break-up following your first love, crying may seem like a strange physical

response to your emotional turmoil. Why do we start the waterworks when we feel

really sad? Is there a biological advantage or purpose other than washing

your face or streaking your mascara? Well crying does not only happen when you are

emotional, there are actually three types of tears. Basal tears are perpetually

lubricating your eyes keeping them from drying out, while reflex tears act in

response to an irritant like onions or dust.

They begin a chain reaction releasing hormones from the brain which then

trigger a tear response from the glands in the eyelids. And these tears help to get rid

of the irritant.

But tears of sadness? Strangely this leaky face phenomenon is exclusive to

humans with a couple different theories as to why. And one is strikingly similar

to the reason we blush, which we described in a previous video here. In

many cases emotional tears are able to act as a signal to others of our

genuine sadness or distress. That is not always easy to fake. Your tears blur

your vision, essentially handicapping any aggressive or defensive actions sending

those nearby a signal of need appeasement or attachment.

From an evolutionary perspective, this increases communication with those close

to you and ultimately your chance of survival.

Some experiments have even taken photos of people crying and made copies

with the tears digitally removed. Not surprisingly, people rated the pictures

with tears to be more sad, while the ones without were often confused with puzzlement,

awe or other expressions.

But what about tears of joy? Well perhaps they are not so different, afterall tears of

happiness may still be used as social signals for how we feel, and are thought to

strengthen bonds between people. Also both emotions see activity in similar

regions of the brain, such as the hypothalamus and basal ganglia

which just happen to be connected to your tear glands.

Another theory suggests that crying is one of your body's mechanisms to

literally shed your stress. Interestingly reflex tears and emotional tears have

very different compositions. Emotional tears have much higher levels of

proteins, in particular some called adrenocorticotropic hormones

which are linked to high stress levels. And some say crying helps to release these

stress chemicals from the body, but the research here is limited and not yet conclusive.

So go on,

have a good cry,

let the world know how you feel and potentially let out that stress.

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