When did people discover air?

No, seriously. Air is invisible – you can’t see it, you can’t taste it, and you can’t really feel it (unless the wind is blowing, and even then, ancient cavemen might not have made the connection.) So when did humans figure out that air is something that actually exists, and without it you die?

Well, when I was a kid, I was taught that air is matter – it takes up space, and has mass. That is, a bubble of air remains underneath an inverted hollow object, like a mug, coconut shell or canoe. A people know how uncomfortable they get when they force themselves to stop breathing, or if they’re without air, underwater without a convenient inverted canoe. So I’m thinking the concept of air has been around as long as, well, earth, fire and water.

The other trick, to prove air’s mass, was to balance two balloons, then let the air out of them, and they won’t balance – dunno who figured that one out first. But I did hear of Otto von Guericke, who used a vacuum pump to seal two metal hemisphere together so teams of horse couldn’t pull them apart. That was in the 1600’s so many of the individual concepts behind air took some time to work out.

Even animals know that you can drown, choke or suffocate.

Sails on ships go way back; diving bells and jars that float as well. I doubt you’ll find a recorded date.

The Greeks knew about siphons.

The Ancient Greeks thought there were 4 elements. The Greek classical elements were fire, earth, air, and water. I suspect that they realized you breathed air and felt wind, hence calling air an element. Yeah, it’s a Wikipedia reference, but I heard about that when I was a kid.

Try inhaling deeply, then blowing on the back of your hand. On on your child’s hair. On into the coals of a dying fire.

Easier yet. Take a breath. Obviously you’re breathing in something. Hold your breath. Obvious you need that something to survive. Blow bubbles in the water. Watch that something displace water. Watch the wind move objects, feel the force of it. Obviously there is something there.

I don’t think it would have taken the very first sentient being more than 10 seconds to figure this one out. For that matter, as chacoguy420 points out, it would be obvious even to animals.

On a more modern level, it wasn’t until the 1760-1770s that “air” was discovered/proven to be made up of several components, and not a single element. Joseph Priestly, Antoine Lavoisier, Henry Cavendish and Wilhelm Scheele all have some claim on the discovery of oxygen, hydrogen and the other gases that make up air. The “chemical revolution” started around that time, where a lot of the theories laid out by the ancient Greeks (such as the accepted belief that only 4 elements made up all matter) began to be disproved.

Well these are all practical applications of interacting with your environment, but humans & critters “know” about gravity too as evidenced by our aversion to cliffs, our instinctive reaction to reach down for something we’ve dropped as opposed to wondering which way it’ll go, etc. So part of being even semi cognizant means that you have an UNCONSCIOUS understanding of how to manipulate your world.

But I read the OP more to mean, “When did the light come on?” Like when did someone finally notice that we are surronded by this invisible stuff and say, “What the hell is that anyway?”

Empedocles knew this in 450 BC. See the footnote: http://books.google.com/books?id=H3ZaIYAaOSQC&pg=PA710&lpg=PA710&dq=greek+aristotle+air+pour&source=web&ots=971qmMZkFm&sig=iueCWmGU75IgPRDq8Kv4gwcNOwU&hl=en&sa=X&oi=book_result&resnum=8&ct=result

There may have been others previously.

Note that hydrogen forms a remarkable small fraction of air - about 1 part in 2 million. The abundant gases are, of course, nitrogen, oxygen, argon and carbon dioxide - these make up more than 99.99% of the total.

And you can leave out the carbon dioxide unless you’re measuring quite carefully.

Again, it’s not hard to notice that it’s easy to breathe through a wide-open mouth, harder if you make a tiny o with your lips.

Air was invented by Benjamin Franklin in the 1750s, when he realised he would need it for his kite. This innovation was eagerly received by the public, who had all been holding their breath waiting.

Hehe yes, I knew that. I tossed in Hydrogen because I mentioned Cavendish, and kind of lumped it all into “air” even though that’s not really a significant part of air, without noticing how silly that sentence was! The thing is, the identification of gases, even the understanding of what gases are, wasn’t easy, and that was more my point. It’s very hard to understand something you cannot see, touch, hear, taste or smell, and so the 1770s saw a huge leap forward in that regard (from a chemistry point of view)

Probably when the ancient Greeks first investigated the phenomenon of suction. Aristotle claimed that “nature abhors a vacuum”, and so it’s clear that he distinguished air from “nothing”.

Those Greeks, they were some wise cats, man.

Is there evidence that earlier civilizations, or even hunter/gatherers, understood the concept of a vacuum? (Which would’ve been a better question, now that I think about it…)

I once made a survey of basic vocabulary (my version of the Swadesh list) from about 200 languages around the world. I included the words for fire, water, air, and earth. At least I assumed that air would be a basic word. Actually, the Swadesh list includes fire, water, and earth-- but not air.

My survey found that a great many languages had no word for air per se. Often the nearest equivalents were the words for either wind or breath.

Of the languages that did have a word for air, many of them had it as a loanword from one of four languages which provided the philosophical and learned vocabulary for their respective civilizations: Greek, Arabic, Sanskrit, or Chinese.

Thus English & French air, Irish aer, Italian aria, Albanian erë < Latin aer < Greek aer.
Persian/Tatar/Turkish/Urdu hava, Uzbek havo, Javanese howo < Arabic hawa’.
Sinhalese vayuva < Sanskrit vayu; Assamese batah, Bengali batash < Sanskrit vata; Khmer akas, Lao & Thai akat < Sanskrit akasa.
Korean konggi, Japanese kuki, Vietnamese không khí < Chinese kongqi.

These data suggest to me that “air” is a more abstract concept than concrete wind or breath, because it so often occurs as a loanword from the languages of the major philosophical traditions. Therefore it isn’t something immediately perceptible to the mind the way fire, water, and earth are. The concept seems to be the result of thinkers reflecting on the underlying principle that accounts for phenomena like wind, breath, and why would water fail to enter an inverted container.

There are some notable exceptions, like vozdukh in Slavic languages (probably derived from dukh ‘breath’) and luft (originally meaning ‘sky’) in Germanic languages. But the less a language is connected to literate learned traditions, the less likely it is to have a word for air separate from words for wind or breath.

Duck’s Breath?

>Otto von Guericke, who used a vacuum pump to seal two metal hemisphere together

These hemispheres were a quaint plot foil in some ancient fable until I stood for a good twenty minutes staring at them from a meter away, in a museum in Munich. It is amazing how real the cutting edge between knowledge and ignorance is.

When did people discover air? There was a time when the vacuum was the thing, and it was some kind of negative pressure on the otherwise blank slate we live in. “Air” sounds to me like a very old word in English, and I know it has many spellings, 5 or 10 or so, which means that we have created and used words for a long time whose only purpose is to refer to this thing which didn’t exist when Shakespeare was topping the charts.

>AER: Air God of the Lower Atmosphere.
He floats under AETHER and is in charge of the air we breathe.

[from http://www.godchecker.com/pantheon/greek-mythology.php?deity=AER]

Apropos of this is the very commonly held misconception that “we breathe in oxygen and breathe out carbon dioxide.” Every year, my graduate students in science education look at me with blank stares when I ask them, “If this is true, why do we give artificial respiration to a person who isn’t breathing? What’s the purpose of breathing carbon dioxide into someone who needs oxygen?”