The horror of the blazing Notre-Dame cathedral in Paris has been slightly quenched by the fact that so much of the French landmark has been saved. But what was it about the structure of the roof, with some the beams dating from the 13th century, that meant it burned like a well-stacked bonfire? Guillermo Rein is Professor of Fire Science at Imperial College London , and he explains to Adam Rutherford how wood burns and how it was the intricate mixture of large and small beams, and very poor fire protection measures that made the iconic roof, so vulnerable. An experiment to see whether isolated dead pig brains could be preserved at the cellular level in order to study post mortem brains, had a surprising outcome. The BrainEx technology of perfusing the brains with chemicals that should have just halted the rapid degradation of cellular structure in the brain, that occurs soon after death, actually caused them to start firing neurons, reacting to drugs and generally behaving as if they were alive. Although, it has to be stressed, there was no whole-brain connectivity or consciousness achieved, it does raise ethical questions about death, if this method was to be developed for use in humans. Bioethicist at Kings College London, Silvia Camporesi explores the facts that reveal that death is a process rather than a single event and what this might mean for patients that are diagnosed as brain dead. Where is the Martian methane? This is the question Mannish Patel at the Open University has been left pondering after the ExoMars Trace Gas Orbiter came up empty handed in detecting the gas on Mars. Methane could be a signature of past of present life on the Red Planet, it's been measured by NASA's Curiosity rover and by telescopes on Earth, but the far more sensitive and specialised TGO has so far failed to detect the gas. It could be because methane levels in the thin Martian atmosphere is a seasonal event, we'll just have to ait for an entire Martian year of surveys to be able to solve this mystery. Our faces are incredibly important in our lives, we feed through them, they are the conduit for our sensory interaction with the universe, via smell, hearing and vision; we speak, and we convey the subtlest emotions with a raised eyebrow, a wry smile, a clenched jaw or eyes wide open. It is the central importance of these features that has meant we’ve been intensively studying the evolution of the face for decades, to work out why we look the way we do, and how much of our looks reflects adaptations that enhanced our survival, and how much is just down to quirks of evolution. Anatomist, Paul O’Higgins from York University is interested in how all that has influenced our faces. Producer: Fiona Roberts