David Attenborough

David Attenborough hosts "First Life" Sunday on Discovery Channel.

Sir David Attenborough, he of the BBC diction and eternal wonderment of all things natural, tackles huge questions in his latest nature documentary, "First Life," airing on Discovery Channel Sunday, Oct. 24.

Relying on Attenborough's infectious curiosity and tremendous technological advances, the two-hour special re-creates what some of the first creatures on Earth looked like. Even after a lifetime of studying the natural world, Attenborough says he learned "a very great deal" while making this special.

"I used to think, and I dare say most people think, the very, very earliest things must have appeared so long ago and must be flimsy and insubstantial, and the chance of anything surviving from them were insubstantial," he says. "Most people thought so until 30 or 40 years ago. Then somebody discovered the place where the conditions were absolutely perfect for fossilization of these sorts of things, and you get a whole range of systems."

Using fossils, computer-generated imaging and tapping into the research from an international corps of scientists, the documentary is able to replicate what some creatures looked like a half billion years ago.

"Nobody has ever tackled it before," Attenborough says of this time period and trying to visualize these beings. "Nobody has seen these creatures before. It is a completely untouched subject."

Once he had fossils, and computer experts started working their artistry, images were sent to scientists around the world to glean their input.

In "First Life," we see the creature with the first teeth, another with the first eyes, or rather some 500 of them, all of which is extrapolated from fossils. Attenborough is his usual engaged and engaging self.

"After billions of years of single-cell life, something amazing happened in the deep," he says on camera. "Cells began to stick to one another."

Though scientists have long known the timeline, it was the discovery of a wealth of fossils and the advances in technology that helped bring this all together. The technological advancements during Attenborough's career have made for huge changes in nature films.

"The first cameras we used, we had to wind up," Attenborough says. "There is almost nothing we can't film now. The one thing we haven't really cracked is deep-water filming. On land we can do everything."

Here, he traverses the land, standing atop Mistaken Point in Newfoundland, a beautiful and harsh peninsula rich in Precambrian fossils. Attenborough puts this wind-swept cliff in its historical perspective by explaining, "Five hundred sixty-five million years ago, this was the bottom of the ocean."

Fossils show the earliest ancestors of mollusks, and CGI brings to life how they moved -- very slowly. They had sensory organs and could smell food before eating it.

Later fossils show how sea animals' bodies evolved into segments. One scientist shows off her sexy discovery: wormlike underwater creatures that shared their DNA some 600 million years ago -- the first evidence of sexual reproduction.

Over the next 10 to 20 million years, animals increased in variety and size as never before, Attenborough says. Much of this has to do with oxygen levels, which resulted in a shrimplike creature more than 3 feet long; sea scorpions grew to more than 8 feet long.

"Here, you can see the beginning of life, the beginning of advanced life before this life was on the molecular level," Attenborough says. "These were the first big animals you could see. Darwin didn't know what they were. They weren't known until recently. It is a thrill because that is the way science progresses. This was an unwritten page in the history of life until 50 years ago."

The goal for the film is that it will encourage viewers "to think back to a period long, long ago, to think how life itself and the first animal evolved," executive producer Anthony Geffen says. "People know bits of it. To be able to see the creatures in a very animated way, David is fantastically good at bringing this to the audience. He has fans who are 4 and fans who are 90. It's this journey where life started and how it evolved, and a lot of this is new."

"This could easily have been done as a scientific paper," Geffen says. "But we wanted to make it also something someone could take, and in 90 minutes (commercials stretch it to two hours), you go on a journey, and it allows you to understand that journey, the evolution of life and animals."

Many of the people who worked on the CGI end of this special had worked on the Harry Potter films.

"We are taking that skill usually in fantasy and harnessing that energy and using it in science processes for real things we have never seen," Geffen says. "Reality is a lot more fascinating. Some of those creatures you could not have invented."

"We worked with scientists across the world who knew their business," Geffen says. "They hadn't really thought how the next one related to theirs. I like to think of it in some ways as a new Attenborough. These animals have, of course, existed, but we haven't seen until now it completes his whole look at the animal world."