When James Smith first heard about mirror bacteria, he was sceptical. But within two weeks, he’d dropped everything to work on it full time, considering it the worst biothreat that he’d seen described. What convinced him? Mirror bacteria would be constructed entirely from molecules that are the mirror images of their naturally occurring counterparts. This seemingly trivial difference creates a fundamental break in the tree of life. For billions of years, the mechanisms underlying immune systems and keeping natural populations of microorganisms in check have evolved to recognise threats by their molecular shape — like a hand fitting into a matching glove. Learn more, video, and full transcript: https://80k.info/js26 Mirror bacteria would upend that assumption, creating two enormous problems: Many critical immune pathways would likely fail to activate, creating risks of fatal infection across many species. Mirror bacteria could have substantial resistance to natural predators: for example, they would be essentially immune to the viruses that currently keep bacteria populations in check. That could help them spread and become irreversibly entrenched across diverse ecosystems. Unlike ordinary pathogens, which are typically species-specific, mirror bacteria’s reversed molecular structure means they could potentially infect humans, livestock, wildlife, and plants simultaneously. The same fundamental problem — reversed molecular structure breaking immune recognition — could affect most immune systems across the tree of life. People, animals, and plants could be infected from any contaminated soil, dust, or species. The discovery of these risks came as a surprise. The December 2024 Science paper that brought international attention to mirror life was coauthored by 38 leading scientists, including two Nobel Prize winners and several who had previously wanted to create mirror organisms. James is now the director of the Mirror Biology Dialogues Fund, which supports conversations among scientists and other experts about how these risks might be addressed. Scientists tracking the field think that mirror bacteria might be feasible in 10–30 years, or possibly sooner. But scientists have already created substantial components of the cellular machinery needed for mirror life. We can regulate precursor technologies to mirror life before they become technically feasible — but only if we act before the research crosses critical thresholds. Once certain capabilities exist, we can’t undo that knowledge. Addressing these risks could actually be very tractable: unlike other technologies where massive potential benefits accompany catastrophic risks, mirror life appears to offer minimal advantages beyond academic interest. Nonetheless, James notes that fewer than 10 people currently work full-time on mirror life risks and governance. This is an extraordinary opportunity for researchers in biosecurity, synthetic biology, immunology, policy, and many other fields to help solve an entirely preventable catastrophe — James even believes the issue is on par with AI safety as a priority for some people, depending on their skill set. The Mirror Biology Dialogues Fund is hiring! Deputy director: https://80k.info/mbdfdd Operations lead: https://80k.info/mbdfops Expression of interest for other roles: https://80k.info/mbdfeoi This episode was recorded on November 5-6, 2025. Chapters: Cold open (00:00:00) Who's James Smith? (00:00:49) Why is mirror life so dangerous? (00:01:12) Mirror life and the human immune system (00:15:40) Nonhuman animals will also be at risk (00:28:25) Will plants be susceptible to mirror bacteria? (00:34:57) Mirror bacteria's effect on ecosystems (00:39:34) How close are we to making mirror bacteria? (00:52:16) Policies for governing mirror life research (01:06:39) Countermeasures if mirror bacteria are released into the world (01:22:06) Why hasn't mirror life evolved on its own? (01:28:37) Why wouldn't antibodies or antibiotics save us from mirror bacteria? (01:31:52) Will the environment be toxic to mirror life? (01:39:21) Are there too many uncertainties to act now? (01:44:18) The potential benefits of mirror molecules and mirror life (01:46:55) Might we encounter mirror life in space?