Can neuroscience explain complex human traits such as altruism?<\/p>\n

Pfaff (2007) argues that nearly every cultural system, past and present, has a type of golden rule: a rule so ingrained in human behavior as to be “intellectually invisible” (p. 7) and rarely questioned. But where does it come from? Pfaff (2007) explains:<\/p>\n

Some experts would claim this principle is a product of evolution. Individuals who behave altruistically\u2014that is, they aid others, even at some cost to themselves\u2014help their group to survive better and ultimately to produce more offspring like themselves. The impulses toward this behavior have been passed down along with the rest of the genetic code for the human brain, and now appear not only in behavior but also in brain activity that we can detect and track. If this is so, we can understand why this rule and its many variations have survived in human ethical systems, philosophies, and religions. (pp. 7\u20138)<\/p>\n

If you agree with the experts (Pfaff mentions that we are biologically predisposed to altruism), then would it logically follow that altruism is not limited to human behavior? Consider the following comments by Carl Sagan and Ann Druyan (1992):<\/p>\n

In a laboratory setting, macaques [rhesus monkeys] were fed if they were willing to pull a chain and electrically shock an unrelated macaque whose agony was in plain view through a one-way mirror. Otherwise, they starved. After learning the ropes, the monkeys frequently refused to pull the chain; in one experiment only 13% would do so\u201487% preferred to go hungry. One macaque went without food for nearly two weeks rather than hurt its fellow. Macaques who had themselves been shocked in previous experiments were even less willing to pull the chain. The relative social status or gender of the macaques had little bearing on their reluctance to hurt others. (p. 117)<\/p>\n

After pointing out the cruelty of the experiment (“our own moral sympathies do not lie with the scientists”), Sagan and Druyan (1992) note:<\/p>\n

By conventional human standards, these macaques\u2014who have never gone to Sunday School, never heard of the Ten Commandments, never squirmed through a single junior high school civics lesson\u2014seem exemplary in their moral grounding and their courageous resistance to evil. (p. 117)<\/p>\n

Researchers at the University of Minnesota have studied the influence of genes and the environment on psychological traits of identical (monozygotic or MZ) and fraternal (dizygotic or DZ) twins raised together and apart (Minnesota Twin Family Study, n.d.). Their findings are summarized below:<\/p>\n

Preliminary analyses of the data so far collected, on some 2,400 twin pairs, suggest that the broad heritability of socioeconomic status, years of education, and present income level ranges from about 0.30 to 0.40. Not surprisingly, education and SES are correlated positively with Positive Emotionality and Self Esteem, negatively correlated with negative Emotionality and Alienation. There is a weak but significant tendency for twins from larger families to produce more offspring themselves. The within-pair correlation for number of offspring, for MZ pairs where both twins have been married, is about 0.30, which should be compared with a maximum possible correlation on the order of 0.50. Similarly, the risk of divorce, like procreation, is a two-person game, and should probably be compared with a maximum possible risk of about 0.50. This risk is nearly 3 times the risk for MZ twins whose co-twin has never been divorced. Since all of these variables – attained SES, years of education, family income, number of offspring, risk of divorce – are plainly complex, multi-factorial outcome variables, it is clear that this evidence of significant heritability implies that many of the diverse personality, interest, and aptitude variables that act together to influence these outcomes are themselves substantially influenced by genetic variation. (p. 3)<\/p>\n

John E. Dowling, in his 2004 book The Great Brain Debate: Nature or Nurture<\/em>, summarizes things nicely (Dowling, 2004):<\/p>\n

What the neurobiology is telling us\u2014bottom line\u2014is that genetic directives are clearly most critical in brain building, although the environment can also play some role, whereas environmental factors play the fundamental role during brain maturation, although there is genetic restraint. (p. 165)<\/p>\n