Biologists who study lion prides have spent decades documenting a pattern that looks, at first glance, like a fixed rule: When a new male takes over a pride, he kills the cubs. A nursing lioness won’t return to fertility for up to two years, and a new male, whose hold on the pride will likely last only a few seasons, cannot afford to wait that long to father his own offspring. Genetically, those cubs are strangers to him. Whatever distant relatedness exists at the population level is far too diluted to register in the fitness math that favors infanticide. The calculation runs as if relatedness were zero, because effectively it is.
Read more The View’s Sunny Hostin says American flags make her feel ‘unsafe’
But the pattern isn’t as fixed as it first appears. Risk is heavily concentrated in cubs under roughly a year old. As cubs near independence, outcomes become far less predictable — some survive, some don’t, in a way that no longer follows a clean rule.
What’s happening at that threshold has an exact name in ecology: It’s a real-world case of what biologist Eric Charnov formalized in 1976 as the Marginal Value Theorem — a model, originally built to describe when foraging animals should abandon a depleting food patch, that applies generally to any situation where a strategy pays diminishing returns. The theorem’s answer is precise: Abandon the current strategy not when it stops working, but the moment its marginal return drops below what’s available elsewhere. For an incoming lion, killing an eleven-month-old cub barely accelerates the mother’s fertility compared to killing a two-month-old — the marginal benefit has collapsed, even though the underlying incentive (father my own line, not another male’s) hasn’t changed at all. A related model, John Maynard Smith’s War of Attrition — built to explain when animals should escalate a contest versus back down — runs on the same logic: the winner isn’t whoever is strongest at the outset, but whoever’s cost to continue crosses his expected payoff last.
None of this involves the lion weighing options. It’s a threshold built into behavior by selection pressure over millions of years, tuned to fire exactly where the math favors it. But it’s still worth naming precisely what kind of selection is doing the work here. The lion killing cubs unrelated to him is a clean case of individual selection — a behavior favored because it maximizes his own reproductive output, full stop, with zero regard for the pride’s cohesion or continuity as a group.
That’s only half the picture in nature. The other half deserves its own example, because lions don’t illustrate it well. Belding’s ground squirrels do. When a predator approaches, some squirrels give a loud alarm call that draws the predator’s attention to the caller while the rest of the colony flees — a behavior that measurably raises the caller’s own risk of being killed. Biologist Paul Sherman’s long-running field studies found that the callers were disproportionately females, with close relatives nearby, and rarely isolated males with no kin in earshot. This is the behavior W.D. Hamilton’s 1964 rule was built to explain: A costly act toward others is favored by selection when the benefit to the recipients, discounted by how closely related they are to the actor, exceeds the cost to the actor doing it. Below that threshold, self-interest wins. Above it, a real, measurable willingness to accept personal cost for kin or group benefit takes over — not because the animal is virtuous, but because the genetic math favors it.
This isn’t a settled matter in biology. Kin selection, built on Hamilton’s rule, remains the dominant framework, but in 2010, E.O. Wilson and Martin Nowak published a widely discussed challenge arguing for a stronger role for group-level selection instead — and were met with a rebuttal signed by well over a hundred evolutionary biologists defending the original framework. The debate over exactly how individual selection and group-level selection interact is real and ongoing, even if the basic phenomena — cub-killing on one end, alarm-calling on the other — are not in dispute.
Read more The question the media refuses to ask
What lions and ground squirrels illustrate together, then, isn’t one force, but two, running on the same underlying currency: how much capacity an individual or a group has to spend (call it depth); how long the window lasts before that capacity is gone (call it time); and — separately — whose interest a given expenditure actually serves, the individual’s or the group’s. A creature, or a system, can be well short of running out of depth or time and still be spending both unwisely, if the balance between those two forces has shifted too far toward pure individual extraction to sustain the group that depth depends on.
Human conflict runs on a version of the same problem, raised into conscious judgment rather than fixed instinct. What Clausewitz called the culminating point of victory — the moment an army’s aggressive momentum, pressed further, stops serving the war’s purpose and starts consuming the capacity needed to hold what’s already been won — is the Marginal Value Theorem applied to human warfare: The marginal return of continued attack falls below what patience or consolidation would yield, whether or not the attacking commander recognizes it in time. The Confederacy fought with real skill and determination but lacked the industrial depth and political time to outlast a Union that kept regenerating its capacity through years of costly setbacks. Napoleon’s operational brilliance kept winning battles in Spain and Russia long past the point where his empire had the depth left to hold what conquest had won — a commander who never located his own culminating point until it had already passed. Paul Kennedy’s study of imperial decline across five centuries found the same failure recurring at civilizational scale: great powers that kept expanding military commitments well beyond what their economies could sustain, not because expansion had stopped working, exactly, but because nobody in command located the threshold before it was gone.
The individual-versus-group axis runs alongside this, not underneath it as some hidden master force, but as a genuinely separate variable that shapes how fast depth gets spent. Rome’s long dominance rested substantially on switching, region by region, from destruction to incorporation — extending citizenship, absorbing local elites, turning conquered populations into soldiers and taxpayers rather than simply garrisoning them, a strategy that pushed toward group-level payoff once outright conquest had done its narrower work. The Allied victory in the Second World War rested on industrial mobilization that required exactly the kind of costly, individually borne sacrifice ground squirrels model in miniature — rationing, conscription, years of foregone consumption for collective capacity — sustained long enough, and widely enough, to outproduce adversaries who could not match it.
None of this settles where the United States sits today, and it shouldn’t pretend to. But it does offer two separate, honest questions to ask, rather than one vague sense of national anxiety. First: Is the country still well short of its culminating point — still possessing enough generative depth and enough time to recover from present strain — or is it closer to that threshold than its public conversation admits? Second, and separately: Is the balance between individual and group-level behavior, across its institutions and its politics, closer to the lion’s math or the ground squirrel’s? And if the country has drifted farther toward pure individual and factional extraction than it once stood, is that drift itself a form of spending down the depth a nation needs to survive its next real test?
Read more Biden-Harris opened the borders. Americans still pay the disastrous price.
<p text-align:=”” center;”=”” style=”text-align: center;”>
Image via PickPik.