Mind blowing facts about your eyes

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human eye
human eye

Here are some other facts about human eyes, so that you can appreciate the superhuman strength of the deceptively simple human eye.
1. The focusing muscle of the human eye moves about 1000,000 times every day.
It’s crazy how much the focusing muscle of the eye gets done. On an average, this spectacular muscle of the human eye moves about 1000,000 times every single day. If that doesn’t blow your mind, let’s put it in perspective. For your leg muscles to get the same kind of workout, you would have to walk 50 miles, every day.
2. Until about 10,000 years ago, all human beings had brown eyes. Blue eyes are a more recent phenomenon caused by a genetic mutation, a sign that humans are still evolving.
Originally, every single human being had brown eyes. However, about 10,000 years ago, someone who lived near the Black Sea developed a genetic mutation that turned brown eyes to blue.  There are many theories about how blue eyes have still persisted, so many generations later. For instance, one theory suggests that blue eyes act as sort of a paternity test. This means that since there is strong evolutionary pressure on a man not to invest his paternal resources in another man’s child, he would actively seek out blue-eyed mates. Since it is impossible for two blue-eyed partners to create a brown-eyed baby, this instinct may have led to the genetic preservation of blue eyes.
3. How far can the human eye see? Assuming a flat earth and complete darkness, the human eye is sensitive enough to spot a candle flame, flickering up to 30miles (48 km) away
Although the Earth’s surface curves out of sight at a distance of 3.1 miles (5 km), our ability to see extends far beyond that distance. If Earth were completely flat, or if you were standing on top of a mountain surveying a larger-than-usual patch of the planet, you could see bright lights that are hundreds of miles away! On a particularly dark night, you could even see a candle flame flickering in the distance, specifically up to 30 miles away.
The eye’s ability to perceive things in the distance depends on how many particles of light, or photons, an object emits. After extensive research, vision scientist Selig Hecht discovered that the absorption of 5 to 14 photons, or, equivalently, the activation of just 5 to 14 rod cells is enough to tell your brain that you’re seeing something. The farthest object that is visible to the naked eye is the Andromeda galaxy, wherein its constituent 1 trillion stars collectively emit enough light for a few thousand photons to hit each square centimeter of Earth every second.

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