Before the rise of ownership of mirrors in the 15th century, people mostly identified themselves with others. It was their reflection that made them appears as individuals.
The portable oil canvass in the 16th century accelerated the self-absorbed trend. Self-portraits became the predominant way to flaunt one's importance and durability. Artists, in particular, were the first to latch on to painting technology to curate their image the way people edit their selfies today.
Modern-day photography with software editing tools like Photoshop wishes to make people look better than they actually are, unlike the television which adds five pounds.