April 8, 2005 • Posted in Science Papers
Greek, R., Greek, J., & Shanks, N. (2005). Written for Project R&R.
Chimpanzees are Homo sapiens’ closest evolutionary relative. If any animal is an appropriate model of humans for research into diseases such as AIDS, Alzheimer’s, Parkinson’s and drug testing; it would have to be the chimpanzee. Therefore, an examination of the scientific preconditions surrounding such use is justified.
Historically, chimpanzees and other animals were successfully used to learn things about humans. In the past centuries, we have learned basic anatomy, physiology, and biochemistry from such research. Even today, chimpanzees can be used as bioreactors, for example to grow hepatitis B or other viruses that are difficult to grow in culture medium. These uses have their scientific as well as ethical downsides. The use of chimpanzees is based on their genetic similarity to humans. Because chimpanzees are our closest relatives, one would expect their response to drugs and disease to mirror ours. Obviously, this similarity also has ethical implications.
Today, science is seeking answers to very different questions than when chimpanzees were dissected in the 2nd century AD by Galen. As our examination of living systems has become increasingly fine-grained, we have found that subtle differences between organisms tend to outweigh gross similarities, as explanations for biologic activity. Science successfully used chimpanzees and other animals to shed light on shared functions, however, today we are studying drug response and disease at the level that defines not only a species, but in many cases the individual.
Differences in gene regulation and gene networks, as predicted by evolutionary and molecular biology, explain why even two nearly identical complex systems, such as a chimpanzee and a human, or even identical twins, may respond differently to the same stimuli (e.g., medication), and hence why one complex system, or species, cannot reliably predict response for a different complex system, or species. Current biomedical research is studying disease and drug response at the level where the differences between complex systems, be they two different species or even two different humans, manifest. Hence using animals as causal analogical models for human disease and drug testing is a scientifically invalid paradigm.
We are living at the beginning of the age of personalized medicine. Soon your genetic profile will be known to you and your physician. This will allow tailor-made treatment. You can take measures to avoid diseases for which you are at risk and the most appropriate medications will be selected for you. You will be prescribed dugs which complement your genetic makeup, rather than fight it. If we are to expand and refine our current gene-based treatments, our medical research must be more narrowly focused, not broadly focused for example on an entirely different species such as Pan troglodytes.