Homicide Studies
Volume 9 Number 4
November 2006 1-16
© 2006 Sage Publications
10.1177/1088767906292645
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Book Reviews
Johan M. G. van der Dennen University of Groningen

Keywords: Evolutionary Psychology, Killing Module, Mate Killing, Slipup or Byproduct Theory, Adaptations to Kill.

Buss, D. M. (2005). The Murderer Next Door: Why the Mind is Designed to Kill. New York: Penguin.

David M. Buss is a professor of psychology at the University of Texas at Austin and well-known among evolutionary psychologists and human ethologists for his books such as The Evolution of Desire: Strategies of Human Mating (2003), The Dangerous Passion: Why Jealousy is as Necessary as Love and Sex (2000), and Evolutionary Psychology: The New Science of the Mind (2004) and his numerous articles, single author and with his collaborators Todd Shackelford, Joshua Duntley, Heidi Greiling, Martie Haselton, and David Schmitt. Have you ever fantasized about killing someone? If you answered yes, you are not alone. A ground-breaking study by leading psychological researcher Buss reveals that 91% of men and 84% of women have had at least one vivid fantasy — often intense and astonishingly detailed — of committing murder. Though we may like to think that murderers are either pathological misfits or hardened criminals, as Buss highlights, the vast majority or murders are committed by people who, until the day they kill, seem perfectly normal. The Murderer Next Door is a riveting look into the dark underworld of the human mind and why, Buss reveals, the pressures of evolutionary competition have adapted our minds for murder. Buss takes us on a fascinating journey into the killing mind with gripping stories about specific murder cases, murderer’s own accounts of why they killed, and many astonishing quotes from the most massive study of homicidal fantasies ever conducted, with people’s amazingly detailed accounts of the murders they considered committing . . . . Whereas previous theories of murder propose that homicide is something outside of human nature–a pathology imposed from without by the distorting influences of culture, media images, poverty, or child abuse–Buss argues that killing is fundamentally in our nature. Because of the aeons of human evolution, murder was so surprisingly beneficial in the intense game of reproductive competition, our minds have developed adaptations to kill. (dust jacket text) Buss’s main thesis, in brief, is that “there is a fundamental logic to murder — ruthless but rational — and that it resides not only in the minds of people who actually become murderers, but in the minds of all of us” (p. 5). The human mind has developed adaptations for killing — deeply ingrained patterns of thought, often accompanied by internal dialogue, anchored in powerful emotions — that motivate us to murder . . . . Sometimes hate motivates murder; sometimes envy; sometimes greed; sometimes fear; sometimes jealousy; sometimes spite. And sometimes, a complex combination of emotions motivates murder. (p. 8) “Murder is a product of the evolutionary pressures our species confronted and adapted to” (p. 9). Buss critically reviews the main theories of violence and criminality in general — social-environment theories, pathology theories, and sociological theories — and, not unexpectedly, finds them hopelessly inadequate, not in the last place because murder, in these theories, is viewed as merely an extreme manifestation on a continuum of violence or criminality, whereas, according to Buss, “murder is qualitatively different from all other forms of violence” (p. 24). The patterns that I discovered in the triggers of homicidal fantasies support a radical new theory of murder — that all of us house in our large brain specific specialized psychological circuits that lead us to contemplate murder as a solution to specific adaptive problems. (p. 30) (Elsewhere these specialized psychological circuits are called “psychological circuits for homicide” and “killing module” or “homicide module.”) This homicidal ideation — like sexual fantasies — allows us to fashion alternative scenarios and evaluate the extended costs, benefits, and consequences of each. Though homicidal thoughts usually precede murder, they do not invariably, or even very often, lead to murder. In fact, most fantasies help put the brakes on murderous impulses, inhibiting the intent to kill, because we usually appraise the costs as too high and choose more effective, less risky solutions (p. 31). That is not to say, however, that they are not real expressions of murderous intent. Homicidal ideation almost invariably precedes carried-out kills (p. 32). On pages 36 to 44, Buss presents his arguments for why murder, in the intensely competitive game of reproductive competition through the eons, has been a remarkably effective method of achieving evolutionary success. These arguments can be summarized in this one quote: “To deprive others of their life is one of the most effective means of increasing one’s fitness” (Lopreato, 1984: 137-138). Consider just a few of the specific benefits our ancestors could have secured by killing other human beings:

● Preventing injury, rape, or death to oneself, one’s spouse, or one’s kin
● Eliminating a crucial antagonist
● Acquiring a rival’s resources or territory
● Securing sexual access to a competitor’s mate
● Preventing an interloper from appropriating one’s own mate
● Cultivating a fierce reputation to deter the encroachment of enemies
● Avoiding investment in genetically unrelated children (stepchildren)
● Protecting resources needed for reproduction
● Eliminating an entire lineage of reproductive competitors

Of course, Buss once again asserts, many of us never come close to killing someone, and that is true for several reasons: legal systems and other cultural deterrents to murder and evolved antihomicide defenses (giving rise to a coevolutionary arms race). In chapter 3, “The Dangerous Game of Mating” (pp. 45-65), Buss explains the logic and heated competition of sexual selection and the sex differences in mating preferences, including “mate guarding,” and the accompanying sexually dimorphic patterns of mate killing. “Many, many murders can be explained by the evolved psychology of reproductive competition — an explanation more powerful than the others that have been offered to account for the high rates of male violence” (p. 61). One might think that killing would be a great turnoff to women, but apparently that is not the case. Buss quotes Gore Vidal as noting: Women are always attracted to power. I do not think that there ever could be a conqueror so bloody that most women would not willingly lie with him in the hope of bearing a son who would be every bit as ferocious as the father. Amazingly, even today convicted murderers remain highly appealing to some women. (p. 64) In chapter 4, “When Love Kills” (pp. 67-101), Buss discusses mate killing and the prima vista paradoxical finding that the majority of women are killed by men who love them deeply. Women frequently kill to defend themselves against men who are enraged by women’s (putative) infidelity or defection. Buss next presents his idea about the evolution of love as a solution to the problem of commitment, the excruciatingly painful experience when the partner falls out of love as crushingly as he or she fell in love, the harshness of the mating market, and how sudden increases in status open up new mating opportunities: “A ‘9’ who was previously out of reach now becomes accessible” (p. 78), why women have sexual affairs (the “shopping-for-good-genes” motivation), the dangers of a broken heart, the costs of cuckoldry to males, which men murder their mates, and women’s defenses against murderous mates. This chapter is the pivot of the book in which Buss goes to great length to defend his idea that mate killing may have been adaptive in the motherland (the environment of evolutionary adaptedness or EEA). In chapter 6, “Sexual Predators” (pp. 103-133), Buss expounds his findings about mate killing by women. Women are far less murderous than men. But when women do turn murderous, there are specific adaptive reasons, and these differ markedly from those that motivate men. The main motives for murder committed by women are self-defense and a desperate desire to escape a dangerous, abusive marriage. Abuse of their children provides an additional trigger. Interestingly, women’s homicidal thoughts also reveal a fundamental sex difference — women are far more likely than men simply to want the partner dead, often not wishing to do the killing themselves. Chapter 6, “Mate Poaching” (pp. 136-162), discusses the motives, tactics, and dangers of mate poaching; mate poaching is a risky business. Sometimes the former partner of a poached mate becomes violent. An additional “revenge effect,” ironically, is increased anxiety about how faithful the poached mate will be. After all, if one has succeeded in luring another away from a committed relationship, that person has proved to be susceptible to advances by other poachers. Killing is certainly not the most frequent solution to the problem of mate poachers. But it is a solution seriously entertained by plenty of people facing the pain of this dilemma. In fact, killing a rival who has sexually trespassed is so common across cultures that it is often recognized as a legitimate means of dealing with mate poachers. This is the famous crime passionel. In chapter 7, “Blood and Water” (pp. 163-194), Buss explains why and under what circumstances parents sometimes murder their children (neonaticide, filicide, infanticide): when the child has a serious birth defect, illness, or deformity; when a mother already has children and investing in a new infant would put too great a burden on her resources for raising the others; and when a woman has children but is neither married nor in a committed relationship with a man willing to support the children. (These conditions were first presented by Sarah Hrdy, 1999.) Subsequently, he explains why stepfathers are such a hazard for stepchildren. In America, children living with one or more surrogate parents are a staggering 40 to 100 times more likely to be killed in the home than are children living with both genetic parents (p. 174). This has been a well-known phenomenon ever since Daly and Wilson’s (1988) pioneering research. The contrary cases, when kids kill their parents (parricides), is presented next. Fathers fall victim twice as often as mothers, and most children who kill their parents are male teenagers. In many of these cases, the father was abusive to the mother and the child acted to defend her. Siblicides are statistically rare, and when they occur, they almost invariably involve brothers killing brothers (and the motive almost invariably revolves around the parental resources that are ultimately critical in attracting women). In chapter 8, “Status and Reputation,” Buss explains the evolutionary logic of status competition and hierarchy negotiation among males. Public affronts to a male’s status (losing face), exacerbated by additional humiliation in front of peers, are very risky, indicated by the prevalence of homicidal fantasies prompted by threats to status. “But it’s worth pausing to consider that for every carried-out kill, for every man who actually ‘goes postal,’ there are hundreds or thousands who ruminate and revel in vivid fantasies about doing precisely the same thing” (p. 203). People, both men and women, perceive public insults as challenges to a man’s masculinity and virility, his strength, his worth as an ally, and his ability to protect his woman from sexual trespass. That is — in a nutshell — why “trivial altercations,” “little ol’ arguments over nothing at all” are so potentially dangerous: The loss of face, and the attendant plunge in status, carry disastrous consequences for men in the mating game. For women, the type of threat to reputation that tends to trigger homicidal thoughts is that prized social commodity a woman possesses — her sexual reputation. Buss argues that the underlying motivations that drive serial killers to kill are the same as those behind the everyday killings over status and reputation: “Serial killers murder because they seek vengeance for status denied, and mass murderers kill to get to the top in a status hierarchy and stay there” (p. 219). The harsh truth is that, throughout human history, men have used murder, often mass murder, as a strategy to rise to power and to suppress potential rivals from rising up from the ranks to usurp that power. The psychological circuitry behind killing the competition to get ahead and stay ahead became installed in the male brain over evolutionary time because it worked (p. 228). In the last chapter, “The Killers Among Us” (pp. 229-245), Buss gives some examples of raiding in tribal societies such as the Yanomamö, Jivaro, Dani, and Maori In anthropological accounts of tribal warfare we find powerful evidence that killing raids have historically been a strategic means of winning the merciless competition for survival and reproduction. The spoils that have traditionally flowed to the victors in warfare do not surprise us now — territory, food, water, weapons, and women. (p. 231) He comments on the social learning theory, advocated by Rowell Huesmann and Leonard Eron, which cannot explain why killing is more common in cultures lacking television, movies, and violent video games. The child abuse and pathology theories advocated by Richard Rhodes (1999) in Why They Kill and Jonathan Pincus (2001) in Base Instincts cannot explain why perfectly normal next-door neighbors with no apparent evidence of psychological abnormalities commit murder. Finally, Buss exhorts: “Our moral abhorrence of homicides should not cause us to reject the compelling evidence that a deep psychology of killing has been and is an essential component of human nature” (p. 231). The book contains notes, a brief bibliography, and a composite index. Clearly, this book is written for a lay audience and not for the scientific community. But it is worthwhile to let readers know Buss’s ideas about lethal violence, and it is challenging to (attempt to) criticize these ideas. What immediately struck me while reading this book was Buss’s “male intellectual proprietariness”: What he presents as the outcome of his own research has actually been presented previously by other researchers, notably Daly and Wilson, Ghiglieri, Ann Campbell, and Hrdy. Sometimes this intellectual heritage is not even acknowledged: The paragraphs about women as sexual reputation defenders is clearly based on Campbell’s work, though any reference to this literature is lacking. What struck me throughout the book was a curious kind of déjà vu — that I was reading a weak derivative of Daly and Wilson’s (1988) classic Homicide (the book frequently reads like a kind of “Daly and Wilson for Dummies”). What struck me somewhat later was the careless way manslaughter, killing, murder, and homicide are conflated in one overall concept. It is often not clear whether Buss conceives of one general “deep psychology of killing” or whether he envisages several specific adaptive “neural circuits” or “modules”, as may be deduced from the following quote from Buss and Duntley (2003): The idea that humans might have evolved adaptations whose dedicated function is to murder other humans seems to be so abhorrent that it has not been seriously entertained, scrutinized, or examined. In contrast, we have proposed a theory that appears to be radical in this context — that humans have evolved not one, but many adaptations whose proper function is to produce the death of other humans. (Buss & Duntley, 2003: 121)

Some “Ancestors”
This book belongs in the tradition of, what I have called, the “Dark-Side-of-Man industry” (e.g., Bloom, 1995; Ghiglieri, 1999; James, 1890; Lopreato, 1984; Wrangham & Peterson, 1996), which triumphantly announces that evil is hard wired in man, with each author individually claiming to having discovered this profound truth. Here, for instance, is Ghiglieri’s auto-da-fé, which sounds very “Bussian”: We must first admit the plausibility that human murder is no accident. Instead, murder is encoded into the human psyche. People who murder do so deliberately based on their own personal decisions favoring their own ultimate self-interests. They do not murder because they themselves are hapless victims of a society gone haywire. (Ghiglieri, 1999: 131-133) Overall, most men can become murderers if given sufficient provocation. In fact, what fascinates us most about murder is that we know most murderers are sane, and that nearly all of us recognize that we could be driven to commit homicide given the “wrong” or “worst” set of circumstances affecting our ultimate need to survive or reproduce successfully. The data in this chapter answer many of the questions posed at the outset — although why men kill so much more than women still needs a clarifying statement on ultimate causation: Homicide is an instinct coded into the human male psyche in a design that prompts men to kill (1) to expand their personal gains leading to reproductive advantage or (2) to keep major gains they have already made. Women, meanwhile, usually kill to protect their personal security or reproductive future. Clearly, the implication here is that whereas violence by women is finite and more predictable in perceived selfdefense (however twisted), men’s violence tends to be more infinite and opportunistic. Murder is an ever-present possibility in all cultures because its roots are biological. Murder is coded in our DNA, just as it is in the genes of our close ape cousins. (Ghiglieri, 1999: 154)

The Competition: Alternative Theories
As already noted, this book is a popular version of a theory and hypothesis developed elsewhere by Buss (2000), Buss and Duntley (1998, 2002, 2003), and Duntley and Buss (2005). It is (somewhat) understandable that Buss does not bother to present alternative theories, other than the social learning theory he criticizes. But there is serious competition. Buss fails to take into account (a) Daly and Wilson’s theory of killing as byproduct or slipups of ever more desperate mate guarding tactics; (b) murderous propensities, like many other human anatomical and behavioral traits, may be normally distributed, such that a minority is ready to use lethal violence even without provocation, a minority refuses to kill, even under extreme provocation, and the majority somewhere in between; (c) murderers are a special group (or taxon), as Buss suggests, but not for the reasons he proposes. Buss ignores all the cumulative evidence of neuropsychological defects in murderers and habitually violent (lifetime persistent) offenders (brain dysfunction, hormone and neurotransmitter abnormalities, etc., in limbic system and prefrontal cortex). Other alternatives are (d) Bailey’s phylogenetic regression theory, and (e) Megargee’s overcontroll theory. I shall briefly present these theories.

Daly and Wilson’s (1988) Slip-up Theory
This theory of partner or spouse killing as byproduct of male mate guarding is more extensively discussed below.

Normal Distribution and Coincidental Status-Striving Theory
Another possibility not considered by Buss is that killing propensities or the willingness to use extreme violence (or whatever one may name it), like many polygenetic human anatomical and behavioral traits, is normally distributed in the population (bell curve), so that a few individuals need no or few excuses or incentives to kill and a few individuals will never kill — not even under extreme provocation — with the majority somewhere in between these polar opposites (cf. Rowe, 1996). Studies of behavior of soldiers in combat (van der Dennen, in press) do not generally, I tend to believe, corroborate the killing module. In fact, it takes a lot of drill and indoctrination to make effective soldiers out of average high school boys, and killing each other does not seem to be men’s favorite sport, even on the battlefield, under most circumstances. This is a common finding in military psychology. The percentage of active fighters is estimated to range from 1% to 5% in contemporary Western armies (van der Dennen, 2006); the remainder are passive or reactive fighters and nonfighters. Trigger-happy Rambos are more a Hollywood fiction than reality. Several neo-Darwinians have theorized that, although natural selection may never have favored criminal and antisocial behavior per se, it has favored extreme competitiveness, especially in the case of males (e.g., Rowe, 1994). Sometimes this competitiveness is expressed in ways that so offend others that it is deemed illegal. This theory is known as incidental status-striving theory. Most notably, competition for status and resources is central to the ability of males to attract mates. Thus, over numerous generations, men who have been extremely competitive and prone to strive for status have been chosen as sex partners by women more often than other men. As a consequence, they have sired a disproportionate share of offspring, more than other men. At the same time, extremely competitive behavior can be irritating and even injurious to others, especially when it is exhibited by relatively young and inexperienced men. The irritation may be particularly keen to older adults who have already acquired significant resources and are at a point when their main interests are in preserving the offspring they already have rather than attempting to produce more. Another point worth making is this: Traits that have been subjected to natural selection often overshoot and undershoot the exact optimum in terms of their reproductive advantage. As with most other normally distributed traits, males who are competitive and status striving to moderate degrees may be most favored by natural selection. Males who are the most extreme in their competitive and status-striving activities are likely to annoy others to such degrees that laws are instituted to curtail their victimizing activities. The result is that extreme status striving and competitive behavior is criminalized in nearly all societies, and males are much more likely than females to violate nearly all criminal statutes (Ellis, 1998: 89-90).

Taxon
Buss assures us that killing, murder, and homicide are qualitatively quite different from all other kinds and forms of violence. Indeed, viewing murder as merely an extreme manifestation on a continuum of violence and criminality, he maintains, is the main reason for the inadequacy of the theories proposed to explain violence and criminality in general. But the reasons why murder is qualitatively different (especially why the motives are vastly different from other forms of violence) are not very convincing: Unlike with other forms of violence, murder victims are gone forever. When you kill someone, you not only take away everything they have, you take away everything that they ever could have in the future. Murder is often a highly orchestrated act with a dead body as the outcome. Moreover, the motives for murder turn out to be vastly different from the motives for other forms of violence, such as beatings, robbery, or rape. Finally, murder is not a single homogeneous phenomenon; different types of murders require different types of explanations. Wife killing, same-sex rivalry killing, infanticide, stepchild killing, and mass slaughter in war, for example, differ vastly in motive, perpetrator, and method. General theories of violence simply cannot explain the differences we find among the many forms of murder. (pp. 24-25) Murderers may indeed constitute a special category or taxon, as Buss suggests, but not for the reasons he proposes. Buss virtually ignores the avalanche of studies of neuropsychological defects, brain dysfunction, especially in the limbic system and 8 Homicide Studies prefrontal cortex and other neuropathology (hormones, neurotransmitters) in murderers and habitually violent (life-course persistent) offenders. As the sophistication of such techniques as fMRI and PET scan increases, it will probably augment our knowledge of substrate dysfunctions in murderers and severely violent offenders. van der Dennen (1984) reviewed the manifestations of aggression or violence in the clinical (neuropathological or psychopathological) literature and concluded that two distinct types or patterns of aggression or violence are discernible in the clinical context: (a) paroxysmal rage outbursts of an impulsive, relatively uncontrollable nature, evidently related to lesions of an “offensive aggression” circuitry in the limbic system and (b) a pattern that manifests assaultiveness, combativeness, and hostility because of delusional beliefs, hallucinations, and paranoid ideation. The eventual violence used is essentially self-defensive and panicky — the preemptive strike of a cornered cat —  preceded and accompanied by overwhelming emotions of fear and terror. A study by Raine, Buchsbaum, and LaCasse (1997) concluded that convicted murderers had a network of abnormal cortical and subcortical brain processes that predisposed them to violence. The murderers had lower glucose metabolism in the prefrontal cortex and in other brain areas, including the limbic system, than did the controls. This result indicates that these brain areas in the murderers were not as active in using the energy source, implying some disorder in the functioning of these brain areas. This is consistent with other brain imaging studies that generally have found reduced functioning of the prefrontal cortex in violent offenders (for a review, see Raine, 1993). Quantitative electroencephalographic research by Lindberg et al. (2005) and the study of paraphilias in sexual murderers with brain abnormalities (Briken, Habermann, Berner, & Hill, 2005) provide further support to the growing evidence of brain dysfunction in severely violent and lethal behavior. Finally, intermittent explosive disorder is far more common than previously thought (Coccaro, Posternak & Zimmerman, 2005).

Phylogenetic Regression Theory
The most horrifying accounts — at least to me — of murderers of their own motives are those accounts that profess they were absolutely ignorant of their motives or that they did it “just for kicks” or that they “just felt like it” (see Nash, 1992). Such “senseless violence” provides evidence for Bailey’s (1987: 2002) phylogenetic regression theory and the continued existence of a reptilian brain inside the neomammalian cortical brain. (By the way, as reptiles do not care much about the sexual fidelity of their copulation partners, the theory does not imply mate killing per se.) As explained by Bailey (2002: 11) phylogenetic regression implies: The idea that atavistic predatory tendencies lie in the deep recesses of the reptilian brain which can erupt into overt patterns of stalking, brutal killing, and cannibalism . . . .When in the hypothetically deepest of regressive states, primitive emotions and drives of the subcortical centers are in full control; . . . psychological functions are dominated by unconscious, . . . narcissistic, selfish . . . and opportunistic themes; finer linguistic outputs, future projections, self-control, and abstract problem-solving are muted or lost; and the motive apparatus is dominated by the “selfish gene,” kin-selective processes, and current and/or ancestral fitness-targeted imperatives. At such times, the person truly is not himself or herself but is rather a temporary creation of past evolutionary processes. Once the state passes, the person may be quite shocked and dismayed by his or her loss of humanity. The Columbine attack showed the ease with which ancient and culturally repulsive processes can be suddenly re-activated, especially in young males of the species. Moreover, the young killers gave every evidence of enjoying the killing spree, and the event was a kind of killing festival for them. This disturbing fact cannot be explained by any existing sociocultural theory, and the “pleasure” aspect of the killings force us to acknowledge the predatory nature of the attack. (Bailey, 2002: 20)

Overcontrol Theory
Many of the cases of killing described by Daly and Wilson and Buss reminded me of the simple typology that was delineated in the early 1960s by Megargee (1966): under- versus overcontrollers. The chronically overcontrolled person has extremely high inhibitions and minimal habit strength. When exposed to extreme or recurrent frustration or provocation, the excessive inhibitions of these mild-mannered and unassertive people prevent them from expressing their anger. As a result, instigation accumulates to a point where their inhibitions are overcome, so they explode into an uncharacteristic outburst of extreme violence. This characterization dovetails excellently with all other criminological, neuropathological, and psychopathological research: Most murders occur in the context of paroxysmal, impulsive, apparently uncontrollable, sudden — without previous warning or prodromes — temper outbursts, with, sometimes, lethal consequences. In the clinical literature, these cases were diagnosed formerly as “episodic behavioral disorders” or “dyscontrol syndrome.” Overcontrol theory does not stipulate normal distribution, nor claim that killing is an daptation.

The Problematic Mate Killing Module
Buss and Duntley, under their mate-killing module theory, focus on the circumstances of wife killings, which, they contend, are not heat-of-passion crimes at all but premeditated acts of mate aggression and fantasy. Their primary contention is that the argument of Daly and Wilson fails because premeditated killings cannot result from the mere slipups central to the byproduct hypothesis. According to our theory, men have evolved specific mate killing mechanisms that are engaged in specialized circumstances — when they are discovered committing a sexual infidelity and when they unceremoniously “dump” the man. Indeed, our empirical studies 10 Homicide Studies of homicidal fantasies reveal that rejected men frequently contemplate killing the woman who has spurned them, even though they do not act on these fantasies . . . .Many men in this situation have the recurrent thought: “If I can’t have her, no one can.” Some state that “If she won’t live with me, then she won’t live at all.” And empirically, sexual infidelities and breaking up with a husband or de facto spouse who wants to continue the relationship are the strongest risk factors for adult women being killed . . . especially if they are young and hence highly reproductively valuable. (Buss & Duntley, 2003: 125-126) It is not difficult to accept that neonaticide or infanticide, rival killing, and so on were, formerly at least, adaptive under specific circumstances (I think Daly and Wilson have made that abundantly clear), but the adaptiveness of mate killing (femicide, uxoricide) stretches credulity. Mate killing is not a strategy of mate guarding; it is the ultimate negation, the failure of mate guarding. Wife killing ensures that a husband will not have any future offspring with his dead former mate. So, why would behavior so deleterious to reproductive success be spawned by interests in maintaining that success? Daly and Wilson argue that uxoricide is the extreme, nonadaptive byproduct of selection for males to use various forms of coercive mate guarding (Mealey, 2000: 338). Daly and Wilson contend that wife killings by husbands may be considered slipups in a dangerous game where husbands use threats and violence to maintain control over their wife. These killings may then be described as “nonadaptive byproducts of masculine psychological processes,” which themselves evolved from “sexually differentiated mental mechanisms of sexual proprietariness.” The classical statement of the slipup or byproduct hypothesis is the following: In attempting to exert proprietary rights over the sexuality and reproduction of women, men walk a tightrope. The man who actually kills his wife has usually overstepped the bounds of utility, whether utility is assessed in fitness or in more proximal currencies. Killing provokes retribution by the criminal justice system or the victim’s relatives; at the least, murdered wives are costly to replace. But killing is just the tip of the iceberg: For every murdered wife, hundreds are beaten, coerced, and intimidated. Although homicide probably does not often serve the interests of the perpetrator, it is far from clear that the same can be said of sublethal violence. Men, as we noted earlier, strive to control women, albeit with variable success; women struggle to resist coercion and to maintain their choices. There is brinkmanship and risk of disaster in any such contest, and homicides by spouses of either sex may be considered the slips in this dangerous game. (Daly & Wilson, 1988: 205; see also Kenrick & Sheets, 1993) One of Buss and Duntley’s adaptive explanations, to “prevent other wives from cheating or leaving,” applies in the context of polygamous societies. Any man would lose genetic fitness by killing a wife able to bear and raise children but would avoid rearing a child adulterously conceived; a polygamous man would also gain paternal certainty through deterring adultery by his remaining spouses.
A flaw in this explanation is apparent when one asks why deterrence cannot be achieved by threats of violence and assaults short of actual murder. Surely, assaultive behavior occurs in many polygamous cultures with both specific and general deterrent effects. In those cultures, is the murder of an unfaithful spouse just a “slip-up” in lessongiving? (Goldstein, 2002: 12) Suppose a male mutant would not kill his adulterous wife or mate but would just punish her (for deterrence) and continues breeding and siring progeny with her; he would outbreed all mate killers and have an enormous reproductive success. Obviously, the non-mate killer would prevail in the evolutionary long run. This seems to me the inexorable logic of evolution. In his review of Buss’s The Dangerous Passion, Fisher (2002) pointed out it remains unclear why the arguments specifically support an evolved module rather than an alternative explanation: “In fact, ‘Error Management Theory’ (Haselton, DeKay & Buss, 1998) seems to be a better explanation for mate homicide, but Buss ignores this possibility” (p. 17). Moreover, I know many (mammalian, avian) species that have mate guarding in their behavioral repertoire but not, as far as I can ascertain, mate killing.

Premeditation?
Buss maintains that virtually all killings are premeditated acts. To make his point — and to refute Daly and Wilson’s slip-up theory — Buss has to establish that most or all killings are premeditated, but the evidence sometimes seems to flatly contradict this. Many criminologists have commented on the lack of premeditation they observed in their material. Katz (1988), for example, stated: One feature of the typical homicide, then, is its character as a self-righteous act undertaken within the form of defending communal values. The next feature is its lack of premeditation. These homicides are not morally self-conscious acts on the order of calculated political assassinations or coldly executed acts of vengeance. They emerge quickly, are fiercely impassioned, and are conducted with an indifference to the legal consequences. Thus, the second feature of this form of homicide is that the attacks are conducted within the spirit of a quickly developing rage. (p. 18)
Male-male homicides triggered by “trivial altercations” are not a modern phenomenon. Of 13th- and 14th-century Oxford, England, for example, a university town with a homicide rate about equal to that of Miami in 1926, historian Carl Hammer (1978) writes: When all the evidence is considered, one is left with the overwhelming impression that most homicides were not premeditated, but were, rather, spontaneous, arising on the 12 Homicide Studies spot . . . . Thus, sharp tongues, quick tempers and strong drink often seem to have been a fatal combination. (p. 20, quoted in Daly & Wilson, 1988: 126) Having analyzed homicide data from 17 American cities, the authors of the 13-volume Staff Report on Crimes of Violence (Mulvihill, Tumin & Curtis, 1969) concluded that: “Altercations appeared to be the primary motivating forces both here and in previous studies. Ostensible reasons for disagreements are usually trivial, indicating that many homicides are spontaneous acts of passion, not products of a single determinations to kill” (p. 230). The report continued by quoting a Dallas homicide detective: Murders result from little ol’ arguments over nothing at all. Tempers flare. A fight starts, and somebody gets stabbed or shot. I’ve worked on cases where the principals had been arguing over a 10 cent record on a juke box, or over a one dollar gambling debt from a dice game. (p. 230) Studies of juvenile murderers (e.g., Solway, Richardson, Hays & Elion, 1981) typically find three categories of perpetrators: the largest number of homicides are perpetrated in an impulsive, spontaneous, highly emotional context without apparent forethought; the second largest number commits the crime in the context of another crime, and the homicide seems incidental to the total situation; and the minority group of homicides occur in what may be defined loosely as a planned act. In these cases, the adolescents may have been involved in some type of interaction or altercation or argument or fight with someone, left the scene, and after a period pursued the victim and killed him or her. Thus, the majority of juvenile killers do not evidence “malice aforethought.”A criminological classic even states that “probably less than 5 per cent of all known killings are premeditated, planned and intentional” (Wolfgang & Ferracuti, 1969: 189). Moreover, many statements can be found in the criminological literature from which one may deduce that the killing was an accident, despite premeditation (this is no oxymoron, contradiction, or paradox). Some cases of wife killing Buss presents (statements such as “I love her . . . . I didn’t mean to kill her” on p. 91) illustrate this phenomenon. Theories are designed to fit the evidence, not the other way around.

The Role of Homicidal Ideation
The role of fantasy in killing, especially in serial and other pathological killing, is not a discovery by Buss, but has been known for quite some time. According to Norris (1988), for example, the compulsion to kill represents the serial performance of a “morality play” in which the same story is repeated, again and again, with different victims. In telling the obsessive tale, the killer establishes elaborate rituals, setting up a “behavioral skeleton” that he wears on the outside like an insect, using this architecture to support his fantasies. Do these killing fantasies play any causal role? In other words, do these killing fantasies predispose individuals to kill? The answer is apparently not, just as sexual fantasies do not predispose individuals to rape or indiscriminate promiscuity. Sex dreams do not normally make us sex maniacs. When we find, in retrospect, that all killers had killing fantasies, does that point to a causal role of these fantasies? Many people who had murderous fantasies never killed, as Buss himself admits several times. The significance of the killing fantasies remains obscure. Moreover, recent research could not confirm the close relationship of homicidal ideation and criminally dangerous behavior generally. The research literature on homicidal and sexually violent fantasies in both nonincarcerated and offender populations was examined by Gellerman and Suddath (2005). No consistent predictive relationship between violent fantasies and criminally dangerous behavior was reported in the available scientific literature.

Finally
Buss’s theory can not, no more than the other criminological theories, explain why one man murders, the other man commits suicide and the third man just gets drunk. Buss is aware of this (p. 8), but his theory is far from explaining why this is so, except by invoking personality and temperament variables and situational variables including opportunity, provocation, and probably a huge component of sheer bad luck. Suicide is, worldwide, even more frequent than homicide (World Report on Violence and Health, 2002). This means that people are more ready, able, and willing to take their own lives than the lives of others. I do not know what the implications of this fact are for our evolved psychology, but it does not seem to corroborate Buss’s main thesis. The nagging question remains: What is the use of postulating a killing module that does not seem to work most of the time?

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Johan M. G. van der Dennen Ph.D.
Dr Johan M.G. van der Dennen, born in Eindhoven (the Netherlands) in 1944, studied behavioral sciences at the University of Groningen, and is at present a senior researcher at the Section Political Science of the Department of Legal Theory, formerly the Polemological (Peace Research) Institute, University of Groningen, the Netherlands. He has published extensively (more than 200 publications) on all aspects of human and animal aggression, sexual violence, neuro- and psychopathology of human violence, political violence, criminal violence, theories of war causation, macro-quantitative research on contemporary wars, ethnocentrism, and the politics of peace and war in preindustrial societies. In 1995 he published his dissertation The Origin of War: The Evolution of A Male-Coalitional Reproductive Strategy, an evolutionary analysis of the origin of intergroup violence in humans and animals.