12 January 2010

Evolution to blame for modern-day health problems?

by Kate Melville

The subtle but relentless pressures of human evolution could explain the rise of disorders such as autism, autoimmune diseases, and reproductive cancers, say scientists who believe that evolutionary perspectives should be part of medical school curricula. The researchers, from Yale University, the University of Michigan, Harvard University and the Boston University School of Medicine, speculate that certain adaptations that once benefited humans may now be helping such ailments persist in spite of - or perhaps because of - advancements in modern culture and medicine.

"This work points out linkages within the plethora of new information in human genetics and the implications for human biology and public health, and also illustrates how one could teach these perspectives in medical and premedical curricula," says Harvard's Peter Ellison, the author of the paper.

Previous research in the field of evolutionary medicine has helped explain why disease is so prevalent and difficult to prevent - because natural selection favors reproduction over health, biology evolves more slowly than culture, and pathogens evolve more quickly than humans. Delving deeper, the paper, published in the Proceedings of the National Academy of Sciences, explores how:

  • Autism and schizophrenia may be associated with the over-expression of paternally or maternally derived genes and influences.
  • Maternal and paternal genes engage in a subtle tug-of-war well into childhood with consequences for childhood development.
  • Humans may be susceptible to allergies, asthma, and autoimmune diseases because of increased hygiene. Without being exposed to intestinal worms and parasites, as our ancestors were, our immune systems are hypersensitive.
  • Natural selection still influences our biology, despite advances in modern culture and medicine. It has been established that natural selection favors heavier women and reduces the age at which a woman has her first child. The researchers have called for the integration of evolutionary perspectives into medical school curricula, to help future physicians consider health problems from an evolutionary perspective. "We're trying to design ways to educate physicians who will have a broader perspective and not think of the human body as a perfectly designed machine," says Ellison. "Our biology is the result of many of evolutionary trade-offs, and understanding these histories and conflicts can really help the physician understand why we get sick and what we might do to stay healthy."

    Autism, Asperger's and Evolution
    Unnatural selection: Courtesy of The Pill
    Ugly males more fertile
    The "perfect" body not always perfect
    The Personal Face Of Evolution

    Source: Harvard University