Though Barbara Oakley's Evil Genes: Why Rome Fell, Hitler Rose, Enron Failed, and My Sister Stole My Mother's Boyfriend is ostensibly about Machiavellian behavior, it is also a testament to her intellectual ambition. The subheading is a clear pointer to this. Oakley attempts to synthesize a wide range of fields, behavior genetics, cognitive neuroscience, clinical psychology, diplomatic history, evolutionary psychology, economic history, along with heavy dollops of political and personal biography, to produce a portrait of how Machiavellian intelligence emerges from its biological substrate, develops, and impacts us on a personal and social level. With any such project there is bound to be some disappointment due to the limitations of what one can communicate and construct in about 400 pages of narrative. But the attempt still produces something of definite worth and intellectual value. A minor, but perhaps not trivial, observation is that the subheading itself is somewhat deceptive as to the substance of the book. There really isn't much on Rome, and relatively little on Hitler. I think from a historical perspective what is said about Rome and Late Antiquity is actually rather contentious, but as it is all of a few paragraphs that is of little note. On the other hand, Evil Genes does explore Hitler's psychology, but the author puts more energy into deconstructing the lives of Mao and Slobodan Milošević, to whom she devotes a chapter each. From a publisher's perspective the rationale for highlighting Hitler, and not Mao, let alone Slobodan Milošević, is rather obvious, but be warned. I was a little disappointed by the macrohistorical scope of the book which might be implied by a reference to the "Fall of Rome," but with that accounted for one can shift to the strengths of Evil Genes. The encyclopedic narrative gumbo is hinged ultimately around behavior genetics; the discipline which attempts to extract the proportion of variation in behavior due to variation of genes. This means that focusing on one individual can be problematic, but so long as we keep in mind that they may serve as illustrations for the general principle, which deals in population level analysis, they can still illuminate. This is where the author's sister, Carolyn, comes to the fore. The subheading delivers on the money as the author recounts in vivid detail the peculiar ticks which her sister exhibited,. These seemed to manifest in an almost amoral selfishness whereby other humans were means to Carolyn's ends. In an interesting twist it seems that her behavioral characteristics might have been due to a childhood bout of polio which shocked cognitive development and shifted it off its typical channel. In the alphabet soup of genes, neurotransmitters & cortexes, Oakley is careful to emphasize that a great deal of behavioral variation is due to the vicissitudes of the environment, and focusing on the genetic component of variation does not entail ignorance or discounting of environmental variation. But the heart of the book are the welter of new research at the interface of behavior genetics and cognitive neuroscience. Much of this work on loci such as MAOA, COMT and the various genes which control dopamine receptors, is very provisional. With that in in mind, Oakley constructs a story where the genes serve as knobs which modulate the mix within the "mental soup." This soup, sensitive to outside inputs, shifts the probability of a given set of behaviors conditioned upon certain inputs. The author's sister represents the case of an individual who seemed relatively thin on the essential need for reciprocity and empathy in human relations, even in the case of her close family members. Tracing her psychological development is aided by the fact that Carolyn kept detailed diaries, which are now in the possession of the author after her death. Therefore, one notes that on the day she found out her father died Carolyn's diary was extremely banal and selfish, noting what implications the event might have had upon her need for dental work. In fact, her father was on some level terrified of her amorality, and as an individual with Alzheimers he was frightened of the prospect that his care would ever be delegated to her, as opposed to his more psychologically normal daughter. Of course Carolyn was never truly evil, even if she was inconsiderate and selfish. Though the author's analysis of the psychological profile of tyrants of history might titillate, I think a more important point is that a small proportion of humans seem to lack the universal moral sense which we as a species share. These psychopaths are pure Machiavellians, who become expert at manipulating the expectations of other human beings. For example, some murderers can claim their innocence, and convince many because of their manner, only later be found to have been guilty all along due to DNA evidence. Oakley points out that the reason that this occurs is that most humans simply extrapolate a basic sense of decency to other human beings, and are not equipped to detect the "cheaters" who ride along the wave of accumulated social capital. And it may be that at some point in the near future various neuroscientific techniques such as fMRI along with genetic profiling can allow us to adduce with a high degree of certitude who these individuals are. Explicit in Evil Genes is the idea that in the future these sorts of diagnostic techniques could forestall the emergence of psychopathic demagogues who drag whole nations along their amoral and insane track. But I think at the end of the day these new tools will have a bigger impact in terms of a broad-based campaign to understand the psychological predilections of humans as a whole. Can you imagine genetic and neuroscientific clues as to time preference being more important than a credit rating? Perhaps. But the flip side of these "pathological" variations in biopsychology is that there is likely an evolutionary reason that these types persist at particular frequencies. The very mental signatures which might make one a high credit risk might also mean that they are a better athlete or foot soldier. The egotism which might make someone a difficult wife or husband might make them an efficient captain of industry. Evil Genes' ultimate morality has less to do with evil and genes than it does with mapping out the what and why of how humans vary, and how that might help us constructing a society which is just to all. Related:Author's website.