Velvl Greene, epidemiology professor at Ben-Gurion University of the Negev, is a man with an impressive resumé.

He's a former NASA scientist. A Fulbright scholar. He's also a talmudic expert and the head of the Lord Jakobovits Center for Jewish Medical Ethics. But there is one thing Greene insists he isn't.

"I'm not a fire-breathing radical," said Greene in a phone interview last week from Minnesota.

So when Greene expostulates, in his hybrid Israeli-Canadian baritone, that Martians visiting Earth in search of Jewish life should avoid both Jews for Jesus and a lesbian rabbi convention, he says he's speaking as a scientist.

Not as a polemicist.

Equally at home deconstructing dinosaurs and talking Torah, Greene will be discussing a gamut of topics this weekend. Tomorrow night, he will speak on "The Torah Science Conflict" at a Chabad of Contra Costa event in Walnut Creek. On Sunday, he will address the Chabad of the East Bay dinner in Oakland. During that talk, called "Body and Soul — Medical Ethics in the Light of Jewish Tradition," the scientist may touch on everything from evolution to the epidemiology of assimilation.

He brings in a wide galaxy of examples to illustrate his belief that the secular world has embarked on a wayward course.

"Listen, I've got nothing against dinosaurs, y'know," said Greene, offering a hint of his Canadian roots. "But fossilized bones don't have any flesh, emotions or internal organs. Many of the bones are actually missing. And yet somehow, museums see fit to build whole skeletons and add musculature. That's serious interpolation."

"By the time you get around to adding skin, texture and color, you're way out there."

What really sticks in Greene's craw, though, is the number he believes interpolaters have performed on the Torah. "Over the past 150 years, we have been replacing the Torah with experimental science. These philosophers have denigrated the entire narrative of creationism."

And Greene is prepared to name names. Freud. Marx. And, of course, Darwin. As expected, the Orthodox scientist and the champion of evolution have a different take.

"If you remove God from people, they act like animals," Greene said. "That's evolution." Greene's own process of evolution took him from Midwestern farmlands to the Warsaw Ghetto.

Back in the early '60s, when Greene was making a name for himself in space exploration –"[Carl] Sagan and I ran in the same circles" — he was the guest on a talk show in North Dakota. The talk-show host asked him questions he knew nothing about. Greene answered anyway.

"All of a sudden, I found myself talking about juvenile delinquency and farm subsidies. I didn't know a thing about either one of them. But I had no problem giving lengthy answers to the questions."

Watching himself on TV later that night, Greene said that it was "the first and last time I'd been really humbled. It made me look buffoonish. I resolved to live a more spiritual existence."

Shortly thereafter, Greene and his wife visited the Warsaw Ghetto and other historical sites. Greene came away from the visit with a renewed connection to his faith and culture. Slowly, he and his wife began to live an Orthodox life.

"Judaism is transmitted by profession, not by blood," said Greene, who grew up in Winnipeg, Manitoba, and made aliyah in 1986. In addition to serving as a professor of epidemiology and public health, he heads the Jewish medical ethics department at Ben-Gurion University in Beersheva.

The scientist uses NASA's criteria for life on Mars to explain the paucity of Jewish life on earth. "In order for there to be life on Mars, there has to be molecules and life conditions such as water and warm temperatures. Additionally, these conditions must be capable of changing the environment.

"So what is the essential ingredient of being a Jew?" Greene asked. "The answer is simple — the Torah. Adhering to the teaching of the Torah is the only way of maintaining a Jewish identity. Any other factors, including genetics, are irrelevant."

"The Torah is the raison d'être of the Jewish people. It's why we were all created in the first place."