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{"success":true,"source":{"id":"68dfaad8-7ec0-419b-b8a1-091b9568277d","url":"https://www.anthropic.com/institute/recursive-self-improvement","title":"When AI builds itself","source_type":"report"},"origin":"stored","total_chars":34128,"offset":0,"content":"Skip to main content News Research Policy Commitments\n\nCompany\n\nTry Claude\n\nWhen AI builds itself\n\nOur progress toward recursive self-improvement, and its implications.\n\nFor most of AI’s history, humans drove every step in its development cycle. But at Anthropic, we are delegating a growing share of AI development to AI systems themselves, which is speeding up our work.\n\nTaken far enough, and given enough compute, that trend points to an AI system capable of fully autonomously designing and developing its own successor. This is called recursive self-improvement . We are not there yet, and recursive self-improvement is not inevitable. But it could come sooner than most institutions are prepared for.\n\nUsing public benchmarks and previously unreported data from within Anthropic, The Anthropic Institute is showing that AI is already accelerating the development of AI systems. To take just one example: today, Anthropic engineers on average ship 8x as much code per quarter as they did from 2021-2025.\n\nThe technical trends discussed in this piece suggest that AI systems are going to become much more capable in coming years. These trends have huge implications. AI that can build itself would be a major development in the history of technology—one that could bring enormous good for the world in science, healthcare, and beyond. But full recursive self-improvement also might increase the risks of humans losing control over AI systems. If systems are capable of fully building their own successors, the ways we secure them, monitor them, and shape their behavior all grow much more important.\n\n2021–2023\n\nBuilding the first Claude\n\nIn the early days, work at Anthropic looked like work at any other tech company: people writing code and docs on laptops.\n\n2023–2025\n\nChatbots\n\nPeople used early chatbots to help with parts of the process, like generating short code snippets and copying the output into text editors.\n\n2025–2026\n\nCoding agents\n\nAs the agents became more capable, they were able to write and edit code on their own, sometimes entire files.\n\nToday\n\nAutonomous agents\n\nAgents can now run code themselves and delegate hours of work to other agents.\n\n20XX?\n\nClosing the loop\n\nIn the future, agents could become capable enough to build and train models themselves. If this happens, future versions of Claude could be continuously improved by Claude itself.\n\nEvidence from the outside world\n\nThe rate at which AI models improve is accelerating. The length of tasks that they can reliably complete on their own has been doubling roughly every four months, up from an earlier trend of doubling every seven months. In March 2024, Claude Opus 3 could complete software tasks that take humans about four minutes to complete. A year later, Claude Sonnet 3.7 managed tasks that took about an hour and a half. A year after that, Claude Opus 4.6 managed 12-hour tasks. 1 If this trend holds, tasks that take a skilled person days could come into range this year. In 2027, AI systems could be capable of tasks that take a person weeks.\n\nThe same pattern appears on coding and research benchmarks. Benchmarks measure the performance of models in a given domain, and they’re “saturated” when models achieve close to 100% performance. 2 SWE-bench is a standard test of real-world software engineering: it hands a model an actual open-source codebase and a real bug report, and asks it to write a code change that fixes the issue and passes the project’s own tests. Models have gone from scoring in the low single digits to saturating the benchmark in two years.\n\nCORE-Bench tests whether a model can reproduce existing research, a prerequisite for them to conduct original research. It gives an AI model the code and data behind a published paper, and asks it to rerun everything and confirm it can replicate the paper’s results. AI systems went from succeeding at reproducing the results roughly 20% of the time in 2024 to saturating the benchmark fifteen months later. METR, which runs the benchmark measuring how well models can complete long-duration tasks, found that Claude Mythos Preview could work for “at least” 16 hours and was “at the upper end of what [METR] can measure without new tasks.”\n\nPublic benchmarks say a lot about the capabilities of these systems. But they can’t reveal the impact AI systems are having on speeding up AI development itself. For that, we need direct evidence from within AI companies like Anthropic.\n\nEvidence from within Anthropic\n\nBuilding a frontier model takes two broad categories of work. There is engineering : writing the code, standing up the infrastructure, and overseeing the model training. And there is research : deciding what experiments to run, interpreting what comes back, and figuring out which ideas to try next.\n\nAcross both engineering and research, the picture is consistent. In engineering, Claude can be handed an underspecified problem and figure out how to solve it; humans supply the goal, but they no longer need to supply the method. In research, Claude can already match or outperform skilled humans at executing a well-specified experiment. However, large performance gaps persist when it comes to Claude exercising judgement in choosing goals in both engineering and research. That’s the gap between AI today and a future system that could autonomously design its own successor.\n\nIt’s common for employees at Anthropic to receive more open-ended and important tasks as they gain more experience. Early on, they execute a task someone else specified, like, “The export button isn’t working, please fix it.” With experience, they’re handed a goal and design the approach themselves, such as, “Investigate why the network slows down under heavy load.” At the most senior levels, they are deciding which problems are worth working on at all: “What should the team build next quarter?” We can use internal Anthropic data to see how far Claude has come in being able to handle these different kinds of tasks.\n\nClaude writes a significant proportion of Anthropic’s code. As of May 2026, more than 80% of the code we merge into Anthropic’s codebase was authored by Claude. 3 Before Claude Code launched in research preview in February 2025, this number was in the low single digits. That shift also shows up in the amount of output per engineer. Lines of code merged per engineer per day stayed constant through Anthropic’s first four years (2021-2024), then began to climb upward in 2025 when Claude began to run code rather than just suggesting it for an engineer to copy and paste. The slope steepened again in 2026 when models began to work autonomously over longer time horizons. These two inflection points are shown in the chart below. In the second quarter of 2026, the typical engineer was merging 8× as much code per day as they were in 2024. 4 This is because much of the code is written by Claude, with the engineer directing and reviewing, rather than typing it themselves.\n\nA caveat: Lines of code is an imperfect measure, as it measures quantity over quality. So 8 × lines of code/engineer/day in the second quarter of 2026 is almost certainly an overstatement of the true productivity gain. Nonetheless, it indicates an acceleration. At Anthropic, we don’t reward people for how many lines of code they write; rather, team members are producing more code simply because they’re using AI systems to write more code.\n\nThe increase in lines of code written lines up with subjective impressions of large productivity increases. In a March 2026 poll of 130 employees from across Anthropic research teams, the median respondent estimated that they produced around 4x as much output with Mythos Preview as they would have without access to any AI models, on the kinds of projects they would have been working on regardless. 5 We expect that the true degree of uplift in March was somewhat lower. 6 Nevertheless, we find the overall claim plausible, and in line with our other observations: a significant fraction of An","truncated":true,"next_offset":8000,"facts":{"authors":[],"publisher":null,"published_date":null,"doi":null,"archived_url":"https://web.archive.org/web/20261111053955/https://www.anthropic.com/institute/recursive-self-improvement","events":[],"versions":[],"copy_of":[],"interests":[{"party":"Anthropic","stake":"Anthropic develops and sells the Claude models the report describes, and the report is published by its own institute. It gains commercially and reputationally from its models being seen as highly capable, and its account of their limits shapes how regulators and the public judge the pace of AI development.","claim_id":null,"recorded_at":"2026-11-13T21:36:33.847Z"}]},"note":"More text follows; call again with offset 8000 to continue."}