Researchers at the University of Vermont, Tufts University, and the Wyss Institute for Biologically Inspired Engineering at Harvard University have discovered an entirely new form of biological reproduction and applied their discovery to create the first-ever, self-replicating living robots.
Last year, the same team created the first living robot, the Xenobot, a new type of organism made using cells scraped from frog embryos and assembled into entirely new life-forms. The Xenobots are less than a millimeter (0.04 inches) wide and could move, work together in groups and self-heal.
The researchers have now discovered an entirely new form of biological reproduction different from any animal or plant is known to science. These computer-designed and hand-assembled organisms can 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. Then these new Xenobots can go out, find cells, and build copies of themselves.
Researchers explain the Xenobots were initially sphere-shaped and made from some 3,000 cells. The sphere-shaped Xenobot can make children, but then the system normally dies out after that. But an evolutionary algorithm was used to find the Xenobot body shape that allowed the cells to be more effective at the motion-based “kinematic” replication reported in the new research.
With an artificial intelligence program working on the Deep Green supercomputer cluster at UVM’s Vermont Advanced Computing Core, the algorithm was able to test billions of body shapes in simulation – triangles, squares, pyramids, starfish – to identify a Xenobot design that increases the ability to reproduce.
“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 Sam Kriegman, Ph.D., the lead author on the new study. “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 Doug, 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.
“People have thought for quite a long time that we’ve worked out all the ways that life can reproduce or replicate. But this is something that’s never been observed before,” says co-author Douglas Blackiston, Ph.D., the senior scientist at Tufts University and the Wyss Institute who assembled the Xenobot “parents” and developed the biological portion of the new study.
The team sees promise in the research for advancements toward regenerative medicine – that’s the solution to traumatic injury, birth defects, cancer, and aging. They aim 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, says Joshua Bongard, who co-led the research.