The past 24 hours have been saturated with commentary on how candidates did at the first GOP presidential debate, but Senator Marco Rubio’s strongest performance came this morning, in an interview with CNN’s Chris Cuomo.  Cuomo tried to corner Rubio on whether he would support exceptions for late-term abortion bans, but Rubio gave a strong defense of the need to protect all human life under the law.  That led to an embarrassing exchange (for Cuomo) about the scientific definition of human life.  The full exchange is here, and their exchange on human life is below:

MARCO RUBIO: And I recognize that this is a tough question, this is a very tough question, a very difficult question, and I understand that, believe me I do, but by the same token if I have to weigh the two equities here, I’m always going to err on the side of life, and I think that’s a timeless principle. Certainly our economy has evolved, but when it comes to the value of every human life, I think it’s a timeless principles that’s true now and will be true in the future.

CHRIS CUOMO: I know, but you’re deciding when it is human life. Let me ask you something. You – when you’re looking at the future —

MARCO RUBIO: No, science has decided when it is human life.

CUOMO: Science has not decided it’s at conception.

RUBIO: No, let me correct you. Science has — absolutely it has.

CUOMO: Not at conception.

RUBIO: Science has decided that when a — science has concluded — absolutely it has. What else can it be? It cannot turn into an animal. I can’t turn into a donkey. That’s the law. The only thing that that can become is a human being.

CUOMO: But you — no, but you know that the law has perused this. The fact that — look, of course, I understand the logic but it’s a little too simple with —

RUBIO: Every human — human like. It can’t be anything else.

Nick Arnold is a researcher for American Principles in Action.