While discussing the decline of civilizations throughout history, SpaceX CEO Elon Musk said he is "concerned about decreasing birth rates" in many countries and explained that with "birth control" and "abortion" people can enjoy intimacy but not "procreate."

He added that, "if we don't make enough people ... then civilization is going to crumble."

Musk made his remarks during an April 18 interview on Tucker Carlson Tonight. 

"[I]f you look at the history of civilizations, the rise and fall of the ancient Egyptians, the ancient Sumerians, Rome, you know, just throughout the world, there had been rise and fall of many civilizations," said Musk. "So there's an arc -- there is sort of a lifecycle arc to civilizations, just as there is to individual humans."

He continued,  "And I think we just want to make sure that, you know, we have civilization go onward and upward. And that's, for example, why I'm concerned about decreasing birth rates and the fact that, for example, Japan had twice as many deaths last year as births. And there are leading indicators this is --."

At that point, Carlson interjected, "Can I just say -- and you've written on and talked a lot about this -- but can I just ask you to pause just for a parenthetical note. Why is that? I mean, the urge to have sex and to procreate is, after breathing and eating, the most basic urge."

"Yes," said Musk, and Carlson asked, "How has it been subverted?" 

"Well, it's just that in the past, we can rely upon, you know, simple limbic system rewards in order to procreate," said Musk.

"But once you have birth control, and, you know, abortions and whatnot, now you can still satisfy the limbic instinct, but not to procreate," he added. "So we don't -- we haven't yet evolved to deal with that, because this is all fairly recent, you know? Last 50 years or so for birth control."

Musk continued, "I'm sort of worried that, hey, civilization, you know, if we don't make enough people to at least sustain our numbers, perhaps increase a little bit, then civilization is going to crumble."

"There is the old question of, like, will civilization end with a bang or a whimper?" said Musk. "Well, it's currently trying to end with a whimper in adult diapers."

The conversation continued:

Carlson: "Yes."

Musk: "Which is depressing as hell."

Carlson: "The most depressing."

Musk: "I mean, seriously. Yes."

Carlson: "War is less depressing."

Musk: "Yes, I'd rather go out with a bang."

Carlson: "Yes, with your shoes on."

Musk: "Yes."

Carlson: "Not with your diapers on."

Musk: "More exciting."

Carlson: "Yes."

Musk, 51, has been married twice and has 10 children. He is the CEO of SpaceX, Tesla, and Twitter, and the founder of the Boring Company, Neuralink, and OpenAI. He also is the president of the Musk Foundation.  He has an estimated net worth of $189 billion.