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April 4, 2013 Volume 34, No. 25

Influential evolutionary psychologist joins MU’s anthropology department

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HUMAN BEHAVIOR Martin Daly, a distinguished research professor in the Department of Anthropology, is working on a book that examines the link between economic inequality and violence. In 1998, Daly became a fellow of the Royal Society of Canada. Photo by Rachel Coward.


Homo sapiens are hard-wired to favor blood relatives over friends and strangers, researcher says

People sacrifice time and money to raise their children. They also help their nieces, nephews, brothers and sisters, though to a less extent.  

Sometimes people help friends, but strangers are pretty much out of luck. Compared by degree to what people do for their offspring, their help toward strangers is nominal. 

“Blood really is thicker than water,” Professor Martin Daly said.

Diminished affection toward people outside one’s family tree was the provocative theme of Daly’s talk March 16 at MU’s three-day Life Sciences & Society Symposium. This year’s symposium examined kinship and its connection to evolutionary biology and psychology. 

In his talk, Daly argued that the “favoritism” Homo sapiens show toward kin has evolutionary roots. 

Daly joined the MU anthropology department last November after retiring in 2011 as professor emeritus of psychology, neuroscience and behavior at McMaster University in Ontario, Canada. As a distinguished research professor, he teaches one course a year, advises students and performs research. In 1998, Daly was named a fellow of the Royal Society of Canada.

With the recent hiring of him and Napoleon A. Chagnon, an anthropologist famous for his research of the Amazon tribe the Yanomamö, the department is poised to be a leader in evolutionary anthropology. 

 “The quality of MU’s faculty is reaching new levels, and that is translating into attracting even more top scientists to our campus,” Provost Brian Foster said.  “Through these new faculty, our students will be exposed to some of the world’s greatest minds.”

Daly said he was drawn to MU because of the department’s emphasis not only in cultural anthropology, but also behavioral endocrinology (the study of hormones), developmental psychology and evolutionary theory. He’s currently researching the link between economic inequality and homicide rates.

The Canadian has been a leader in evolutionary psychology for decades, with a particular interest in kinship studies. His 1988 book, Homicide, written with his late wife, Margo Wilson, debunked the notion that people are more likely to kill relatives than strangers. Another well-received work by the writing team was The Truth About Cinderella: A Darwinian View of Parental Love, published in 1998. 

Known as the Cinderella Effect, the idea is that parents are at risk to showing bias against stepchildren, probably, Daly said, because they are not the children’s biological parents. “In a stepfather household, kids are far less able to get economic support for college,” Daly told an audience of scholars, students and the curious in Jesse Auditorium. “In a stepmother household, less money is spent on them, such as for dental care.”

But it gets worse. Stepchildren from birth to age 5 are at risk of being killed by their stepparents. In the national homicides archive in Canada from 1974 to 1990, stepfathers killed children in this age group at a per capita rate that’s 120 times higher than those killed by biological fathers. 

Sitting in his office in Swallow Hall, his feet propped on a chair, Daly said there’s utility to his research. “I lean toward the view, which is possibly naïve, that getting better information about anything that is a social problem improves the likelihood something can be done with it to help people.”

Daly embraces the late evolutionary biologist W.D. Hamilton’s inclusive fitness theory, formulated in 1964. In Darwinian thought, an organism’s fitness is how many offspring it creates through mating. Expanding on this, Hamilton showed mathematically that an organism preserves its genes for the next generation through kin relations. 

For example, a brother and sister share half their genes, and if the sister has a baby, the brother indirectly accomplishes Darwin’s imperative. 

Gene sharing creates favoritism; the brother might help his sister secure a well-paying job, or contribute to the child’s college fund. Chances are the brother won’t do either for a friend or stranger, though there are exceptions. 

The brother is unconscious of his primordial motivations, Daly said. 

“A huge bit of our stream of consciousness between our ears is that business of building a coherent narrative of who we are and what we are up to for our public consumption and private consumption,” he said.

OK, so blood relations rule for Homo sapiens. But what about friends? A lot of people are emotionally closer to friends than family. 

Some scientists argue that friendship is a holdover of tribalism, where alliances outside kinship offered benefit to the tribe, such as bolstering a hunting party or reciprocating favors.

Daly did not disagree, but he brought up a recent study by a McMaster University postdoc. In the study, participants were offered a choice: $75 for you and $75 for your friend, or $105 for you. Most participants took the $105. But when the potential benefactor was a sibling, participants liked to split the $75. This was the case even when the participants said they were closer and spent more time with friends than with family. 

“Friendship can be extremely close, but it can also be disrupted,” Daly said. “You have really close friendships, and then you move apart and it goes away. But you can’t get rid of your bloody relatives.”