June 17, 2005

They Saved Einstein's Brain (and cut it up into little pieces)

There's an interesting article on Yahoo, coming originally from the Los Angeles Times.

Deep, Dark Secrets of His and Her Brains

It is a discussion of the work of Sandra Witelson, who has the world's largest collection of brains. The article touches on her analysis of Einstein's brain, but is mainly focused on her work analyzing the difference between the brains of men and women. She's found many, but fortunately Witelson's managed to avoid hysterical picketing by Harvard faculty.

The one problem I had with the article is that the author, Robert Lee Hotz, seems to not understand the whole of the situation in the anecdote that serves as his epilogue:

Brain Conquers All

Last year, a worried farming couple brought their youngest child to McMaster University Medical Center.

They were no longer certain whether their child was a girl or a boy. The youngster had traits of both, as occurs in about one in 5,000 births. In this child, nature had devised a living test of gender and the brain.

The medical experts determined that the child's body was a composite of normal and abnormal cells. Some had a girl's usual complement of two female sex chromosomes. Many, perhaps due to a mutation, had only one female chromosome and consequently were almost male.

"Which cells got to the brain?" wondered Witelson, who was called in as a consultant. "You have to consider the sex of the brain."

The doctors all suspected the child's brain was masculine. There was no way to know for sure. They could not safely take a sample of neural tissue to biopsy.

Until recently, reconstructive surgery based on a doctor's best guess was the rule in such cases. But in Hamilton, they counseled patience, Witelson recalled.

"We said, 'Let the child's behavior tell us what sex the child is.' "

Given time, she believed, the brain would reveal itself.

The problem is here: Some had a girl's usual complement of two female sex chromosomes. Many, perhaps due to a mutation, had only one female chromosome and consequently were almost male.

A little background in human genetics:

Normal females have two X chromosomes, XX.
Normal males have one X and one Y chromosome, XY.

People with Turner's syndrome have only one copy of the X chromosome, XO.

But people with Turner's syndrome are pretty clearly female! A person made up of XX and XO cells isn't going to be exhibiting any specially masculine traits due to that combination.

What strikes me as what is most probably the case is that the kid is an XX/XY chimaera. This isn't a result of a mutation. What has happened is that the child's mother released two eggs. Both were fertilized, one by a sperm carrying the Y chromosome (generating a male embryo), the other by sperm carrying the X chromosome (generating a female embryo).

The usual outcome of this is that the nine months later, the mother gives birth to a pair of fraternal twins, one female, one male. But that didn't happen; instead the embryos fused, creating what is called a chimaera -- a child composed of cells with two distinct origins.

Posted by jeffreyb at 12:44 AM | Comments (0)

June 03, 2005

I'm a Systemiser, Are You?

Simon Baron-Cohen, author of Essential Difference: Men, Women and the Extreme Male Brain and director of an autism research center, wrote an article some time ago in the British newspaper, the Guardian. In it he lays out people's mental faculties on a two-dimensional map, with one axis representing a tendency towards systemisation, and the other for empathisation. From here he segues into the difference between the typical male brain (tending towards systemisation), and the female (tending towards empathising). He finishes with a special look at autism and its close cousin, Asperger's syndrome, both of which are dominated by extreme systemisers and poor empathisers.

An adjunct to the article features a pair of quizzes to determine your own place on the map. Being a natural systemiser, I took them.

Average women have a Systemising Quotient of 24, and the average male score is 30. Asperger's and the highly-functioning autistic only tend to range between 40-50. I scored a 54.

50-80 = You have a very high ability for analysing and exploring a system. [...] Three times as many people with Asperger Syndrome score in this range, compared to typical men, and almost no women score this high.

My Empathy Quotient was rather miserable, only 25.

0-32 = lower than average ability for understanding how other people feel and responding appropriately. Most people with Asperger Syndrome of high-functioning autism score about 20. on average, most women score about 47 and most men about 42.

So at least I'm more sociable than the folks with Asperger's! (As well as *very* manly.)

What seemed odd to me was the way Baron-Cohen's empathising quotient ties together two very seperate things: one's empathy and one's social skills. Let's take psychopaths as an example. They may be very charming and socially savvy individuals, but the great characteristic that defines them is a complete lack of empathy (though their social skills may be high enough that they can fake it).

I mention this because I am something of the reverse: I have a very hard time "reading" people, and feel that my social skills are sub-par. But I have no problem empathising with others, to the extent that as a child I could never sit through a whole episode of "The Greatest American Hero". It was my favorite TV show, but I would just feel so awful for the embarrassing situations in which the poor guy found himself that I'd have to leave the room.

Update: Thinking about it, there may be another problem with the empathising test, which seems to have a large number of questions around "how do you feel about your ability to do X", as opposed to the systemising test, which has more questions along the lines of "do you X?" These are very different types of questions, and may not track each other well; nor may either branch tell us much about people's actual capabilities.

Posted by jeffreyb at 08:43 PM | Comments (0)