https://medicalxpress.com/news/2017-05-mile-hazardous-health.html
The short version: there are two kinds of empathy and one allows for greater 'distance' from the pain of others, but the 2nd kind - 'walking a mile in their shoes' - attempts to 'feel their pain'. Anyone who has experienced the suffering of others (who hasn't) will probably know if they enjoy a proper detachment from the pain or not, I tend to be in the 2nd group.
That creates an interesting problem... If greater intelligence produces more empathetic people, and greater empathy can be bad for our health, does that mean the more 'cold-hearted' among us (and by that I dont mean anything other than having a safer detachment from others' suffering) are better suited for survival?