Infrarojo is different from light visible only by wavelength and energy.

Nothing to do with intelligent design, evolution is a self -regulating process due to environmental conditions. Given that the life of a human being is relatively long, naturally last generational evolutionary changes in a very complex organism, due to viable positive genetic variations, where a 99.99% is not, much longer until optimization. Somewhat more than 2 millon years isn't enough for this, less with continuous changes in the environment and conditions. Simple organism with a short life cycle can optimize in days, but complex organism like humans can't. Other beings have needed hundreds of millions of years for a perfect body, but with the price of already have the veto of evolving more. After perfection there can only be decay.