After a long wait, I& #39;m excited to share new research on ants, infrastructure, and resilience https://abs.twimg.com/emoji/v2/... draggable="false" alt="🐜" title="Ameise" aria-label="Emoji: Ameise"> Our @PNASNews paper shows army ants self-assemble into “scaffolds” that keep others from falling – an adaptive collective response emerging from individual sensing and decisions (1/7)

In field experiments on Barro Colorado Island, Panama, I coaxed raiding Eciton burchellii ants across an adjustable slope to study scaffold growth. As the video above shows (50° v. 90° at 20x speed), we found scaffolds grew larger, and formed more often, on steeper slopes. (2/7)

To assess their functional benefits, we measured the effect of scaffolds on traffic by counting ants slipping or falling before and after scaffolds formed. We found their presence associated with reduced slips and falls (and thus less disruption), even at steep angles. (3/7)

Informed by this, we devised a mechanistic model of scaffold growth, proposing ants that slip while crossing will tend to join a scaffold, with a probability conditioned on slipping. At higher angles, slips are more likely, which leads to larger scaffolds forming rapidly. (4/7)

Slipping is reduced as scaffolds grow, with ants less likely to slip (or join a scaffold) over time, until growth saturates when slips are rare. As shown in A & B below, with input parameters similar to our observations, the model predicts scaffold growth dynamics well. (5/7)

Ants require information only about their own state, linking individual error sensing to the collective response of scaffold formation. This mechanism may inform the design of other systems that must respond rapidly to disruption, without complex sensing or communication. (6/7)

More in our #OpenAccess paper: https://doi.org/10.1073/pnas.2013741118

Many">https://doi.org/10.1073/p... thanks to co-lead author @ChrisRReid1 and coauthors Chris Lustri, @albert_kao, @sjmgarnier, and PI @icouzin!

& @MPI_animalbehav, @UniKonstanz, @CBehav, @Princeton, @stri_panama, @NJIT, @Macquarie_Uni, @sfiscience (7/7)