We ran the largest independent test of AI vs human content performance in search. Over 12 months, we published 500 articles — 250 AI-generated and 250 human-written — across 10 different websites in various niches. Here's what we found.
The headline result: human-written content outperformed AI content by 42% in organic traffic after 6 months. But the full picture is more nuanced than that simple comparison suggests.
Pure AI content (generated and published without editing) performed poorly. These articles ranked for fewer keywords, earned fewer backlinks, and had higher bounce rates. Google's content quality systems are effective at identifying generic AI output.
AI content with heavy human editing performed nearly as well as fully human-written content (within 10% on average). The human editor added expertise, original insights, fact-checking, and brand voice that AI alone couldn't provide.
The best performing content was human-written with AI assistance. Writers used AI for research, outline generation, and draft sections, then added their expertise, original data, and unique perspectives. This content outperformed both pure approaches.
Topic complexity mattered significantly. For simple informational queries ('what is X'), AI content performed adequately. For complex topics requiring expertise ('how to solve Y in Z situation'), human content dominated. Google's E-E-A-T signals clearly favor demonstrated expertise.
Content freshness was a differentiator. AI content tends to reflect its training data, which can be months or years old. Human writers incorporating current data, recent examples, and timely references consistently outranked AI content on trending topics.
Original research and data were the strongest ranking signals. Articles containing unique data, original surveys, proprietary benchmarks, or novel case studies outperformed everything else regardless of who wrote them.
Our recommendation: Use AI as a writing assistant, not a replacement. The optimal workflow is: AI generates research and outlines, humans write with their expertise and original insights, AI assists with editing and optimization, and humans review for accuracy and brand voice.