It’s probably safe to say that longtime journalist Dan Rather knows a big story when he sees one. And with the new documentary, “Human Nature,” he says he might be reporting on the biggest story of his lifetime — gene editing and engineering.

He said the technology known by the acronym CRISPR is “literally life-changing and world-changing, and we need to have a conversation about what we want to do with this knowledge.”

That conversation, he said, has been the goal of “Human Nature” from the beginning. “The public needs to be engaged now, at the front end of this,” said Rather, who was an executive producer on the film. “Scientists are eager for a global conversation about this, but it needs to be a conversation based on facts and understanding.”

“Human Nature,” which has its world premiere Sunday at the South by Southwest Film Festival, presents those facts without an agenda — neither endorsing nor condemning the technology, which has the potential to eliminate genetically inherited diseases and to produce so-called designer babies from modified embryos. The documentary sees the benefits of using the new technology in finding cures to many diseases, but it also points out the ethical questions surrounding our newfound ability to alter the DNA of future generations.

“I’ve haven’t been as excited about anything like this in a long, long while,” Rather said. “It’s hard for me to rein in my passion for this subject.” He said the film has been in the works for 3½ to four years, ever since he interviewed the pre-eminent gene-editing expert, University of California-Berkeley biologist Jennifer Doudna, for the internet-based group iBiology (www.ibiology.org).

After the interview, Rather said he “walked out of there, saying to myself, ‘I’ve been very fortunate and I’ve covered some really big stories over the course of my career — and I don’t mean that as self-serving — but this could very well be the biggest story of my lifetime, and I don’t want to miss it. From that moment on, I wanted to do a documentary.”

Rather teamed up with his longtime colleague Elliot Kirschner, a documentary filmmaker who knew Rather at CBS-TV, to put together a group of people to raise money and make the movie, most notably director Adam Bolt.

Bolt had worked with Rather as a freelancer on “Dan Rather Reports,” the high-definition satellite and cable series that was the brainchild of Dallas billionaire Mark Cuban. It aired on HDNet, and then AXS TV, from 2006 to 2013.

“Elliot and I thought Adam was brilliant,” Rather said. “And he has been absolutely key to this, using a combination of graphics and film to make the complex CRISPR technology clear to the audience.”

As Bolt and the rest of the team were putting the movie together, the CRISPR technology became even more controversial with the November 2018 announcement by a Chinese scientist, He Jiankui, that he had edited the genes of twin girls to help them resist HIV infection — and that a third gene-edited baby was on the way.

The news caused a stir internationally, and “Human Nature,” which was being edited at the time, refers to the development but understandably does not dwell on it. Instead, the documentary lays out the differing opinions of scientists around the world — and explores both the positive and the negative possibilities, without fear-mongering.

That’s not to say that some fears aren’t valid, as the documentary makes clear. But the point of “Human Nature” is to start the conversation.

“As is often the case, once knowledge gets out, you can’t put it back in the bottle,” Rather said. “The knowledge is out there, and it’s spreading at various levels worldwide. The United States leads in this kind of research at the moment, but one of many questions is, ‘Do we want to remain world leaders in this?’ This development in China is just the first ripple of wave after wave of events that are coming quickly, raising all kinds of ethical questions.”

Rather said the invention of internet was really something, so was the moon landing: “But here is something that is just as revolutionary, perhaps even more so.”

Rather said he’ll be at the premiere of “Human Nature” on Sunday. “I wouldn’t miss it,” he said.

And then he’s asked a question that many people might be wondering about after seeing “Human Nature”: If the technology were available and you were considering having a baby, what characteristics would you consider most important if you chose to edit the embryo’s DNA?

There’s no easy answer, as Rather quickly notes. “I’m not sure that I would want to be involved with a designer child,” he said, “but in answer to your question, I would want the child to have courage and compassion. And I’m not sure that even with the gene editing and engineering that we call CRISPR that designing a child with such attributes would be possible.”

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