CNN  — 

What if you could help nature by simply going out for a run? That’s the idea behind Rewild the Run, a 3D-printed shoe outsole that fits over regular sneakers. It’s covered in small loops that function as hooks, grabbing dirt and seeds and carrying them along for the ride.

The loops are designed to mimic how certain types of seeds hook themselves onto the fur of wild animals, and the bottom of the outsole is shaped like the hoof of a bison, which is regarded as a keystone species — an organism that plays a crucial role in the upkeep of its own ecosystem. Bison aerate the soil as they graze with their unique hoof shape, also pressing down seeds into the ground.

The hope is that by spreading seeds, shoes fitted with the outsole could help with rewilding, a form of nature restoration that enables the environment to take care of itself, with reduced human intervention.

“Living in London, I felt very disconnected from our local environment and our nature,” says Kiki Grammatopoulos, the product designer who created the outsole as a master’s student at Central Saint Martins. “So I started thinking about ways that I could replicate keystone species in London,” she adds, “because obviously, I can’t really bring in bison or wolves into King’s Cross.”

Inspired by nature, the 3D-printed blue outsole, shown here over a running shoe, could help disperse seeds and promote rewilding.

Mimicking nature

Following the principles of biomimicry (the practice of replicating techniques or processes that occur in nature), Grammatopoulos looked at two seed types to get inspiration for the structure of the loops at the sides of the outsole: the cocklebur, and the grapple plant or devil’s claw. “The cocklebur has a straight spike, and the grapple plant has a slight curve,” she says. “I tried to incorporate them both.”

The cocklebur is famous for having inspired the invention commonly known as Velcro, a fastener system that contains tiny hooks on one side and tiny loops on the other. George de Mestral first came up with the idea in 1941 after he found cockleburs routinely clinging to his dog’s fur after walks in nature.

Grammatopoulos used Velcro during early testing of her outsole prototype. “Before I did any 3D modeling, I’d cover my shoes in Velcro to just have a look at what my shoe would pick up and over what areas of the shoe,” she says.

When worn during a run, the outsoles can pick up smaller seeds within dirt or larger seeds hitching along for a ride, and disperse them in a different area — at least in a more effective way than regular trainers, according to Grammatopoulos. But she points out that the outsole is just a concept, not a commercial product.

“I wouldn’t expect anyone to run in these as they are right now,” she says, “It’s more about exploring … the environment you’re running in, and also to allow people to feel a bit more comfortable in running in greenery and not be scared of it.”

The designer adds that she’s interested in developing the idea further, with the help of rewilding experts and more advanced production technologies, although she’s unsure whether a more refined design would still be an outsole — to apply to existing footwear — or a standalone shoe.

Unwanted guests

Rewilding is part of a wider approach to enabling nature recovery, according to Ralph Fyfe, a professor of Geospatial Information and rewilding expert at the University of Plymouth in the UK. “In urban landscapes, the focus is often to increase biodiversity and support a series of environmental services that nature can provide – for instance contributing to net zero, supporting pollinators or reducing urban runoff,” he says.

Rewilding can be deliberate — by introducing particular species that have become rare or absent – or can happen by simply enabling nature to take control. “This shoe-based approach lies firmly in the latter camp,” according to Fyfe. “I’d say every little bit helps.”

We know, he adds, that long-distance dispersal is possible via seeds attached to the fur of animals, and that this can enable genetic diversity in plant populations by introducing seeds over longer distances. “I don’t think the shoes will fully replicate this process, and of course people will run in different places to animals, so there inevitably would be some inadvertent selection of plant species that benefit,” Fyfe says.

However, this could have unwanted effects, according to Stephen Carver, a geographer and senior lecturer at the University of Leeds in the UK. “It’s an interesting idea, but my first impression is that it’s a great way to spread non-native, invasive weed species,” Carver says. “How will these shoes distinguish between the seeds of native and non-native plant species?”

Carver is skeptical about the principle of urban rewilding itself. “Rewilding needs to take place at scale, where we give nature the space and the time to determine its own trajectories and outcomes,” he says. “While we can utilize nature-based solutions in urban environments and restore some urban spaces to a wilder condition, thereby increasing biodiversity, rewilding cannot be fully realized within the constraints of the urban fabric. I like the idea of the shoes, but I fear they will have little good effect or even the opposite.”

Grammatopoulos agrees that it’s crucial to address the potential spread of invasive species, which requires ongoing development of her design, discussions with experts and a wider effort by cities or councils. “Nonetheless, as the project is still in development, the design could be refined to select for certain species, or the user can avoid areas with known invasive species,” she says.

She also shares the vision of rewilding taking place at scale and by giving nature space, and says that would be the ideal in cities such as London. “However, with this project, I am discussing what rewilding could look like on a smaller, more local scale,” she says, “where there isn’t the luxury of space.”