Evolution has helped many members of the animal kingdom adapt to overcome or resist a range of medical issues that scientists are trying to solve in humans.
The giraffe, for example, has a gene that protects the heart from being damaged by blood pressure that would be high enough to ruin a human heart. Elephants possess multiple copies of a gene, one that’s common in mammals, that makes them highly resistant to cancer. And naked mole rats seem almost immune to aging.
Now, scientists in an emerging field of study are studying the evolution of those and other traits to better understand the origins of human diseases — and to pursue cures for conditions that seem intractable.
In a paper published Feb. 28 in Frontiers in Science, an international team of scientists led by two UCLA evolutionary biologists lays out a research plan for “evolutionary medicine.”
Evolutionary medicine applies insights from ecology and evolution to inform, direct and improve biomedical research, public health measures and clinical care. Observing that there are likely countless disease-resistance mechanisms among the vast diversity of life on Earth, the authors argue for the need to systematically search out those mechanisms, uncover their physiological bases and use those findings as the foundation for new clinical treatments and improved public health policy.
“Our bodies and minds evolved in one environment but are living in another — and that mismatch causes disease,” said Dr. Barbara Natterson-Horowitz, the paper’s first author, a cardiologist and evolutionary biologist at UCLA and Harvard University. “Evolutionary mismatch underlies many forms of heart disease, cancer, reproductive disorders and even mental health challenges.”
Conditions like those often are treated as lifestyle diseases; current interventions tend to place the responsibility for treatment on the patient — calling for exercise and dietary changes, for example. However, changing health behaviors doesn’t always work.
“It’s not about treating diabetes when a person gets it at 40, but about making the investment during childhood,” said Daniel Blumstein, a UCLA professor of ecology and evolutionary biology and a co-author of the paper. “Policies that promote interventions early in life can have an immensely positive effect on future health and welfare.”
The paper presents four broad areas in which insights from evolution and ecology could bring the biggest benefits to human health.
- Identifying evolutionary and developmental mismatches with human behaviors could lead to new interventions for obesity, Type 2 diabetes, cardiovascular disease, allergies, conditions related to gut health and mental illness.
- Studying infectious disease epidemiology, such as the evolution in virulence and transmissibility of viruses, could help prevent or stop future pandemics.
- Improving understanding of human development in an evolutionary perspective, could help solve problems in growth, reproduction and aging.
- Learning more about the evolutionary tradeoffs that influence human behavior could inform efforts to promote habits that improve health and longevity.
“Understanding our collective human evolutionary history can help us forecast future public health burdens,” said Molly Fox, a co-author of the paper and a UCLA assistant professor of anthropology and of psychiatry. “Across the animal kingdom and the fossil record, we can draw from a vastly larger pool of information than traditional epidemiology to understand how environments and lifestyles shape the basic processes underlying disease.”
An evolutionary approach could also help guide the development of drugs that don’t induce bacteria to become antibiotic-resistant — interfering with bacteria’s ability to evolve, for example, or using viruses called phages that could infect bacteria and cause them to become more susceptible, rather than more resistant, to treatment.
The authors also describe a possible evolution-inspired approach to overcoming chemotherapy resistance in people with cancer: treating the cancer like an organism undergoing extinction.
“The idea is that an effective way to eradicate a population is to first critically reduce its size with an ecological catastrophe — like the meteor strike for the dinosaurs,” Blumstein said. “And then kill remaining individuals with a second disaster — like the famine that followed the meteor.”
“Extinction therapy” would translate that principle into a clinical strategy. Patients would receive a high dose of one cancer drug to reduce a tumor’s size, as in current protocols. But before drug resistance has a chance to arise, the first treatment would be replaced by another to kill off the remaining cancer cells.
“Knowledge from the wild can inform our understanding of human health,” said Natterson-Horowitz, adding that her own thinking on the subject changed during her time as a medical consultant to the Los Angeles Zoo. “Biodiversity in the natural world can be a powerful source of insights that can accelerate biomedical innovation.”
Frontiers in Science