In order to really understand why animals are not predictive models of human disease and drug response you need to understand at least the following.
Science in general.
What models are and how they are used.
Complexity and its relationship to reductionism.
Gene networks, regulation, and expression.
How medicine is practiced.
(See Animal Models in Light of Evolution for more on the above).
Most people are never going to understand all of the above and that is OK. An examination of the empirical evidence is sufficient for making an informed decision. (See FAQs About the Use of Animals in Science: A handbook for the scientifically perplexed.) Monkeys have been vaccinated against HIV-like viruses but all those vaccines failed in humans. Many methods to treat spinal cord injuries have tested well in animals but failed in humans. Of 22 drugs tested on animals and shown to be therapeutic in spinal cord injury by 1988, none were effective in humans (1).
Curry in Ann N Y Acad Sci 2003:
The failure, in the clinic, of at least fourteen potential neuroprotective agents expected to aid in recovery from stroke, after studies in animal models had predicted that they would be successful, is examined in relation to principles of extrapolation of data from animals to humans. (2)
And, allow me once again to quote Dr. Richard Klausner, then-director of the National Cancer Institute: "The history of cancer research has been a history of curing cancer in the mouse . . . We have cured mice of cancer for decades—and it simply didn't work in humans." (3)
Unfortunately, we read or hear almost daily, scientists touting great breakthroughs in animals, which are discredited in years or decades. This occurs far to frequently and one result is society's general mistrust of science as a whole. And why shouldn’t they? One day they hear on TV or read in the newspaper that some cancer has been cured in a mouse but that same cancer continues to kill their relatives and friends. Obviously there must be something wrong with science.
Recent polls show that many Americans deny evolution and some polls even show that more people believe in pseudoscience like astrology than in science. Paul Thagard stated:
. . . society faces the twin problems of lack of public concern with the important advancement of science, and the lack of public concern with the important ethical issues now arising in science and technology . . . One reason for the dual lack of concern is the wide popularity of pseudoscience and the occult among the general public. Elucidation of how science differs from pseudoscience is the philosophical side of an attempt to overcome public neglect of genuine science. (4)
But based on what animal modelers presents to the public, it should not be surprising that society neglects genuine science. Parading animal models as predictive is not helping distinguish science from pseudoscience. Until scientists start being honest with the public they should not be surprised when the public believes in sheer nonsense which in turn results in society ignoring potentially catastrophic problems. The animal model community is not the only scientific discipline that has made unfounded claims but they are high profile and have no excuse for deceiving taxpayers. Scientists cannot claim to be children of the Enlightenment while simultaneously claiming animal models are predictive models for humans.
The animal-based research community should not appeal to society’s emotions by introducing the promise of paralyzed people walking again or of children with brain cancer being cured. These are simply ad populum arguments meant to deceive (or raise money). The real question is whether animal models can predict human response. If they can, then there is reason to hope when rats walk again. But if animal models are not predictive then paralyzed rats walking again or mice being cured of cancer should not be news and should not be used to raise the hopes of vulnerable people suffering from these diseases. The reason to oppose funding research on paralysed rats is because it has a track record of not working in humans. And remember, every dollar that goes to funding animal models is one dollar that cannot go to funding human-based research. The research pie is not infinite.
Animal-based research is not predictive for human disease and drug response while human-based research is. So, if you want cures for human conditions and diseases, then you should demand that the government and charities fund human-based research.
As I have mentioned in this blog, money is a large reason animal-based research continues. Universities, researchers, companies that sell animals and related equipment, even the media profits. In order to keep the status quo, this industry has a history of assuring society that many breakthroughs in animals are mere months away from curing paralysis, stroke, cancer, Alzheimer’s or whatever in humans. Sadly, these checks bounce when society tries to cash them.
1. American_Paraplegia_Society, J Am Paraplegia Soc 11, 23 (Jul-Oct, 1988).
2. S. H. Curry, Ann N Y Acad Sci 993, 69 (May, 2003).
3. M. Cimons, J. Getlin, T. H. Maugh_II, “Cancer Drugs Face Long Road From Mice to Men,” LA Times, 1998.
4. P. Thagard, in Philosophy of Science: The Central Issues, M. Curd, J. A. Cover, Eds. (Norton, 1998), pp. 27-37.