Dr Joshua Mezrich is a leading transplant surgeon. He tells Andrew Marr how death and life are intimately connected in his field of expertise. And he explains the extraordinary breakthroughs that have emerged in transplant surgery, along with the ethical questions that arise when choosing who will be given the chance of a new beginning.Scientific research needs to be evidence-based. But it can too easily be based on underlying assumptions and biases. The science writer Angela Saini reports on the history - and recent revival - of race science, a field of study that sees race as a biological fact.

Caroline Criado Perez exposes the gender biases in medical and scientific research. She argues that women have often been excluded from the data which has had a huge impact on the efficacy of the pills prescribed, and the treatment offered.

The latest promise of better healthcare is personalised medicine, which aims to get the right dose to the right patient at the right time. But Richard Ashcroft, Professor of Biomedical Ethics, cautions that grouping patients by their genetic constitution may well create new forms of inequality.

Producer: Katy Hickman