Medical research has always relied on other species—animals, plants, and microbes—to help us understand human physiology and treat human disease. While evolution has resulted in significant differences between humans and other life forms, Nature has a striking uniformity that allows us to use a wide variety of other organisms—from the simplest bacteria to non-human primates—to better understand ourselves.
While research animals must be treated humanely and with great care and respect, unnecessary experiments strictly prohibited, and research involving animals, particularly sentient animals, allowed to proceed only after alternative means have been fully considered and deemed inadequate, the use of animals in medical research has made possible innumerable medical advances, including anesthetics for surgical procedures and insulin for diabetes, heart and lung bypass machines for open heart surgery, vaccines for meningitis and polio, and countless other vaccines, medical procedures, and medicines. In fact, all human medicines (and all veterinary medicines) must first be tested in laboratory animals for toxicity, dosing, and efficacy before they can be tested on people.
Many avenues of research could be used to illustrate the contributions that various animals, plants, and microbes have made to our knowledge about how our bodies function in health and disease. One research area that has paved the way for our understanding of many diseases and for developing treatments for them is that of genetics. A very brief review of this area will be given here.
Several organisms have contributed essential insights to our knowledge of human genetics. These include: the Common House Mouse (Mus musculus), which has been used to develop different mouse strains that lack specific genes, similar to ones present in people, so that the function of these genes can be determined; the bacterium E.coli, which has provided fundamental information about how DNA copies itself, how genes turn on and off, and how DNA makes RNA that in turn makes proteins; the bacterium Thermus aquaticus and the fruit fly Drosophila melanogaster both of which have contributed to our ability to map the human genome; baker’s yeast (Saccharomyces cerevisiae) which has taught us how cells make copies of themselves by cell division; the microscopic roundworm C. elegans, which has led to an understanding of “programmed cell death” (called apoptosis), a natural process which is essential for the normal development and functioning of tissues and organs, and which, when disrupted, can lead to cancers; and Zebrafish (Danio rerio), which have been central to our understanding of how genes function in the formation of various organs, especially the heart.
While laboratory organisms are not threatened with extinction, we mention them here because they illustrate the kinds of critically important medical information that they, and perhaps they alone, contain. Other organisms in the wild clearly also contain such information, unique to themselves, but what they have to teach us about human health and disease may be lost if they become extinct before we have a chance to discover their secrets. This is true for the 1.9 million species we have already identified, and for the many millions of others we haven’t yet discovered.
Zebrafish (Danio rerio), photo by Bob Jenkins | Flickr.com