Almost nine in ten late-2025 biomedical papers showed signs of AI-assisted writing
A preprint analyzed more than one million English-language open-access biomedical papers and estimated that 89 percent of papers published in December 2025 showed signs of some large-language-model-assisted writing. Nature reports estimates of 77 percent for 2025 overall and 52 percent for 2024, with signs appearing more often in discussions than results. The number is startling and easy to misuse. It does not mean AI authored 89 percent of biomedical papers, fabricated their data, or influenced the entire scientific literature. The method detects shifts in vocabulary within a specific PubMed Central corpus, the paper has not been peer reviewed, and other researchers told Nature that representativeness and methodology need further analysis. The finding still matters because AI assistance is moving from exceptional to ordinary while disclosure, attribution, data verification, citation checking, and journal policy remain inconsistent. Science needs provenance that distinguishes language editing from analysis, protects responsibility for claims, and lets readers audit the contribution without treating every polished sentence as misconduct.