Episode one tells the story of the first 8 weeks when a single cell, no bigger than a speck of dust, transforms into the most sophisticated organism on the planet — a human fetus. The clock starts with the moment of conception, but days after our story can take the most unexpected turn.Holly, Jessica, Ellie and Gorgie are the ‘1 in 64 million' identical quads whose lives changed forever when they were a clump of a few hundred cells. For reasons no-one can really explain the connections binding their cells were mysteriously broken and four clumps of cells started to behave independently from the rest. Against the odds these cells each went on to form four entirely separate young lives. In The Gambia an extraordinary 70-year-long study has been looking into the seasonal effects of life expectancy — and it's returned some shocking results. Babies conceived during the dry months are seven times more likely to die in young adulthood than those conceived when it's wet. And this extraordinary difference may be all down to what a mother is eating during the very first week of life in the womb.Follow the story of how, from a fertilized egg, you took on human form in the womb. Chart the metamorphosis from the lizard-like, mouse-like and monkey-like forms you once took on until the moment around 12 weeks when you became unmistakably human.