A New Field

The Invention of Xenobots

In early 2020, Joshua Bongard (University of Vermont) and Michael Levin (Allen Discovery Center at Tufts University) were among the lead authors of a paper showcasing a remarkable achievement: the world’s first computer-designed organism. The New York Times called them “a new class of living robotics.” The scientists named the xenobots after the frog species from which they are derived, Xenopus laevis.

The scientific journal articleThe New York Times

Xenobots are living, swimming, self-powered biological robots less than a millimeter across, evolved by artificial intelligence and engineered with computational design tools. Xenobots replicate, repair themselves, and affect their environments.

Xenobots are part of a new class of biology that exploits life’s incredible capabilities — collective intelligence, cellular memory, and independent drive — that we call agential materials. They could open new frontiers of virtually every field, from pharmaceuticals to beauty.

A Timeline of Agential Biology

• 2020 — Evolutionary algorithm. An evolutionary algorithm searched millions of body plans in simulation against a stated goal. The best were built by hand from Xenopus laevis skin and cardiac cells. Under a millimeter across, powered by their own embryonic yolk for about a week before biodegrading, the first xenobots walked, pushed particles into piles, worked in groups, and healed themselves after being cut. The achievement was the pipeline: a repeatable path from a specified behavior to a living thing that performs it.
• 2021 — Self-assembly, swarms, and memory. The second generation was grown rather than sculpted. Stem cells self-assembled into spheroids, grew their own cilia, and swam on them. They navigated narrow capillary tubes, swept larger particle piles as a swarm than any bot could alone, closed most of a full-length laceration within five minutes, and lived up to ten days on embryonic stores. The team also gave them a memory — an engineered protein that switches from green to red under 390-nanometer light — so a bot returns carrying a record of where it has been.
• 2021 — Self-replication. Placed in a dish of loose stem cells, xenobots gathered those cells into piles that matured into new xenobots, which did the same. An AI search found a C-shaped body plan that sustained this across generations. It is a form of reproduction not seen in any other organism.
• 2023 — Anthrobots. Biobots built from adult human tracheal cells, no genetic modification, 30 to 500 micrometers across, surviving 45 to 60 days. Clustered into “superbots” and laid across a scratch in a sheet of human neurons, they induced regrowth across the gap. Nothing grew where they had not touched. Xenobots proved the method; anthrobots proved the substrate is not particular.

A New Concept of Life

Xenobots are the first example of agential material, more generally known as biobots (biological robots). Derived from cells from the Xenopus laevis frog, they repair, replicate, and make decisions in their environment. In principle, any cell could be used to make biobots.

In the very recent past, we reserved characteristics such as intelligence, agency, and purpose for whole organisms, if not solely for humans. Breakthroughs by the Levin Lab and the Bongard Lab have demonstrated that these properties operate all the way down to the cellular level — and that they can be manipulated. Scientists exploit morphogenesis — the process by which cell groups build or repair a complex organism — by literally reshaping cells at different points in their early development, programming biobots to perform goal-directed tasks.

Read NYMag’s profile of Mike Levin

And because of life’s internal engine, agential materials can self-replicate, making them ideal workers. Moreover, biobots store cellular memory: they have an inherent drive to grow, develop, and repair biological materials in situ. They can even heal neural material. Agential biology, then, both relies on core aspects of life and capitalizes on its extraordinary malleability.

Thus, agential biology is not only a new way of doing science; it ushers in novel philosophical orientations about life itself. There is an incredible opportunity, right now, to lead cutting-edge scientific research with a growing community, commercialize biobots at scale with the inventors’ IP, and to define a field that is poised to impact all levels of culture and society.

Further reading — full bibliography