A big part of being human is feeling sympathy, but how early on in our lives do we learn this? Scientists find that babies respond to other people by crying when other babies cry. However, babies can't distinguish between themselves and others until they're eighteen to twenty months old. Toddlers start to show concern for others around this time. Kids also begin to do things like comforting other people. And by the time they're three, most children will try to protect a victim in a fight.