In this course I want to discuss what I think an educated person should know about biology, the science of life. Biology is the most dynamic field of science today. Its ramifications affect us as individuals and as citizens. This is most obvious in modern medicine, where surgical replacements of ailing organs have become routine in developed countries. The benefits of immunizations against infectious diseases are reaching developing countries as well. Modern contraceptives can help to avoid unwanted pregnancies, while new fertility treatments allow otherwise sterile couples to have the children they want.
Some applications of modern biology are controversial. For instance, we are now able to decipher the entire genetic information, or genome, of any organism including the human. Our genome controls to a large extent how we look, function, think, and feel. Just as humans look basically similar but still have individual characteristics, so their genomes are variations of a common theme. Since the cost of deciphering genetic information is coming down, it will become affordable for individuals to have their personal genomes analyzed. For a few hundred dollars, we can already buy a personal inventory of most health-related genes that we carry. While this can be a good investment in our personal health, there are major concerns. How reliable would this information be? Who would control access to it? Could employment or life insurance be made dependent on such information? Will it become customary for couples to exchange their genomic inventories before they become engaged?
There are many other areas where biotechnology is racing ahead of law and public acceptance. Genetically modified (GM) food is an example. Some GM foods are more nutritious, and can be grown in greater quantity, than their natural counterparts. Indeed, GM foods may be the only way of feeding a growing world population. However, for consumers with certain allergies or other conditions, GM food may pose a health risk. Also, many GM plants have been made resistant to insects and fungi. If such plants are grown in the open where they can crossbreed with wild plants, they may give rise to "superweeds" that have escaped control by their natural enemies. Similar problems may arise with GM animals, such as fast-growing fish raised in fish farms, which could wreak havoc on natural marine life if they escaped and survived in open waters.
An ever-growing human population is now aspiring to raise its standard of living by industrialization, which requires the generation of more energy. Currently, we generate most of our energy by burning fossil fuels: coal, oil, and natural gas. The carbon dioxide released in the process is causing global warming. This and other ways of environmental degradation have set us on a collision course with the survival of natural communities of plant and animal species that support one another and eventually us humans. Rational solutions to this problem are difficult to find and depend on progress in science, technology, and politics. The purpose of this course is to familiarize students with the biological underpinnings of some of the issues that they will have to deal with. At the same time, I hope you will also enjoy the sense of excitement and the better understanding that come from studying the living world.
After introductory remarks on the scientific method, the remainder of the course will be organized in four parts. Part I is on human evolution; it explores how we got to where we are. We have evolved from ancestors that we share with chimpanzees and bonobos. When these common ancestors lived in Africa some eight million years ago, they were caught up in a change of climate that replaced much tropical forest with open grassland. While the precursors of today's chimps and bonobos stayed in the canopy of the receding forest, our human forerunners slowly learned to make a living on the ground. They managed to do this by acquiring those traits that are uniquely human, from upright walking and tool-making to language and art.
Part II introduces genetics as the key to modern biology. After reviewing the basic patterns and mechanisms of inheritance, we will focus on ways of estimating the extent to which human traits are heritable. Relevant data, for example on intelligence or sexual orientation, are of great interest to administrators, lawmakers, and the general public. A central topic will be the human genome project. We have already touched upon the benefits and problems of personalized medical treatment based on individual genomic information. More revolutions in medicine will come from gene therapy and cell replacement therapy. However, these unprecedented therapeutic powers need to be accompanied by counseling services, legal guidelines, and insurance contracts that are helpful and fair.
Part III explores genetic and hormonal effects on human behavior. It will start out from the observation that all plants and animals behave so as to raise maximum numbers of offspring. As we will see, this is a strong component of average human behavior as well, although individuals have the option of following cultural norms that are not always biologically adaptive. We will explore these topics in particular in the context of sexuality, aggression, and cooperation. Our explorations will lead us to experiments on animals as well as to studies on human subjects using legal and medical records, questionnaires, standardized tests, and sophisticated brain scans. These studies touch the way we see ourselves as very special animals.
Part IV is on topics of great concern revolving around human population growth and environmental degradation. We are about to turn Earth into a gigantic farm and playground just for us humans, but the energy and the chemicals we spend in the process are saddling us with new diseases and are destroying many other forms of life. Instead of being good stewards of the world we have come to dominate, we have allowed the natural rate of species extinction to increase dramatically. This is an ethical problem because we cannot recreate any species that is gone. But even from a utilitarian view this is an alarming trend because species depend on one another in ecosystems. Like a garment with too many torn threads, an ecosystem may come unraveled if too many critical species are lost.
The topics discussed in parts I through IV are connected. The same traits that have sustained us through millions of years of evolution are now bringing us to the brink of disaster. Our superior skills as tool-makers, which originally compensated for our lack of natural weapons, have led to arsenals of weapons that can destroy all of us. The same technical skills have promoted, in the developed countries, an energy-burning life style that wreaks havoc on our environment. Unfortunately, this life style feeds into a traditional way for males to acquire status and mating opportunities. The problem is compounded by an innate aversion to discrimination, which is now leading developing countries to emulate the environmentally destructive lifestyles of developed countries.
Some of my colleagues believe that life as we know it is headed for a mass extinction, and that some bacteria surviving in the depth of the ocean will start another billion years of evolution leading to entirely new life forms. I am not that pessimistic. I believe that we have a chance to survive. But this will take a major effort, and our children and grandchildren will not thank us if we continue with business as usual. Toward the end of this course we will collect some thoughts on how it may be possible for us humans to sustain most of our own kind while saving a major fraction of the other 10 million species that keep us alive.
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Last modified: 19 August 2010