The gene code. Part 1, The code of life.

The first in a two-part series in which genetist and science journalist Adam Rutherford looks in depth at DNA. In this part, Rutherford looks back in time and discovers how DNA reveals the story of our evolution. He visits Iceland and sees the hot springs which have clues to the start of life. The DNA of archea, a simple microbial cell-like being, shares many similar genes. Dr Steve Jones explains the differences in genetic theory between the 'creeps' and the 'jerks' in evolution, whether evolution happen gradually or in leaps. Dr Nick Jones explains how leaps may have happened and how archea and bacteria combined. Next, the evolutional history of veterbrates is looked at. Amphioxus, a small invetebrate worm, holds the secret: when its genome was mapped, it was discovered that the human genome contains four identifiable sequences from the amphioxus. Rutherford explains how some genes become 'fossilised'; for example, aspects of the sense of smell which in humans have become 'mothballed'. Rutherford visits Hydrabad in India to see Dr Kumarasamy Thangaraj at the Centre for Cellular and Molecular Biology in order to discover whether his DNA reveals anything about his ancestry. In fact due to centuries of marriage within the caste system, a genetic variation has arisen where Vicears from the merchant class are unable to recover quickly from a commonly used anaesthetic. In India, people are screened before operations take place.