Generative coding tools promise big productivity gains, but uneven uptake could widen skill and income gaps. We train a neural classifier to spot AI-generated Python functions in over 30 million GitHub commits by 160,097 software developers, tracking how fast, and where, these tools take hold.

Currently AI writes an estimated 29% of Python functions in the US, a shrinking lead over other countries. We estimate quarterly output, measured in online code contributions, consequently increased by 3.6%.

AI seems to benefit experienced, senior-level developers: they increased productivity and more readily expanded into new domains of software development. In contrast, early-career developers showed no significant benefits from AI adoption.

This may widen skill gaps and reshape future career ladders in software development.

S. Daniotti, J. Wachs, X. Feng, F. Neffke, Who is using AI to code? Global diffusion and impact of Generative AI, Science (2026) eadz9311.