The cover of the book features a drawing of a sectioned head with numbered pointers to brain features and other items. But A Very Short Tour of the Mind: 21 Short Walks Around the Human Brain, by Michael C. Corballis, is about psychology, not physiology. In fact, the structures and features of the brain are scarcely mentioned. Rather, the 21 essays in this small book (scarcely 100 pages) feature the workings of minds, ordinary and not-so-ordinary, rather than the "hardware" in which they operate.
The author provides welcome relief from the nearly universal notion that our brain is some kind of computer and the mind is what it computes. The term "compute" cannot really apply to what the brain/mind does, but we have no other verb anyone likes, not even the slightly arty "cogitate". Come to recall, I don't remember seeing the word "compute" anywhere in the book. Nice!
So what word can we use for mental activity? "Think" is too narrow, and implies only conscious action. Most of what goes on inside is not willed. In fact, try to take over your breathing; breathing can be put under totally conscious control for short periods of time, but the least distraction results in an automatic system regaining control. We need a new word, and it is not likely a useful one will arise until we know a lot more about just what "mental activity" actually is. Cogito, ergo sum ("I think, therefore I am") was fine for Descartes in his day, but does that mean non-thinking items do not exist? He said that while kicking a rock…
OK, on to what Dr. Corballis writes. He writes of evidence that creatures other than ourselves think creatively and use language. "Not at our level, of course", is the mantra of human chauvinism. He discusses the Encephalization Quotient, a function of the 2/3 power of body mass. Naturally, the function yields its largest result for humans. However, the number for porpoises/dolphins (you know, those mini-whales like Flipper) is very close. I suspect if you discount body fat, the EQ for porpoises is higher than ours. Oceangoing mammals need a lot of insulation, and blubber fits the bill.
Hmm, let's do a riff on this. The expected weight of a brain, for a mammal, is discussed by Jim Moore in a 1999 article:
Ew(brain) = 0.12w(body)2/3
Reading this article, I find that all the data used were for female mammals. Presumably, this was done to reduce the effect of sexual dimorphism (males in species that compete for females are much larger). So, if a female monkey weighing 1 kg has a brain weighing 19 grams, is this greater or less than the expected brain weight (Ew)? In other words, is this monkey's EQ greater or less than 1? The steps:
- 10002/3 = 100.
- 0.12×100 = 12.
Thus Ew=12g, so the EQ for this monkey is 19/12 = 1.58. The table in this Wikipedia article lists the EQ for a Rhesus monkey as 2.1. It also uses the house cat as the standard, with an EQ of 1.00. An average cat weighs 3.3 kg. Ew is thus 26.5. Most cat brains weigh from 25 to 30 g, so the "standard" number must have been for a slightly large cat with a slightly small brain. My cat weighs 5 kg and is of a large-headed breed. Her Ew is 35 g. I suspect her brain is closer to 30 g, so her EQ is probably less than 1. Now, on to humans and porpoises.
A Euro-American female in optimal health, of average height (1.65 m), weighs about 60 kg (BMI=22). Her Ew is 184 g, but with the average female human brain weighing in near 1,400 g, her EQ is 7.6. Suppose instead her BMI were 18.6, like my wife? Now with a weight of 51 kg, her Ew is 165 leading to an EQ of 8.5! Is my wife a lot smarter than average? She's smart, but no genius (unless she's a great actor!). And what of an obese woman? Height of 1.65 m and BMI of 30 implies a weight of 81.5 kg. This leads to EQ of 6.2.
Now, the EQ for a Bottlenose Dolphin is listed as 4.14. It is hard to discern where this figure arose. These dolphins range from 2 to 4 m in length, but average size for populations near the U.S. east coast is 2.5 m, with weights in the 250 kg range. The Ew for a 250 kg dolphin is 476 g, so the brain weight used for the table must have been about 1,970 g. Now, suppose we discount the blubber? This is typically 20% of the total, or 50 kg for our example. Considering that this blubber is in addition to ordinary body fat, let's figure EQ for a 200 kg dolphin with a 1,970 g brain: it comes to 4.8. This is closer to the human range.
Now to my point. Do dolphins think? Well, of course they do, but do they think like humans do? Of course not. They "see" by sonar, a sense we don't have, and live in a more 3-dimensional world. But they have social lives and friends and enemies, just as we do.
OK, the book is about the human mind. A quite different measure of mental capacity is the breadth of one's circle of relationships. The Dunbar Number for humans is about 150. While troop size in baboons can be larger than this, stable groups that tend to hang together tend to number 20-30. Yet the naked mole rat, with a truly tiny brain, lives in colonies that average 75 individuals. Perhaps a rat's circle of good buddies is smaller than this.
We may have the capacity for 150 active relationships, but I think few of us take full advantage of it. I am probably more solitary than most. Prior to moving to the Philadelphia area 20 years ago, I seldom lived in any neighborhood longer than 5 years. This led to a habit of shedding relationships every few years. Most of our neighbors live near many relatives, and socialize mainly with them. But I'll just compare the social circles of myself and our son. We moved here when he was 6, so he spent all 12 years of schooling in one district. My high school yearbook has lots of signatures from classmates, but only a handful wrote more than their name. I don't recall signing very many yearbooks with more than my initials. The day our son brought home his middle school yearbook, I found him circling pictures. I inquired, and he said, "These are my friends." I checked later; it was about half the student body, more than 300. He has kept up with quite a number of them. Many are now his FaceBook friends.
OK, I have 127 FaceBook friends. My Friends page lists the number of friends they have, for nearly all of them (some folks hide this). Dropping the page into Excel and filtering a little, I find the range is from 3 to 4,979. This last number is for an evangelist, who has a strong interest in reaching people! But there are 8 others who have at least 1,000 FBF's, our son included. The mean of the numbers I have is 461 and the median is 319, so FB facilitates keeping at least a tenuous connection with large numbers of people, compared to village sociodynamics.
So does Picasa or other picture album applications. The number of People albums in my Picasa archive is just over 500. There are large "slush" albums of "HS Kid" and "Church Kid" and a few other collections, for faces that Picasa found among my photos, and I can recognize them but don't have a name I can recall, just an association.
Well, it will be a while before dolphins or any other creature comes up with something like FB. The human brain is remarkably powerful. Yet it is limited. Chapter 13 opens with words worth remembering: "Got a bad memory? It's actually much worse than you think, for the simple reason that you don't know how much you have forgotten." Truth to tell, when my wife and I have a "blast from the past" and remember someone, the stories she tells me, and the stories I tell her, are wholly different. Our memories overlap no more than 20%, for the same event and person(s)! Without the ability to forget, though, even the amazing memory capacity we have would get too cluttered for us to function. We remember what we find useful, freely edit many parts so our self-story is more pleasing, and skate most of the rest off to limbo.
Now, if a little 100-page book, in 12mo size, can trigger such a bunch of fun riffs, I say you gotta give it a read. It wasn't what I expected. It was a whole lot better!
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