enable will be inexorable.
Connectomes will come to dominate our thinking about what it means to be human, so Part V concludes by taking the science to its logical extreme. The movement known as transhumanism has developed elaborate schemes for transcending the human condition, but are the odds in their favor? Does the ambition of cryonics to freeze the dead and eventually resurrect them have any chance of succeeding? And what about the ultimate cyber-fantasy of uploading, of living happily ever after as a computer simulation, unencumbered by a body or a brain? I will attempt to extract some concrete scientific claims from these hopes and propose how to test them empirically using connectomics.
But letâs not entertain such heady thoughts about the afterlife just yet. Letâs begin by thinking about this life. In particular, letâs start with the question mentioned earlier, the one that everyone has thought about at some point: Why are people different?
Part I: Does Size Matter?
1. Genius and Madness
In 1924 ANATOLE FRANCE died near Tours, a city on the Loire River. While the French nation mourned their celebrated writer, anatomists from the local medical college examined his brain and found that it weighed merely 1 kilogram, about 25 percent less than average. His admirers were crestfallen, but I donât think they should have been surprised. In the photographs of Figure 5, Anatole France looks like a pinhead next to the Russian writer Ivan Turgenev.
Â
Â
Â
Figure 5. Two famous writers whose brains were examined and weighed after death
Â
Sir Arthur Keith,one of the most prominent anthropologists in England, expressed his perplexity:
Â
Although we know nothing of the finer structural organization of Anatole Franceâs brain, we do know that with it he was performing feats of genius while millions of his fellow countrymen, with brains 25 percent or even 50 percent larger, were manifesting the average abilities of daily labourers.
Anatole France was a âman of average size,â Keith noted, so the smallness of his brain could not be explained away by invoking a small body. Keith went on to express his bemusement:
Â
This lack of correspondence between brain mass and mental ability . . . has been a lifelong puzzle to me. I have known . . . men with the most massive heads and sagacious appearances who proved failures in all the trials to which the world submitted them, and I have known small-headed men succeed brilliantly, just as Anatole France did.
Â
Keithâs confession of ignorance surprised me with its honesty, and the thought of Anatole France as a neural David triumphing over a world of Goliaths made me chuckle. At a scientific seminar I once read Keithâs words out loud. A French theoretical physicistshook his head and commented wryly, âAnatole France was not such a great writer after all.â The audience laughed, and laughed again when I noted that his amateur scribbles had earned him the 1921 Nobel Prize in Literature.
Â
The case of Anatole France shows that brain size and intelligence are unrelated for individuals. In other words, you cannot use one to reliably predict the other for any given person. But it turns out that the two quantities have a
statistical
relationshipâone thatâs revealed by averages over large populations of people. In 1888 the English polymath Francis Galton published a paper entitled âOn Head Growth in Students at the University of Cambridge.â He divided students into three categories based on their grades, and showed that the average head sizeof the best students was slightly larger than that of the worst students.
Many variations on Galtonâs study have been done over the years, using methods that have become more sophisticated. School grades were replaced by standardized tests of intellectual abilities, colloquially known as IQ tests. Galton estimated head volume by measuring