Why we cannot see in the dark
Ever woken up in the dark room and frantically searching for the light switch so that the you can see properly? Or a friend of yours just came up to you from a dark room and frightened you!! Well ever wonder why that happened? Because it was dark one might say! But why we cannot see in the dark ? Well that's something to think about because there are some species of animals, birds say cheetah, cat, owl, wolves, mice etc to mention a few!
Let's try to understand why!
Well, firstly we are able to see in the dark up to some extent not totally but to some extent our eyes are able to capture some amount of light and help in getting a vision for the same. Why not fully is because how humans have evolved over the period of time or how the human eye works!
Simply put, we are able to see any objects because when light falls on the object, it reflects back the light which when captured by the eye helps us in seeing the object with help of some brain processing. So in absence of light, there is no reflection hence no visual image formed and hence the reason why we cannot see in the dark.
Every organism depends on photo or light receptors present in the eyes which capture the light and this information is then processed by the brain to form a image for us to visualize.
Also our eyes have light/photo receptors in form of cones and rods. Cones (present mostly in the center of the retina) which helps us primarily in identifying colors and are useful in the day time and rods(present at the ends of the retina) which are more sensitive to low light and help us in understanding the night vision. So in short cones helps us in color identification while rods helps us in low light conditions. Rods are why we are able to see with more clarity after being in dark for some amount of time.
Also our eyes sense only the lights that comes in the visible spectrum not like infrared. Say if we could have been able to use infrared it might have helped in the night but in the day might have blinded us.
Now why can some animals or bird can see in the dark ? Well its not total dark there is some source of light present even if considered to be negligible from human standards. Also there are multiple other reasons why this is the case.
- Anatomically the eyes of such nocturnal species are bigger as compared to humans which help in capturing more light and hence aid in visibility.
- Also there is a presence of a layer which sits behind the photo receptors called as tapetum lucidum in some species which reflect the incoming light back again to the photo receptors to maximize the image clarity. This is the reason why we see glowing eyes of some species in the dark.
Similarly there are many more biological adaptations that happen in other species. Well if the next question is why can't we add more rods to the retina or add a layer of tapetum lucidum in our eyes as well, let's understand what might happen..
As we mentioned cones are responsible for colors and rods more on the lines of black and white picture, adding more rods might lead to losing the ability to identify colors.
Presence of tapetum lucidum although it helps in the night time, during the day time it adds a lighter second or double image in front of the eyes so that may be difficult for some.
For every pro there is a con, nature has found its way of balancing and providing with the best features required for adapting and evolving as per our conditions. There is much to appreciate about it.
Well we may have got some understanding about how our eyes work in the dark, haven't we?? That is it for this time, until next time let the curious mind wander!! :)
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