In 1965, the young American scientist Leland Hartwell had to make a decision crucial to his research on understanding how cells divide, a key step toward curing cancer.
Hartwell had to decide whether to place his bet on simple single-celled organisms like baker's yeast, which were easy to study but might be too distantly related to humans for the information to matter. Or he had to cast his lot on cells from humans and mice, which were clearly relevant but difficult to study. Hartwell gambled that over the course of evolution, certain genes would be so important that natural selection would conserve their key features, making them recognizable even between yeast and humans. Over the next few decades, this speculation was confirmed, and in 2001 Hartwell was awarded the Nobel Prize.
The importance of evolution to Hartwell's work exemplifies a key perspective that has been overshadowed by recent attacks on science and evolution from creationist ideologues advocating "intelligent design". While it is essential to explain the flaws in the pseudoscience of "intelligent design" and to review the overwhelming evidence supporting the facts of evolution, such discussions of fossils and extinct species can seem irrelevant to everyday concerns. So let's focus on some of the many practical applications of evolution in an area that matters to all of us: breakthroughs in medicine.
Evolution, in addition to being solid science, provides us with a practical and powerful tool-kit. Applied techniques based on evolution play central roles in the biotechnology industry, and in recent advances in genomics and drug discovery. Bioinformatics, the application of computers to biology and one of the hottest career opportunities in science, is full of evolution-based computer code. Tens of thousands of researchers in the multibillion-dollar field of biomedical research and development use evolution-based discoveries and concepts as a routine part of their important work.
For instance, our interpretation of the human genome is largely based on comparisons to genomes of other species. Coincidentally, the statement by President George W Bush in support of teaching "intelligent design" (see p 13) occurred just weeks before the publication of the chimpanzee genome, work led by Washington University's Genome Sequencing Center.
In a peer-reviewed article, many of the same world-renowned scientists responsible for sequencing the human genome presented in detail the differences between the DNA of humans and chimps. Consistent with chimpanzees' being our closest living relatives, the researchers reported that across billions of bases in the genomes, about 97.4% of the human and chimp DNA is identical. And the differences in the remaining 2.6% are fascinating, showing the signatures not of creation or design but of evolution. The DNA sequence differences show change driven over the last 6 million years by the forces of mutation and natural selection, from the selection for genes that aid in our defense against infection to the movement of transposable elements (parasitic DNA).
To see the integral role of evolution in biomedical research, consider Nobel Prizes, a good indicator of the most important breakthroughs in biology. Reviewing the last 50 years of Nobel Prizes in medicine or physiology, I asked, "Is training in evolutionary biology necessary for a thorough understanding of the award-winning discoveries and work resulting from each breakthrough?" By my criteria, understanding of evolution is necessary in 47 of 50 cases. From vaccines, viral cancer genes, and nerve cell communication to drug trials, and genes controlling cholesterol and heart disease, evolutionary insights are crucial.
In Hartwell's case, a bet on the simple yeast cell revolutionized our understanding of how cells of all organisms replicate. Versions of most of the genes found in yeast cells by Hartwell and his co-recipients Tim Hunt and Paul Nurse were later found in humans. Despite over a billion years of evolution since they diverged from their common ancestor, humans and yeast still maintain similar gene-encoded machinery for cell replication. Drugs aimed at this replication machinery are currently in clinical trials for the treatment of breast, lung, kidney and other cancers.
In Kansas, backers of "intelligent design" have scoffed at the idea that watering down the evolutionary biology curriculum would have a negative effect on that state's fledgling biotech industry.
What does evolution have to do with biotechnology? As the president of a biotech firm in St Louis, I can tell you that evolutionary biology is an integral part of what we and other companies do. I hire scientists who are well-trained in molecular evolutionary biology; who know how to recognize the business end of enzymes simply by looking at DNA sequences; who know which changes in a protein are important; who can design research tools based on the way a species manipulates the genetic code. Today, these skills are as important to discoveries in the laboratory as knowing how to use a microscope, and it takes an understanding of evolution to master them.
Creationists ask, "Do you really think an ape was your ancestor?" Biologists are actually saying something much more profound. From anatomists, biochemists and immunologists to molecular biologists, neurobiologists and cell biologists, we are stating that all aspects of biology support the conclusion that humanity shares ancestry not only with primates, but with mammals, reptiles, fish, insects, worms, plants, and yes, even yeast and bacteria. We have evolved as part of one inseparable living world — one ancient tree of life that inhabits this planet. And for many scientists of diverse religious traditions, this realization does not pose the conflict with their faith that fundamentalist ideologues assert.
Americans, in addition to being a passionate people of many faiths, are also practical people. We are innovators who expect to lead the world in medical breakthroughs and products. Open-minded Americans must know that the assault on evolution in the science curriculum not only puts at risk our understanding of natural history, ecology and environmental change, but also jeopardizes the science literacy of our students and our international competitiveness in making biomedical breakthroughs of Nobel-Prize caliber. Americans have been awarded the Nobel Prize in Medicine in 39 of the last 50 years. At a time when we face international competition that is more intense than ever, a good start toward success is to put the attacks on evolution, biology, and science behind us.