Why only use big dogs as sniffer dogs?

Vitamin D for coronavirus? Narcissism and the brain. Why use big dogs as sniffer dogs? Understanding conversations in noisy places, and why that gets harder as we age. Why does my hand itch before I receive money? Is the new coronavirus linked to type I diabetes in children? And attaching significance to coincidence! Join Dr Chris on 567 CapeTalk for all the answers... Like this podcast? Please help us by supporting the Naked Scientists