Depres­sion is an emo­tional response that has evolved to pre­vent us from expe­ri­enc­ing men­tally dam­ag­ing events, a num­ber of recent stud­ies are start­ing to suggest.

As pain stops you doing dam­ag­ing phys­i­cal things, so low mood stops you doing dam­ag­ing men­tal ones—in par­tic­u­lar, pur­su­ing unreach­able goals. Pur­su­ing such goals is a waste of energy and resources. There­fore […] there is likely to be an evolved mech­a­nism that iden­ti­fies cer­tain goals as unat­tain­able and inhibits their pursuit.

This ‘evolved mech­a­nism’, it appears, is depression.

As one study showed, mild depres­sion is actu­ally a some­what healthy response:

Those who expe­ri­enced mild depres­sive symp­toms could […] dis­en­gage more eas­ily from unreach­able goals. […] Those who could dis­en­gage from the unat­tain­able proved less likely to suf­fer more seri­ous depres­sion in the long run.

It’s an inter­est­ing the­ory and the neg­a­tive cor­re­la­tion between mild depres­sion and seri­ous depres­sion later in life is a telling sign that there may be some truth in the theories.

Oh, and the image Intel­li­gent Life is using on the arti­cle? A self-portrait of yours truly look­ing slightly dejected. So head on over and read the article/look at my ugly mug.