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The Biology of Love and Hate

by Sally Mayasich, June 29, 2008

When we talk of love and hate we are speaking of feelings that are not only a hair's breadth from each other, but hang on that metaphysically sliding scale between instinct and reason.  In other words, our strong positive and negative passions and how we act on them are what has been considered a nature-nurture debate.

In 1977, Edward O. Wilson, a naturalist who had been studying social animals, especially ants, had a bucket of cold water dumped on him because of his ideas that human behavior may be based in our biological make-up.1 The protestors were people who considered themselves to be fighting against racism, fearing Wilson's ideas might lead to renewed belief in old stereotypes.  They feared also that his theories would become an excuse for eugenics or even genocide; if people believed that undesirable traits were unchangeable, then they would feel justified in removing the carriers of these traits from the human gene pool, thus improving society.

This was not Wilson's intent, just like it was not Charles Darwin's intent for people to twist his ideas about survival of the fittest into Social Darwinism.  However, it is ironic to talk about the intent of someone who believes that our behavior is based on instinct rather than free will. 
And when we talk about instinct versus free will and inherited versus learned behaviors we are talking about evolution, and inevitably, religion and God's part in human behavior.
Many Judeo-Christian religious leaders dispute atheists claims that people can be moral and ethical, that we can love our neighbors, without the threat of punishment in the afterlife.  But according to three major biological and social scientist schools of thought, it is not only theoretically possible but demonstrable in our present society.  Theoretically, many atheistic psychologists and philosophers have believed that people would be ethical and moral as a philosophical standard, because it is "the right thing to do," and also because we reason that treating others ethically will result in their "rewarding" us with reciprocal ethical treatment.

In practice, from our life experiences, it doesn't always work that way, but we know over time and many dealings, that ethical treatment is reciprocated more often than not, and hurting someone is also likely to result in them hurting you back.  Social scientists have believed that we start out as blank slates, and human behavior comes from social learning throughout one's lifetime rather than instincts.  However, evolutionary psychologists and sociobiologists believe that these experiences over the millennia have evolved into behaviors hard-wired into our brains.2 They say it would be highly unlikely for society to break down because our ethical behavior is an inborn trait that we can't easily override.  We love because our brains and bodies tell us to.  On the flip side, the same is true for hate.  Sociobiologists believe we feel hatred and act aggressively because of millennia of having to defend our own social group against other social groups competing for the same resources.3 This is where loving and hateful acts are really tied closely together.  A tribesman would hate a member of another tribe for threatening the mate or offspring that he loved, and would act aggressively out of both of those feelings.

One finds in reading the literature that not only are the proponents of these various disciplines in radical personal disagreement, but also that there are contradictions within each school of thought.

At least 85% of the world's people believe in God, or a higher power or powers than human beings.4  These 85% are divided into various religions with differing views and differing texts, these texts (including the Bible) containing vastly contradictory passages about love and hate.  Four major genocides in the Bible were ordered or managed by God, who also tells us we must love our neighbor as ourselves. 

Quoting from Deuteronomy chapter 7, verses 1 and 2, "When the Lord your God brings you into the land you are entering to possess and drives out before you many nations...then you must destroy them totally. Make no treaty with them and show them no mercy." When we were acting as entire societies, such as America pursuing Manifest Destiny in the 1800's wiping out Native Americans, or Germany pursuing lebensraum (living space) in the 1930's and 40's wiping out various "undesirable" people (Jews, Slavic people, gypsies and homosexuals among them), this Bible passage was considered a reasonable permission.  But there had to be a lot of hate in order for people to carry out the associated atrocities.
Since we can, and have, as larger societies, made treaties, ended wars, and become friends with our former enemies, it could be said that we were following those other passages about being good, merciful and loving.  Or maybe we realized hate had begotten hate and we were all at risk for pain, suffering and death when we acted on these emotions.
By the same token as for religious excuses, there were plenty of holocausts perpetrated by atheists like Joseph Stalin and Mao Zedong, who sought political gain and to control thought and culture.  And large numbers of people considered eugenics and social Darwinism to be reasonable and supported by scientific theory.  The survival of the fittest was interpreted, mostly by non-scientists, to mean that it was proper for the intelligent, clever industrialists to monopolize resources, thereby leaving the "unfit" to die of disease and starvation.  Eugenics was more altruistically intended by some in the U.S., including Minnesota's Charles Fremont Dight, a medical doctor who considered it scientifically-supported social justice to control the reproduction of the mentally defective, diseased and criminal.5

Konrad Lorenz,6 E.O. Wilson, and several other scientists have tried to find the answers to the questions of behavior with empirical evidence, by studying social animals in nature.  Wilson had been observing programmed behavior in ants since he was a boy growing up in Alabama, and when he became a Harvard professor in 1956, he took on a graduate student who wanted to study the social behavior of rhesus monkeys.  Not only was primate social research virtually unknown at that time, but the idea of comparing data on behavior between such widely different species had never been done before.  Wilson started to realize that behaviors were at least connected among species, if not sharing the same biological origin.  So in 1975 when he published Sociobiology: The New Synthesis, he reasoned that the innateness of these behaviors, as seen in other animals, extended to humans, we being animals ourselves, and having been subject to earthly environmental influences just like the other species.  That was what got protestors dumping ice water on his head, and telling him he was "all wet". 

The next step was to provide empirical evidence that human emotions and the behaviors they spawn evolved through the physiological structures and chemistry of our brains.  The big questions that actually led these naturalists down the road to finding molecular clues to the origins of behavior were the questions of altruism, sex, and aggression. 

It had been the contention of the "blank-slate" sociologists that aggressiveness and violence were only a learned behavior.  Theoretically, though, emotions leading to aggression were relatively easy for Lorenz, Wilson, and other sociobiologists to connect biologically to survival and reproductive value. Aggression toward rivals would insure reproductive rights and be useful in killing prey and protecting offspring.    Therefore, aggressive behaviors based on reactions of fear of and hatred toward people outside of one's own social group would be genetically self-perpetuating.
Some aggression can be explained by the "fight or flight" response, in an area of the brain called the hypothalamus.  A sequence of nerve cell firing and chemical release, which may include hormones like adrenaline, prepares our body for running or fighting.  Other hormones like the male sex hormone testosterone have also been implicated in aggressive behavior.  Although we don't act aggressively all the time, and some people appear to be completely peaceful, the predisposition for aggression can be triggered in groups, from small tribes to large nations, by factors such as a response to population density, which goes back to territoriality and protecting those precious reproductive and survival resources. 

But the reason for the existence of altruism--the willingness to sacrifice oneself for the good of others--is harder intuitively to connect to an evolved genetic basis.  Why would I jump in front of a train to save someone I don't know, and risk losing the opportunity to pass my genes on to the next generation?  That would mean, in early society, that altruist genes would be less and less prevalent in the population.  The 1964 work of William Hamilton proposed that the all-female workers of certain ant species would sacrifice themselves for each other because they were closely-genetically-related sisters.7  Even if an individual died, her sister would pass on virtually the same set of genes to the next generation.  With some modification, Wilson incorporated this theory, known as kin selection, into his sociobiology synthesis as applied to humans.  In his follow-up book called On Human Nature in 1978 he discusses altruism as having evolved in the small hunter-gatherer tribal units when all members were closely related.8 It has extended beyond kin to our friends, fellow soldiers, and sometimes even strangers, through hypertrophy, the "overgrowth" of the basic hunter-gatherer social response into a more elaborate and complex social construction through thousands of years of cultural evolution.  Again, this response we think of as a form of love of our fellow man occurs in the same part of our brain as hate and aggressive behaviors.

The biological reason for sex itself is obviously reproductive.  But sexual reproduction is much less energy efficient than asexual reproduction, like the fast-dividing cells of bacteria.  The advantage of sexual reproduction is the creation of more diverse sets of offspring, with different traits that might allow survival of at least some of the offspring under sudden changes in the environment.   But even so, most sexual species can produce thousands of diverse offspring without all the effort of roses and boxes of chocolates.  We all know there is much more to a relationship that includes sex than just reproduction.  Wilson reasons that our elaborate courtship rituals are much more important in promoting strong pair-bonding, thus insuring family cohesiveness and survival of the offspring, again through the intra-group love and outsider hate responses.   

Chemistry in our brains and bodies might draw us to a potential partner, but consider the fact that animals and even early humans didn't even make the connection between the sex act and the appearance down the line of a new baby.  So people just acted on their feelings.  Then religion and cultural constraints on sexual practices evolved.  Religious teachings and leaders have contended that there is no moral justification for any sex act that does not have the production of children as its primary goal.

This leads to another conundrum of a trait that should presumably die out due to lack of reproduction--homosexuality. This, religious leaders and sociologists have explained, is because it is a chosen deviant behavior that is not natural.  However, scientists have shown homosexuality to be prevalent in the animal world.  Bruce Bagemihl's 1999 book, Biological Exuberance: Animal Homosexuality and Natural Diversity is a comprehensive collection of studies documenting homosexuality and bisexuality in over 300 mammal and bird species.9  In animal societies, sexual bonds may create leadership alliances that promote survival within the group and for the group as a whole.  Wilson points to the likelihood of kin selection as the mode for homosexuality genes being passed to successive generations.  There might be a selective advantage for the group, again back to the hunter-gatherers, in having members who forgo their own reproduction to help care for the children of close relatives.  But I think, that because homosexuals do not physiologically differ from heterosexuals in capability for reproduction, and with the concomitant evolution of cultural and social pressures to marry and have children, homosexuals have likely reproduced almost as much as heterosexuals.  Also, women, whether lesbian or straight in orientation, were controlled as reproductive resources in early societies, usually forced to mate without any choice in the matter.  So genes for homosexuality could have been passed mostly by women.
Maybe, as Bagemihl seems to indicate, homosexuality is just another form of natural diversity that may carry with it other survival traits that will be useful when the environmental need arises.  Even proven as a natural behavior however, detractors would say that hate and aggression are natural behaviors as well.  If we must learn to curb our innate aggression, then we could--some say should--also learn to limit our sexual practices to only heterosexual reproduction.  But that might actually detract from the beneficial value of pair bonding that has been observed in humans and animals to work the same for all orientations. The premier difference in these natural behaviors is that hate and violent aggression cause harm, and homosexual relationships between consenting adults, in the same settings considered acceptable for heterosexual relationships, do no harm to either individuals or society.  So why would some people hate or fear gays and lesbians?
It is likely according to the theories of evolution for the basic emotions and behaviors of hate and aggression, that homophobia exists as part of the same response to those different from oneself as racism, ethnic hatred, and even violence against the disabled.  Hate crimes are defined as those committed due to the offender's bias against a race, religion, ethnicity, sexual orientation, or disability. Certainly based on skin color, no harm is done by a particular race, and attacks on disabled people are evidence that the hate is from the realm of unreasoning, innate primal fear, since disabled people may have little capacity to do actual harm.

Hate crimes overwhelmingly--consistently 80-85% of violent hate crimes--are committed by young adult males.10  Biologically, young males would have been the members of the early tribes who were expected to react and defend the rest of the tribe, to hunt and kill prey, and to be primarily responsible for procreation.  The rules of society have changed, but our brains have changed very little since the Stone Age. 

What seems to make a difference at both small group and large social levels is leadership, from the parental level to teachers, coaches, clergy, and presidents.  According to Centers for Disease Control statistics, parental involvement is the single largest factor in preventing youth violence.11

Wilson and evolutionary psychologists don't think our species will evolve further. But our intellect, our ability to think and reason, is already highly evolved. It is the quintessential override button to bypass our primal fear and hate reactions--all we have to do is use it to continue to be curious (that's natural too) in divining the truths of our natural world.  Maybe we don't have a choice in feeling love or hate, but we do appear to be able to choose how we act on these feelings.  With experience, knowledge and wise advice we can act positively, on the side of love.

References

  1. Wilson, E.O., Naturalist, Island Press, 1994.  (Also see PBS.org, Nova, "Lord of the Ants", http://www.pbs.org/wgbh/nova/eowilson/
  2. Evolutionary Psychology: A Primer, Leda Cosmides & John Tooby, Center for Evolutionary Psychology, University of California at Santa Barbara, 1997 http://www.psych.ucsb.edu/research/cep/primer.html
  3. Wilson, E.O., Sociobiology: The New Synthesis, Cambridge, MA: Harvard University Press, 1975.
  4. http://www.religioustolerance.org/worldrel.htm
  5. Phelps, Gary, "The eugenics Crusade of Charles Fremont Dight", Minnesota History 49:3 (Fall, 1984).
  6. Lorenz, Konrad, 1963, Das sogenannte Böse. Wien: Borotha-Schoeler. (German original edition).On Aggression, (English translation) A Harvest Book, New York: Harcourt Brace Jovanovich, 1966, 1974.
  7. Wilson, Naturalist
  8. Wilson, E.O., On Human Nature, Cambridge, MA: Harvard University Press, 1978.
  9. Bagemihl, Bruce, Biological Exuberance: Animal Homosexuality and Natural Diversity, New York: St. Martin's Press, 1999.
  10. Department of Justice, Federal Bureau of Investigation, "Crime in the United States", annual publications, 1995-2007, http://www.fbi.gov/ucr/ucr.htm
  11. Centers for Disease Control, "Youth Violence Prevention," 2008, http://www.cdc.gov/ncipc/dvp/YVP/default.htm

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