Some areas identified as particularly human are the regulation of the cone cells of the retina (which are involved in colour vision) and the regulation of nerve-cell growth.
At 220 pixels-per-inch, the Retina display's pixel density is so high the human eye cannot distinguish individual pixels from a normal viewing distance, so text and graphics look incredibly sharp.
The laptop's 12.85in (32.64cm) display's resolution is similar to the so-called Retina Display of Apple's MacBook range, aimed to have pixel density high enough for the human eye not to notice pixelation when looking at the screen at a typical viewing distance.