In my most recent video, I built a digital camera in order to show how the eye evolved. If you haven’t seen that yet, this post might not make as much sense, so check that out first:
My camera was far from perfect, but it turns out that so our are eyes. They even have a blindspot! Here is how to find your blindspot:
- Close your right eye and look at the cross (image below) with your left eye. You should still be able to see the circle in your peripheral vision.
- Slowly move your head closer to the screen, keeping your right eye closed and your left focussed on the cross.
- It may take some exploring, but at the right distance, the circle will disappear from your peripheral view – your brain will have photoshopped it out.
The distance that works is different for everyone, and different depending on the screen. For me, I need to have my head 40 cm away from my computer monitor, or 20cm away from my cell phone.
Our eyes could be so much better! Octopi have no blindspot, because their photocells actually point the right way.
You know how I mentioned we have three types of photocells for seeing colour? Some mantis shrimps have 16. That means they see WAY MORE colour than we can. Snakes like pythons can see heat (infrared) and butterflies can see ultraviolet.
If you think about the entire electromagnetic spectrum, the part labelled “visible” is actually just a tiny fraction. So, thinking big picture, we don’t just have a blindspot – we are mostly blind.
My eyes are blue (yup, thats my eye up there ^^), but neither of my parents have blue eyes – so where did I get that from? Luckily, I know, because my entire family has our DNA sequenced. So, as you may guess – next months video is all about genes.