Physics Nature Is Weird

Even for ants, taking the 'shortcut' can actually screw over the whole group and slow everyone down.

March 30, 2026

Original Paper

Braess's paradox in tandem-running ants: When shortest path is not the quickest

Joy Das Bairagya, Udipta Chakraborti, Sumana Annagiri, Sagar Chakraborty

arXiv · 2603.26226

The Takeaway

We usually think of ants as the ultimate team players, but they fall into the same traffic traps as humans: shortcuts can actually make a journey longer. Because the ants are hard-wired to prefer the shortest distance, they crowd the path and create a bottleneck that slows down the entire colony's move.

From the abstract

Braess's paradox -- where adding network capacity increases travel time -- is typically attributed to selfish agents. Although eusocial colonies maximize collective fitness, we find experimentally that \emph{Diacamma indicum} ants exhibit this paradox: Leaders favour the shortest path even when it slows the colony. We present a quantitative model of the exploration-exploitation trade-off, demonstrating that evolutionary forces selecting for shortest-path identification can force suboptimal globa