This week's best in photos

They all soak in diluted formaldehyde in an oversized fridge at McMaster’s school of medicine, but one of the 125 brain slides in McMaster’s collection is extra-special: It’s a preserved slice of Albert Einstein. For three decades, Sandra F. Witelson has been weighing and measuring grey matter to explore the relationship between brain structure and cognitive function. Einstein’s reasoning-responsible parietal lobe, as it turns out, proved 15 per cent larger than average.