The Science of Self

Scientists of a generation ago would be astonished by what we know today about the human condition based on the study of genes. Introducing this revolution in knowledge, Professor Silver examines the nature of science and how theories are systematically tested.

Throughout history most people have assumed that living things are animated by an immaterial spirit or soul. Learn that more than 2,000 years ago, the Greek philosopher Aristotle came up with a remarkably prescient scientific model of life, which has been further refined by discoveries since the 18th century.

Examine what distinguishes humans from other living organisms by probing the insights of Aristotle and Charles Darwin, among others. Genetically, humans and chimpanzees are 99% identical. Also, conduct a thought experiment that illustrates the difficulty of using biological criteria to define a human being.

Explore the laws of heredity that Gregor Mendel formulated in the 19th century, marking a huge advance over the existing understanding of genetics based on thousands of years of plant and animal breeding. Mendel's laws went unnoticed by other scientists until after his death.

Learn that most traits result from more complicated interactions than Mendel's simple laws and that nongenetic factors come into play in determining differences in appearance, physiology, and personality. These multiple influences explain why identical twins are not identical in every respect.

Delving deep into the cell nucleus, investigate the chromosomes that are the material substance in which genes exist. A normal human cell contains 23 chromosome pairs. During sexual reproduction, each parent contributes one member of each pair, providing a physical manifestation of Mendel's laws.

How do chromosomes actually encode information? Learn how a famous 1953 paper by James D. Watson and Francis Crick described the elegantly simple structure of the DNA molecule, present in all chromosomes. Their work accounted for the chromosome's information storage capacity and also its mechanism of replication.

Professor Silver shows how the digital code within DNA is transformed into an animated, analog form of life at the cellular level. The structure and function of living things emerge primarily from proteins, which are assembled according to the recipe in DNA through the intermediary of messenger RNA molecules.

How can scientists decipher processes inside cells? Learn about the powerful new tools of biotechnology, including DNA sequencing. This technique reads the "digital" code inherent in the DNA that comprises the genome, which is the complete set of genes present in an organism.

The human genome is like a complicated landscape with intricate details revealed wherever one zooms in for a closer look. Professor Silver tours several features on the genome, including chromosome 11, which codes for hemoglobin, the critical oxygen-transport molecule.

Analyze how gene regulation produces a whole human being with an intricate system of specialized tissues and organs, each expressing different portions of the genome. Many diseases, such as cancer, are caused by an aberration in gene regulation.

Where does complexity in living things come from? Investigate how Darwin presented the first comprehensive scientific theory to explain both the diversity of life on Earth and a rationale for the form and function of every individual organism.

Darwin would be amazed at our ability today to pinpoint the exact biochemical mechanisms of evolution and of individual variations. Learn how some people, including James D. Watson, have had their own genomes mapped, allowing detailed comparisons of the slight differences in human DNA sequences.

Use the findings of gene technology to explore the past history of life on Earth and the DNA changes that ultimately gave rise to humans. The recovery and sequencing of Neanderthal DNA provides a revealing comparison with human DNA.

Focusing on the last 50,000 years, chart how different populations of humans migrated across the world, as revealed by the genetic divergence among the present descendants of these groups. Also explore other secrets hidden in our genomes.

Professor Silver explains how pedigree analysis is used to map genes and diseases to each other. He starts with the innocuous trait of blue eyes before moving to the mutations that produce cystic fibrosis, Huntington's disease, and some forms of breast cancer.

All 6 billion people on Earth can be looked at as members of a single extended family. Learn that by studying large numbers of people, scientists have discovered DNA variants that predispose individuals to a variety of diseases, including hypertension, diabetes, cancer susceptibility, heart disease, and mental illness.

After humans migrated out of Africa, they encountered new environments that promoted adaptive evolutionary changes. Investigate several such cases, including the adaptation of lighter skin color at higher latitudes, and adult lactose tolerance in response to the innovation of cattle domestication for milk production.

Explore the revolutionary concept of the selfish gene, which may explain the altruistic behavior of an individual who sacrifices for the benefit of close relatives or other members of the species. Seen from the gene's point of view, such behavior enhances survival, rather than diminishes it.

Examine the various model systems that scientists use to study brain function. Also consider how the human brain evolved from less neurologically complex brains and how signals are transmitted across the synapses between neurons.

This lecture looks at individual genetic differences that influence synapse function in the brain, sometimes with dramatic effects on personality and behavior. In some cases, aberrant neurotransmitter signaling across synapses can lead to diseases such as anxiety, aggression, depression, and Parkinson's disease.

Learn about the genetics of bipolar disease and schizophrenia. The underlying genetic variants behind them may be beneficial to other individuals when present at a subthreshold level. The beneficial traits are not yet known but may include a balanced mood and increased creativity.

Take a tour of the current state of genetics and its increasing ability to explain both human disease and normal human behavior. Given the rapid advances of the past decade, the developments of the next 10 years and beyond promise to be exciting and unpredictable.

Professor Silver closes by asking: What does the future hold for our species? Will it go extinct like nearly all others that have ever existed? Will it survive in essentially the same form as today? Or will human descendants evolve into something completely different?