverer—than monkeys


Actually chimps are monkeys. As I keep trying to explain to biologists, the term monkey has no coherent scientific meaning, it's just a generic term for all sub-human higher primates.

Rohan Swee said...

I hate all apes, chimps, and monkees. They're like little retarded humans, who want to grab your ass and make fart noises when you walk by. Plus, they'd chew your face off given the chance.

Tell me about it. Why are they ever held up as any kind of model instead of anything but cautionary tales, or "there but for the grace of natural selection..."? It's like being advised to take life lessons from your loser wino cousin.

Monkeys - screechy little bastards, the lot of 'em. Common chimps are total ass*****, as we all know. And sheesh, bonobos, who'd make a gay bathhouse look like the height of sexual morality and decorum. Gorillas are even bigger losers, eking out a precarious existence as big kittens, er, research subjects for weird homo sapiens females who weren't satisfied with adopting cats or exotic human babies. Hey, there's a reason they've all been reduced to ever-shrinking areas of mostly unpleasant tropical real-estate.

(I got nothin' against gibbons, though. No gibbon ever chewed off the face of me or mine, afaik, and they always look like they're having a blast brachiating around their jungle-gyms.)

PC Makes You Stupid said...

To paraphrase Steve:

The Rube Goldberg ish logic underlying the conventional wisdom is, roughly, that

A) If it became socially acceptable to admit in public that bigger brains might have on average higher IQ; then

B) It might become acceptable to admit that maybe blacks have smaller brains and lower average IQs for genetic reasons; which would then

C) Let the gentiles find out that Jews might higher average IQs for genetic reasons; thus,

D) The goyim will come for us with their torches and pitchforks; and therefore,

E) We will hold periodic media show trials for heretics to prevent A from ever happening.

Reg Cæsar said...

Related question: isn't a passive intelligence the ideal situation in picking a wife? I mean, low intelligence leaves you with stupid descendants, while high and active intelligence leaves you with none.

So don't complain about those historical novels she reads! (Besides, they let you sneak off to read iSteve.)

Re: monkeys-- isn't the difference in the number of tails?

Apes: 0
Monkeys: 1
Bell curves: 2

So, is the intelligent, tailless Curious George really a chimp, or just an unfortunate victim of (literal) mayhem?

CanSpeccy said...

Maybe there is an optimum size.

For example: " British Telecom scientists investigating the information processing capacity of the human brain have concluded that greater capacity is possible only with faster signalling (New Scientist, January 18, 1997). Faster propagation of nerve impulses can be achieved with larger diameter neurons. However, larger diameter neurons mean a larger brain. A larger brain means longer signal path lengths, which negate the advantage of faster impulse propagation. To quote Peter Cochrane, a member of the Advanced Applications and Technologies Section of BT Laboratories, Ipswich, England, "There is no incremental improvement path available to the brain." Source

Galtonian said...

"Far more assume Stephen Jay Gould had the last word on the subject."

During the last half of the 20th century the major authority on the relationship of brain size to intelligence and behavior in animals was Professor Harry J Jerison.

http://hjerison.bol.ucla.edu/Shortcv-hjj1.htm

Interestingly in the early 1960s Dr. Jerison was a mentor to the young Stephen Jay Gould who was then an undergraduate student at Antioch College.

Here is an excerpt from Gould's laudatory prologue to a 2001 book entitled EVOLUTIONARY ANATOMY OF THE PRIMATE CEREBRAL CORTEX:

"I [Stephen Jay Gould] met Harry Jerison in the early 1960s, when I was an undergraduate at Antioch College, and he a scientist at a local research lab, and a professor. We were both working - at the maximally disparate levels of undergraduate research projects vs. professional papers - on the application of allometric equations (power functions) to problems of growth and evolutionary size increase: I on the domed shapes of land snail shells, he on the history of vertebrate brain sizes.


I thought, in all the arrogance of youth, that his bold project could never work (whereas my petty, little contained study could at least be brought to rigorous completion, albeit without earthshaking results). I had two major objections, both recording the timidity of a tyro, to Jerison's procedures. First, why should something so coarse and general as overall brain volume measure anything of biological significance? Second, how (especially in fossils) could one hope to get reliable measures in any case, especially for the independent variable of body size required by the allometric analysis? I expressed my doubts to Harry, and he had the courtesy, and professorial skill, to respond with bemusement, but not derision or condescension - and to warn me about the dangers of stifling prejudgment (a lesson I never forgot).


The results embodied Mark Twain's famous comment about his changing perceptions of his father's mental capacities: that Twain, when in his late teens, had considered his father a fool, but then, ten years later, became amazed as at how much the old man had learned during the intervening decade. My snail studies proceeded nicely and rightly; perhaps half a dozen people read the published results. Harry's work culminated in one of the most influential books of the late twentieth century organismal biology: Evolution of the Brain and Intelligence, published in 1973 and still inspiring new thoughts and researches, as this volume so directly and amply testifies.


Harry's work succeeded so brilliantly for two basic reasons (that I, as an undergraduate, had been too inexperienced and generally sophomoric to understand). First, Harry's methodology had been right and sophisticated for the circumstances. Yes, size may seem too coarse to yield anything meaningful, but how can you know until you try? And what else do you have to work with you, at least for the fossil record, in any case? Science, as my favorite biologist and essayist Peter Medawar wrote in a book title, is 'the art of the soluble.' Better to try with something measurable and operational, however crude, than to grouse at nature's recalcitrance and do nothing. Moreover, even if a measure of volume does not record the desired mental property directly in se, size may still serve us as well as an operational surrogate (and perhaps the only accessible one at that) through its predictable correlation with the attribute we seek to assess."

Dunnyveg said...

I have to agree with Gould on brain size. About a year ago, I got myself a border collie of working dog stock. These dogs are not only markedly more intelligent than other breeds, but are also more agile and coordinated; they are not only the intellectuals of the dog world, but its jocks as well. These dogs are also much more gracile, even delicate, than most other breeds. They hardly have bigger brains than other breeds. My guess is that a border collie's brain-to-body ratio may actually be smaller than that of other breeds.

Anonymous said...

The spare capacity theory is probably right but in a slightly different way -

there are lots of things that can go wrong with a brain

lots of these are basically random events

the larger the brain, the higher the spare capacity against these events

however, some brains just genetically or environmentally luck out and have few insults, so spare capacity is not actually needed, just statistically useful

also, within population environmental insult could also be avoided not by building big, but by having very expensive repair mechanisms, so some of the best brains will also be brains that suffer lots of insult but have tight repair mechanisms, weakening the correlation between size and quality once again.

Anonymous said...

"also more agile and coordinated; they are not only the intellectuals of the dog world, but its jocks as well"

Only if "jocks" = "gymnasts".

Collies are very bright though.

http://www.fwi.co.uk/articles/25/03/2009/114893/39extreme-shepherding39-the-story-behind-the.htm

Anonymous said...

Brain size is *fast* evolution.

If a population need to be 5% smarter in a hurry to survive then the groups with enough individuals who already have 5% bigger skulls survive and the rest don't.

After a few generations when that group has a now permanent average 5% bigger skulls and some of them break off and head further north and need another 5% boost - same thing happens.

Ergo skull and brain sizes get bigger.

At some point there'll be a trade-off and further improvements will need some other method i.e. more efficient brain rather than just bigger brain. This may take a lot longer to achieve and require the right conditions e.g. high density agriculture and social complexity.

But even then bigger + better will > smaller + better.