Why does a slice of toast land butter side down?

Do dolphins and whales yawn? Is yawning contagious in animals? What progress has been made on brain chip implants? What is the difference between kidney thrombosis and renal vein thrombosis? Why does a falling slice of toast land butter side down, and does fall height matter? Is it unsafe to receive the wrong blood type? Why are birds adapted to have birdsong? What keeps all the water up in a cloud? Why can I feel my phone buzz in my pocket when it's actually on the table? And how to improve blood iron levels? Dr Chris Smith and Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists