Time, Love, Memory

Time, Love, Memory: A Great Biologist and His Quest for the Origins of Behavior is a book by Jonathan Weiner about the origins of molecular and the search for the genetic roots of behavior. Weiner starts with an overview of the discovery of genes and the structure of DNA. In the early 1900's the biologist Thomas Hunt Morgan began studying fruit flies, Drosophila. Drosophila was easy to study because of its fast reproductive cycle, the ease with which its genes mutate, and the ability to look for the mutations under the microscope. Using the basics of heredity from Mendel and others, Morgan and his students were able to establish the basic theory of genetics. It is amazing to see such great science at work, especially given the basics of the tools and the rudimentary understanding they had. They had to invent the concepts from the ground up with little to go on. Without understanding how DNA was structured, they mapped the different traits to genes and in turn mapped those genes in relation to each other, based on how often they mutated at the same time. The process was brilliant.

Mapping physical traits is is a fairly straightforward matter of looking at the subjects under a microscope. But to measure behavior, different methods are required. The physicist turned biologist Seymour Benzer, the main subject of the book, was determined to track down the genetic foundations of behavior. In his first behavior experiments, he separated flies who flew towards a light from those that didn't. With this and other experiments Benzer and his associates were able to track down specific genes that codes for behaviors. After finding the appropriate mutant they would cross breed it with a mutant with a known genetic defect and look at the offspring and their offspring. The results would show where the genes were in relation to each other. In this way scientists were able to find a gene they called clock, which determines the rate that certain proteins build up and disperse in a cell, thus determining the biological clock. This gene could make a fly's metabolism run fast or slow. What's more striking is that the same gene is found in organisms throughout nature.

More experimentation led to the discovery of a gene for the flies' memory, and a gene that when mutated would direct males to court with other males. Eventually technology would enable the mapping of the entire genetic code of the fruit fly, and of course the human genome. Genes have been tied to all sorts of human behavior. Weiner cautions that the link between genes and behavior is not direct; there is embryonic development, the growth of the brain, and many factors of experience that can play a part.

The book is a blend of science experiments, science theory, biography, and political and social discussions. The men and women who made breakthroughs in genetics and molecular biology were very intelligent and very bold. Weiner explains the experiments very clearly. He also paints a great picture of Benzer and the other scientists, including their antics and their disagreements. They all come across as not just intelligent robots but humans with the drive to find the building blocks of life. Benzer is portrayed as a driven man who wants to find the origins of behavior. Despite the complex factors involved in human behavior, these scientists have gone a long way toward tracking the links from our genes to our actions. A-

The Blank Slate

Steven Pinker's The Blank Slate: The Modern Denial of Human Nature is a fascinating review of evolutionary psychology and the backlash against it both in academia and popular culture. Pinker illustrates a broad range of scientific studies and evidence in support of evolutionary psychology. He then shows the reaction against it and provides counterarguments.

Evolutionary psychology is the study of how genes and natural selection affect human behavior. The first important concept Pinker introduces is the difference between ultimate cause and proximate cause. An ultimate cause is an historical factor that led to a decision to be made or a behavior: generally one's genes and one's upbringing. The proximate cause is the immediate factor that led to the behavior. It seems obvious that a person's behavior is influenced by their past and the formation of their brain.

Yet there is a strong reaction against the idea that we may be influenced by the genes our ancient ancestors passed on to us. This reaction seems to come in two particular ways. First, there is a general aversion to any ultimate cause that appears to detract from the moral responsibility from one's actions. This can be dealt with by acknowledging that we do not act in a vacuum, and that one's past does not give one absolution for behavior. Just like we do not absolve someone due to a poor childhood, we do not grant a pass due to bad genes.

The other reaction against the idea is by those who believe that the human mind is empty of any inherent structures and is formed by the culture surrounding it. This view is often held by Marxists and other idealists who believe it is possible to recreate society based on their own ideas of human nature. The less basic human nature we are both with, the easier it is to transform humanity for different purposes. If there is a large set of behaviors built in, then it is impossible to shape society to an ideal. Moreover, certain behaviors such as prejudice and violence may be an inevitable consequence of being human. The idea that violence is a part of human nature goes against some ideologies or academic disciplines such as sociology, and is a repellent idea for many others. (I was struck by the revelation that E. O. Wilson was attacked for being a Nazi after his publication of Sociobiology, his seminal 1975 popular science book. Apparently the final chapter on humans was too cold a look at behavior.)

It seems pretty obvious to me (and Pinker does a good job of showing this) that society is largely responsible for reducing violence in the face of a strong genetic predisposition. We are after all primates, and it is unlikely that violence would be eradicated from our DNA completely. He shows that primitive human societies are more violent than Western society. Studies have shown little or no correlation between violent media and violent children.

I found the most persuasive evidence the studies evaluating the correlation in behavior between parents and children. To quote Pinker: "First, adult siblings are equally similar whether they grew up together or apart. Second, adoptive siblings are no more similar than two people plucked off the street at random. And third, identical twins are no more similar than one would expect from the effects of their shared genes." This comes from the chapter on children and parents. It is astonishing to learn that about 50% of children's behaviors can be accounted for by their genes, with much of the rest accounted for by their peers. What is more astonishing is to learn of people's reactions such as "So it doesn't matter how I treat my kids?" Of course it matters! They are human beings after all. Pinker shows how silly and reductionist this argument can be.

Pinker does a great job at showing the evidence against a blank slate, the arguments for it, and the counter arguments. He makes important points, like just because men or women have different abilities doesn't mean we should have artificial barriers of opportunity: everyone should be equal under the law. Abilities are after all part of a normal distribution. We should not take any scientific discovery as a reason to change our moral codes. He addresses the naturalistic fallacy square on: the notion that something that occurs in nature must be moral. There are many behaviors in nature that we know are immoral, such as murder, rape and theft. The discovery that there is a natural basis for these does not mean that we should promote or tolerate them. To use his analogy, when Galileo showed that the heavens were not immutable spheres of crystal, people were scandalized to imagine what would happen to morality. "It's hard for us to imagine why the three-dimensional arrangement of rock and gas in space should have anything to do with right and wrong or with the meaning and purpose of our lives.... because the very idea that morality has something to do with a Great Chain of Being was daffy to begin with." Likewise, we shouldn't link our principles of freedom and equality to any scientific theory or set of facts.

I highly recommend this book to anyone who wants to understand human nature, as well as the framework that society has used to deny it. A+