By Amanda Peppe
Remember your Covid pod? Your ‘quaranteam’ culled from a roomful down to a handful of friends? I was in a pod of seven. Some of those members were in other pods, which also seemed to have seven. As a network, we were single-minded in following the rules to keep each other safe.
Research now shows that 7.2 was the average number of people in a Covid pod, small groups which provided a safer way to socialize with people outside your household. Curiously, It turns out that seven is a key number across multiple species that gather in schools, flocks or herds to outwit predators or to balance asymmetry of power.
Take the starling for example. Each starling becomes a vital team player in a murmuration that can run to a hundred thousand strong, yet they appear to dive, twist and turn as one. For all these rapid maneuvers, somehow, the flock’s boundaries remain intact. There are no outliers. No collisions. It’s awe inspiring to watch the aerial grace and mathematical symmetry of a murmuration because at the core of this spectacle, something feels inherently ‘right’.
It was understood why this phenomenon existed: shapeshifting into a giant cloud-sized opponent is a great way to outwit predators. But no one knew how they communicated with such speed across large distances with utter cohesion. Where was the leader?
Various theories were touted: the birds might be using frequencies beyond our detection, or a highly sensitive magnetic substance in the beak helped them follow earth’s electromagnetic fields, but neither of these explanations explained the uncanny group cohesion or how a sudden shift in direction lacked any lag time.
Professor Andrea Cavagna, Research Director at the Institute for Complex Systems, CNR, Rome, studied starling flight patterns with a team of scientists who set up an observation post on a roof in Rome’s Palazzo Massimo.
Each bird was tracked using stereoscopic cameras and their paths were translated into a computer-generated mathematical model. After three years of painstaking work, it appeared that there was no group leader, no central intelligence.
Each starling was tracking its seven nearest neighbours, and those neighbours were tracking their seven neighbours. It seemed that seven was the optimal number to maintain group cohesion. A number that seems to crop up in many species, including tuna, honeybees, carpenter ants, meerkats, finches and swallows.
The Starling Murmuration Optimizer (SMO) is one of many algorithms now being studied. Dr. Robert Romanofsky, Senior Technologist at NASA’s Glenn Research Center, says: “Given a centralized algorithm has a single point of failure, decentralized control is more resilient. In an artificial swarm, instead of each drone communicating a complete map of safe space to every other drone, a decentralized algorithm requires information sharing only with immediate neighbors.”
Swarm intelligence algorithms are creating novel answers for old problems. The military is building a network of robots for high-risk search and rescue missions so that victims can be found faster and with greater efficiency. Businesses are using bee algorithms to hive-mind intelligence and enhance group decision making.
The study of collective animal behaviour is becoming a cross-disciplinary field where mathematics, biology, computer science and physics blend into a new discipline.
So, it’s no surprise that humans ‘pod’ in a crisis, especially in the face of a novel virus, what is surprising is that when facing unknown danger, it seems seven is the lucky number for us, too.
Amanda Peppe is a produced screen writer, novelist and nerd. Her obsession with patterns, resonance and the weird world of non-Euclidean geometry is grist for her second novel, Blue murder.