Scientists flag quantum effects in biology

Quantum biology is the idea that some living systems may use genuinely quantum behavior — coherence, tunneling, spin effects — for jobs that matter biologically. That sounds a little sci-fi because cells are warm, wet, and noisy, which is exactly the kind of environment that usually kills delicate quantum states. But the picture has changed. The strongest work now says a few biological systems may not just tolerate quantum effects for an instant — they may exploit them on useful timescales, especially in photosynthesis, magnetoreception, and some enzyme reactions. (science.org) ### What counts as a “quantum effect” here? Not every weirdly efficient biological process is quantum biology. The bar is higher. Researchers usually mean one of three things: a particle tunnels through an energy barrier instead of climbing over it, two states stay coherent long enough to affect transfer dynamics, or electron spins evolve in a way that changes chemistry. Basically, the quantum part has to do real(science.org)(frontiersin.org) ### Why is photosynthesis always the headline example? Because photosynthesis moves electronic excitation energy through pigment-protein complexes with absurd efficiency. For years, the fight was over whether the observed signals were truly electronic coherence or just vibrations masquerading as something fancier. A 2025 Science Advances paper pushed that d(frontiersin.org)can persist at 77 K and even at room temperature on picosecond timescales — roughly the same window as energy transfer itself. That does not prove every leaf is a quantum computer. But it does make the “too noisy to matter” dismissal harder to keep. (science.org) ### What about birds sensing Earth’s magnetic field? This is the other big contender. The leading model says light activates cryptochrome proteins in the retina, creating radical pairs whose spin dynamics are weakly sensitive to Earth-strength magnetic fields. In 2021, a Nature paper showed that cryptochrome 4 from the migratory European robin is magnetically sensitive in vitro, and more sensitive than the same p(science.org)ific molecule to a plausible quantum mechanism instead of leaving the whole idea at the hand-wavy level. The catch is that molecule-to-behavior remains the hard bridge. In vitro sensitivity is not the same thing as a fully proven compass inside a living bird. (nature.com) ### Are enzymes really using tunneling? Sometimes, yes — but this is the place where people overclaim most easily. Proton or hydrogen tunneling in enzymes has been discussed for years, and there is strong evidence that tunneling contributes in some catalytic steps. But contribution is not the same as control. A 2025 paper on designed enzymes and directed evolution found only modest tunneling involvement, and mainly whe(nature.com)marter version of the claim is that tunneling can matter in enzyme catalysis, not that enzymes broadly owe their magic to exotic quantum tricks. (pmc.ncbi.nlm.nih.gov) ### Is this field suddenly becoming engineering? Sort of — but in two different ways. One track is biological: figure out whether nature already uses quantum effects and then borrow the design principles. The other is computational: use quantum computers to model enzymes and reactions that are hard for classical methods. A 2025 Nature Catalysis perspective is about that second track. It is not evidence that c(pmc.ncbi.nlm.nih.gov)ls may help people design better biocatalysts. (nature.com) ### So what is actually solid? Bird cryptochrome chemistry looks serious. Some enzyme tunneling cases look serious. Photosynthetic coherence looks more plausible than it did a few years ago, especially after the 2025 simulation work. But the field is still uneven. The real shift is not that “biology is quantum” in some sweeping mystical sense. It is that a few specific mechanisms have survived enough skepticism to beco(nature.com)ifiable, and maybe eventually useful. (science.org)