American Museum of Natural History
- How evolution saves lives and promotes prosperity
- Solving problems with phylogenetic trees
- Conservation genetics and conserving biodiversity
- Genes and health—moving beyond race
- Malaria—natural selection and new medicine
- Our balancing act with viruses
- What is a virus?
- Quiz: Evolution and human health
- Exploration Questions: Evolution and human health
- Answers to Exploration Questions: Evolution and human health
by Dr. Joel Cracraft
Suppose you were asked what the science of chemistry had contributed to the world. You might come up with important products such as herbicides or pesticides. How about the contributions of pharmaceutical science? The design and manufacture of drugs. Genetics? Our ability to diagnose and treat inherited human diseases, and improvements in plant breeding and agriculture to help feed an expanding global population.
But what about evolutionary science? How do people see it as being important in their daily lives? Some might propose that it helps us understand the past and where we came from: "Our place in nature" is a common phrase. But most people would be hard pressed to come up with concrete applications that benefit us daily.
Why is this the case? A simple answer is that as scientists and teachers we have not explained the real-world importance of evolution to students and to the public as well as we should. This is one reason so many people distrust or misunderstand evolution and thus undervalue the importance of teaching it. Consequently, an important first step is teaching some of the many ways that evolutionary science—including tree-thinking, molecular evolution, population genetics, and studies of natural and artificial selection—adds to our individual and collective well-being.
Those important contributions of science mentioned in the first paragraph? All of them depend on the basic principles of evolution.
Understanding the basic mechanisms of evolution helps us solve societal problems
The foundational principles of evolutionary biology include mutation and variation, patterns of inheritance, natural selection and fitness, and environmental adaptation. Over the years, these basic principles have been used to build a large body of knowledge that advances human well-being. To be sure, this underlying knowledge is much more extensive than we can cover in this course, but the principles we have already discussed make the following examples accessible. Scientists now have a term for the evolutionary study of societal challenges and their solutions: applied evolutionary biology.
Improving human health
Today, around 25 percent of the medicines we use were originally derived from wild plants discovered by systematists and ethnobotanists. And many of the “synthetic” medicines we take are, in turn, based on many of those from wild plants. Moreover, more traditional medicines are still used widely by billions of people. Well-known medicines from wild plants include aspirin (from willows and relatives), which was synthesized in 1899; the important anti-cancer drug taxol, from the bark of the Pacific yew tree; and, of course, quinine for treating malaria, derived from the bark of the cinchona (quina-quina) tree, a remedy that goes back to the 17th century. These are well-known examples, but many other drugs used as anesthetics, analgesics, cancer inhibitors, muscle relaxants, and so on, are derived from the wild.
Today, modern pharmaceutical companies employ genomic information from organisms as well as phylogenetic comparisons. These companies then combine vast chemical knowledge with computational informatics to search for and to design new types of drugs. Much of this work depends on knowing similarities and differences among biochemical pathways that are present across different life forms (plants, microbes, fungi). That way, researchers know where to look for chemicals that might make good drugs, for methods of producing those chemicals, and for targets the drugs might treat effectively. Knowing these similarities and differences, in turn, depends on knowing phylogenetic relationships. With new technologies, many of the genomic components that chemists identify can be transferred to microorganisms for further biosynthetic studies. These results can lead, for example, to crops that resist pests, tolerate heat or cold, or produce higher yields.
The story of food production is a great example for appreciating the role of evolutionary biology. It’s an endless, cyclical arms race. Humans create pesticides and herbicides, which provoke adaptive responses in pests. The pests then evolve resistance, humans modify their weapons, and pests evolve anew. Dealing with this cycle is a very large scientific endeavor for agricultural science around the world. To give you an idea of the scope of the problem: There are around 11,000 examples of pesticide resistance known for over 1,000 pathogens, as well as over 500 insect species known that resist insecticides. New pesticides yield new adaptations.
For thousands of years, as humans moved around the world, they met the challenges of changing environments by modifying domesticated crops and animals through interbreeding and husbandry. For today’s scientists, identifying the closest wild relatives of these domesticates is extremely important. Often these species live in novel or marginal environments and possess genetic adaptations not found in domesticates, such as responses to changing climate. By interbreeding domesticates with close wild relatives, scientists can capture genetic variation that often improves crop yields or protects crops from disease.
A good example is cultivated corn. Phylogenetic analysis has identified the teosintes of Mexico and Guatemala as the wild relatives of corn and has traced domestication back 9,000 years. A new species of teosinte, Zea diploperennis, found on a Mexican mountaintop, was discovered in the late 1970s. It turned out to be resistant to numerous pathogens that damage domesticated corn. Interbreeding Zea diploperennis with domestic corn improved disease resistance, preventing billions of dollars of crop loss.
There is considerable urgency within agricultural sciences to address the effects of climate change on our food supply. For example, selectively breeding and planting wheat varieties that are more drought or heat resistant, we can maintain food supplies in regions with difficult climates. Doing so depends, of course, on background knowledge about where these varieties first evolved and what those climates were like.
Human agricultural systems result in a complex network of evolutionary changes in pests, crops, and organisms that live in the natural ecosystems interwoven with croplands. All agriculturalists have had to confront the arms race between pests and anti-pest agents such as pesticides and herbicides. Without an understanding of evolution, scientists would have a far harder time fighting disease and hunger.
Want to join the conversation?
- Is Zea diploperennis (Improving agriculture section) resistant to Ustilago maydis the common corn smut?(1 vote)
- The entire article confuses evolution with the science USED and DEVELOPED to understand and even prove evolution. Evolution itself, the slow process of change and adaptation, does not provide immediate or everyday benefits, but the science and technologies used in studying evolution do provide the benefits, as discussed at length in the article.(0 votes)