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-