A Look Inside an Amazing Machine

With 100 trillion cells built from 100 billion miles of DNA coding, the human body has been called one of the world’s most exquisite machines. That machine’s limits are always being pushed, whether it be through in-vitro fertilization, for example, or innovative brain surgery using 3-D imaging as a map.

Now, a National Geographic special stretches the bounds of the biological documentary, using dazzling digital effects along with the stories of four groups of people to peer inside “The Incredible Human Body” (9 tonight, PBS).

Filmmakers Karen Goodman and Kirk Simon start with a chronicle of conception, showing in-vitro fertilization at work for one couple, step by microscopic step.

Next, in a triple-overtime victory, the NBA’s Charlotte Hornets illustrate how extensive repetition rewires the brain for peak performance, enabling the body to move with elegant precision.

London cabbies, who study for years to gain an encyclopedic familiarity with the city’s twisting streets, exemplify how the brain’s memory sector can grow, boosting optimism for Alzheimer’s research.

In the most intense sequence, Mayo Clinic doctors extricate a massive brain tumor from a man who must stay awake throughout the surgery. The slightest slip can impair the patient’s speech or movement--or worse--so the doctors must query him constantly to monitor his cognitive responses.

Ultimately, as a Johns Hopkins University researcher points out, “We do not know what the human potential is. Everything we think is a roadblock to what a human can do physically and mentally has been proven to be wrong.”

In the best National Geographic tradition, “The Incredible Human Body” evokes a sense of wonder and lives up to its title.