‘Xenobots’, using harvested cells from African frogs Xenopus laevis, were designed by artificial intelligence and can now reproduce under controlled lab conditions.
First came the announcement, in January 2020, that robots made from frog skin and heart cells are alive – the world’s first ‘living robots.’
Now comes the announcement that these living robots, ‘Xenobots’, can reproduce.
A news release by the University of Vermont announces that “scientists have discovered an entirely new form of biological reproduction — and applied their discovery to create the first-ever, self-replicating living robots.”
These “computer-designed and hand-assembled” organisms do not reproduce by laying eggs, or bonding in pairs resulting in a pregnancy.
The study’s authors write “Like the other necessary abilities life must possess to survive, replication has evolved into many diverse forms: fission, budding, fragmentation, spore formation, vegetative propagation, parthenogenesis, sexual reproduction, hermaphroditism, and viral propagation.”
Well, Xenobots do none of these things.
Instead, they “swim out into their tiny dish, find single cells, gather hundreds of them together, and assemble ‘baby’ Xenobots inside their Pac-Man-shaped ‘mouth’ — that, a few days later, become new Xenobots that look and move just like themselves,” Brown explains.
Brown writes that, “And then these new Xenobots can go out, find cells, and build copies of themselves. Again and again.”
Joshua Bongard, a computer scientist and robotics expert at the University of Vermont who co-led the new research, says “With the right design — they will spontaneously self-replicate.”
The results of the new research are featured in the December 7, 2021 issue of the Proceedings of the National Academy of Sciences. The authors discuss ‘kinematic replication’ of the Xenobots in the paper, marvelling that this new version of replication has taken no time to evolve at all: “We find that synthetic multicellular assemblies can also replicate kinematically by moving and compressing dissociated cells in their environment into functional self-copies. This form of perpetuation, previously unseen in any organism, arises spontaneously over days rather than evolving over millennia.”
“These are frog cells replicating in a way that is very different from how frogs do it. No animal or plant known to science replicates in this way,” says Sam Kriegman, the lead author on the new study, who completed his PhD in Josh Bongard’s lab at UVM and is now a postdoctoral researcher at Tufts Allen Center and Harvard University’s Wyss Institute for Biologically Inspired Engineering.
“We asked the supercomputer at UVM to figure out how to adjust the shape of the initial parents, and the AI came up with some strange designs after months of chugging away, including one that resembled Pac-Man,” says Kriegman.
“It’s very non-intuitive. It looks very simple, but it’s not something a human engineer would come up with. Why one tiny mouth? Why not five? We sent the results to [co-author Douglas Blackiston] and he built these Pac-Man-shaped parent Xenobots. Then those parents built children, who built grandchildren, who built great-grandchildren, who built great-great-grandchildren.” In other words, the right design greatly extended the number of generations.
These millimeter-sized living machines, entirely contained in a laboratory, easily extinguished, and vetted by federal, state and institutional ethics experts, “are not what keep me awake at night. What presents risk is the next pandemic; accelerating ecosystem damage from pollution; intensifying threats from climate change,” says UVM’s Bongard. “This is an ideal system in which to study self-replicating systems. We have a moral imperative to understand the conditions under which we can control it, direct it, douse it, exaggerate it.”
Bongard puts forward the race to find vaccines for multiple strains of the coronavirus as an example. “The speed at which we can produce solutions matters deeply. If we can develop technologies, learning from Xenobots, where we can quickly tell the AI,: ‘We need a biological tool that does X and Y and suppresses Z,’ —that could be very beneficial. Today, that takes an exceedingly long time.”
The team, Brown writes, aims to accelerate how quickly people can go from identifying a problem to generating solutions—"like deploying living machines to pull microplastics out of waterways or build new medicines,” Bongard says.
“We need to create technological solutions that grow at the same rate as the challenges we face,” Bongard says.
Brown also mentions how the researchers see promise in Xenobots for regenerative medicine. “If we knew how to tell collections of cells to do what we wanted them to do, ultimately, that's regenerative medicine—that's the solution to traumatic injury, birth defects, cancer, and aging,” says Levin. “All of these different problems are here because we don't know how to predict and control what groups of cells are going to build. Xenobots are a new platform for teaching us.”
THUMBNAIL IMAGE: On the left, the anatomical blueprint for a computer-designed organism, discovered on a UVM supercomputer. On the right, the living organism, built entirely from frog skin (green) and heart muscle (red) cells. (Sam Kriegman, UVM)
HEADLINE IMAGE: The probability of halting (α) or replicating( 1 − α) depends on a temperature range suitable for frog embryos, the concentration of dissociated cells, the number and stochastic behavior of the mature organisms, the viscosity of the solution, the geometry of the dish’s surface, and the possibility of contamination. (PNAS)