Punctuated Equilibrium

Since its debut in 1972, punctuated equilibrium (PE) has been both a source of controversy and a catalyst for new thinking in evolutionary biology. Proposed by Stephen Jay Gould and N iles Eldredge, PE argued that most species spend long periods in morphological stasis, only to undergo rapid bursts of change during speciation. At first glance, this seemed to clash with the prevailing model of genome-based, gradual evolution—where natural selection operates on the steady accumulation of small mutations. But in recent years, developments in genomics, developmental biology, and systems theory have begun to bridge the gap. What once seemed like a dichotomy now appears to be a case of different lenses on the same underlying process. ...

When we imagine evolution, we often picture it unfolding at a leisurely, predictable pace—small changes stacking up over time like bricks in a wall. That’s the traditional view: gradualism, the slow grind of nature perfecting its handiwork. But what if evolution doesn’t always play by those rules? What if nature has a taste for the dramatic—long stretches of calm, interrupted by bursts of sudden transformation? That’s the idea behind punctuated equilibrium (PE), a theory introduced in the 1970s by palaeontologists Stephen Jay Gould and Niles Eldredge. Rather than a smooth evolutionary curve, PE proposes a jagged rhythm: long periods where species remain largely unchanged, punctuated by short, intense episodes of change—often triggered by environmental disruption or internal developmental shifts. ...

When we think about evolution, we usually imagine something like survival of the fittest—organisms scrabbling to adapt to harsh environments, with only the strongest traits passing on to the next generation. But what if much of the story wasn’t written in the open battlefields of nature, but quietly, deep inside the womb? That’s exactly the idea behind the work of paleoanthropologist Anne Dambricourt-Malassé. Her research suggests that one of the most important drivers of human evolution isn’t some dramatic change in diet, climate, or hunting technique—but the early developmental behaviour of a small, oddly shaped bone at the base of the skull: the sphenoid. ...