Authors: David Eagleman
Incognito (39 page)
3
As for the history of the phrase, the Roman poet Juvenal suggested that “Know thyself” descended straight from heaven (
de caelo
); more sober scholars attribute it to Chilon of Sparta, Heraclitus, Pythagoras, Socrates, Solon of Athens, Thales of Miletus, or simply popular proverb.
4
Bigelow, “Dr. Harlow’s case.”
5
Boston Post
, September 21, 1848, crediting an earlier report from the
Ludlow Free Soil Union
(a Vermont newspaper). The version of the text quoted corrects a confusion in the original report in which the word “diameter” was incorrectly replaced with “circumference.” See also Macmillan,
An Odd Kind of Fame
.
6
Harlow, “Recovery.”
7
For clarity, I am not compelled by traditional religious stories of the soul. What I mean with the question of a “soul” is something more like a general essence that lives on top of, or outside of, the currently understood biological processes.
8
Pierce and Kumaresan, “The mesolimbic dopamine system.”
9
In animal models, researchers will shut down serotonin receptors and demonstrate changes in anxiety and behavior, then restore the receptors and restore normal behavior. For example, see Weisstaub, Zhou and Lira, “Cortical 5-HT2A.”
10
Waxman and Geschwind, “Hypergraphia.”
11
See Trimble and Freeman, “An investigation,” for studies of religiosity in patients with temporal lobe epilepsy, and Devinsky and Lai, “Spirituality,” for an overview of epilepsy and religiosity. See d’Orsi and Tinuper, “ ‘I heard voices,’ ” for the view that the epilepsy of Joan of Arc was a newly described type: idiopathic partial epilepsy with auditory features (IPEAF). See Freemon, “A differential diagnosis,” for a historical diagnosis of Muhammad in which he concludes, “Although an unequivocal decision is not possible from existing knowledge, psychomotor or complex partial seizures of temporal lobe epilepsy would be the most tenable diagnosis.”
12
I have often wondered whether the promotion of sexual behavior in humans would be the most obvious mechanism for a sexually transmitted virus to advance self-survival. I do not know of any data that support this, but it seems an obvious place to go hunting.
13
There are many more examples of small biological tweaks causing big changes. Patients with herpes simplex encephalitis often get damage to specific areas of their brains, and show up at the doctor’s office with problems in using and understanding the meaning of words—for example, past tense irregulars such as
drive
and
drove
. If you ever intuited that something as impalpable as past tense irregulars is not directly connected to the microscopic knobs, think again. And Creutzfeldt-Jakob disease, a problem caused by abnormally folded proteins called prions, almost always ends in a global dementia characterized by self-neglect, apathy, and irritability. Bizarrely, victims have specific problems with writing, reading, and left-right disorientation. Who would have thought that your sense of left and right had a dependence on the exact folding structure of proteins that are two thousand times smaller than the width of a hair on your head? But there it is.
14
Cummings, “Behavioral and psychiatric symptoms.”
15
Sapolsky, “The frontal cortex.”
16
See Farah, “Neuroethics.”
17
According to one hypothesis of the relationship between schizophrenia and immigration, continual social defeat perturbs dopamine function
in the brain. For reviews, see Selten, Cantor-Graae, and Kahn, “Migration,” or Weiser, et al., “Elaboration.” Thanks to my colleague Jonathan Downar for first bringing this literature to my attention.
18
As of 2008, the U.S. had 2.3 million people behind bars, leading the world in the percentage of its citizens in jail. While society benefits from incarcerating violent repeat offenders, many of those behind bars—such as drug addicts—could be dealt with in a more fruitful manner than imprisonment.
19
Suomi, “Risk, resilience.”
20
The genetic change in question lies in the promoter region of the serotonin transporter (5-HTT) gene.
21
Uher and McGuffin, “The moderation,” and Robinson, Grozinger, and Whitfield, “Sociogenomics.”
22
Caspi, Sugden, Moffitt, et al., “Influence of life stress on depression.”
23
Caspi, McClay, Moffitt, et al., “Role of genotype.” The genetic change they found was in the promotor region of the gene encoding for monoamine oxidase A (MAOA). MAOA is a molecule that modifies two neurotransmitter systems critical for mood and emotional regulation: noradrenaline and serotonin.
24
Caspi, Moffitt, Cannon, et al., “Moderation.” In this case, the link is a small change in the gene encoding catechol-O-methyltransferase (COMT).
25
Scarpa and Raine, “The psychophysiology of antisocial behaviour.”
26
Is it possible that understanding gene–environment interactions could inform preventative approaches? Here’s a thought experiment: should we modify the genes once we understand them? We have seen that not everyone who suffers childhood maltreatment follows the path to violence in adulthood. Historically, sociologists have focused on social experiences that might protect some children (for example, can we rescue the child from the abusive home and raise him in a safe and caring environment?). But what has not yet been explored is a protective role of genes—that is, whether genes can protect against environmental insults. While this idea is currently science fiction, it will not be long before someone proposes a gene therapy for such situations: a violence vaccine.
But there’s a downside to this sort of intervention: genetic variation is beneficial. We need variation to produce artists, athletes, accountants, architects, and so on. As Stephen Suomi puts it, the “variation seen in certain genes in rhesus monkeys and humans but apparently not in other primate species may actually contribute to their remarkable adaptability and resilience at the species level.” In other words, we have a deep ignorance of which genetic combinations end up being most beneficial for a society—and this ignorance provides the firmest argument against genetic intervention. Further, depending on the environment in which one finds oneself, the same set of genes may cause excellence instead of crime. Genes predisposing for aggressiveness may make a talented entrepreneur or CEO; genes predisposing for violence may make a football hero, admired and paid a handsome salary by the population.
27
Kauffman,
Reinventing the Sacred
.
28
Reichenbach,
The Rise of Scientific Philosophy
.
29
One potential sticking point in drawing a relationship between neuroscience and quantum mechanics is the fact that brain tissue is roughly three hundred degrees Kelvin and is in constant interaction with its immediate environment—these features are not amenable to interesting macroscopic quantum behaviors such as entanglement. Nonetheless, the gap between the two fields is beginning to close, with scientists from both sides making overtures to reach a meaningful hand across the gulf. Moreover, it is now clear that photosynthesis operates with quantum mechanical principles in this same temperature range, which further bespeaks the likelihood that Mother Nature, having figured out how to exploit these tricks in one arena, will exploit them elsewhere. For more on the possibility of quantum effects in the brain, see Koch and Hepp, “Quantum mechanics,” or Macgregor, “Quantum mechanics and brain uncertainty.”
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