Question: Why, as you get older, does your behaviour change from hormones in your body and why is that the purpose of the the hormones?

Emily Mattacola answered on 13 Nov 2019:

Great question! Hormones serve as messengers, controlling and coordinating activities throughout the body. As you reach puberty, different messages need to be sent to prepare your body for adulthood, so different hormones start to be released, which cause your body to go through the physical changes you experience during puberty.

Hormones don’t necessarily change our behaviour per se, but they are highly related to our behaviour. This can be positively or negatively. Hugging, for example, releases a hormone called oxytocin. Oxytocin is known as the “love hormone”, though really it’s purpose is to help us form bonds with other people. That warm glow you feel when you get a good hug is the oxytocin at work. It helps us to see what what we’re doing is good for us, and makes us want to do it more. On the other hand, a hormone that’s released when we’re stressed is called cortisol. Over time, cortisol can be bad for us; it can damage our immune system (amongst other things), which is why we’re more likely to get a cold when we’re stressed. Cortisol is released due to evolution. Thousands of years ago, the stress we experienced was likely to be acute, like getting into fights with rivals. Cortisol is to help us manage the damage we might have got from that fight, as it’s an anti-inflammatory (kind of like ibuprofen). However, in our modern world, the stress we experience is different. Now, we’re more likely to experience chronic stress, for example from our jobs. This means that cortisol is being released for too long, far longer than our ancestors needed it to be, and it’s this prolonged exposure to cortisol which starts to have a negative impact on our health.