02 Nov

Gender on the Neocortex

Mean Bean Counter

The moment a speaker starts “the human brain is the most complex thing in the Universe”, I lose all respect for them.  I am sure they have turned every rock in the Universe and looked underneath before making such a tall claim.  Or, why can’t they perceive that two human brains is more complex than one human brain.  Or, how exactly do they define complexity?  Or brain?

Similarly, when someone says that we use only 10% of the our brain, you can immediately conclude that this person doesn’t understand evolution.  Since we know that human brain is an energy-expensive organ in the body, and that evolution just won’t build such a wasteful organ.

Another brain myth, but less well knows is the number of cells we carry in the brain: 100 billion neurons and 1 trillion glial cells (neurons do the thinking and glial cells do the housekeeping).  But recent studies give us very reliable cell count in the brain.  We know know that we have about 85 billion neurons and 86 billion glial cells.  In all, about 170b in total.  Not the originally claimed 1,100b.

We humans are very proud of our huge cerebral cortex.  We believed that it is brimming with neurons.  Even though our cerebral cortex occupies 80% of the brain, it has only 20% of total neurons!  Interestingly, the cerebellum (‘small brain’ in Latin), a small inconsequential bulb of the brain that hangs behind the big-mean-cerebral cortex, contains 80% of all the neurons; whereas it is only 10% by volume!  By the way, we only have a vague idea of what cerebellum does.  The state of the art in neuroscience is truly embarrassingly primitive.

We love to think that the human brains are somehow different from rest of the primates.  Anatomically speaking, the only difference between us and other primates is the brain size.  Human brain seem to be just a blown up version of monkey brains.

I save the best for the last: In the neocortex (the seat of human uniqueness, including intellect and executive functions), men have 21% more neurons than women (23b/19b) and 33% (65b/49b) more glial cells!  I don’t think anyone knows what to make out of this information because men and women have very similar average IQ.

Of course, I don’t know the significance any of the other information in this post either.  At this point in time, all of them seem to be completely useful pieces of trivia.  But I will end up remembering them anyway.  You, my reader, I am sure you will end up remembering at least the last one for sure!

29 Oct

Sexual Ornament

Sexual Ornament

We didn’t grow a large brain to help ourselves find better food, fend from predators or to change the very landscape of the planet, like we are doing today.  We evolved a large brain hundreds of thousands of years before we did all that.

In his book Descent of Man, Charles Darwin discusses two types of evolutionary pressures:  Natural Selection and Sexual Selection.  Natural selection arises from the struggle to survive (fangs and hooves).  Sexual selection (antlers and peacock tail feathers) arises from pressure to reproduce.  There are two types of sexual selection.  One is challenge between the same sex to outwit one another (intrasex).  Other is a challenge to charm and attract the opposite sex more successfully (intersex).

A feature that evolved due to intersex sexual pressure is called a sexual ornament.  It is usually un-fakeable.  For example, only a healthy antelope can afford huge antlers.  Similarly, only a healthy peacock can afford a long and lustrous tail feathers.  To start with, an animal needs plenty of nutrition (i.e. physical fitness) to build and maintain a sexual ornament in top condition.  Sexual ornaments also adds more handicap, often in the form of burden over animal’s ability to move around freely.

For the huge cost that an animal suffers, sexual ornaments usually have zero utility value.  They don’t help the animal to fend a predator, catch/gather food, shelter from nature or increase the longevity.  If at all, sexual ornaments increases the animal’s chances of dying an early death!  If you think for a moment, there is a common theme for all sexual ornaments: Only I can afford the wastage!

In his wonderful book The Mating Mind, psychologist Geoffrey Miller puts forward a hypothesis that the brain developed as a sexual ornament.  During the initial days, Miller proposes, women selected men for men’s ability to excite and entertain the women.  Over time, pressurized by choosy women, men ended up developing larger and larger brain.  Of course, women were not left behind either.  They needed to evolve an equally intelligent brain to appreciate what men produced.

These are some of the implications of Miller’s ‘ornament brain’:

  • In a romantic situation, wastage (and luxury) is essential.  Waste is what keeps a fitness indicator honest!  A act or gift of high romance usually carries huge cost on the giver, but zero utility value to the receiver (e.g. diamond, flower, poetry, etc.)
  • Brain evolved as an entertainment system; we eventually hijacked it for doing rocket science
  • All activities that put a high demand on the brain are perceived as sexy.  Examples are singers, sportsmen (excelling in sports is a matter of the brain; not just the brawn), actors, poets, etc.  Of course, if you work in Intel you might find nerdyness sexy too!
  • Men are major producers and women are major consumers
  • While men are usually busy searching for women who would appreciate their sexual ornament, women are busy sifting through all suitors.  It is wrong to think that women don’t actively participate in the mate selection process.
  • Monogamous species do not have to develop sexual ornamentation (in all monogamous species, both the sexes look identical).  Humans developed sexual ornamentation because they were (moderately) polygynous (at best, serially monogamous) by nature.
29 Oct

Honest Signal

Honest Signal

There is a term called “honest signalling” in evolutionary biology.  It is not a new insight, but it is going to form basis for some of the key discussions we are going to have in the future.

Peacock’s tail is a wonderful example of a honest signal.  The luxury of the tail fathers correlates well with the fitness level of the animal which carries it.  A peacock with lower fitness can’t fake a luxurious tail feathers.  So, peahens have come to use the fitness of the tail feathers as a primary mate selection criteria.

Gazelles are known to stot (quadruple jumping) in the presence of a predator.  By stotting, the gazelles  signal their fitness level to the predator (Hey, look, I am very fit.   No use chasing me.  Find someone else easy).  As a weaker animal can’t stot as well as a fitter animal, stotting turns out to be a honest signal.

In humans, wealth indicators are easily understandable honest signals.  A Rolls Royce car is a honest signal of one’s financial resources.  Or, a Nobel prize is a reliable indicator of one’s mental resources.  Great skin, shining nails or lustrous hair is a honest signal of someone’s physical fitness.  But with humans, there is one ‘not so obvious’ fitness indicator: The Brain!

While a Nobel prize might be a reliable indicator of one’s cognitive resources (but then again, several Nobel prize winners had notoriously troubled family lives), brain itself is thought of as a honest signals of an individual’s genetic fitness.  In a wonderful book Mating Mind (which has cart load of politically incorrect assertions), Geoffrey Miller claims that the large humans brain evolved as a honest signals of genetic fitness.

No other animal has evolved large brain because large brain is a pain.  Consider these:

  • Large brain is simply redundant for eking out a life on this planet.  After all, none of the other animals have bothered to evolve a large brain.
  • Our brain is metabolically very expensive.  We end up spending about one fifth of our energy budget on the upkeep of the brain.
  • Large brain makes child birth a very risky venture for both the mother and the child.
  • Large brain made it difficult and awkward for us to move quickly like most of our primate cousins could.

A large brain has loaded us with plenty of disadvantages.  There must have been some compelling evolutionary advantage that the large brain brought us.  Otherwise, evolution would have weeded it out.

If we think that the intelligence of a large brain gave us any survival advantage, you may  be wrong.  After all, till the advent of agriculture, our life was hardly any different from that of any other animal on the planet.  We were not even the top predators on earth, even though we evolved our large brains some 200,000 years ago!  Why did we go through so much of trouble and evolve such large brain if it didn’t afford us any survival advantage?

Geoffrey Miller argues that a large brain evolved as a honest signal of the genetic fitness of the individual who carries it.  So, we have probably come to regard all ‘products of mind’ highly.

This has several interesting implications.  We will address them tomorrow.

26 Oct

Selfish Gene vs Altruistic Human

Altruistic Animal

There is a human gene called DRD4.  A mutation in the DRD4 gene can give ADHD (Attention Deficit Hyper Activity) to the people who have the mutation.  People who have ADHD have difficulty with controlling their impulse.  Many of them marry young, have early pregnancy, have many kids, etc.  In all, there is every reason to expect the DRD4 mutation (and ADHD) is going to increase in the human population.

ADHD, of course, can pre-dispose a person to several setbacks.  Learning difficulty is the most well known affliction of ADHD.  People with ADHD are more vulnerable to addictive behavior, temper outbursts, poor job performance, etc.  About 65% of the inmates in Western prisons suffer from ADHD spectrum disorders.

DRD4 is clearly behaving in a way that is detrimental to the carrier animals.  But the same behavior is helping the gene to maximize the number of its own copies in the population.

Genes behave in a way that increases the number of its copies.  Over time, any gene that doesn’t doesn’t toe the line gets ‘subsumed’ by other aggressive genes. Because our language lacks adequate words to describe such behavior, we talk as if the genes are people (anthropomorphic thinking) and claim that the gene is behaving selfishly and we call such a gene a selfish gene.  Obviously, the gene is not people and it doesn’t think or act.  More importantly, genes don’t have any objective or motive.  They are mindless.

While the genes always act in a purest self-serving way (or they perish), sometimes their behavior is counter intuitive.  Altruism is one such paradox.  An altruistic animal seem to be an evolutionary dead end.  But among pack/herd animals, taking care of one another had increased the chances of all the animals in the pace/herd.  Over time, only the animals with altruistic genes were alive and the rest perished.  While altruism appears self-less, it is in reality promoted by a gene acting in pure selfish fashion.

But when an animal feels altruistic, the feeling of altruism is very real.  Even though the altruism is a product of a selfish gene, that is a mere technicality.  It is like saying “oxytocin release in your brain makes a mother bond with her child”.  Of course it is true.  But the technicality doesn’t make the mother-child bonding any less real.

We often confuse the selfish motives of our genes with the motives an the animal.  We shouldn’t.  We are not our genes.  We are not more.  We are not less either.  We are different.

25 Oct

IQ and Gender Politics

Man, Woman & IQ

Way back in 1932, Scotland got the IQ of all the 11 year old kids in the country, about 80,000 of them, tested.  The population was made up of equal number of boys and girls.  Called the Scottish Mental Survey (SMS), till this day, SMS is the largest such test carried out anywhere in the world.  The test methodology and the findings of SMS have not been contested seriously till today.  SMS has become the gold standard to understand the gender difference in IQ.  The result of the test is plotted in the chart below.

Scotland Mental Survey

The chart shows the number/percentage of girls of various IQ, plotted against the number/percentage of boys.  Let’s see that result test implies.

  1. Boys and girls are equally smart.  Boys had an average IQ of 100.5 and girls had an average IQ of 100.6, the difference being insignificant.
  2. 85% of the girls are smarter than the boys.  Can you guess why the (Second Wave) feminists never used this proof to argue that women or smarter than men?  Well, you must take a look at “4” below
  3. Lower the IQ, you will find more boys than girls.  This may be one of the reasons why there are more boys with learning disability issues.
  4. Now, this is the kicker: Higher the IQ, you will find more boys than girls!  At around IQ 140 (little above the IQ of University Professors and PhD holders), there are 35% more boys than girls.  Given how smooth this curve it, if I dare extrapolating it to 160-165 range (where all the Nobel laureates loiter), we have a 65:35 boys to girls ratio!  It means that at this range, there are 70% more boys than girls.

Interesting.  If you have noticed the distribution, something more interesting shows up.  It appears as if women the are made in an assembly line with better quality control (so, they confirm closer to the mean of 100).  Whereas, men are made on an assembly line that requires some fine tuning (so, their quality is all over the chart).

I wonder why most of us never know anything about this study, even though it was conducted 80 years ago and no one has been able to find any serious flaw in it till today.  My guess is, gender politics!

By the way, you can click on this link to download an academic paper, discussing the results of the Socttish Mental Survey 1932.  Before you go away, please remember that IQ is not the only indicator for success in life.  It doesn’t even test all types of intelligence that there is.