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Foreword
Consider just three of Earth's inhabitants: a bright yellow daffodil that greets the spring, the single-celled creature called Thermococcus that lives in boiling hot springs, and you. Even a science-fiction writer inventing a story set on a distant planet could hardly imagine three more different forms of life. Yet you, Thermococcus, and the daffodil are related! Indeed, all of the Earth's billions of living things are kin to each other.
And every living thing does one thing the same way: To make more of itself, it first copies its molecular instruction manual—its genes—and then passes this information on to its offspring. This cycle has been repeated for three and a half billion years.
But how did we and our very distant relatives come to look so different and develop so many different ways of getting along in the world? A century ago, researchers began to answer that question with the help of a science called genetics. Get a refresher course on the basics in Chapter 1,"How Genes Work."
It's likely that when you think of heredity you think first of DNA, but in the past few years, researchers have made surprising findings about another molecular actor that plays a starring role. Check out the modern view of RNA in Chapter 2, "RNA and DNA Revealed: New Roles, New Rules."
When genetics first started, scientists didn't have the tools they have today. They could only look at one gene, or a few genes, at a time. Now, researchers can examine all of the genes in a living organism—its genome—at once. They are doing this for organisms on every branch of the tree of life and finding that the genomes of mice, frogs, fish, and a slew of other creatures have many genes similar to our own.
So why doesn't your brother look like your dog or the fish in your aquarium? It's because of evolution. In Chapter 3, "Life's Genetic Tree," find out how evolution works and how it relates to genetics and medical research.
Can DNA and RNA help doctors predict whether we'll get diseases like cancer, diabetes, or asthma? What other mysteries are locked within the 6 feet of DNA inside nearly every cell in our bodies? Chapter 4, "Genes Are Us," explains what researchers know, and what they are still learning, about the role of genes in health and disease.
Finally, in Chapter 5, "21st-Century Genetics," see a preview of things to come. Learn how medicine and science are changing in big ways, and how these changes influence society.
From metabolism to medicines to agriculture, the science of genetics affects us every day. It is part of life ... part of your life!