Another study concludes what will happen in humans based on what happened in animals, in this case—monkeys. Researchers at the University of Wisconsin-Madison have located areas of the brain that they believe are responsible for anxiety in monkeys. The study is published in the August 12 edition of Nature.
According to Health Newstrack: “This study may lead to new strategies for early detection and treatment of at-risk children.” According to RedOrbit.com: “By studying young monkeys, scientists from the University of Wisconsin-Madison School of Medicine and Public Health believe they have found the areas of the brain that cause childhood anxiety.” The press release from UW was not modest either: “A new study focused on anxiety and brain activity pinpoints the brain regions that are relevant to developing childhood anxiety.”
As I said in my last blog on spinal regeneration, the only way a reasonable person could equate disease physiology in a mouse with disease physiology in a human is if there is a history of successes in this area. Superficial resemblances do exist but this is a far cry from applying results from mice or monkeys to humans. Such trans-species extrapolation has a very poor track record complete with many human deaths. (See my last blog on spinal regeneration and our book Animal Models in Light of Evolutionfor details as to why this is the case.)
Now lets compare the monkey research with this news item from research with dogs. An article and commentary in PLoS Biology describe research that reveals the genomes of dogs are very similar and that the differences between traits like body size are actually due to differences in a very small number of genetic regions. According to ScienceDaily:
"We've found that only six or seven locations in the dog genome are necessary to explain about 80 percent of the differences in height and weight among dog breeds," said Carlos Bustamante, PhD, professor of genetics at Stanford. "In humans these are controlled by hundreds if not thousands of variants."
There are two important points here. Number one, as I have said a few hundred times before, it does not take large genetic differences between species or breeds to generate very dramatic differences in drug or disease response, or, in this case, size. Small differences, even between monozygotic twins, can translate to one twin suffering from a lethal disease while the other does not.
Number two, note that the human condition appears to be more complex that the canine. Six or seven locations in the dog genome control traits that apparently require thousands of variant in humans. So once again, the dog differs from the human in important details.
Now, let’s put what we learned from the dog study in the context of anxiety in humans. Almost all agree that the human brain is the most complex thing in the known universe. While there will certainly be similarities with other species, the human brain is not the monkey brain writ large. It is qualitatively and quantitatively different. If the genes controlling body size in dogs do not translate to those controlling size and so forth in humans then what chance is there that a much more complex trait like anxiety will have a one to one correlation?
But in order for animal-based research that uses animals like monkeys to continue to be supported by society, researchers will continue to ignore the effects of evolution on complex systems and sell their research as applicable to children suffering from diseases.