THE BLOG
05/21/2010 05:12 am ET | Updated May 25, 2011

Let's get amoebic: The charitable slime mold as a model for facing climate change

A dirty, but heroic protozoan might be able to revamp our hopes in climate reform. But first, let's talk about viruses and a very Y2K view of our own species.

I recently decided to re-watch The Matrix to see if it would blow my mind as much as it did in 1999. It didn't even come close (neither, I suppose, would Napster, Ask Jeeves, or the Thong Song). But I was struck (again) by a moment in which the sentient, ever-monotonous program "Agent Smith" compares humans to viruses. Unlike mammals, which maintain a balance with their environment, Smith reports that we (and viruses) "multiply and multiply, until every resource is consumed."

We're nothing like viruses; our thoughts, emotions, and even cell nuclei exempt us from this comparison. Nonetheless, one feature of viral life--relentless consumption--might be a fair comparison to our treatment of climate change. Last December in Copenhagen, world leaders' resolution to prevent global warming was pulled apart like so much taffy by many countries' reluctance to reduce their carbon emissions. Cap and trade, the central feature of the US's attempt to cut emissions, has died on the vine because it is considered too expensive. And last month, Yvo de Boer, the UN climate chief who has embodied reform efforts for several years, announced his resignation, saying that bickering and mistrust will stall any international climate agreement until at least 2011. Given the consensus that enormous change will be required to prevent environmental catastrophe, we might as well be wrestling on a sinking ship instead of plugging its leaks.

According to economists, this shortsightedness is nothing new. Resources shared by many (anything from a pie to a polar ice cap) naturally create tension between cooperation and self-interest: a group is best served when each person consumes equal and sustainable amounts, but individuals tend to take more than their share, thinking that their excesses will go unnoticed. This miscalculation--repeated by each person in the group--eventually leaves everyone with nothing. Garrett Hardin, who first described this phenomenon as The Tragedy of the Commons 40 years ago, didn't cut us much slack, concluding that "Ruin is the destination toward which all men rush, each pursuing his own best interest." Agent Smith would probably agree!

But both of them would be wrong. Humans may act selfishly towards public resources, but the success of our species depends on working together to survive in situations no individual could weather alone. We also demonstrate enormous selflessness when others are in need, as demonstrated during outpouring of altruism following January's earthquake in Haiti. This cooperative side of humanity makes the virus metaphor seem unrealistic. To replace it, I'd like to propose a better analogy for our behavior in the single-celled world: Slime Mold. Although not the most glamorous evolutionary relative, the amoeba Dictyostelium discoideum has some pretty amazing properties, including primitive forms of cooperation and altruism.

Under normal conditions, slime mold cells live pretty self-centered lives, pulling themselves through soil and engulfing bacteria like e coli. But when resources become scarce, unlike viruses, Dicty don't consume themselves into oblivion; they get together. Starvation causes each single-cell organism to release a chemical that attracts others, and soon enough tens of thousands of amoeba from different, unrelated strains merge into a "slug," that crawls towards signs of better prospects (like heat and light). Once it has found a promising spot, this slug undergoes a second metamorphosis, this time into a kind of amoebic dandelion. About 20 percent of the individual amoebas making up the slug become a "stalk" that supports an orb full of spores. Like a dandelion's airborne "parachutes", spores in this orb float towards richer environments. The amoebas in the stalk die, never to pass on their genes.

Of course, amoebas like the slime mold are not altruistic in the classic sense. They don't share each other's suffering, or consciously sacrifice themselves in a blaze of selflessness. They're simply running genetic programs. Nonetheless, Dicty's behavior is downright poetic. Imagine an analogous situation: 1,000 people trapped on the barren side of a crevasse, with no way to get across. If we were as (genetically) brave or charitable as Dicty, 200 of those people would form a human bridge so that the others could cross over, even if it meant possible death to the bridge-makers. There are, in fact, examples of such sacrifice, such as when soldiers jump on top of live grenades to rescue their platoons, or when people climb down onto subway tracks to save trapped strangers from oncoming trains.

Dicty's charity is also genetically smart. In a recent article, biologists demonstrated that some Dicty strains "cheat" by floating to freedom as spores while letting other strains make up most of the doomed stalk. However, Dicty evolve, over generations, to defend against cheating, by acting charitably much less when paired with a cheater strain. Humans demonstrate this selectivity also, contributing fairly to public resources most often when they can trust others to do the same, a phenomenon known as "conditional cooperation."

Dicty present a much more optimistic analogy for human behavior than viruses. Nations could emulate amoebae, and realize that saving any of us means making serious sacrifice (in our case, not of lives, but of profit). But will we? If our behavior at Copenhagen is any sign, maybe we don't have the instinct to sacrifice personal gain in the service of a common resource.

This may, however, be a matter of how present a threat we're facing. Remember, Dicty only cooperate when their resources are almost entirely depleted, a state of extremely danger. People, like Dicty, may be most amenable to selfless cooperation under truly desperate circumstances. Although images of a shrinking Lake Victoria and melting sea ice are threatening, they may be too abstract to hit many people's panic buttons. In this regard, apocalyptic summer blockbusters may be more insightful than we think. On Hollywood's view, alien invasions, meteors, and ice ages inspire slime mold-like collectivism, with people the world over fighting together to preserve the fruits of human culture. In 2012, humans' endgame strategy--stuffing paintings, giraffes, and attractive physicists into survival pods while sacrificing everyone else--might as well have been stolen straight from the Dicty playbook. If any of these renditions are right, things may have to get a lot worse before we get amoebic.