Everybody wants to be a genius, setting the intellectual agenda of the day and shaping the future of theories to come. Are we any closer to knowing what marks out the glittering few from the pedestrian many? Sandra Witelson of McMaster University in Hamilton is a good person to ask. She鈥檚 the only neuroscientist to get her hands on Albert Einstein鈥檚 brain. What鈥檚 more, she reckons she鈥檚 the first academic with 150 鈥渘ormal鈥� brains for comparison and psychometric tests of their owners while they were alive. Alison Motluk talked to the woman who stalks genius . . .
How did you get the chance to study Einstein鈥檚 brain?
When Einstein died in 1955 in Princeton, the family asked for a clinical autopsy. The pathologist on call was Thomas Harvey, who removed the brain for scientific study. From 1955 until he contacted me in 1995, Harvey kept the brain wherever he lived. He tried to see who was out there and who might have the interest, the ability, the expertise. He contacted me by fax, out of the blue, and asked if I would like to collaborate with him. After I agreed, he spent a week here in Hamilton. He brought the whole brain. It exists in more than 200 pieces-in two glass jars. Harvey also had a magnificent set of photographs that he had taken of the brain before it was cut up.
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There鈥檚 been a lot of controversy about how Einstein鈥檚 brain got into Harvey鈥檚 hands. For many years, not even the family knew where the brain was . . .
There鈥檚 been a lot of information in the media that鈥檚 not quite accurate. The family might not have known where Harvey was at any point in time, and because he moved, the brain moved. But there鈥檚 no question that they gave him permission.
To keep it?
Yes.
Still, isn鈥檛 it unusual for a pathologist to hold onto such a gem, especially since he wasn鈥檛 doing any research on it?
What I suppose is unusual is that he didn鈥檛 stay on at Princeton. And what else is unusual is that he was a clinical pathologist as opposed to a research pathologist. He contacted me because he knew I had a bank of normal brains. I guess he just thought it would be good to have a control group of brains to compare it with, and we had approximately 100 brains that were documented to be from cognitively normal people.
What were you looking for?
When we first started, all we wanted to do was to document gross measures, like brain weight and volume, and the size of different regions. It had never been done. No one had ever had the full brain except Harvey. We did that not as an end in itself, but as a baseline. But as we began to look, it became very clear that, although the brain was quite typical, there was something unique in the anatomy of the Sylvian fissure-which divides the temporal lobe from the parietal lobe.
Unique or just unusual?
Unique in the sense that we鈥檝e never seen it in any other brain. The Sylvian fissure is present when a child is born. It has a definite place and pattern. But in Einstein鈥檚 brain, the Sylvian fissure runs into another major fold in the brain, the so-called post-central sulcus. In fact, it鈥檚 hard to know where one fold ends and the other begins. That makes a brain region known as the inferior parietal lobule larger. It鈥檚 literally the geography which is unique. Let me give an example. Clearly the arrangement of features on a face has a pattern. You never see the eyebrows under the eyes.
But if I saw a face with eyebrows under the eyes, I鈥檇 know immediately that it was an unusual face. Wouldn鈥檛 anyone casually examining Einstein鈥檚 brain have been able to see that feature?
Nobody would be able to make any statement about an individual brain and how much it varies from the norm if they didn鈥檛 actually have quantitative data, records of large groups of people and specimens.
How might this feature explain some of Einstein鈥檚 abilities?
The larger region is in just the part of the brain that is important for visual imagery, three-dimensional perception and mathematical intuition-crucial for the thought experiments that led to the theory of relativity. So we made the obvious suggestion that this unusual anatomy may be related to this extraordinary ability.
If you saw an infant with this brain geography, would you predict the child might grow up to be mathematically gifted?
If we saw this kind of anatomy in another individual, we鈥檇 expect extraordinary ability. If that wasn鈥檛 the case, it would certainly undermine this association. One can鈥檛 argue with the empirical results of the anatomy. That鈥檚 what it is. But it鈥檚 hypothetical that the anatomy has anything to do with the brilliance. All we have is an association. Thanks to imaging, these days one doesn鈥檛 have to wait for a post-mortem specimen.
What else will you look at in Einstein鈥檚 brain?
A difference in the gross anatomy means that there could be some differences in the underlying microscopic anatomy. It could mean there are connectivity differences, circuitry differences.
Are you doing that work now?
Certainly. But that鈥檚 not anything I can speak about publicly.
What about your normal brains? Where do you get them from?
We have about 150 now. To my knowledge, it鈥檚 the only brain collection in the world that sets out specifically to test people while they are alive, but who have serious medical problems, usually cancer, so that their life expectancy is short. These are people who haven鈥檛 died from any brain disorders.
What do you test?
Basic measures of intelligence, memory ability, musical ability. A lot of reading tests, some mathematics tests, language tests, spatial tests. For example, they鈥檇 be shown pictures of three-dimensional objects flattened out into two dimensions and have to match them to three-dimensional objects. In total, the tests take about 30 hours.
How long after the person dies do you get the brain?
We get them within hours. We weigh a brain immediately while it鈥檚 fresh, then it鈥檚 fixed in formalin. We take measurements and make a plaster cast. Then the brain is cut in a predetermined way. The brain is in many pieces by the time the whole procedure is done. And that鈥檚 how it鈥檚 stored.
Have you done work on the normal people to specifically look at how their brains鈥� structure relates to their intelligence?
Absolutely. For example, the corpus callsum. The size of the corpus callosum, a fibre tract that transmits information from one hemisphere to the other, correlates with how well people do on certain tests of speech fluency and visuospatial ability. There is another report which shows a difference in the size of some of the auditory regions between musicians with perfect pitch, musicians without perfect pitch and non-musicians. The musicians with perfect pitch were different from musicians without it. Another example is packing density-the number of neurons packed into a unit volume of tissue. Packing density in the frontal area correlates extremely highly with the ability to do problem-solving. A lot of other work is in progress and that isn鈥檛 something I want to discuss in detail.
You鈥檝e compared men鈥檚 and women鈥檚 brains and you鈥檝e found big differences鈥�
Yes, but it is not so much that the anatomy is different. What鈥檚 obvious is that what men do with their brains, which are on average 100 grams larger, women also do with their brains. Different parts of the brain do different things in men and women, so the relationship between anatomy and cognition is different. In women, for instance, it looks like the frontal part of the brain is much more involved in the comprehension of language than it is in men. It鈥檚 not just that there may be a difference in ability between the sexes, and not just that the anatomy is different, but it鈥檚 as if the division of labour in the male and female brain is not congruent.
Yet the brains look similar?
Yes, I think we would be hard pressed to know if a brain was male or female.
You鈥檝e also looked at brain differences between people of different sexual orientations?
We wanted to see if there were any neurobiological differences between people of different sexual orientations. We also wanted to see what the role of sex hormones might be in lateralisation-the way the two halves have different roles in thinking. When we tried to control for handedness, we noticed we were getting a lot of left-handed people. Twice as many lesbians, for instance, were left-handed as in the general population. So we hypothesised: if lateralisation was crucial for sexual orientation, is there something atypical about lateralisation in gay men who are right-handed? One approach was to look at the corpus callosum.
Because you already knew about the differences between right-handed and left-handed straight men?
Exactly. We showed several years ago that the size of the corpus callosum is highly related to handedness. The more left-handed you are, the bigger your corpus callosum. So the specific prediction here was that the corpus callosum among right-handed gay men would be larger than in right-handed heterosexual men.
Indicating?
That even though they had a phenotype of right-handedness, their corpus callosum and their brain structure did veer towards this bilateral representation, even though for some reason they were right-handed. And that鈥檚 exactly what we found.
What does this say about what determines sexual orientation?
It looks like there are neurobiological correlates of sexual orientation that can only be explained by very early developmental processes. But this doesn鈥檛 mean that biology is destiny. It doesn鈥檛 mean that environment isn鈥檛 relevant.
Your work unnerves people. Why is that?
The whole premise of looking at scans and the chemistry of brains with psychiatric disorders has the working assumption that there is something in the brain that is causing-not just correlating, but causing-this behaviour. One can鈥檛 say this is only true for disordered behaviour. How could it just be true for that? The brain has to be relevant for people who are functioning normally. One of the reasons why the Einstein report got so much attention is not just that it鈥檚 Einstein鈥檚 brain. There鈥檚 no way anyone reading the paper could come away without saying: 鈥淥h my goodness, is there some very early biological set-up of the brain that puts some constraints on our abilities?鈥�