Level 6: Xenobots as Game Characters
Building robots out of living cells.
Welcome to The Gameful Scientist! This newsletter explores the intersection of bio and gaming. Enjoy!
Imagine playing a game where the main character is not a human, an animal, or a machine, but a living robot made of frog cells. This may sound like science fiction, but it’s very real. Meet xenobots: the world’s first synthetic lifeforms that can move, cooperate, and even reproduce. These tiny creatures challenge our ideas about life, intelligence, and technology.
In this article, we’ll explore what xenobots are, how they’re created, how they behave, and what they can do. We'll also explore how games can help us understand and interact with them, imagining xenobots as main characters in different game genres like sandbox, biotic, and swarm games. By showing how games can make learning about these incredible creatures fun and immersive, we hope to inspire new ways of engaging with them.
Welcome to Level 6.
Tiny Living Robots
Xenobots are tiny living robots made of frog cells. They’re only a few millimeters wide and get their name from the African clawed frog (Xenopus laevis), whose stem cells are used to make them. But xenobots don’t look or act like frogs. They have novel shapes and behaviors that are designed by computers and built by scientists using microsurgery. These cells are free to form new patterns and functions that go beyond “frogness”.
Here’s a primer video by Scientific American:
Here’s another with Dr. Michael Levin on the Lex Fridman Podcast:
Designed in a Computer, Made in a Lab
Xenobots are created using a computer program that simulates how different combinations of cells would behave when put together. This program uses evolutionary algorithms, which mimic natural selection by generating and testing many possible designs, then selecting and improving the best ones based on specific behavioral goals, such as walking, swimming, pushing pellets, carrying payloads, or working together in a swarm. The selected designs are then taken to a lab, where scientists use stem cells harvested from early frog embryos to grow different cell types. These cells are cut and joined together using tiny forceps and electrodes to form xenobots that match the computer designs.
Dr. Douglas Blackiston, one of the pioneers in this space, says:
I think there’s this misconception that all of biology is this hard, rigorous discipline, and that there’s no creativity, or beauty or artistry. But it’s incredibly amazing to look down the eyepiece and to build something that no one has ever seen before.
This approach to creating new machines, designing them in simulation and then selecting the best design to build and test, is similar to the approach used in the game Eterna. In Eterna, players design RNA molecules using a computer game, which then get tested in a cloud lab that links the game to real-life experiments. Dr. Rhiju Das, co-founder of Eterna, calls this a "massive open laboratory" Could a similar approach be used to create a "massive open laboratory" for xenobot research?
Shape-Shifting Code
When we think about programming biology, we often think about genetic engineering, where we go into a cell, change its genetic code, and make it do what we want it to do. But with xenobots, programming is different. They offer a new way of programming biology by designing and assembling cells into novel shapes and functions that are not found in nature.
These organisms behave based on their physical shape and cellular composition. They're made up of two types of cells: skin cells and heart muscle cells. Skin cells are typically stationary, while heart muscle cells can move and contract. By combining these cells in different ways, scientists can program xenobots to move in certain ways. For example, xenobots with more heart muscle cells tend to move faster than those with more skin cells, while xenobots with a fork-like appendage can push or carry objects better than those without it.
Xenobots can also adapt to their environment by changing their shape or behavior over time. They can heal themselves after being cut or damaged by regenerating new cells or rearranging existing ones. Xenobots can even reproduce through a process called kinematic self-replication, where they release smaller versions of themselves that inherit some of their traits, but also have some variations due to random mutations or environmental influences. This is a completely new form of biological self-replication that has never been seen in nature before.
Dr. Joshua Bongard, another pioneer in this space, says:
We don't want uncontrolled self-replication. That's a dangerous thing. But for a roboticist, the realization that xenobots could self-replicate is a huge deal because roboticists have been trying to create self-replicating machines for a very long time.Seems that when you do this with living materials, it's suddenly much easier.
Endless Possibilities
It's still early days, but xenobots have the potential to achieve many applications that conventional robots or organisms can't. These include:
Environment: Xenobots can clean up radioactive waste, collect microplastics in the oceans, or remove plaque from clogged arteries by moving, pushing, carrying, or aggregating objects.
Drug delivery: Xenobots can carry medicine inside human bodies by surviving for weeks without food or oxygen and healing themselves after damage.
As we move towards human medicine, the next step is going to be to make these out of mammalian and eventually out of a patient's own cells. Dr. Michael Levin
Bioengineering: Xenobots can restore organs or develop body parts for transplant using their own cells or those of a patient. They can also create new generations of themselves with novel features or functions not initially programmed into them.
Exploration: Xenobots can explore inaccessible or hazardous terrains by swimming, crawling, working in swarms, and communicating with external devices using light signals or chemical cues.
As we improve our ability to control and program xenobots, we'll uncover more exciting possibilities. One of these is the emergence of a community similar to iGEM, an international competition for undergraduates exploring synthetic biology. While iGEM primarily uses bacteria to solve environmental and medical challenges, a similar community could emerge for developing and applying xenobot technology to a wider range of problems.
Playing with Xenobots
Games are powerful tools for exploring and understanding biology. They can help us visualize how biological systems work, their capabilities, and consequences. Games also offer feedback that helps us learn from our mistakes and improve our decisions based on the outcomes of our actions.
But what would a game with xenobots look like? How do we bring these living robots to life on our screens? What kind of challenges and adventures would we design for them? And how do we create a connection between players and these tiny creatures?
Here are some ways to design games with xenobots:
Sandbox games: We discussed these types of games in Level 5. These games are digital playgrounds where players get an incredible level of creative freedom to experiment, build, and create without predetermined goals or paths. For example, you can build a house in Minecraft, design a planet in No Man’s Sky, or create a skybridge in Terraria. Some features of sandbox games include:
Open world: Researchers can create simulated environments where digital xenobots can play and interact with each other or with other objects. For example, they can create a maze and see how the xenobots navigate them
Creativity and freedom: Players can design their own virtual xenobots with different structures and behaviors, then test them in different challenges or environments. For example, they can design xenobots that can move faster, communicate better, cooperate more, etc., then see how they perform in different tasks.
Minimal predefined goals: Researchers can set their own goals for what they want to achieve with their virtual xenobots.
Biotic games: We discussed these types of games in Level 4. These are games where players use living organisms as characters or controllers. In these games, the xenobot would be the bioware. Some features of biotic games include:
Real-time interaction: Players can remotely control real xenobots using augmented reality or haptic feedback devices. They can see what their xenobots see using a camera attached to them, or feel what they feel using a glove or a joystick.
“So the obvious next step from a robotics perspective is to add sensors so they can move towards or away from a stimuli.” - Dr. Sam Kriegman
Communication: Players can communicate with their xenobots using light signals or chemical cues. They can send commands or feedback to their xenobots, or receive information from them.
Learning: Players can experience what it is like to be a xenobot, as well as learn about their biology and ecology. They can observe how xenobots move, heal and work together.
Competition: Players can compete against each other to see who can program the most efficient xenobot or who can create the most complex self-replicating organism. They could also challenge other players to battle bots matches, where they pit their xenobots against each other in an arena.
Swarm games: These are games where players work together with other human or artificial agents to solve problems using a swarm of cooperative entities. Popular examples include Starcraft and Age of Empires. We’ll explore this game genre in a future “Level”.
Xenobots exhibit cooperative swarm activity, in this case working together to gather piles of tiny particles. Image by Dr. Doug Blackiston.
Through games, researchers can better understand how xenobots behave, learn how to program them for specific tasks, and discover new applications. As technology advances and our knowledge of these living robots expands, the potential for creating new and exciting games with xenobots will continue to grow.
I’ll leave you with a quote from Dr. Michael Levin:
Think about it. We were all single celled organisms once. We were bacteria before that. And now you and I feel like an integrated, centralized intelligence with our own memories and hopes and preferences. There was no time at which a magic lightning bolt said, Okay, before you were just chemistry and physics, but boom, now you're a cognitive creature. That doesn't happen.
We can't roll the tape of life back on Earth, but we can create xenobots to ask how do small, competent subunits work together to make a larger mind?
Maybe games can help with this.
See you next week :)
Thanks for reading The Gameful Scientist! Thanks to Dr. Michael Levin for the very helpful chat.
Interested in learning more about xenobots? Check out these resources:
Dr. Sam Kriegman’s Xenobot Lab
Dr. Josh Bongard’s Youtube channel
Dr. Blackiston’s “Images/Videos”
Talks by Dr. Michael Levin
Great general overview by AsapSCIENCE
Feel free to contact me here or chat with me on Twitter @ATrotmanGrant :)