A researcher at Anthropic has tendered his resignation, warning that artificial intelligence (AI) labs “gambling with our lives” in the race to develop their systems.

Jacob Coxon’s departure was first reported by the Wall Street Journal, which said it was “one of the first examples of an Anthropic employee leaving over AI safety fears”.

In a thread on the social media platform X, Coxon — a researcher who specialises in training new AI models by having them consume vast amounts of data — said: “I resigned from Anthropic today. I spent the last three years doing pre-training research at both OpenAI and Anthropic.

“Neither company is acting responsibly. They are racing straight to self-improving superintelligence and gambling with our lives,” he added.

“Do not underestimate the power of this technology. These will soon be superhuman systems that can hack anything, revolutionise any field overnight, and acquire real power and resources,” he said.

“We have all witnessed the progress in each of these domains, and progress is not slowing,” he added.

Coxon also warned of fears among AI researchers and executives about the potential consequences of the technology.

“The people building AI earnestly believe that it could kill us all by the end of the decade. This is not a marketing stunt. If anything, many executives and senior researchers will couch their phrasing in the press to sound sensible — but I hear the same people express fear privately. No other human activity poses this level of danger,” he said.

Coxon questioned why companies continued developing AI despite such concerns.

“A common response is ‘if they truly believe this, why are they still building it?’ At OpenAI, many have not deeply internalised the civilisational stakes,” he said.

“At Anthropic, the stakes are well-understood, but they are locked in a race to get there first — they believe no one else will act responsibly, so they must do it themselves, despite the risk,” he added.

Coxon urged AI researchers to reconsider the pace of development and the risks involved, saying: “If you are a lab researcher, I urge you to consider what the next few years will actually feel like.

“Do you want to kick off a superintelligent RL run without a rigorous understanding of its mind? Should you put your head down because ‘it’s happening anyway’ — or take this moment to call for different conditions?” he asked.

Speaking to the Journal, Coxon had voiced the same reasons for his departure, saying he did not want to participate in an industrywide rush to “build AI systems that can improve themselves, worried such systems could spiral out of control and destroy humanity”.

He also said that many of his industry colleagues now used phrases like “crunchtime” and “endgame” to describe the trajectory toward self-improving models.

The report said that he was also among more than 1,000 AI researchers who recently signed a statement urging global government coordination on a system to “slow AI development if a brake pedal is needed to control models capable of improving on their own”.