Evolution, to me, is a lens that provides structure and meaning to many different problems, including applied problems with substantial potential benefits to humanity. On this day to celebrate Charles Darwin, I want to share some insights I’ve learned over the years. I’ve been fortunate to be involved in interdisciplinary projects that bring an evolutionary approach to two very different disciplines—security and defense, and medicine.
Under the leadership of Evolution: This View of Life co-editor Rafe Sagarin and working with co-editor Dominic Johnson, our Natural Security research group asks what are the lessons from 3.5 billion or so years of life on Earth than can inform us on what defensive strategies are more or less likely to be effective in a given situation. I’ve thought a bit about how we live with risk.
As I’ve previously written in Wired, one lesson is that avoiding all risk is impossible. We’ve got to learn to live with risk. Politicians who promise us perfect safety are making an unachievable promise. A common behavioral ecological paradigm envisions individuals trading off the probability of starvation versus the probability of predation. Imagine a refuging rodent, like a marmot in an alpine meadow. It lives in a burrow but must come out to forage. If it remains in its safe burrow, it will ultimately starve to death. If it emerges, it faces some risk of predation. Virtually all animals must live with some risk of predation at some point in their lives and we must too. Much of behavioral ecology focuses on trade-offs like these that all animals must make.
The sheer diversity of life shows us that there are multiple ways to solve a problem: animals have evolved different ways to ensure safety. For instance, some animals, like marmots, reduce the time they are exposed while foraging in risky areas, while others, like many kangaroos and wallabies, increase the time spent vigilant while foraging in risky areas. Both strategies may work to reduce risk. By not looking when in risky areas you reduce exposure, and by being vigilant, you increase your ability to detect threats.
Outside the Green Zone, we see both strategies at work: transport vehicles drive quickly to reduce exposure, while soldiers on patrol are highly vigilant, ready to respond at a moment’s notice. The more general lesson from nature is that having a diversity of solutions may be OK and should be encouraged because different solutions may be best in a particular situation.
Why do animals such as impala (the African ungulate, not the car) jump up and down in a stiff-legged ritualized display upon detecting predators? Why do many birds vocalize when they see their predators and may even attack their predators? For predators that require stealth for their hunting success, such detection signaling tells the predator that it’s been detected and that the game’s up. We can learn from nature and communicate to our adversaries that we’re on to them. One possible explanation for the changes in the DHS threat levels in the early years following the September 11th attacks, is that we were strategically signaling to terrorists that they’ve been detected. Such strategic use of detection signaling could be used in many adversarial situations.
Animals spend a lot of time reducing their uncertainty about threats. Simply because a predator is present doesn’t mean that a given individual is at risk. For instance, imagine a group of African ungulates walking by a sleeping pride of lions. Many small fish, such as guppies, approach and inspect their predators, and marmots spend more time looking around after they hear alarm calls from an unreliable individual. Such uncertainties should elicit more investigation. If the FBI analysts who received reports of foreigners enrolling in flight schools followed up on those reports, the September 11th attacks may have been averted.
Revealing the presence or strength of an adversary is important as seen in both penguins and squirrels. When Adelie penguins enter the water from an ice shelf they may be preyed upon by waiting leopard seals. The penguins typically bunch up, waiting for someone to go in first to see if the first one in is attached. Sometimes, however, they may ‘encourage’ another penguin in with a flipper-butt! Probing for safety is also seen in California ground squirrels that kick sand in the face of rattlesnakes so as to elicit a rattle—warm snakes rattle faster and big snakes produce lower pitched rattles. Big and warm snakes are riskier than cool and small snakes.
Studying nature shows us that it’s essential to reduce costly defenses when risk decreases. In many cases, costly anti-predator behaviors are lost when there are no longer any predators around. For instance, guppies become less cryptic and less wary when they find themselves in predator-free locations, and wallabies are less wary when they find themselves isolated on islands with no predators. Such responses are adaptive in that they by no longer allocating energy or time to anti-predator behavior, animals are able to allocate energy or time to other activities. Our defense budget should be particularly sensitive to the true risk and be modified appropriately. After all, one hypothesis for the fall of the Soviet Union is that we forced them to spend more on defense than they could afford.
Given some estimate of risk, should we be conservative—and overestimate risk, or blasé—and underestimate risk? Theoretical models suggest that when faced with a starvation-predation risk trade-off, and imperfect information about the true risk of predation, being conservative—that is, overestimating risk—may be an optimal strategy. However, it’s clearly costly to over-estimate risk too much. In fact, many autoimmune diseases emerge from an overactive immune system. There’s an optimal amount of time/energy/treasure that should be allocated to defense, and it’s necessary to identify it in a given circumstance.
We should probably favor generalizable and adaptable defenses. Whenever possible, we should seek to adapt defenses from pre-existing resources. The Maginot line <http://en.wikipedia.org/wiki/Maginot_Line> is an example of a colossal failure in creating a specific defense (the Germans just waltzed around it!). For instance, rather than creating a novel and unique “Department of Bio-attack Detection”, health care systems can be better developed and communication among hospitals and government agencies improved, so that biological attacks could be quickly detected. Importantly, an improved public health system will have positive benefits for citizens even when there are no terrorist attacks, and a strong public health system will help us respond to natural pandemics. Similarly, first responders should be given radiological and chemical weapons monitors (as some are because they will be the first to encounter such threats), rather than creating an entirely new agency tasked to detect a low-probability (but admittedly high consequence) threat.”
Our group believes that these lessons from life are all around us, just waiting to be identified. And this brings me to my work on evolutionary medicine.
Randy Nesse, George Williams, and Paul Ewald are key players in founding this integrative field that brings evolutionary and functional logic into medicine. The field of evolutionary medicine has been generating wonderful ideas and some clinical successes, but the question remains, how do we effectively teach it.
Working with my UCLA colleague, Dr. Barbara Natterson-Horowitz, a cardiologist at the UCLA David Geffen School of Medicine, we have established an evolutionary medicine program at UCLA that seeks to expose undergraduates, graduate and medical students, and medical residents to evolutionary principles and thinking. We are starting a minor in Evolutionary Medicine, we are creating opportunities for physicians and ecologists to work together on research programs, we embed ecologists and evolutionary biologists into hospital rounds where residents and medical students discuss cases, and we’ve been bringing evolutionary biologists to give Grand Rounds lectures to the Department of Medicine.
These well-attended and highly stimulating lectures and experiences are all designed to get physicians thinking about some key principles of evolutionary medicine. For instance, traits that are being treated (e.g., anxiety) may have been designed by natural selection (it’s good to be cautious and fear things that could be potentially harmful) and thus understanding their adaptive utility may shed light on their disregulation and its treatment. Or, there may be mis-matches between the current environment and the historical environment under which some defense evolved. For instance, the hygiene hypothesis suggests that autoimmune diseases result directly from living in an excessively clean environment and suggests novel treatments, such as giving people benign infections of worms, may be useful to reduce the negative impacts of an over-active immune system. Or, the rule that pathogens under attack will evolve resistance, a fundamental insight that has all sorts of implications, as our recent speaker Andrew Read from Penn State believes, to how we treat cancers and bacterial infections.
Of course, these are just two disciplines that evolution can be applied to. The work of the Evolution Institute shows that the logic and focus that an evolutionary approach brings to problems may very well generate new insights and solutions to humanities ills. I think we all should be grateful to Darwin and Wallace’s big idea.