Why Can't You Have Black Eyes + Other Body Facts

BRIGHT SIDE・2 minutes read

Human eyes may appear black due to high melanin levels, but they are actually dark brown. The human microbiome includes bacteria, fungi, and other microorganisms, each performing specific functions.

Insights

  • Human eyes may appear black due to high melanin levels, but they are actually dark brown, showcasing the complexity and depth of eye color beyond initial impressions.
  • The human microbiome, consisting of bacteria, fungi, and other microorganisms, plays a vital role in health and disease, presenting a promising avenue for medical advancements through microbial medicine.

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Recent questions

  • What color are human eyes?

    Dark brown

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Summary

00:00

Fascinating Facts About Human Body Functions

  • Human eyes may appear black due to high melanin levels, but they are actually dark brown.
  • Eyelashes last for about 150 days, with the longest recorded eyelash being 3 inches.
  • Brown is the most common eye color, with blue eyes having a shared ancestry.
  • Tears are composed of lipids, water, and mucus, with antibacterial properties due to salinity.
  • The human eye has 576 megapixels, superior to the best camera with 200 megapixels.
  • Humans blink approximately 4,200,000 times a year, once every 8 seconds.
  • Skin cells renew every month, shedding about 30,000 dead cells every minute.
  • Fingernails grow faster than toenails due to less damage, with toenails growing four times slower.
  • Saliva production ranges from half a quart to 1 liter daily, with antibacterial properties.
  • Human bones are stronger than concrete, capable of bearing 19,000 lbs per cubic inch.

16:48

Human Feet, Finger Traits, and Unique Features

  • Human feet are typically rigid for efficient walking on uneven terrains, unlike other Apes with flexible feet for grasping branches.
  • Tree-dwelling Apes have flexible feet that bend at the ball, halfway between the ball and heel, similar to human feet with a joint at that point.
  • Majority of people have stiff ligaments at the midfoot joint, keeping it rigid, while rare individuals with chimp-like feet have softer ligaments allowing midfoot bending.
  • Researchers suggest finger isolation ability is hereditary, with some individuals able to isolate their ring finger, unlike most who struggle to move their middle finger or pinky independently.
  • Around 5% of the population can touch their nose or chin with their tongue, indicating a unique genetic trait.
  • Tetrachromats, individuals with four types of cones in their eyes, can see 100 million colors, with researchers from Newcastle University discovering one such person in 2010.
  • Some people are born with a double row of eyelashes, a condition known as distichiasis, with Elizabeth Taylor being a celebrity example.
  • Most people struggle to draw the number six with their big toe in a clockwise direction, as the brain tends to move the foot in the opposite direction due to the counterclockwise circle in the number.
  • The heart beats around 115,000 times daily, pumping approximately 2,000 gallons of blood, with the right lung larger to accommodate the heart.
  • Hydrochloric acid in the stomach aids in digestion and acts as a defense mechanism against food toxins, viruses, and bacteria, while saliva helps in tasting food and making room for dessert.

32:34

"Microbes in Human Body: Health and Function"

  • Only 43% of the body is made up of human cells, with the remaining 57% being microbes and bacteria.
  • Microbes are present on every corner of the skin, and there are more microbes than human cells in the body.
  • The human microbiome includes bacteria, fungi, and other microorganisms, each performing specific functions.
  • Microbes can both improve health and cause diseases, with microbial medicine offering potential cures.
  • Studying human microbes is more cost-effective and efficient than genetic engineering for health improvements.
  • Microbes play a crucial role in chemical reactions on Earth and are essential for various processes.
  • Humans have a unique chin, possibly for chewing, speaking, or attractiveness, unlike other primates.
  • The human brain has around 100 billion neurons, with each having 1,000 connections to others, leading to vast memory capacity.
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