This picture is the oldest anatomical documentary of the heart and resembling it as the center of life. It was drawn over than 15,000 B.C. ago in a cave in Spain called “El Pindal cave”.

The drawing may have been used to teach young hunters where to aim their arrow or spear.
Prehistoric societies were primarily hunting societies and the heart must have been the organ that attracted the attention of man from earliest times because he found it beating as long as there was life and he soon must have discovered that the best way to kill an animal was to spear it through the heart Figure 1.

The drawing probably also served as teaching material to young hunters. I can imagine an older and seasoned hunter using such illustration to coach young hunters which part of the animal they should direct their arrows.
Although this same form of heart which currently expresses feelings of love, in reality, it was once a target to be focused on by the Homo sapiens to kill the mammoth (Hajar, 2011).

Heart symbol once was a place for ending someone’s life by a physical arrow, accidentally, it’s now a place for the same purpose but by ending someone’s dreams by the name of love.

References:

Hajar, R. (2011). Medical illustration: art in medical education. Heart views: the official journal of the Gulf Heart Association, 12(2), 83.