system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What is it, physically or psychologically, that makes direct eye contact so intimate and/or uncomfortable?
gpt
Besides the people who are shy or socially anxious, for which the reason is simply that, anxiety, other than that, evolutionarily, eye contact, especially in primates, is seen as a sign of direct confrontation and challenge. 

For example in some apes, direct eye contact means challenging the leader of the group to a fight, to take over his position or banish him etc. Thats why apes avoid eye contact, especially with the leader of the group.

And i guess same got transferred to us. Eye contact is uncomfortable because its a signal of “im not afraid of you”. Which causes tension as you may guess.