Biology and the Deep History of Homicide

8/22/2019 Biology and the Deep History of Homicide

1/21

BIOLOGY AND THE DEEP HISTORY OF HOMICIDE

Randolph Roth*

Social science historians are discovering deep patterns in the history of homicide rates. Murders ofchildren by parents or caregivers correlate inversely with fertility rates and appear to be a function ofthe cost of children relative to parental resources and to parental ambitions for themselves and theirchildren. Murders among unrelated adults correlate with feelings towards government and society.These patterns may represent facultative adaptations to variable or unstable habitats (includingsocial habitats) that may favour the nurture or neglect of children in the first instance, or coop-eration or aggression among unrelated adults in the second. Human neural and endocrine systemsmay have evolved to facilitate such shifts in behaviour.

Keywords: biocriminology, child murder, facultative adaptation, homicide, hormones

Introduction

As Nicole Rafter argues in her superb book, The Criminal Brain(2008), criminologistshave for centuries been fascinated by biological theories of crime. Most biologicaltheories proved bankrupt or even dangerous because of the prejudices they fosteredor justified. But the biological sciences have changed since the Second World War in

ways that are making it possible, in Rafters opinion, to create a biosocial criminol-ogy that avoids the pitfalls of early biocriminology. For the first time, she writes,

there is a genuine possibility for collaborations between social scientists and cogni-tive, genetic, and neurological scientists working on crime. Biologists no longer be-little the possibility that social factors might affect criminal behavior, becausethey recognize that the way in which genes are expressed depends on social factors(Rafter 2008: 243, 246). Brain damage, lead poisoning, childhood traumas, stress,poor diet, drug abuse and other factors can reshape our bodies in ways that predis-pose us to antisocial behaviour. Genes play a role in human behaviour, but they donot determine it. Further, biologists today emphasize human similarities as much asdifferences, which makes it impossible to draw a sharp physical line between crim-inals and non-criminals, between us and them. That is why Rafter is so excited byrecent research on acquired biological deficits, cognitive deficits, genetics and neu-

roscience. Recent research will not improve our understanding of crime, however,unless historians and social scientists acknowledge that biological factors affectcrime (Rafter 2008: 246).

That acknowledgement is well underway, thanks to the pioneering work of scholars suchas Margo Wilson and Martin Daly (1988) and Sarah Blaffer Hrdy (1999; 2009), who havetaken a deep interest in neurology, endocrinology, primatology and evolutionary science(Walsh 2009). Of course, much of the work to date remains provisional. It will take decades

* Department of History, Ohio State University, Columbus, Ohio, USA; [email protected].

The Author 2011. Publishedby OxfordUniversity Press on behalfof theCentre forCrime and Justice Studies (ISTD).All rights reserved. For permissions, please e-mail: [email protected]

doi:10.1093/bjc/azr029 BRIT. J. CRIMINOL. (2011) 51, 535555Advance Access publication 15 April 2011

535


2/21

or perhaps centuries for the knowledge of history, society and biology to reach the level ofprecision at which we can speak definitively about the patterns and causes of particularcrimes. But, given the strides that scholars have made in the past 65 years through collab-oration and cross-disciplinary research, it is time, as Anthony Walsh argues in his recent pleafor a biological synthesis (2009), to take stock of the deep patterns that criminologists havediscovered in human behaviour and to consider the possible biological causes and conse-quences of those patterns.

As a social science historian, my primary concern is to map the incidence of variouskinds of crime, particularly homicide, and to determine why such crimes are prevalent atsome times and in some places and nearly absent in others. Why do some societies takethe lives of a third or more of living children, when, in others, neonaticides, infanticidesand murders of older children by parents or caregivers are rare? Why do homicide ratesamong adults rise into the tens or hundreds per 100,000 adults per year in some circum-stances and drop below 1 per 100,000 in others? As primatologist Franz de Waalobserves, we are a bipolar species (de Waal 2005: 22750). Our capacity for coopera-tion, teamwork, love, friendship, empathy, kindness, forbearance, forgiveness, compro-

mise and reconciliation is unparalleled, because our happiness and survival depend onthe strength of our social groups (especially our families) and on our commitment tothem. But we also have an unparalleled capacity for competition, factionalism, hostility,sadism, cruelty, intransigence and domination. Which side of our nature prevailsdepends on historical circumstances.

But, in a larger sense, many social animals are bipolar. As biologists have long known,animals that live in social groups may change their behaviour drastically when circum-stances change. They can be cooperative in one instance and ruthlessly competitive andaggressive in another. Biologists consider such behaviours the products of facultativeadaptation. In variable or unstable habitats (including social habitats), natural selectionfavours organisms that can sense changes in their environment and respond to them

behaviourally to maximize their reproductive fitness (Sober and Wilson 1998: 12730).A classic example is the honeybee. Worker bees (all of them female) dedicate their livesto helping their queen, raising her brood and defending her hive to the death. Doing somakes sense in evolutionary terms, because the queen is the mother (or, during a monthof succession, at least a half-sister) of each worker bee. Workers propagate their genes farmore effectively by labouring cooperatively and sacrificing themselves for the good oftheir mothers brood than if they were to try to raise broods on their own. Worker beesare not infertile. They are capable of laying eggs that will develop into male bees (malebees are haploid, meaning they carry only the genes of their mothers, whereas femalebees, which carry genes of their mothers and fathers, are diploid). But, while the queenis alive, or while there are larvae of new queens ready to emerge, the reproductive sys-

tems of worker bees are suppressed by pheromones from the brood, so few are capableof laying eggs. Those that do are attacked by their fellow workers and their eggs aredestroyed, since worker bees prefer to raise the broods of their mothers rather thanthe broods of their sisters, which have only a small chance of having the same fathers(since queens typically mate with a dozen or more males). Workers can detect the dif-ference between eggs of fellow workers and the queen because of a pheromone that thequeen applies to each of her eggs. Most worker eggs are destroyed within two hours ofbeing laid, which is why, although 10 per cent of all eggs are laid by workers, only 0.1 per

ROTH

536


3/21

cent of drones in a hive with a living queen are derived from worker eggs (Seeley 1985: 58, 225, 28, 301; 1995: 913).

If the queen dies, however, and there are no successors in the larval stage, theovaries of worker bees develop. Within 15 days, 5 per cent are capable of laying eggsand, within 30 days, 50 per cent. A fierce struggle ensues. The workers maul each otherand destroy each others eggs in the hope of raising a son who will carry their genesand mate with a queen from another hive. In these circumstances, natural selectionfavours competitors who stop at nothing in the fight to propagate their genes.Thus, the worker beethe epitome of the cooperative, social animalis capable ofruthless aggression when circumstances dictate. Facultative adaptation facilitates coop-eration and sacrifice in one social situation, and aggression and self-aggrandizementin another.

It makes sense, therefore, to consider how facultative adaptation has shaped thebipolar behaviour of humans. What social or environmental circumstances elicitaggression and violence, and which cooperation, forbearance and nurture? Andhow have our neural and endocrine systems evolved to facilitate such shifts in behav-

iour? The answers to these questions can help us understand the deep history ofhomicide, to determining why rates of violence against children or adults have variedso markedly.1

Homicides of Children by Adult Relatives or Caregivers

Compared to most animals, humans are capable of extraordinary acts of care, concernand sacrifice for children, including children who are not biologically their own. In bi-ological terms, humans are cooperative breeders. Their children are raised not only bymothers, but by fathers and a wide range of alloparents who can, if necessary, shoulder

all or part of the parental rolegrandparents, older siblings, step-relatives, neighbours,guardians and others. A fifth of all primates engage in some form of cooperative childrearing, but the system of cooperative breeding is most complex and interdependentamong humans because of the extraordinary energy required to nurture children.Humans must consume roughly 13 million calories to reach maturity. No motherhas the capacity to provide by herself for a single child, let alone a family of children.The human system of cooperative breeding co-evolved with the prolonged period ofchildhood dependency and neural development, each facilitating the other (Hrdy2009; Konner 2009).

Humans, like other mammals that engage in cooperative breeding, are physiolog-ically primed for an intense commitment to children. Mothers experience surges

after birth in prolactin, oxytocin and estradiolhormones that help them bondwith their infants by reducing anxiety, elevating mood and activating neural circuitsassociated with romantic love, empathetic social relationships, pain suppressionand physical pleasure (Numan et al. 2006; Hrdy 2009: 21215; Konner 2009:3215). Adult mothers (but not teen mothers), in response to cries from theirinfants during the first months after birth, experience increases in heart rate

1The term deep history is borrowed from Daniel Lord Smail (2008: ixx, 16), a pioneering scholar who believes there is a need

for histories that are informed by natural history, evolution, and the theory of natural selection.


537


4/21

and the stress hormone cortisol that make them acutely alert, attentive and affec-tionate (Fleming and Gonzalez 2009). Fathers experience parallel changes in hor-mones, particularly a decline in testosterone and an increase in estradiol, thatfacilitate paternal care and pair bonding with the mothers of their children(Berg and Wynne-Edwards 2001; Gray et al. 2006; Gray and Campbell 2009). Thephysiology of alloparental care is not yet well understood, but some evidencesuggests that such care is facilitated by lower levels of testosterone, higher levelsof prolactin and a dense network of receptors for oxytocin, a hormone that pro-motes calm and connection. Oxytocin lowers blood pressure, slows the heartrate, reduces anxiety and stimulates parenting behaviour and more intimate rela-tionships with non-kin (Konner 2009: 4478; Sanchez et al. 2009: 31921; Feldmanet al. 2010; Naber et al. 2010). In and of itself, experience with infants and childrenstimulates the desire to nurture in mammalian cooperative breeders, even in pre-pubescent humans. But physiology as well as experience facilitates cooperative childrearing.2

But there is a dark side to cooperative breeding. It works effectively when

children are born in the right numbers, at the right time and with the rightqualities into a world of abundance, strong families and strong social support.But, when those conditions do not prevail, cooperative breeders face a difficultchoice, given the time, effort and sacrifice required to raise their offspring.Does it make sense to invest in a particular child under particular social orenvironmental circumstances, or to invest instead in older children, or in children

who could be conceived at a later date under more favourable conditions? Maternalneonaticide and infanticide, which are rare in nature, are common amongcooperative breeders, including not only humans, but a number of other primates.

As Melvin Konner observes, Mothers are designed by evolution not to produceidealized infant and child care under all circumstances but adaptively to adjust

their investment depending on the offspring and the circumstances. Becausecooperative breeders have been shaped by facultative adaptation, we should expectthat mothersconsciously or not, with deliberation or in the midst of a psychoticdepressionmake strategic choices about their investment in offspring. Forinstance, female tamarins and marmosets neglect or kill newborns if they sensethat they do not have the resources or social support to raise them to maturity.Human mothers and fathers make the same calculations. When switched on,the parental instincts of cooperative breeders are very powerful, but, like allmotives and sentiments, they can be modulated, muted, or switched off whencircumstances change (Konner 2009: 544, 4225; Hrdy 2009: 82109; Penn andSmith 2007; Ziegler and Snowdon 2009). Adoption, fosterage, abandonment, selec-

tive neglect, abuse and homicide are all possible when natural or social conditionsare unfavourable.

The physiology of the dark side of cooperative breeding is less well understoodfor humans than for other mammals. Research has only begun and has largely been

2The debate among scientists is ongoing, however, over the exact nature of the neurological and endocrinological mechanisms

that facilitate cooperative breeding in mammals, and the relative importance of physiology and of parental or alloparental expe-

rience. See, for instance, Wynne-Edwards and Timonin (2007), Schradin (2007), Wynne-Edwards (2007), and Ziegler and Snowdon

(2009).

ROTH

538


5/21

restricted to women. But the evidence gathered thus far shows that, under stressfrom a lack of social support, economic reversals or disruption in their intimate rela-tionships, women are less likely to conceive children, more likely to miscarry and lesslikely to bond with their children emotionally and care for them attentively. Theseare exactly the facultative adaptations we would expect for cooperative breeders fac-ing adverse conditions. A pioneering study of the impact of stress on reproductivesuccess, which followed women in a Mayan community in the highlands ofGuatemala, found that high levels of cortisol steroidsthe hormonal indictors ofchronic stressinterfere with reproductive hormones. Elevated cortisol levelscause untimely increases in gonadotrophin and progestin during the follicularphase of the menstrual cycle and a decrease in progestin during the middle ofthe luteal phase. All these changes lower the chance of conception. Women suffer-ing from elevated cortisol levels who do conceive are three times more likely to mis-carry during the first three weeks of gestation (Nepomnaschy et al. 2004; 2006;Nepomnaschy and Flinn 2009: 3657). Other studies have found that mothers

who suffer high levels of cortisol from chronic stress are less attentive and attached

to their newborn children, because their response to short-term stressors (such asthe cries of their infants) is blunted by a stress response that is always on (Flemingand Gonzales 2009: 30516). And, over the longer term, high cortisol levels are as-sociated with depression, unhappiness and more negative interactions with infants.Postpartum depression, which severely weakens attachment to infants and increasesthe likelihood of maternal violence, also correlates with a mothers belief that shehas little social support, with unplanned or unwanted pregnancies, with stressfulexperiences in the year before birth and with stress over the care of older children(Wile and Arechiga 1999; Miller 2002; Hagen and Barrett 2007). Chronic stress andsocial isolation thus lead to physical responses that diminish maternal investmentand increase the risk of maternal neglect and abusefacultative adaptations to so-

cial and environmental circumstances that are unfavourable to cooperativebreeders.

The history of child homicide makes sense in light of these facultative adaptations. Ho-micide rates for children follow a clear pattern from the mid-sixteenth through the nine-teenth centuries in locations that have been studied to date in North America and WesternEurope. The rates move up and down in long, smooth curves that are visible only whentraced over 100 years or more. The rates at which children are murdered by parents orguardians follow the inverse of the birth rate. Low murder rates for neonates, infantsand children correlate with:

higher birth rates; lower ages of mothers at the births of their first children; higher proportions of women who marry at least once; higher rates of premarital pregnancy; lower rates of abortion-related deaths; longer life expectancy for children; higher adult heights (a function of net nutrition).


539


6/21

These correlations hold for data gathered from multiple sources in New England, Ohio,Virginia and Maryland, and for the official data on neonaticides and infanticides fromPhiladelphia, England andWales, and France. They do not hold for the murders of childrenby other children or by unrelated adults; these follow the sharp ups and downs of thehomicide rate among unrelated adultsa rate that has a very different set of correlates(Roth 2001a; 2001b; 2009).3

How are birth rates, premarital pregnancy, marriage, abortion, life expectancy and heightrelated to murders of children by parents or guardians? The child murder rate and thefertility rate appear to be driven by the same forces. The child murder rate is a functionof the cost of children relative to parental resources and to parental ambitions forthemselves and their children (an investment strategy). When real wages dropped by morethan a third for the poorest 40 per cent of the population in England in the late-sixteenthand early-seventeenth centuries, young women and men found it harder to marry and raisefamilies. The birth rate dropped, life expectancy dropped, heights fell, premaritalpregnancy rates fell, the age of the mother at first birth rose, fewer women marriedand the neonaticide indictment rate jumped fivefold. When real wages rose in the late-

seventeenth and early-eighteenth centuries, the trends reversed and the neonaticideindictment rate fell to its previous level (Roth 2001b).

The rise in child homicides in the mid-nineteenth century was driven more by risingambitions than economic want, even though most murderous parents were poor. Real

wages rose among the poor, but ambitions rose faster. Women in particular embracednew educational opportunities, sought economic independence through work outsidethe home in teaching, needle trades and factory work, became more active in commu-nity affairs and voluntary organizations, and raised their economic expectations forthemselves and their children.4 These rising ambitions made children more costly interms of time and money, so parents limited their child-rearing duties and financialobligations by beginning childbearing later and ending it sooner through abstinence,

3The research conducted by the author on colonial Maryland and Virginia, and on selected counties in Ohio and Virginia, 1785

1900, has not yet been published. For a description of the sources, see Roth (2009: 4804, 486). On Philadelphia, see Philadelphia

County Court Indictments, 18701901, and Philadelphia Board of Health Annual Reports, 18701901.

The statistics on neonaticide, infanticide and manslaughtersof infants in England and Wales are from the annual reports of the

Registrar-General, 1837/38 to 1900, and the statistics on arrests and prosecutions for concealing the birth and death of illegit-

imate infants are from Judicial Statistics, 18291900. The series are available in the Parliamentary Papers of the British House of

Commons. The earliest murder statistics available from the Registrar-General (for 1837 and 1838) are implausibly low, however.

Arrest s tatistics are not availa ble before 1856, so the earlier data on prosec utions f or concealing the birth and death of illegi timate

infants are spliced to the arrest data in 1856, based on the ratio of prosecutions to arrests, 185660. The data on prosecutions

before 1829 are not used, because they are implausibly low. Reporting procedures appear to have changed in 1829. The statistics

on births through 1871 are calculated from Wrigleyet al. (1997: 61415), spliced thereafter to the statistics in Mitchell (1988: 29

30). On the limitations of official statistics and of the practices of many local coroners in England and Wales, see Jones (1894: 59

64), Behlmer (1979), Rose (1986: 5760) and Sauer (1978). On the publics continuing interest in detecting and punishingneonaticides and infanticides, see Monholland (1989: 1217, 16983).

The statistics on arrests and prosecutions for neonaticide and infanticide in France are from the Compte general de la justice

criminelle, published annually since 1825. They are available in Brouardel (1897: 1417), Chesnais (1982: 111), Fuchs (1984: 105)

and Lalou (1986: 181). They include statistics on cases tried by the courts (infanticides juges), concealed deaths of newborns (sup-

pressions denfant), manslaughters of infants (homicides involontaires), infanticide cases dismissed by justices (non-lieux) and

infanticide cases not carried forward by prosecutors (sans suite). The statistics on births are from Bourgeois-Pichat (1965: 498

9, 506). See also Bechtold (2001).4The literature on the rising ambitions of women in the Western world in the late-eighteenth and early-nineteenth centuries is

voluminous. Ambitions rose when it came to work, marriage, family, romance, education, fertility control and civic involvement. On

the United States, for example,see Cott (1977), Mohr(1978),Dublin(1979),Ryan (1981), Hewitt (1984), Rothman (1984),Stansell

(1986), Graff (1987), Gilmore-Lehne (1989), Lystra (1989) and Faust (1996).

ROTH

540


7/21

contraception and abortion. And when unrealized ambition led to frustration and stress,parents killed newborns, infants and older children (Roth 2001a).

The child murder rate is also a function of the amount of support parents canexpect from society at large (a response to social isolation and stress). Welfare meas-ures have had a considerable impact on the child murder rate, because they affectboth the ability of young parents to form families and raise children and the stressthat young parents experienced. For instance, the child homicide rate went up forblacks and whites in the South after the Civil War because of hard economic timesand the deaths of so many young men of marriageable age. The murder rate fellsharply, however, in Richmond, Virginia, in the 1880s, after a home opened for singlemothers. The home did not ask single mothers to give up their children for adoption.Instead, it offered medical care, child-care and employment opportunities so thatsingle women could raise their children on their own. The home was for whites only.Its impact was stark: the homicide rate dropped only for white children in Richmond,not for black children (Green 1999).

New welfare policies in Western Europe contributed to the increase in neonaticide

and infanticide that occurred there in the mid-nineteenth century. The British gov-ernment amended the Poor Law in 1834 to make it harder for single mothers andlocal parishes to sue the fathers of illegitimate children for child support. The newlaw also forced single mothers who sought poor relief to live with their children indisease-ridden public almshouses and earn their keep. The number of illegitimatechildren receiving public assistance in England and Wales decreased instantly by40 per cent (Higginbotham 1985: 17, 28; Rose 1986: 2234). In the 1830s, the Frenchgovernment launched its own campaign to pressure single women to have fewer chil-dren and to shoulder the cost of the children they had. In Paris, for instance, in the1820s, a quarter of all newborns and half of all illegitimate newborns were aban-doned at the state-run foundling hospital. The government decided to make it more

difficult to abandon children at foundling hospitals and, in return, offered singlemothers one month of assistance after the births of their children (Fuchs 1984:xi, 29, 3446, 6479). Under these circumstances, the temptation to abort or murdera child was enormous.

Social attitudes towards out-of-wedlock pregnancies have also affected the homiciderate of newborn children. When out-of-wedlock pregnancies were re-stigmatized in theNew England during the Great Awakening of the late 1730s and 1740s, the neonaticiderate spiked, because there was tremendouspressure on young peopleto abstain from pre-marital sex. More young women chose to try to conceal their pregnancies rather than beshamed publicly, and there were more neonaticides and more hangings of women foundguilty of neonaticide. The neonaticide rate also spiked in France after an 1825 law made it

illegal to leave an unwanted newborn anonymously at the door of a church or charitableinstitution. Thedesireto shame indigent singlemothers and to hold them personally andpubliclyresponsiblefortheirunplannedpregnancieshaddireconsequences.Conversely,

when public support and sympathy for single mothers was substantial, neonaticide andinfanticide rates fell (Roth 2001a; Fuchs 1984).

These historic patterns in child homicide rates are consistent with contemporarypatterns in the United States. Because of advances in medicine and forensic science,cooperation among physicians, coroners, social workers and law-enforcement offi-cers, and the creation of formal review boards to examine suspicious or unexplained


541


8/21

deaths of infants and children, it has been possible in the past decade to study do-mestic violence against children with great precision. One of the largest studies, orga-nized by the childrens hospitals in greater Pittsburgh and Columbus, Ohio, founda clear and not unexpected pattern. The incidence of child abuse went up during eco-nomic downturns. In fact, the researchers recognized the recessions of 2001 and 2007before economists and government officials did because they noted an increase in thenumber of shaken babies and battered children.5

Historic patterns of child homicide are also consistent with the patterns criminologistshave discovered in mortality data compiled by the World Health Organization. Compar-isons of nations with adequate statistics (most of them affluent) reveal that high homi-cide rates for children of all ages are correlated with economic inequality, lowgovernment expenditures on welfare and a high rate of female participation in the la-bour forcea proxy for higher economic need or ambition (Gartner 1990; 1991; Fialaand LaFree 1988; Briggs and Cutright 1994; Sorenson et al. 2002; Hunnicutt and LaFree2008). Once again, the degree of social support and the economic circumstances andambitions of parents, especially mothers, appear to determine the homicide rate for

children. These patterns are consistent with those found by many anthropologistsand comparative primatologists who have studied infanticide and neonaticide inhunter-gatherer, pastoral and peasant societies. Children who come at the wrong time,in the wrong number or with the wrong qualities (disabilities, non-preferred gender,etc.) are at risk, especially if parents are experiencing economic or social stress (Hrdy1999; 2009).

Child murder is thus caused not only by social or environmental circumstances, but bythe ways in which evolution has enabled parents and caregivers to respond to those cir-cumstances. Humans, like other cooperative breeders, are well adapted to life in variableor unstable habitats (including social habitats) because they can change their fertilityrate, their level of parental investment and their attachment to children as conditions

become more or less favourable for forming families and raising children.

Homicides among Unrelated Adults

Like many other social animals, humans are well adapted to life in cohesive social groupscomposed largely of non-relatives. Of course, like most social animals, humans compete

with each other within their societies, sometimes ruthlessly, for status, power andresources, because they have been shaped by individual-level selection. Selfishnesscan have benefits when it comes to reproductive fitness. But, because their survivalas social animals also depends on the strength and solidarity of their social groups

whether bands of hunters and gatherers, or villages of farmers or herders, or modern

nationsthey cooperate for mutual advantage and in certain cases sacrifice for the goodof the whole. Reciprocity and selflessness also have benefits, because, as social animals,humans have been shaped by group-level selection as well. Mutual aid, reciprocityand altruism can enhance their reproductive fitness (or at least the fitness of their

5Incidence of Child Abuse Skyrocketed During Recent Recession, Childrens Hospital of Pittsburgh of UPMC-led Study Finds,

Childrens Hospital of Pittsburgh, news release, 10 May 2010, at www.chp.edu/CHP/050110; Recession Linked to Increase in

Shaken Baby Syndrome, USA Today, 3 May 2010, atwww.usatoday.com/news/health/2010-05-03-abuse03_ST_N.htm; and personal

communication with Dr Philip Scribano, Medical Director of the Center for Child and Family Advocacy at Nationwide Childrens

Hospital, Columbus, Ohio.

ROTH

542
http://www.chp.edu/CHP/050110http://www.usatoday.com/news/health/2010-05-03-abuse03_ST_N.htmhttp://www.usatoday.com/news/health/2010-05-03-abuse03_ST_N.htmhttp://www.chp.edu/CHP/050110


9/21

surviving kin) by enabling their social groups to outcompete rivals (Sober and Wilson1998; de Waal 2005).6

The ability of humans to cooperate has been enhanced by their capacity, as Michael Tom-asello observes, to establish norms and institutions to govern their interactions with othermembers of their social groups. Unlike other primates, humans create moral rules that bindthem to certain standards of conduct within the group. These rules facilitate trust and tol-erance among cooperators and legitimize sanctions against bullies, free riders and cheats.Humans also adopt social conventions that encourage identification with the group andconformity to the groups way of doing things. These constitutive rules foster a senseof empathy, fellow feeling and common purpose within the group, and facilitate coordi-nated action, although sometimes at the price of turning members of the group againstoutsiders (Tomasello 2009: 2844, 905, 99100).

The ability to cooperate has enabled humans to create societies on a vast scalefar be-yond the capacities of nonhuman primates, who confine their social groups to kin or tosmall bands of kin and non-kin and cooperate almost exclusively on the basis of kinshipor direct reciprocity. But, as Christopher Boehm observes, human societies are nonetheless

rife with conflict because of the determination of some individuals to dominate others andthe determination of others to resist domination. According to Boehm, bands of huntersand gatherers contain aggression by embracing an egalitarian ethos that mandates thatmembers share power within their bands as equals and respect the personal autonomyof others. Any member who belittles, bullies, or otherwise tries to control another facessanctions: ridicule, ostracism or even death. Modern nation states contain aggressiondifferently, by asking subordinates to buy into the notion of social and political hierarchy:

Nevertheless, they subject their dominators to a certain kind of cost-benefit accounting. If their leaders

are fair-minded and attentive to the needs of their people, subordinates remain appreciativeand

docile. If they feel the leaders are abusing their powers, however these may be defined locally in terms

of political legitimacy, they become ambivalent, hostile, potentially rebellious, and disposed to actforcefully. (Boehm 1999: 669, 169)

The human capacity for aggression within social groups is thus a facultative adaptation togroup living, as is the human capacity for cooperation. When human social groups arestable, and when they further members interests or command respect and loyalty, humanstend to cooperate with others and act in a spirit of tolerance, forbearance, generosity andhelpfulness. But, when their social groups are unstablewhen they lose the capacity to pro-tect lives and property or contain the struggle for dominance and no longer serve theirmembers interests, respect their rights or give them a sense of belonging, humans tendto turn against each other and become more hostile, defensive or predatory.

These facultative adaptations to group living are nowhere more evident than in hom-

icides among unrelated adults, including homicides that at first glance appear to have

6As Charles Darwin recognized, natural selection can act on social groups as well as on individuals or kin groups. Altruists and

cooperators may havefewer offspring thannon-altruistsor free-riderswithin their groups,because of their willingness to sacrifice for

the good of others (including non-relatives) or to temper their pursuit of self-interest for mutual benefit. But groups of altruists and

cooperators may have more offspring than groups of non-altruists and free-riders because of their ability to work together, provide

for each other and defend their groups. If the advantages of altruism and cooperation for the social group are great enough, as they

appear to be for many group-living animals, including humans, the proportion of altruists and cooperators will increase in the

species population over time, even though the proportion of altruists and cooperators may decrease within each particular social

group (Sober and Wilson 1998).


543


10/21

nothing to do with feelings towards government and society. As Gary LaFree, ManuelEisner, Roger Gould and I discovered independently in the 1990s, homicide ratesamong unrelated adultsnearly all of which have been committed historically bymalesappear to be determined by such feelings (LaFree 1998; Eisner 2001; Gould2003; Roth 2009). As I put it in my own work, there have been four correlates of lowrates in North America and Western Europe over the past 450 years:

(1) the belief that government is stable and that its legal and judicial institutions areunbiased and will redress wrongs and protect lives and property;

(2) a feeling of trust in government and the officials who run it, and a belief in theirlegitimacy;

(3) patriotism, empathy and fellow feeling arising from racial, religious or politicalsolidarity;

(4) the belief that the social hierarchy is legitimate, that ones position in society is or canbe satisfactory and that one can command the respect of others without resorting to

violence.

When these correlates are in place, the homicide rate among unrelated adults can fallbelow 1 per 100,000 per year. When they are not, the homicide rate can soar to tens orhundreds per 100,000.

Homicide rates on contested frontiers and during revolutions, civil wars and hostilemilitary occupations show how quickly humans can become aggressive during periods ofpolitical instability. As soon as the political order loses its ability to contain the strugglefor dominance and protect lives and property, cooperation and forbearance give way todefensive, hostile and predatory behaviour. Political violence, terrorism and genocideare common in such circumstances, but so too are everyday homicides over honour orproperty and predatory homicides involving robbery or rape. In eighteenth andnineteenth-century France, for instance, the homicide rate rose during every revolu-

tion17891801, 183031, 184850, 187071and not only in places where politicalviolence was common, like Paris, but in places remote from such violence, like Corsica,where there were spikes in feud and honour killings (Gould 2003: 15061). During peri-ods of political instability, warring factions aim to create new stable regimes by dominatingor eliminating political rivals. But those homicides are inevitably accompanied by othersthat may seem at first glance to be apolitical, but that correlate just as strongly with the lackof political stability. For example, some men become predatory killers, raping, robbingand murdering as individuals or members of gangs. They may begin killing as politicalpartisans, but when they find themselves on the losing side or at odds with an emergingpolitical order, they may begin to prey not only on political enemies, but on former alliesand non-combatants, whom they may resent for their weakness, defeatism or indifference

to the cause. They lose their sense of connection with anyone beyond their immediatecircle.

Old neighbourhood feuds are also likely to turn murderous during periods of politicalinstability. When government breaks down, men kill for what appear to be purely per-sonal reasons, avenging wrongs, settling scores or simply getting rid of people they dontlike. They may be moved to do so by a lack of sanctions (because of weak law enforce-ment), a fear that their enemies will kill them first or partisanship (if their personalenemies happen to be on the opposite side in the political struggle). Regardless of

ROTH

544


11/21

motive, these feuds can take on a life of their own and draw in more combatants. Ho-micide rates can thus reach catastrophic levels during periods of political instability andcan remain high for decades. Once learned, homicidal habits can be hard to break andcan be passed down for generations.

Why does aggression break out during periods of political instability? Because, in evo-lutionary terms, it can pay off handsomely. The risks of aggression are always consider-ableinjury, death, the loss of family and friends. But the rewards for successfulaggression during periods of political instability are enormous: more power, more resour-ces, more offspring, and a higher rank in the social hierarchy for oneself or ones faction.Intensified aggression is thus a facultative adaptation to life in unstable or failing socialgroups, just as cooperation is an adaptation to life in nascent or thriving social groups.

These adaptations have deep biological roots. Consider, for instance, the behaviour ofgroup-living monkeys and apes during their own periods of political instability, whendominance hierarchies are contested and the personal relationships and coalitions thatsupport them break down. In these circumstances, plasma levels of testosterone increasein adult males in anticipation of aggression (the challenge hypothesis) and the num-

ber of fights doubles or triples, as individuals and new coalitions struggle for power.Formerly pacific relationships turn violent and former subordinates challenge domi-nants. Males who exhibit the highest levels of testosterone and aggression tend to riseto the top of the new political order, while the level of testosterone and aggression dropsfor males who experience repeated defeats and fall towards the bottom of the socialhierarchyan evolutionarily conservative strategy (conditioned defeat) to protect sub-ordinated individuals from further harm. Once political stability returns, however,plasma levels of testosterone decline generally, as does the number of fights; and, overtime, if stability is maintained, rank depends less on testosterone and aggression than onthe ability to form alliances, reassure subordinates and reconcile with former adversaries(Bernstein et al. 1974; Dixson 1980; Goodall 1986: 75, 209, 336, 404, 410; Wingfield et al.

1990; Nelson 2005: 5078; Blanchard and Blanchard 2006: 2856; Simon and Lu 2006:222; Mehta and Josephs 2006; Fairbanks 2009: 16776).7

Under unstable conditions, serotonin levels decrease in group-living monkeys andapes in anticipation of aggression. Unlike testosterone, which, at natural levels, facili-tates assertiveness and controlled, strategic aggression aimed at achieving dominance,low levels of serotonin facilitate impulsive behaviour and sudden, uncontrolled aggres-sion. Experiments have demonstrated that rhesus monkeys with relatively low levels ofserotonin are more aggressive than others and that lowering the level of serotonin in anentire troop of vervet monkeys (by depleting the amount in the troops diet of trypto-phan, the compound from which serotonin is synthesized) dramatically increases theamount of spontaneous aggression among members of the troop (threatening, hitting,

7The relationship between testosterone and dominance or status-seeking behaviours may be mediated, however, by cortisol and

other stress-related hormones. Recent research suggests that a high level of testosterone may facilitate aggressive behaviour only if

the level of cortisol (i.e. stress) is low. If the level of cortisol is high, a high level of testosterone may impede aggression, by warning

a stressed individual (usually subordinate or oft-defeated) not to fight for status now that an intense struggle for status has broken

out in the group (Mehta and Josephs 2010). Furthermore, the relationship between high testosterone levels and competitive per-

formance may hold only for competition among individuals. Success in competition among groups may be facilitated by lower levels

of testosterone, since individuals with lower levels of testosterone are motivated to cooperate with others (Mehta et al. 2009). Re-

search into such subtleties has only begun. Note, however, that these new findings support the idea that aggression is a facultative

adaptation to life in unstable social groups or contested social hierarchies.


545


12/21

biting and chasing) (Chamberlain et al. 1987; Mehlman et al. 1994; Higley et al. 1996;Manuck et al. 2006: 749). Political instability and disruption of the social hierarchy havethe same effect, because they prime males for aggression by lowering their levels of se-rotonin. During periods of instability, when impulsive aggression can bring greatrewards, males who have the lowest levels of serotonin tend to rise to the top of thedominance hierarchy. But, during periods of political stability, when cooperativeness,political skill and calculated displays of aggression can bring the greatest rewards, males

with moderate levels of serotonin, who are neither impulsive nor passive, tend to rise tothe top (Fairbanks 2001; 2009: 17692; Fairbanks et al. 2004).

Research on nonhuman mammals has shown further that testosterone and serotoninmediate each others effect on aggression: a low level of testosterone inhibits aggressionin low-serotonin individuals and a high level of serotonin inhibits aggression in high-testosterone individuals. But, when testosterone levels are high and serotonin levels arelow, these inhibitory effects are neutralized and aggression is fully facilitated, becausethe areas of the brain that control aggression are rich in receptors for both hormones(Nelson 2005: 51215).

Because of the difficulty of measuring changes in hormones in uncontrived socialsituations, endocrinological research on humans is not as advanced as it is for nonhu-man primates and other mammals. It is not yet possible to say with certainty that politicalinstability and the disruption of social hierarchies trigger increases in testosterone anddecreases in serotonin in human males, which, in turn, facilitate aggression among un-related adults. There is substantial evidence, however, that testosterone levels increase inhuman males before and during competitive sporting events, that males with low baselevels of serotonin are more impulsive and prone to violence, and that lowering sero-tonin levels with a tryptophan-depleting beverage increases the likelihood of aggressionand retaliation in competitive computer games (Bjork et al. 1999; 2000; Dougherty 1999;Nelson 2005: 5089; Simon and Lu 2006: 222; Manuck et al. 2006: 7990).

Some studies suggest that humans, like many other mammals, can be habituated toaggression physiologically if they are subjected repeatedly to dominance challenges orthe threat of violence. For example, as Richard Nisbett and Dov Cohen discovered, when

young, affluent white men from the Souththe most violent and homicidal region inthe United Stateswalk down a hallway unimpeded, they behave no differently than

young, affluent white Northern men. But, when Southerners are bumped by a manwalking in the opposite direction, they behave differently. They feel insulted; they worryabout appearing weak and unmanly; they fantasize about taking revenge; and theirglands secrete larger quantities of testosterone and cortisol (a stress hormone)adaptive responses to the greater number of challenges and threats they face in theirdaily lives. Southern white men carry the violent history of the region with them wher-

ever they go. It is inscribed on their bodies, just as it is on the bodies of nonhumanmammals that have faced an unusual number of threats, challenges or attacks fromdominants, subordinates or peers (Nisbett and Cohen 1996: 4155; Miczek et al.2004; Nelson 2005: 5078; Blanchard and Blanchard 2006: 2826; Berton et al. 2006;Huhman 2006; Garcia-Segura 2009: 2278).

The neurological and endocrinological consequences of a loss of trust and empathy inprimate societies are not as well understood as the consequences of political instabilityor the disruption of social hierarchies, because trust and empathy are difficult to mea-sure, even in human societies. Evidence is accumulating, however, that humans are less

ROTH

546


13/21

aggressive and homicidal when they trust the government and their leaders and whenthey have a sense of kinship with others in their society or social group. For instance, thestrongest correlate of the homicide rate in the United States since the Second World Warhas been the proportion of Americans who say that they trust the government to do theright thing most of the time and who believe most public officials are honest (LaFree1998). That correlation has tracked separately for various social groups, particularlyblacks and white conservatives. In the last five decades, the black homicide victimizationrate peaked between 1971 and 1974, when black trust in government reached a post-Second World War low. The white homicide victimization rate peaked in 1980 during thefinal year of the Carter administration, when white trust in government reached its post-

war low because of accumulated anger over court-ordered busing to integrate schools,welfare, affirmative action, the American defeat in Vietnam and the seizure of Americanhostages in Iran. That rate7 per 100,000 white persons per yearwas, by itself, 315times the homicide rate in other affluent nations. But, as soon as Ronald Reagan and theRepublican Partythe champions of those angry whiteswon the White House and theSenate, the white homicide victimization rate fell (Roth 2009: 44866).

Why does faith in government have a profound impact on interpersonal violence?How people feel about the government plays an important role in determining howthey feel about themselves and society. If people believe that their government sharestheir values, speaks for them and acts on their behalf, they feel empowered, have greaterself-respect and gain confidence in their dealings with people outside their families.

When people feel that the government is antagonistic toward them and they questionits legitimacy, especially on the national level, they can feel frustrated, alienated anddishonoured. And those feelings, in turn, can stimulate the hostile, defensive and pred-atory feelings that lead to violence against friends, acquaintances and strangers.

The degree of empathy and fellow feeling among the members of a society also hasa powerful effect on the homicide rate. Nothing suppresses homicide within a social

group more powerfully than a sense of connectedness that extends beyond the boundsof family and neighbourhood and forges a strong bond among people who share race,ethnicity, religion or nationality. Consider, for instance, the inverse relationship betweenthe homicide rate among unrelated adults in the United States and the proportion ofnew counties named after national heroesBritish heroes in the colonial period and

American heroes in the national period. When that proportion was highan uncon-scious way of saying that Americans believed in their nation and in each otherthehomicide rate among unrelated adults was low. When that proportion dropped, the ho-micide rate soared (Roth 2009: 22, 778, 149, 157, 301, 387). Of course, solidarity isa double-edged sword: it can deter homicide within a group and at the same time incitehomicides among members of different social groups. When humans draw the bound-

ary between us and them in a way that excludes a substantial portion of the popu-lation, the potential for homicide is high. But, when humans draw the boundary in a waythat is encompassing and inclusive, the potential for homicide decreases.

It is as yet uncertain whether humans or nonhuman primates respond physiologicallyto social conditions that foster trust or empathy within their social groups in ways thatfacilitate cooperation and deter aggression. Perhaps there are neurological, endocrino-logical and behavioural consequences to living in social groups in which trust and fellowfeeling prevail and in groups in which they do not. Certainly, humans have evolveddefences that help them distinguish between people they can and cannot trust. Humans


547


14/21

recognize the faces of people they consider untrustworthy more rapidly and accuratelythan they recognize the faces of people they associate with other traits and they are hes-itant to enter relationships with individuals who are known to be manipulative. At thesame time, humans are primed to detect altruists who will be trustworthy partners insocial exchanges (Mealeyet al. 1996; Wilson et al. 1998; Brown and Moore 2000). Humanshave also evolved defences that enable them to determine with 170 millisecondsfasterthan they can thinkwhether an individual is a member of their own group or a strangeror potential adversary. These defences activate almost instantaneously the neural net-

works that tell us whether to approach, fight or flee, and whether to evaluate individualspositively or negatively (Ratner and Amodio 2009; Dickter and Gagnon 2009; Gutselland Inzlicht 2010). Related neural networks prompt us to respond with greater sympa-thy to the pain or distress of members of our own group (Xu et al. 2009; Yahya et al. 2009).

When humans are in the presence of individuals they trust or towards whom they havepositive feelings, they usually experience a surge in oxytocin, a neuropeptide that lowersblood pressure, reduces stress and anxiety, and facilitates social interaction (Sanchezet al. 2009: 31926; Neumann 2002; Kosfeld et al. 2005; Bartz and Hollander 2006;

Lim and Young 2006; Theodoridou et al. 2009). Higher levels of oxytocin increasethe willingness of individuals to trust and cooperate with other individuals, once theyhave had a chance to interact with them. Oxytocin is not indiscriminate: higher levels ofoxytocin impede trust and cooperation with anonymous others whose emotions cannotbe read. But, if social cues are available and if the incentives to cooperate are strong,oxytocin facilitates cooperation by reducing activity in the areas of the brain that governfear and stress and by activating the dopamine reward circuits that foster a sense of hap-piness and well-being (Declerck et al. 2010; Winslow et al. 2003; Heinrichs et al. 2003;Depue and Morrone-Strupinsky 2005; Kirsch et al. 2005; Baumgartner et al. 2008). Ifthese neural and endocrinological responses prove to be plasticif they become stron-ger after repeated interactions with trusted institutions and with people with whom we

feel a sense of kinshipthey would constitute a facilitative adaptation to life in cohesivesocial groups with legitimate institutions, just as a dampening of such responses wouldbe an adaptation to life in incoherent social groups with illegitimate institutions. Thoseadaptations would, in turn, facilitate tolerance and cooperation in cohesive groups anddefensive or hostile aggression within incoherent groupsthe pattern evident in homi-cide rates among unrelated adults.8

It will require many more years of research to understand the precise connectionsbetween the social circumstances that increase or decease homicide rates and the neu-rological and endocrinological mechanisms that facilitate or deter aggression. It is es-sential, however, that criminologists and social science historians continue their effortsto understand the deep patterns of homicide. As endocrinologist Randy Nelson points

out, scientists who study the neurology and endocrinology of animal behaviour havedeveloped sophisticated research tools, but they can only use those tools if there is a clearpattern of behaviour to be explained and if the function of the behaviour is known

8The neuropeptide vasopressin may play an opposite role in the same facultative adaptation. Vasopressin, which is released under

stressful and defensive circumstances and during periods of increased aggression, raises blood pressure, increases anxiety and

interacts with serotonin to facilitate aggression in malemale competition (Sanchez et al., 2009: 31931; Lim and Young 2006; Fair-

banks 2009: 1645, 169). If it were released in great amounts when trust and empathy declined within social groups, and if it had

a plastic effect on the neural and endocrinological mechanisms that facilitate aggression, it, too, could represent a facultative ad-

aptation to life in coherent or incoherent social groups.

ROTH

548


15/21

(Nelson 2005: 1221). If social scientists can improve our understanding of the patternsof homicide across time and space, neurologists, endocrinologists, primatologists andevolutionary biologists may be able to improve our understanding of the physiologicalcauses and consequences of violence.

Funding

The authors studies of homicide have received funding from the National ScienceFoundation, the National Endowment for the Humanities, the Harry Frank Guggen-heim Foundation, and the College of Humanities and the Criminal Justice ResearchCenter at Ohio State University.

References

Bartz, J. A. and Hollander, E. (2006), The Neuroscience of Affiliation: Forging Linksbetween Basic and Clinical Research on Neuropeptides and Social Behavior, Hormones

and Behavior, 50: 51828.Baumgartner, T., Heinrichs, M., Vonlanthen, A., Fischbacher, U. and Fehr, E. (2008),

Oxytocin Shapes the Neural Circuitry of Trust and Trust Adaptation in Humans, Neuron,58: 63950.

Bechtold, B. H. (2001), Infanticide in Nineteenth Century France: A Quantitative Inter-pretation, Review of Radical Political Economics, 33: 16587.

Behlmer, G. K. (1979), Deadly Motherhood: Infanticide and Medical Opinion in Mid-Victorian England, Journal of the History of Medicine and Allied Science, 34: 40327.

Berg, S. J. and Wynne-Edwards, K. E. (2001), Changes in Testosterone, Cortisol, and Es-tradiol Levels in Men Becoming Fathers, Mayo Clinic Proceedings, 76: 58292.

Bernstein, I. S., Rose, R. M. and Gordon, T. P. (1974), Behavioural and Environmental

Events Influencing Primate Testosterone Levels, Journal of Human Evolution, 3:51725.

Berton, O., McClung, C. A., Dileone, R. J., Krishnan, V., Renthal, W., Russo, S. J., Gra-

ham, D., Tsankova, N. M., Bolanos, C. A., Rios, M., Monteggia, L. M., Self, D. W. andNestler, E. J. (2006), Essential Role of BDNF in the Mesolimbic Dopamine Pathway inSocial Defeat Stress, Science, 311: 8648.

Bjork, J. M., Dougherty, D. M., Moeller, F. G. and Swann, A. C. (2000), DifferentialBehavioral Effects of Plasma Tryptophan Depletion and Loading in Aggressive and Non-aggressive Men, Neuropsychopharmacology, 22: 35769.

Bjork, J. M., Dougherty, D. M., Moeller, F. G., Cherek, D. R. and Swann, A. C. (1999),The Effects of Tryptophan Depletion and Loading on Laboratory

Aggression in Men: Time Course and a Food-Restricted Control, Psychopharmacology,142: 2430.

Blanchard, D. C. and Blanchard, R. J. (2006), Stress and Aggressive Behaviors, in R. J.Nelson, ed., Biology of Aggression. Oxford: Oxford University Press.

Boehm, C. (1999), Hierarchy in the Forest: The Evolution of Egalitarian Behavior. Cambridge:Harvard University Press.

Bourgeois-Pichat, J. (1965), The General Development of the Population of France sincethe Eighteenth Century, in D. V. Glass and D. E. C. Eversley, eds, Population in History:

Essays in Historical Demography. Chicago: Aldine.


549


16/21

Briggs, C. M. and Cutright, P. (1994), Structural and Cultural Determinants of ChildHomicide: A Cross-National Analysis, Violence and Victims, 9: 316.

Brouardel, P. (1897), LInfanticide [Infanticide]. Paris: Bailliere.Brown, W. M. and Moore, C. (2000), Is Prospective Altruist-Detection an Evolved So-

lution to the Adaptive Problem of Subtle Cheating in Cooperative Ventures? Support-ive Evidence Using the Wason Selection Task, Evolution and Human Behavior, 21:2538.

Chamberlain, B., Ervin, F. R., Pihl, R. O. and Young, S. N. (1987), The Effect of Raisingor Lowering Tryptophan Levels on Aggression in Vervet Monkeys, Pharmacology, Biochem-istry, and Behavior, 28: 50310.

Chesnais, J.-C. (1982), Historie de la Violence en Occident de 1800 a` nos Jours[History of Violencein the West from 1800 to the Present Day], rev. ed. Paris: Robert Laffont.

Cott, N. F. (1977), The Bonds of Womanhood: Womens Sphere in New England, 17801835. NewHaven: Yale University Press.

de Waal, F. (2005), Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are.New York: Riverhead Books.

Declerck, C. H., Boone, C. and Kiyonari, T. (2010), Oxytocin and Cooperation underConditions of Uncertainty: The Modulating Role of Incentives and Social Information,Hormones and Behavior, 57: 36874.

Depue, R. A. and Morrone-Strupinsky, J. V. (2005), A Neurobehavioral Model of Affili-ative Bonding: Implications for Conceptualizing a Human Trait of Affiliation, Behavioraland Brain Science, 28: 31395.

Dickter, C. L. and Gagnon, K. T. (2009), Early ERP Negativity during Categorization asEvidence for Perceiver Awareness of Multiple Social Categories, presentation to the So-cial and Affective Neuroscience Society, New York City.

Dixson, A. F. (1980), Androgens and Aggressive Behavior in Primates: A Review, AggressiveBehavior, 6: 3767.

Dougherty, D. M., Bjork, J. M., Marsh, D. M. and Moeller, F. G. (1999), Influence ofTrait Hostility on Tryptophan Depletion-Induced Laboratory Aggression, Psychiatry Re-search, 88: 22732.

Dublin, T. (1979), Women at Work: The Transformation of Work and Community in Lowell, Mas-sachusetts, 18261860. New York: Columbia University Press.

Eisner, M. (2001), Modernization, Self-Control, and Lethal Violence: The Long-TermDynamics of European Homicide Rates in Theoretical Perspective, British Journal of Criminology, 41: 61838.

Fairbanks, L. A. (2001), Individual Differences in Response to a Stranger: Social Impul-sivity as a Dimension of Temperament in Vervet Monkeys,Journal of Comparative Psychology,115: 228.

Fairbanks, L. A. (2009), Hormonal and Neurochemical Influences on Aggression inGroup-Living Monkeys, in P. T. Ellison and P. B. Gray, eds, Endocrinology of Social Relation-ships. Cambridge: Harvard University Press.

Fairbanks, L. A., Jorgensen, M. J., Huff, A., Blau, K., Hung, Y.-Y. and Mann, J. J. (2004),Adolescent Impulsivity Predicts Adult Male Dominance Attainment in Male Vervet Mon-keys, American Journal of Primatology, 64: 117.

Faust, D. G. (1996), Mothers of Invention: Women of the Slaveholding South in the American CivilWar. Chapel Hill: University of North Carolina Press.

ROTH

550


17/21

Feldman, R., Gordon, I., Schneiderman, I., Weisman, O. and Zagoory-Sharon, O.(2010), Natural Variations in Maternal and Paternal Care Are Associated with SystematicChanges in Oxytocin Following ParentInfant Contact, Psychoneuroendocrinology, 35:113341.

Fiala, R. and LaFree, G. (1988), Cross-National Determinants of Child Homicide, Amer-ican Sociological Review, 53: 43245.

Fleming, A. S. and Gonzalez, A. (2009), Neurobiology of Human Maternal Care, in P. T.Ellison and P. B. Gray, eds, Endocrinology of Social Relationships. Cambridge: Harvard Uni-

versity Press.Fuchs, R. G. (1984), Abandoned Children: Foundlings and Child Welfare in Nineteenth-Century

France. Albany: State University of New York Press.Garcia-Segura, L. M. (2009), Hormones and Brain Plasticity. Oxford: Oxford University

Press.Gartner, R. (1990), The Victims of Homicide: A Temporal and Cross-National Compar-

ison, American Sociological Review, 55: 92106.Gartner, R. (1991), Family Structure, Welfare Spending, and Child Homicide in Devel-

oped Democracies, Journal of Marriage and Family, 53: 23140.Gilmore-Lehne, W. J. (1989), Reading Becomes a Necessity of Life: Material and Cultural Life in

Rural New England, 17801835. Knoxville: University of Tennessee Press.Goodall, J. (1986), The Chimpanzees of Gombe: Patterns of Behavior. Cambridge: The Belknap

Press of Harvard University Press.Gould, R. V. (2003), Collision of Wills: How Ambiguity about Social Rank Breeds Conflict.Chicago:

University of Chicago Press.Graff, H. J. (1987), The Legacies of Literacy: Continuities and Contradictions in Western Culture

and Society. Bloomington: Indiana University Press.Gray, P. B. and Campbell, B. C. (2009), Human Male Testosterone, Pair-Bonding, and

Fatherhood, in P. T. Ellison and P. B. Gray, eds, Endocrinology of Social Relationships. Cam-

bridge: Harvard University Press.Gray, P. B., Yang, C. J. and Pope, H. G. Jr. (2006), Fathers Have Lower Salivary Testoster-

one Levels than Unmarried Men and Married Non-Fathers in Beijing, China, Proceedingsof the Royal Society of Biological Sciences, 273: 3339.

Green, E. C. (1999), Infanticide and Infant Abandonment in the New South: Richmond,Virginia, 18651915, Journal of Family History, 24: 187211.

Gutsell, J. N. and Inzlicht, M. (2010), The Closed Circle of Empathy: Outgroups Do NotActivate the Neural Networks for Empathy, Journal of Experimental Social Psychology, 46:8415.

Hagen, E. H. and Barrett, H. C. (2007), Perinatal Sadness among Shuar Women, MedicalAnthropology Quarterly, 21: 2240.

Heinrichs, M., Baumgartner, T., Kirschbaum, C. and Ehlert, U. (2003), Social Supportand Oxytocin Interact to Suppress Cortisol and Subjective Responses to PsychosocialStress, Biological Psychiatry, 54: 138998.

Hewitt, N. A. (1984), Womens Activism and Social Change: Rochester, New York, 18221872.Ithaca: Cornell University Press.

Higginbotham, A. R. (1985), The Unmarried Mother and Her Child in Victorian London,18341914, Ph.D. thesis. Indiana University.


551


18/21

Higley, J. D., Mehlman, P. T., Poland, R. E., Taub, D. M., Vickers, J., Suomi, S. J. andLinnoila, M. (1996), CSF Testosterone and 5-HIAA Correlate with Different Types of

Aggressive Behaviors, Biological Psychiatry, 40: 106782.Hrdy, S. B. (1999), Mother Nature: Maternal Instincts and How They Shape the Human Species.

New York: Ballantine Books.Hrdy, S. B. (2009), Mothers and Others: The Evolutionary Origins of Mutual Understanding.

Cambridge: The Belknap Press of Harvard University Press.Huhman, K. L. (2006), Social Conflict Models: Can They Inform Us about Human Psycho-

pathology?, Hormones and Behavior, 50: 6406.Hunnicutt, G. and LaFree, G. (2008), Reassessing the Structural Covariates of Cross-

National Infant Homicide Victimization, Homicide Studies, 12: 4666.Jones, H. R. (1894), The Perils and Protection of Infant Life, Journal of the Royal Statistical

Society, March: 1103.Kirsch, P., Esslinger, C., Chen, Q., Mier, D., Lis, S., Siddhanti, S., Gruppe, H., Mattay,

V. S., Gallhofer, B. and Meyer-Lindenberg, A. (2005), Oxytocin Modulates NeuralCircuitry for Social Cognition and Fear in Humans, Journal of Neuroscience, 25: 1148993.

Konner, M. (2009), The Evolution of Childhood: Relationships, Emotion, and Mind. Cambridge:The Belknap Press of Harvard University Press.

Kosfeld, M., Heinrichs, M., Zak, P. J., Fischbacher, U. and Fehr, E. (2005), OxytocinIncreases Trust in Humans, Nature, 435: 6736.

LaFree, G. (1998), Losing Legitimacy: Street Crime and the Decline of Social Institutions. Boulder:Westview.

Lalou, R. (1986), Linfanticide Devant les Tribunaux Francxais, 18251910 [Infanticide inthe French Courts], Communications: Denatalite Lanteriorite Devant les Tribunaux Francxais,1800 1914[Communications: The Birth Rate Anticipation before the French Courts, 18001914].Paris: Ecole des Hautes Etudes en Sciences Sociales, Seuil, v. 44.

Lim, M. M. and Young, L. J. (2006), Neuropeptidergic Regulation of Affiliative Behavior

and Social Bonding in Animals, Hormones and Behavior, 50: 50617.Lystra, K. (1989), Searching the Heart: Women, Men, and Romantic Love in Nineteenth-Century

America. New York: Oxford University Press.Manuck, S. B., Kaplan, J. R. and Lotrich, F. E. (2006), Brain Serotonin and Aggressive

Disposition in Humans and Nonhuman Primates, in R. J. Nelson, ed., Biology of Aggression.Oxford: Oxford University Press.

Mealey, L., Daood, C. and Krage, M. (1996), Enhanced Memory for Faces of Cheaters,Evolution and Human Behavior, 17: 11928.

Mehlman, P. T., Higley, J. D., Faucher, I., Lilly, A. A., Taub, D. M., Vickers, J., Suomi,

S. J. and Linnoila, M. (1994), Low CSF 5-HIAA Concentrations and Severe Aggressionand Impaired Impulse Control in Nonhuman Primates, American Journal of Psychiatry,151:

148591.Mehta, P. H. and Josephs, R. A. (2006), Testosterone Changes after Losing Predicts the

Decision to Compete Again, Hormones and Behavior, 50: 68492. (2010), Testosterone and Cortisol Jointly Regulate Dominance: Evidence for a Dual-

Hormone Hypothesis, Hormones and Behavior, 58: 898906.Mehta, P. H., Wuerhmann, E. V. and Josephs, R. A. (2009), When Are Low Levels of Tes-

tosterone Advantageous? The Moderating Role of Individual versus Group Competition,Hormones and Behavior, 56: 15862.

ROTH

552


19/21

Miczek, K. A., Covington, H. E., Nikulina, E. A. and Hammer, R. P. (2004), Aggressionand Defeat: Persistent Effects on Cocaine Self-Administration and Gene Expression inPeptidergic and Aminergic Mesocorticolimbic Circuits, Neuroscience and BiobehavioralReviews, 27: 7887902.

Miller, L. J. (2002), Postpartum Depression,Journal of the American Medical Association, 287:7625.

Mitchell, B. R. (1988), British Historical Statistics. Cambridge: Cambridge University Press.Mohr, J. C. (1978), Abortion in America: The Origins and Evolution of a National Policy, 1800

1900. New York: Oxford University Press.Monholland, C. S. (1989), Infanticide in Victorian England, 18561878: Thirty Legal

Cases, M.A. thesis. Rice University.Naber, F., van Ijzendoorn, M. H., Deschamps, P., van Engeland, H. and Bakermans-

Kranenburg, M. J. (2010), Intranasal Oxytocin Increases Fathers Observed Responsive-ness during Play with their Children: A Double-Blind Within-Subject Experiment, Psycho-neuroendocrinology, 35: 15836.

Nelson, R. J. (2005), An Introduction to Behavioral Endocrinology. 3rd edn. Sunderland:

Sinauer Associates.Nepomnaschy, P. A. and Flinn, M. (2009), Early Life Influences on the Ontogeny of the

Neuroendocrine Stress Response in the Human Child, in P. T. Ellison and P. B. Gray, eds,Endocrinology of Social Relationships. Cambridge: Harvard University Press.

Nepomnaschy, P. A., Welch, K. B., McConnell, D. S., Low, B. S., Strassmann, B. I. andEngland, B. G. (2006), Cortisol Levels and Very Early Pregnancy Loss in Humans, Pro-ceedings of the National Academy of Sciences, USA, 103: 393842.

Nepomnaschy, P. A., Welch, K. B., McConnell, D. S., Strassmann, B. I. and England, B.G. (2004), Stress and Female Reproductive Function: A Study of Daily Variations in Cor-tisol, Gonadotrophins, and Gonadal Steroids in a Rural Mayan Population, American Jour-nal of Human Biology, 16: 52332.

Neumann, I. D. (2002), Involvement of the Brain Oxytocin System in Stress Coping: Inter-actions with the HypothalamoPituitaryAdrenal Axis, Progress in Brain Research, 139:14762.

Nisbett, R. E. and Cohen, D. (1996), Culture of Honor: The Psychology of Violence in the South.Boulder: Westview Press.

Numan, M., Fleming, A. S. and Levy, F. (2006), Maternal Behavior, in J. D. Neill, ed.,Knobil and Neills Physiology of Reproduction. 3rd edn., San Diego: Elsevier.

Penn, D. J. and Smith, K. R. (2007), Differential Fitness Costs of Reproduction between theSexes, Proceedings of the National Academy of Sciences, USA, 104: 5538.

Rafter, N. (2008), The Criminal Brain: Understanding Biological Theories of Crime. New York:New York University Press.

Ratner, K. G. and Amodio, D. M. (2009), Responses to Faces Predict Implicit In-GroupFavoritism: Evidence from a Minimal Group Study, presentation to the Social and Affec-tive Neuroscience Society, New York City.

Rose, L. (1986), The Massacre of the Innocents: Infanticide in Britain, 18001939. London:Routledge and Kegan Paul.

Roth, R. (2001 a), Child Murder in New England, Social Science History, 25: 10147. (2001 b), Homicide in Early Modern England, 1549-1800: The Need for a Quanti-

tative Synthesis, Crime, History, and Societies, 5: 3367.


553


20/21

(2009), American Homicide. Cambridge: The Belknap Press of Harvard UniversityPress.

Rothman, E. K. (1984), Hands and Hearts: A History of Courtship in America. New York: BasicBooks.

Ryan, M. P. (1981), Cradle of the Middle Class: The Family in Oneida County, New York,17901865. New York: Cambridge University Press.

Sanchez, R., Parkin, J. C., Chen, J. Y. and Gray, P. B. (2009), Oxytocin, Vasopressin, andHuman Social Behavior, in P. T. Ellison and P. B. Gray, eds, Endocrinology of Social Relation-ships. Cambridge: Harvard University Press.

Sauer, R. (1978), Infanticide and Abortion in Nineteenth Century Britain, Population Stud-ies, 32: 8194.

Schradin, C. (2007), Letter to the Editor: Comments to K.E. Wynne-Edwards andM.E. Timonin 2007, Hormones and Behavior, 52: 5579.

Seeley, T. D. (1985), Honeybee Ecology: A Study of Adaptation in Social Life. Princeton: PrincetonUniversity Press.

Seeley, T. D. (1995), The Wisdom of the Hive: The Social Physiology of Honey Bee Colonies.

Cambridge: Harvard University Press.Simon, N. G. and Lu, S.-F. (2006), Androgens and Aggression, in R. J. Nelson, ed., Biology of

Aggression. Oxford: Oxford University Press.Smail, D. L. (2008), Deep History and the Brain. Berkeley: University of California Press.Sober, E. and Wilson, D. S. (1998), Unto Others: The Evolution and Psychology of Unselfish Be-

havior. Cambridge: Harvard University Press.Sorenson, S. B., Wiebe, D. J. and Berk, R. A. (2002), Legalized Abortion and the Homicide

of Young Children: An Empirical Investigation, Analyses of Social Issues and Public Policy, 2:23956.

Stansell, C. (1986), City of Women: Sex and Class in New York, 17891860. New York: Alfred A.Knopf.

Theodoridou, A., Rowe, A. C., Penton-Voak, I. S. and Rogers, P. J. (2009), Oxytocin andSocial Perception: Oxytocin Increases Perceived Facial Trustworthiness and Attractive-ness, Hormones and Behavior, 56: 12832.

Tomasello, M. (2009), Why We Cooperate. Cambridge: MIT Press.Xu, X., Zuo, X., Wang, X. and Han, S. (2009), Do You Feel My Pain? Racial Group Member-

ship Modulates Empathic Neural Responses, Journal of Neuroscience, 29: 85259.Walsh, A. (2009), Biology and Criminology: The Biosocial Synthesis. New York: Routledge.Wile, J. and Arechiga, M. (1999), Sociocultural Aspects of Postpartum Depression, in

L. Miller, ed., Postpartum Mood Disorders. Washington, DC: American Psychiatric Press.Wilson, D. S., Near, D. C. and Miller, R. R. (1998), Individual Differences in Machiavel-

lianism as a Mix of Cooperative and Exploitative Strategies,Evolution and Human Behavior,

19: 20312.Wilson, M. and Daly, M. (1988), Homicide: Foundations of Human Behavior. Piscataway, NJ:

Aldine Transaction.Wingfield, J. C., Hegner, R. E., Dufty, A. M. and Ball, G. F. (1990), The Challenge

Hypothesis: Theoretical Implications for Patterns of Testosterone Secretion, Mating Sys-tems, and Breeding Strategies, American Naturalist, 136: 82946.

Winslow, J. T., Noble, P. L., Lyons, C. K., Sterk, S. M. and Insel, T. R. (2003), RearingEffects on Cerebrospinal Fluid Oxytocin Concentration and Social Buffering in RhesusMonkeys, Neuropsychopharmacology, 28: 91018.

ROTH

554


21/21

Wrigley, E. A., Davies, R. S., Oeppen, J. E. and Schofield, R. S. (1997), English PopulationHistory from Family Reconstitution, 1580 1837. New York: Cambridge University Press.

Wynne-Edwards, K. E. (2001), Hormonal Changes in Mammalian Fathers, Hormones andBehavior, 40: 13945.

(2007), Reply to Schardins Letter to the Editor, Hormones and Behavior, 52: 560.Wynne-Edwards, K. E. and Timonin, M. E. (2007), Parental Care in Rodents: Weakening

Support for Hormonal Regulation of the Transition to Behavioral Fatherhood in RodentAnimal Models of Biparental Care, Hormones and Behavior, 52: 11421.

Yahya, R., Suleiman, R., Tsoory, S. S., Decety, J. and Pery, D. (2009), How Do We Per-ceive the Pain of In-Group and Out-Group Members? Implicit vs. Explicit Processing,presentation to the Social and Affective Neuroscience Society, New York City.

Ziegler, T. E. and Snowdon, C. T. (2009), The Endocrinology of Family Relationships inBiparental Monkeys, in P. T. Ellison and P. B. Gray, eds, Endocrinology of Social Relationships.Cambridge: Harvard University Press.


555

Biology and the Deep History of Homicide

Documents

Transcript of Biology and the Deep History of Homicide