Nature's Barbell Strategy
What ecology and evolution teach us about making progress
On the sunlit savanna, a dormouse darts from its hole, twitchy and on high alert for signs of danger. Born in large litters, each mouse's life fleeting and dangerous. The mouse's survival strategy is about speed — fast growth, rapid reproduction, short lives. Each moment is a gamble, and survival means leaving as many young behind as possible.
Nearby, a family of elephants gathers at a watering hole, moving with a slowness that mirrors a careful evolutionary strategy. The mother elephant stands protectively over her calf, just one of her few offspring born over many years.The elephant's strategy is rooted in patience: few offspring, slow growth, long life.
The mouse lives for today: swift, abundant, adaptive.
The elephant invests in tomorrow: enduring, deliberate, stable.
Each organism has a wildly different evolutionary approach, and each one works.
There's a model in ecology that categorizes organisms by these reproductive and evolutionary fitness strategies. The fast-growth mouse is r-selected, and slow-growth elephant is K-selected.
The "r" stands for growth rate. Species that follow an r-selection strategy prioritize rapid reproduction. The name comes from the variable "r" in the population growth equation, which represents the intrinsic rate of increase.
The "K" stands for carrying capacity. K-selected species maximize their success in environments that are stable and at or near the carrying capacity of the ecosystem. They focus on quality rather than quantity.
The opportunistic species like the dormouse — or grasses, minnows, or fruit flies — are the ones that fill the ecosystem quickly when subjected to shocks and changes. Preserver species like elephants, redwoods, and tortoises provide a long-lived predictability required to keep ecosystems stable.
Every organism exists somewhere on this continuum.
Humans, at least biologically, are clearly on the K end of the spectrum. Incredibly slow maturation and growth, few offspring, careful and methodical evolutionary selection.
But humans are importantly distinct in evolutionary history: we're the first organisms to ever develop the abstract knowledge of this evolutionary process itself. We not only naturally fall somewhere on this r/K spectrum: we've modeled and understood the spectrum. We developed the ability to notice the opposed r-selection evolutionary tactics and use them selectively to our advantage.
We've developed thousands of cultural and technological advancements that harness an r strategy, to augment our biological K. Humans have created tools that mimic the rapid, high-output qualities of r-selection in the realm of ideas and information. The invention of the printing press, the internet, and social media are all examples of technologies that allow ideas to proliferate and spread incredibly quickly, mirroring an r-selected reproductive strategy: create and disseminate ideas in massive quantities with the hope that a few will take root and influence culture. And lean on systems of error correction and criticism to prune those that don't work.
When faced with changing, unstable environments — social, economic, or ecological — humans rapidly adapt. Though our cells and DNA can't evolve in real time, our ideas can. When the environment shifts, new behaviors, ideas, or technologies can emerge almost instantaneously.
There's a lot to take from this model and translate to the everyday. It reminds me of Nassim Taleb's model of the "barbell" strategy:
When faced with any risky resource allocation scenario (like investing), put the majority of resources into stable, low risk buckets, and a small minority into concentrated high risk, high reward bets. The idea is to bet on two ends of the barbell. The stable end gives you reliable, yet low, return. The volatile one loses you some small bets, but one win delivers outsized reward. Avoid the middle.
The barbell leverages the asymmetry of outcomes, a robustness against loss and potential for gain. The middle is home to the mediocre risks — too exposed to losses in the experiments (meaning you run fewer of them), too underprotected against the Black Swans.
The small bets are your big upside, your experiments to see what works. The big, safe bets don't come with big lottery-like upside, but they keep you in the game. They're the survival safety net that keep you from going broke.
In certain situations we benefit from the fast and loose. Rapid testing of ideas and low-cost-of-entry experiments tell us about what works. In others situations we might favor the careful approach. If you're running a company, experiment with new product improvements for customers (asymmetric upside), not with new innovations in GAAP accounting (little upside, if any).
In one area the winning strategy is to reinvent, while in another it's steady-as-she-goes.
Returning readers of Res Extensa may notice an echo of pace layering in the r/K spectrum. To refresh on the idea, it’s
’s model for understanding the interplay between elements of complex systems, looking at a system in layers that move at different speeds:
r-selected fashion has a “reproductive strategy” that tries new ideas on for size as fast as we generate them. Nearly all of them fade away before they catch on, but a handful resonate and embed themselves into the layers below.
Whereas the K-selected nature and culture layers are the bedrock on which we have the freedom to run our fashion and commerce experiments.
Stewart even used the r/K metaphor to contrast methods of architectural design in How Buildings Learn:
Whereas Low Road buildings are successively gutted and begun anew, High Road buildings are successively refined. These are precisely the two principal strategies of biological populations — the opportunist versus the preserver: "r-strategy" versus "K-strategy" in the jargon. It is the difference between annual and perennial plants — between weeds like dandelions which scatter profuse seed to the winds, and dominant species like oak trees, which nurture their few acorns and build an environment that protects the next generation.
Low Road buildings rely on rapid adaptation, but don’t last. They’re the repurposed Soho lofts and MIT Building 20s. High Road buildings are long-lived and carry our culture. The Florence Cathedral, Monticello, the Vienna State Opera. Both methods serve a purpose with a fitness for specific need.
As I said before about pace layering: rich ideas find purchase and relevance everywhere you look. The r/K dichotomy is everywhere once you have the language to notice it.
As humans, our position on the r/K spectrum isn’t as fixed as our biology suggests. It's important that we recognize our ability to choose our own adventure when it comes to the trade-offs between the fast and the slow. There's much we can learn from ecology in how to build resiliency, on a personal, organizational, and societal scale.
Rallying a group (or even just yourself) effectively toward a goal is hard, and I'm always on the lookout for mental models that help think about how to spend attention wisely.
It's a reminder that there's a home for both "move fast and break things", as well as the "slow and steady wins the race". The right strategy depends on context.