Xenobots: Meet the First Living Machines Made of Frog Cells

The discovery that could revolutionize our understanding of cellular biology

Scientists just got closer to recreating science-fiction movies such as Blade Runner 2049 and Terminator in real life—this time, with real, living robots. Sitting in Petri dishes, tiny blobs hardly one-millimeter wide move, drawing circles and allocating pellets into piles. Some walk with two legs, some swim with beating cilia, and some have holes in the middle of their bodies that function as pouches to carry miniature payloads. Flip them over, and they resemble beetles lying on their backs (1).

These are Xenobots, the literal offspring of artificial intelligence and molecular biology. To create these living machines, researchers from the University of Vermont and Tufts University stitched together skin and cardiac cells scraped from the embryos of the African clawed frog, Xenopus Laevis (from which Xenobots derive their name). This discovery marks the first time scientists have created an entirely new organism, as scientists’ ability to create novel lifeforms was previously limited to varying existing organisms or bioengineering organoids in vitro, according to the researchers’ study published in January (6). Fueled by embryonic energy stores—preloaded proteins and lipids—these organisms can survive for up to seven to ten days. In a nutrient-rich cell-culture media, however, their lifespan can increase to several weeks or even months (2). Although they may have different functions, they all have one thing in common: they look nothing like frogs.

“They’re neither a traditional robot nor a known species of animal,” study co-author Joshua Bongard, a computer scientist and robotics expert at the University of Vermont, said in a statement. “It’s a new class of artifact: a living, programmable organism” (3).

The research team utilized a computer algorithm, which used physics engines similar to those in video games such as Fortnite and Minecraft, at the University of Vermont to “evolve” Xenobots into existence (5). The simulation generated designs, limited in areas such as maximum tissue muscle power and capability to move through watery environments, which were transferable to real cells (3). The more promising simulations were kept and refined, while the failed ones were discarded—similar to the survival of the fittest and the theory of evolution. In total, there were thousands of candidate designs for new life-forms, all with different designs. 

The team then sent the most promising designs to Tufts University. The Tufts team, led by study co-author Michael Levin, director of the Center for Regenerative and Developmental Biology at Tufts University, with key work done by microsurgeon Douglas Blackison, brought the in silico designs to life (1). After the scraped stem cells incubated, scientists, working with tiny forceps and electrodes under a microscope, cut and joined several hundred cells into close approximations of each computer design (1). These newly formed three-dimensional shapes began to move autonomously through the watery Petri dishes; bonded skin cells formed their structure while pulsing heart muscle cells propelled them forwards. Determined by the computer’s design, the beating of heart tissue in specific parts of Xenobots’ bodies would guide their movement patterns (3). 

The simulation designs compared to their living counterparts.

The applications for Xenobots are endless. Their ability to survive in aqueous environments means they are not only suitable for internal drug delivery in living organisms, including humans, but also for cleaning up radioactive waste and collecting microplastics in the oceans (4). The authors contend that if scientists could make 3-D biological forms on demand, they could potentially repair birth defects, reprogram tumors into normal tissue, regenerate limbs after a traumatic injury or degenerative disease, and ultimately, defeat aging (2).

Many technologies used today are composed of steel, concrete, chemicals, or plastic. Because these materials degrade over time, they severely harm ecosystems and generate health side effects—take plastic pollution in oceans, for example (7). In contrast, Xenobots are made of self-renewing and biocompatible materials. Although their living tissue is weaker, they degrade into nothing more than skin cells (6). Using living tissue may come with another benefit: in their study, the authors suggested that living organisms’ “innate ability to resist entropy might enable them to surpass the useful lifetimes of our strongest yet static technologies” (6) In addition, living organisms have had billions of years of practice regenerating themselves; this is no different for Xenobots, which can heal themselves even after being sliced in half (1). 

Paths the Xenobots traced through particulate matter. Note the irregularity of their movement.

The authors of the study also hope that Xenobots’ “eerily advanced behavior” can help scientists better understand how cells work together to form specific intricate anatomies, a question that extends into our understanding of computer science and of life (7). 

“The big question in biology is to understand the algorithms that determine form and function,” says Levin. “The genome encodes proteins, but transformative applications await our discovery of how that hardware enables cells to cooperate toward making functional anatomies under very different conditions” (1).

Yet, this discovery is slightly unsettling, if not downright terrifying for many—for good reason. The implications of Xenobots’ existence possibly include artificially-intelligent machines taking over, which has led to serious questions in ethics arising.  

“An uneducated public may see this as Frankenstein-like,” wrote Susan and Michael Anderson, machine ethics specialists concerned about the regulation of Xenobot development. “Applied ethics should be involved in their creation and development, not just scientists and engineers” (5). 

In response, Dr. Levin stressed how he regularly consults with an ethicist at Harvard’s Wyss Institute and how their research falls under ethical guidelines (5). The study authors also pointed out how without reproductive organs, the machines could not reproduce (2). 

Nevertheless, scientists have hardly scratched the surface in discovering the potential applications of Xenobots. 

“It’s exciting because of what it makes you think about, extrapolating into the future,” Mr. Sims, the virtual creatures pioneer, said. “It’s kind of fun when they feel alive” (5).

– Andrew Zhao


  1. Retrieved from https://www.uvm.edu/uvmnews/news/team-builds-first-living-robots
  2. (2019, April 08). Computer-Designed Organisms. Github. Retrieved from https://cdorgs.github.io/
  3. Weisberger, M. (2019, April 08). World’s First ‘Living Machine’ Created Using Frog Cells and Artificial Intelligence. Live Science. Retrieved from https://www.livescience.com/frogbots-living-robots.html
  4. Yeung, J. (2019, April 08). Meet the xenobot: world’s first living, self-healing robots created from frog stem cells. CNN. Retrieved from https://www.cnn.com/2020/01/13/us/living-robot-stem-cells-intl-hnk-scli-scn/index.html
  5. Sokol, J. (2019, April 08).  Meet the Xenobots, Virtual Creatures Brought to Life. The New York Times. Retrieved from https://www.nytimes.com/2020/04/03/science/xenobots-robots-frogs-xenopus.html?searchResultPosition=1
  6. Kriegman, S. Blackiston, D. Levin, M. Bongard, J. (2019, April 08). A scalable pipeline for designing reconfigurable organisms. Proceedings of the National Academy of Sciences of the United States of America. Retrieved from https://www.pnas.org/content/117/4/1853
  7. Simon, M. (2019, April 08). Meet Xenobot, an Eerie New Kind of Programmable Organism. Wired. Retrieved from https://www.wired.com/story/xenobot/


  1. https://media.wired.com/photos/5e191a3187b5f30008dd4ed0/master/w_1600%2Cc_limit/Science_livingrobots_04_Multiple_Design_Organism_Pairs.jpg
  2. https://media.wired.com/photos/5e191a15a5b5de000898c872/master/w_2560%2Cc_limit/Science_livingrobots_06_Vivo_Group_Behavior_Trace.jpg

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