Lab notes: pigs' brains, mega-galaxies colliding and murder most fowl

This week's biggest stories Neuroscience / Scientists 'keep pigs' brains alive without a body for up to 36 hours' Zoology / Beware the long face: horses remember your mood Mental health / 'Gene map for depression' sparks hopes of new generation of treatments Astronomy / The largest thing in the universe? Cosmic collision 12bn years ago created mega-galaxy Archaeology / Swedish archaeologists uncover brutal 5th century massacre Gender in science / Women not getting a fair say at academic conferences, research reveals Millennials / Loneliness linked to major life setbacks for millennials, study says Artificial intelligence / Scientists plan huge European AI hub to compete with US Whodunnit / Murder most fowl: Oxford dodo 'shot in the back of the head' From the science blog network Neuroscience / Growing brains in labs: why it's time for an ethical debate Lost Worlds Revisited / How do you discover a dinosaur? Head quarters / Why Hunt's screen time limits for kids are scientific nonsense Amy Orben Alex Bellos's puzzle Can you solve it? The puzzle with a twist A one-sided story Podcasts The Guardian's Science Weekly / The science behind why we fight Eye on science Space / 'It's about expanding Earth': could we build cities in space? Meet the startup hoping to colonise the final frontier, one zero-gravity 3D printer at a time Where to find us Twitter: @guardianscience | @guardiansciblog Facebook: Guardian Science Guardian News & Media Limited - a member of Guardian Media Group PLC. Registered Office: Kings Place, 90 York Way, London, N1 9GU. Registered in England No. 908396