Testosterone was long considered the bad boy among hormones. Too much of it in the blood and the man becomes a beast – driven and aggressive. But does the messenger substance actually make us aggressive or does it perhaps even promote social behaviour? This is what the latest scientific studies now suggest. Internationally renowned researchers explain to us in the Arte science documentary how subtly the hormone actually works in humans.  The word “hormone-driven” needs to be re-evaluated.  Unlike in the animal world, the blanket statement “testosterone makes you aggressive” cannot be confirmed in humans.