Tech moguls Elon Musk and Larry Page's friendship collapsed over their differences on artificial intelligence, according to a new book that outlines how Musk believed that his former friend was too "cavalier" about the technology.

Walter Isaacson’s new book reports how Musk, the CEO of SpaceX, got into a heated debate with Page, then the CEO of Google at Musk’s 2013 birthday party.

Musk is said to have argued that unless safeguards are put in place with artificial intelligence, the systems may replace humans entirely. Page then pushed back, reportedly asking why it would matter if machines surpassed humans in intelligence.

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Isaacson’s book lays out how Musk then called human consciousness a precious flicker of light in the universe that shouldn’t be snuffed out. Page is then said to have called Musk "specist."

"Well yes, I am pro-human," Musk responded. "I f---ing like humanity dude."

It would later unnerve Musk when he heard of Page’s attempts to buy artificial intelligence company DeepMind: "The future of AI should not be controlled by Larry," he said as he sought to put together financing to stop the deal.

Musk would go on to warn about the potential dangers of AI, calling it "our biggest existential threat." He would also say that he didn’t "love the idea of being a house cat."

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Musk would go on to co-found a nonprofit AI group called OpenAI, making tech open-source and trying to block Google's dominance in the field. That group would eventually lead to the chatbot now called ChatGPT.

Musk would focus on guardrails and keeping AI as an extension of human goals and values rather than its own entity.

Meanwhile, the friendship between Page and Musk is said to have deteriorated, exacerbated by the snapping up of one of Google’s top scientists by OpenAI. Isaacson reports that the two barely spoke again after OpenAI was launched in 2015.

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"Larry felt betrayed and was really mad at me for personally recruiting [the scientist], and he refused to hang out with me anymore," Musk said. "And I was like, ‘Larry, if you just hadn’t been so cavalier about AI safety then it wouldn’t really be necessary to have some countervailing force." 

Musk has addressed that split before. In April, he told Fox News that he co-founded OpenAI to make "a non-profit that is fully open because Google was closed, for-profit."

He also addressed the claim of being called a "specist" — meaning he favors humans over other mammals: "Yes, I’m a specist, okay. You got me. What are you? Yeah, I’m fully a specist."

Fox News' Andrew Murray contributed to this report.