In January of 2020, scientists from the University of Vermont announced they had built the first living robots; this week they have published reports that those robots, made from frog cells and called Xenobots, can reproduce and have found a new way to do so.
The millimetre-sized xenobots are essentially a computer-designed collection of around 3,000 cells. They were created by taking stem cells from frog embryos, scraping them, leaving them to incubate, then cutting them open and sculpting them into specific shapes. After all that action, the cells began to work on their own – auto-repairing when sliced and moving about inside petri dishes.
With a little design tweak, the creatures could do even more. "With the right design, they will spontaneously self-replicate," said University of Vermont researcher Joshua Bongard, Ph.D. in a canned statement.
This reproduction is not the usual biological reproduction – no soft music, flowers or bottles of wine were involved. Instead, the organisms seem to assemble and incubate their offspring, working kinematically. They swim out to find single cells, gather hundreds together and then assemble "baby" Xenobots inside their Pac-Man shaped mouths. After a few days in the orifice, the new Xenobots look and move like their parents – including the ability to form new creatures on their own.
For those who have difficulty imagining what that looks like, the entire process is demonstrated in a video.
"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," said co-author Douglas Blackiston, Ph.D., who developed the biological portion of the study.
Initially, the parent would form a child, but the system would die off – so the researchers searched billions of body shapes in simulation using an evolutionary algorithm to find the optimal form. The test was conducted using AI and the Deep Green supercomputer cluster at UVM's Vermont Advanced Computing Core.
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One of the shapes the supercomputer came up with was the Pac-Man shape. The researchers found that when formed to that shape, the Xenobots could extend their number of generations.
"It's very non-intuitive. It looks very simple, but it's not something a human engineer would come up with," said study lead author Sam Kriegman, Ph.D., evidently forgetting that a human wrote Pac-Man.
Boffins are working with Xenobots because it's hoped they could do things like carry medicine inside human bodies, clean up radioactive waste or collect microplastics in the oceans. However, the researchers themselves seem most focused on the potential of using the Xenobots as an AI biomedical learning platform.
"The world and technologies are rapidly changing. It's important, for society as a whole, that we study and understand how this works," said Bongard, who insists that the contained project — with its ethics approvals and regulations — does not keep him up at night. What worries him are pandemics, ecosystem damage and climate change.
"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," lamented the boffin.
The results of the new research were published November 29, 2021, in the Proceedings of the National Academy of Sciences. ®