3 ms·

Two eyes give a very very significant increase in information provided over one eye, because two eyes is absolute minimum for depth perception. Three eyes and m

• LarryMullins 4y ago
  Two eyes are necessary for stereoscopic depth perception, but perception of depth can be had with a single eye adjusting its focal length, using context clues, or moving your head around to acquire depth information from motion parallax.
  • dekhn 4y ago
    as an example of a context clue, when driving you tend to use the size of a car as a proxy for its distance, instead of stereo vision depth perception. It's fairly common for people to lose acuity in one eye but can still drive for this reason.
• amelius 4y ago
  Most spiders have 8 eyes ... Anyway, this was not what the question was about. It was more about how this cell culture decides where the eyes go and how many there should be.
  • nine_k 4y ago
    The smaller peripheral eyes of spiders seem to be smaller and simpler then two (or four) "main" eyes. Processing data from more eyes requires more of the expensive brain tissue.
  • kleer001 4y ago
    In my purely speculative mind it's because that's the number of eyes that is in harmony with the rest of the genes.