Human Body
The incredible human body
267 facts
About half of the body's cells are bacteria.
The human body has about 39 trillion bacteria and 30 trillion human cells — a ratio of approximately 1:1.3.
The gut has its own independent nervous system.
The gut's "second brain" contains over 100 million neurons and can function independently from the brain.
Each person has a unique smell, except identical twins.
Body odor is determined by genetics, diet, and microbiome. Identical twins share the same olfactory profile.
The brain is sometimes more active during sleep than when awake.
During REM sleep, the brain processes memories, emotions and solves problems — potentially being more active than…
Humans are technically capable of producing venom.
All reptiles and mammals have that capability. Humans have the necessary genetic tools — it depends on evolution…
The human body has enough DNA to stretch from Earth to Pluto and back 17 times.
If all DNA from all cells were stretched out, it would be about 34 billion km long.
The human brain consumes 20% of the body's oxygen.
Despite being only 2% of body weight, the brain is extremely metabolically active.
The human body produces enough heat to boil 30 liters of water per day.
Human metabolism generates about 2,000 kcal of energy per day, part of which is released as heat.
The human body glows in the dark — it's bioluminescent.
The body emits very faint light, 1,000 times less intense than the human eye can see. It's strongest on the face and…
The human body has about 60,000 km of nerves.
The human nervous system is a vast network connecting the brain to all parts of the body.
The human mouth has more bacteria than people in the world.
The human mouth hosts about 700 species of bacteria and billions of individuals.
The human stomach has acid strong enough to dissolve metal.
Stomach hydrochloric acid has pH 1-2, similar to battery acid. It's strong enough to corrode zinc and iron.
Every day, the human body loses and replaces millions of skin cells.
The human body loses about 30,000 to 40,000 dead cells per hour — about 1.5 kg of skin per year.
The human brain is more active at night than during the day.
Neuroimaging studies show that during sleep, especially REM phase, the brain processes information intensely.
The human body has enough iron to make a 7.5 cm nail.
Iron is mainly in hemoglobin. Without it, blood couldn't transport oxygen.
The human body produces about 2 liters of mucus per day.
Mucus protects the lungs, digestive tract and nasal passages from irritants and infections.
The human brain has more connections than stars in the Milky Way.
The brain has about 100 trillion synapses, while the Milky Way has 100-400 billion stars.
Every second, 4 babies are born and 2 people die in the world.
World population grows about 80 million per year. We are currently over 8 billion people.
The human body contains about 37.2 trillion cells.
This estimate was calculated in 2013 by Israeli researchers. Most are red blood cells.
The human body produces about 25 million new cells per second.
Most are red blood cells, which live about 120 days. Over a lifetime, the body produces trillions of cells.
Tooth enamel is the strongest substance in the body.
It is composed mostly of minerals, making it stronger and more resistant than any bone.
The stomach renews its lining every 3 or 4 days.
It produces a new layer of mucus and tissue to protect itself from the extreme acidity of gastric juices.
Humans are the only animals that blush.
Facial blushing is a complex emotional response associated with self-awareness, dilating facial blood vessels.
Our skin renews itself almost completely every 28 days.
Dead cells from the upper layer of skin (epidermis) are replaced by new cells generated in the lower layers.