How to build a human. Part 4, Forever young.

The fourth in a four-part series looking at the origins of human life and the way in which our increasing understanding of genetics may affect this in the future. This part is about latest scientific research which aims to delay the ageing process by tampering with human growth hormone. While growth hormone injections for older people appear to retard the ageing process, if cancer cells are present it can encourage them to spread. The rest of the programme compares the way animals live and die and attempts to relate these findings to the human ageing process.