At first glance, the rhythm of human life appears simple enough: we are born, we live, and we die. End of story. Yet, at the microscopic level, existence becomes far more complex. Every human being who has ever lived is made up of tens of trillions of cells, alongside vast communities of microbes, all working together to create what we recognise as life. Increasingly, scientists are discovering that for some cells, death may not mark a final stop, but rather the start of something altogether different.
++ The peregrine falcon: nature’s fastest killer in the sky
Growing attention has focused on a new class of laboratory-created, multicellular entities known as xenobots. These structures, designed using artificial intelligence, are formed from living cells that appear to take on new roles once removed from their original biological context. In September 2024, microbiologist Dr Peter Noble, from the University of Alabama at Birmingham, and bioinformatics researcher Dr Alex Pozhitkov, of the City of Hope cancer centre, outlined this work in an article for The Conversation.
Xenobots are notable because their cells reorganise themselves to perform tasks unrelated to their original function. In some cases, hair-like cilia, normally used to move fluids, instead enable locomotion. The researchers argue that this behaviour represents a “third state” of life, in which cells can reassemble after the death of an organism to form something new. While such forms would be unlikely to arise naturally, they demonstrate a striking cellular adaptability. Similar behaviour has also been observed in experiments using human cells, dubbed “anthrobots”. Taken together, these findings challenge long-held assumptions about how cells evolve and behave. The researchers suggest that an organism’s death could itself shape how life changes over time, rather than marking a definitive end.
The implications are potentially far-reaching. In medicine, such cellular systems could one day be used to create personalised treatments grown from a patient’s own tissue, reducing the risk of immune rejection. More broadly, they raise fundamental questions about what a cell is capable of.
One of the most vocal proponents of this idea is evolutionary biologist and physician William Miller, co-author of the 2023 book The Sentient Cell. He argues that xenobots highlight how cells possess decision-making abilities that are routinely underestimated. According to Miller, even when an organism no longer functions as a whole, individual cells can remain active, solving problems and responding to their environment.
This perspective feeds into a wider debate about consciousness, a concept that has long resisted precise definition. While modern science recognises varying degrees of awareness across the animal kingdom, intelligence at radically different scales is harder for humans to identify. Dr Michael Levin, a developmental biologist at Tufts University whose laboratory created xenobots, has noted that people struggle to recognise intelligence when it operates at sizes or speeds far removed from everyday experience.
++ GoPro footage reveals dolphins are not as cute as they seem
Miller believes this shift in thinking could also reshape evolutionary theory. Rather than focusing on “survival of the fittest”, he suggests biology is better explained by cooperation, with cells thriving by working together rather than competing alone. In this view, genes are not masters, but tools used by cells to collaborate, adapt and persist.
Not all scientists are convinced. A 2024 letter published in EMBO Reports dismissed the theory of cellular consciousness as speculative and lacking empirical evidence. Among its authors was Professor Lincoln Taiz, a plant biologist at the University of California, Santa Cruz, who argued that unusual cell behaviour in laboratory conditions has been known for decades and does not amount to a new state of life.
Similarly sceptical is Dr Wendy Ann Peer, a biologist at the University of Maryland, who said the idea of cellular consciousness fails to meet the standards of a testable scientific theory. She points out that when cells are removed from their natural environment, they often express different genes, a phenomenon already well documented in developmental biology.
Despite these disagreements, there is broad consensus on one point: cells are far more dynamic and capable than once believed. Whether or not they can be described as conscious, understanding how cells behave, adapt and cooperate could unlock major advances in medicine and biology. As researchers continue to explore these microscopic building blocks of life, one thing is clear: the future of human health may depend not just on treating the body, but on learning how to work alongside the cells that sustain it.
