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fifty-nine elements are needed to construct a human being.
Six of these—carbon, oxygen, hydrogen, nitrogen, calcium, and phosphorus—account for 99.1 percent of what makes us,
The biggest component in any human, filling 61 percent of available space, is oxygen.
It is a little ironic that two of the lightest things in nature, oxygen and hydrogen, when combined form one of the heaviest, but that’s nature for you.
the full cost of building a new human being, using the obliging Benedict Cumberbatch as a template, would be a very precise $151,578.46.
a figure of $168 for the value of the fundamental components within the human body,
the only thing special about the elements that make you is that they make you.
Well, you blink fourteen thousand times a day—so much that your eyes are shut for twenty-three minutes of every waking day.
In the second or so since you started this sentence, your body has made a million red blood cells.
Altogether it takes 7 billion billion billion (that’s 7,000,000,000,000,000,000,000,000,000, or 7 octillion) atoms to make you.
Unpacked, you are positively enormous.
Your lungs, smoothed out, would cover a tennis court, and the airways within them would stretch nearly from coast to coast. The length of all your blood vessels would take you two and a half times around Earth.
if you formed all the DNA in your body into a single strand, it would stretch ten billion miles, to beyond Pluto.
You are in the most literal sense cosmic.
The basic unit of life is the cell—everyone is agreed on that.
yet somehow all this random motion results in smooth, coordinated action, not just across the cell but across the whole body as cells communicate with other cells in different parts of your personal cosmos.
You would need twenty billion strands of DNA laid side by side to make the width of the finest human hair.
Your DNA is simply an instruction manual for making you.
A length of DNA is divided into segments called chromosomes and shorter individual units called genes. The sum of all your genes is the genome.
You will die and fade away, but your genes will go on and on so long as you and your descendants continue to produce offspring.
What genes specifically do is provide instructions for building proteins.
Some speed up chemical changes and are known as enzymes. Others convey chemical messages and are known as hormones. Still others attack pathogens and are called antibodies. The largest of all our proteins is called titin, which helps to control muscle elasticity.
The paradox of genetics is that we are all very different and yet genetically practically identical.
All humans share 99.9 percent of their DNA, and yet no two humans are alike.
And how do we celebrate the glory of our existence?
Our bodies are a universe of 37.2 trillion cells operating in more or less perfect concert more or less all the time.
You are the product of three billion years of evolutionary tweaks.
IT MAY BE slightly surprising to think it, but our skin is our largest organ, and possibly the most versatile.
Run a finger along a dusty shelf, and you are in large part clearing a path through fragments of your former self.
skin and hair are made largely of the same stuff: keratin.
An interesting thing about touch is that the brain doesn’t just tell you how something feels, but how it ought to feel. That’s why the caress of a lover feels wonderful, but the same touch by a stranger would feel creepy or horrible. It’s also why it is so hard to tickle yourself.
“That,”
“is where all your skin color is. That’s all that race is—a sliver of epidermis.”
“People act as if skin color is a determinant of character when all it is is a reaction to sunlight. Biologically, there is actually no such thing as race—nothing in terms of skin color, facial features, hair type, bone structure, or anything else that is a defining quality among peoples. And yet look how many people have been enslaved or hated or lynched or deprived of fundamental rights through history because of the color of their skin.”
eumelanin but known universally as melanin.
Vitamin D is vital to health. It helps to build strong bones and teeth, boosts the immune system, fights cancers, and nourishes the heart.
it provides warmth, cushioning, and camouflage, shields the body from ultraviolet light, and allows members of a group to signal to each other that they are angry or aroused.
Hair on the head acts as a good insulator in cold weather and a good reflector of heat in hot weather.
a tool of seduction since time immemorial.
“It is plain old unglamorous sweat that has made humans what they are today.”
“The loss of most of our body hair and the gain of the ability to dissipate excess body heat through eccrine sweating helped to make possible the dramatic enlargement of our most temperature-sensitive organ, the brain.”
Sweating is activated by the release of adrenaline, which is why when you are stressed, you break into a sweat.
The microbes that live on you depend to a surprising degree on what soaps or laundry detergents you use, whether you favor cotton clothing or wool, whether you shower before work or after.
tiny mites called Demodex folliculorum.
No one can say why we are so suggestible with respect to itches or even why in the absence of obvious irritants we have them at all. No single location in the brain is devoted to itching, so it is all but impossible to study neurologically.
No matter how else you suffer, you will never have an itchy spleen.
Eighty percent of the air you breathe is nitrogen.
it doesn’t interact with other elements.
When you take a breath, the nitrogen in the air goes into your lungs and s...
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For nitrogen to be useful to us, it must be converted into more sociable forms, like ammonia, and it is ba...
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