Xenobots and the 'Third State' of Life: Do Cells Think After Death?

The familiar arc of life—birth, living, death—looks straightforward at the level of whole organisms. But at the cellular scale, the story is more complex. Each human body is a collective of roughly 30 trillion cells and trillions more microbes, cooperating to produce what we experience as a single living being. Recent laboratory work with engineered cell assemblies known as xenobots suggests that when an organism dies, some cells can reorganize and perform new functions, a phenomenon some researchers call a potential "third state" between life and death.

What Are Xenobots?

Xenobots are multicellular constructs assembled from living cells (originally frog cells) that are programmed or designed—often with the help of artificial intelligence—to form novel structures and behaviors. In laboratory experiments, cells in xenobots have been observed to reassemble, move using hairlike cilia in unconventional ways, and perform collective tasks they didn't carry out in their original organism. Similar experiments with human cell assemblies—sometimes dubbed "anthrobots"—have produced comparable adaptive behaviors.

Why Some Scientists Call This a 'Third State'

Proponents argue that when cells reorganize after the death of their host organism and form new, functioning collectives, they are exhibiting an intermediate mode of biological organization that is neither the original living organism nor classical death. In a September 2024 piece for The Conversation, Peter Noble, PhD, and Alex Pozhitkov, PhD, suggested these behaviors challenge the idea that cellular and organismal evolution are strictly predetermined.

"Taken together, these findings … challenge the idea that cells and organisms can evolve only in predetermined ways. The third state suggests that [an organism’s] death may play a significant role in how life transforms over time." — Peter Noble & Alex Pozhitkov

Does This Mean Cells Are Conscious?

Some researchers take the implications further. William Miller, co-author of the 2023 book The Sentient Cell and a proponent of the Cellular Basis of Consciousness (CBC) theory, argues xenobots show cells can make decisions and solve problems—traits typically associated with cognition. Michael Levin, whose lab developed many xenobot experiments, similarly warns that human observers are poor at recognizing intelligence at very small or very large scales.

"The organism as a whole no longer responds as it had, but subsets of cells are active, decision-making, and problem-solving." — William Miller

However, the term "consciousness" is contested and means different things across disciplines. Mainstream definitions typically require a nervous system and brain to support subjective experience—criteria xenobots and isolated cells do not meet. Critics argue that impressive behavior does not equal conscious awareness.

Skepticism and Alternative Explanations

Many scientists remain unconvinced that xenobots demonstrate cellular consciousness. A 2024 letter in EMBO Reports described CBC theory as lacking empirical support and criticized claims about xenobots. Lincoln Taiz, Wendy Ann Peer, and other critics point out that cells routinely change behavior when removed from their native contexts; this has been known for decades in developmental biology and tissue culture.

Critics emphasize the need for rigorous, falsifiable hypotheses and proper controls. Wendy Ann Peer notes that when isolated cells lose their usual signals from neighboring tissues, gene expression patterns shift—an expected feature of cell biology that does not necessarily imply agency or experience.

Practical Implications

Regardless of the philosophical debate, researchers on both sides agree the technology has tangible potential. Xenobots and anthrobots suggest routes toward patient-specific cellular therapies, biodegradable microrobots, or living medicines built from a person’s own tissues—reducing immune rejection risk and enabling novel forms of repair or delivery.

Scientists urge cautious optimism: explore the possibilities, but pair innovation with careful ethical oversight, reproducible experiments, and clear standards for what claims are being made about cognition or consciousness.

Conclusion

Research into xenobots raises provocative scientific and philosophical questions about what cells can do after an organism dies and whether complex behavior in cell collectives should change how we think about life. The evidence supports real, manipulable cellular capabilities with clear medical promise, while the claim that single cells or small cell collectives are conscious remains controversial and unproven. Either way, cellular engineering is poised to play a central role in future biotechnology and medicine.