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The world’s first ‘living robots’ can self-replicate, furthering hope for regenerative medicine

Last year, scientists created Xenobots, tiny ‘machines’ engineered from frog stem cells. It turns out these organisms are capable of kinematic self-replication.

The world’s first ‘living robots’ can self-replicate, furthering hope for regenerative medicine
[Source Images: Ilya Lukichev/iStock]

In January 2020, scientists created a new breed called the “Xenobots”—the world’s first-ever living robots, engineered from the stem cells of the Xenopus laevis species, or the African clawed frog. The Xenobots functioned as tiny (less than a millimeter-wide) machines that could walk or swim by propelling themselves with hair-like cilia, survive for weeks without food, and work together in groups. Their very existence was a wholly new life-form; a scientific and natural marvel.

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You see, “living robot” is a novel term: A robot isn’t always the hunkering, metallic contraption that popular culture would have you imagine, but rather refers to any machine that can perform useful work in the world. And Xenobots have no whizzing gears or shiny facades—they’re best described as blobs of pink flesh, floating about in a petri dish. Born from the stem cells of embryonic frogs—which would otherwise have matured into the skin and heart of a living, breathing animal in time—Xenobots were cultivated as a “new class of artifact: a living, programmable organism,” Joshua Bongard, a computer scientist and coleader of the project, said at the time. The researchers envisioned future uses for Xenobots ranging from scouring for radioactive waste, to clearing microplastics from the oceans, to scraping plaque from human arteries, to fixing electrical circuits.

Now, the same team—from the University of Vermont, Tufts University, and the Wyss Institute for Biologically Inspired Engineering at Harvard University—has revealed an exciting new development in its futuristic ambition: They discovered Xenobots can actually self-replicate. Researchers stumbled upon this while testing the organisms’ ability to clean their own petri dish; when dye particles and silicone-coated iron beads were spilled among their pond-water habitat, Xenobots would bulldoze the debris into neat piles. What would happen, scientists wondered, if those piles were instead full of Xenobot stem cells? Another experiment later, they had their answer: the Xenobot-constructed piles morphed into baby offspring, sprouting their own cilia and beginning to motor around.

Most fascinatingly, the Xenobots’ curious behavior was occurring spontaneously—without the help of human programming. Researchers employed artificial intelligence to design the cell shape most conducive to Xenobot replication, which turned out to look like the 1980s video game’s Pac-Man character, yielding four generations of new organisms. But the fact that the Xenobots themselves had figured out how to replicate—and in a way never before seen in plants or animals—was astounding. Called spontaneous kinematic self-replication, this type of process has been observed in molecules, but never organisms.

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Couple that with the Xenobots’ already reported self-healing powers—they can regrow after being sliced to pieces—and they could become formidable agents in regenerative medicine, used to fight everything from traumatic injuries, to birth defects, to aging. One day, they could even be used as autonomous surgeons.

But of course, the Xenobots’ display of independence also calls to mind the rise of the machines—alarmingly, perhaps, to some, as science fiction has conjured dystopias where robots with vastly superior intelligence conquer the human race. However, researchers say there’s nothing to fear: Xenobots currently cannot live outside of a laboratory and, without nutrition or energy sources, have short lifespans, dying after only a few weeks. Their creation was funded in part by the Defense Advanced Research Projects Agency (DARPA), under the Department of Defense, which oversees new technologies for military use.

The next step, Sam Kriegman, a scientist who worked on the project, told Insider, will be to give Xenobots sensory organs, such as a way to see. “Right now, they’re essentially swimming around with their eyes closed,” he said. But if their eyes were opened? Who knows! As the team of researchers wrote in their report, “Life harbors surprising behaviors just below the surface, waiting to be uncovered.”

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