the ant expert

I’m watching the seventh episode of Planet Earth III, featuring the animal on Earth with which I am most familiar.

Humans.

“Eight billion people now live on this planet,” Attenborough tells me. “And we are changing the world around us at such speed that, for animals, the challenge is to keep up.”

The episode details how animals have adapted to life with humans. It shows a rhino walking through the busy streets of Sauraha, Nepal, passing the “Rhino Lodge & Hotel” and being filmed by fearless onlookers with camera phones in hand. I watch a long-tailed macaque in Bali eat from a can of Pringles it took from a tourist at the Uluwatu temple. Then, Attenborough takes me to the far-more familiar New York City, where he starts to tell me about ants.

“The segment focuses on my research on ants in New York City,” Penick said. “Ants are small and often don’t get much attention, so I was thrilled when the BBC reached out to help them develop a pitch and serve as a scientific advisor.”

Penick worked with the production team for nearly three years as a paid consultant, and he’s studied these particular urban ants for more than seven years.

“I use New York City as a model to study how urbanization impacts biodiversity, specifically insects,” he said. “New York City is the largest and most densely populated urban area in the United States, and it has a surprising abundance and diversity of ants — there are 2,000 ants for every human living in New York City, and more than 40 ant species can be found within a 10-mile radius of the Empire State Building.”

The episode discussed what are known as pavement ants — a species thought to have arrived with the first European settlers and nicknamed so because they live almost exclusively in towns and cities.

According to Penick, insects play a dominant role in urban ecosystems in terms of both their abundance and diversity, but their role in these ecosystems remains poorly understood. The diversity of insects in cities is barely characterized, let alone the impacts of insects on nutrient cycling, soil health, pollination, disease transmission and other ecosystem processes.

Working in places like New York City, scientists like Penick study the role human foods play in urban food webs and how social insects are adapted to urban life. He’s shown that the most abundant ants in cities are those that exploit human foods.

“The research featured in Planet Earth III focuses on how ants living in the city are able to find and recruit to the foods we drop on the ground,” Penick said. “It also shows the battles ants must fight with competitors, like pigeons, as they try to secure this limited resource.”

Most ants have smooth “skin” — not really skin at all but what is known as the cuticle coating their bodies. However, some ants have elaborate textures and patterns.

Since ants emerged between 160 million and 140 million years ago, records indicate that facial textures have cycled in and out of existence. This led Penick and his former grad student John Paul Hellenbrand (now at the City University of New York) to wonder if the textures on the faces of ants might have evolved purposefully, and their work was published in Science News in January 2024.

Soil-dwelling ants have “almost psychedelic” swirling facial ridges, which could protect them from scratches in sandy soil, Penick said. The ridges are too tight for even a grain of sand to fit between.

But the idea needs further study, according to Penick and colleagues in the field. Some patterns might bolster structural support, influence biofilm growth or function in ant communication, he said. For now, we don’t know.

For the time being, we can thank researchers like Penick for teaching us — through the calming voice of Attenborough — how these foes of suburban yards are carving a place for themselves in cities around the world.