From a recent Sore Thumbs:
"How the heck will Kinect swimming even work?" is a nice example of a use of even that I think is genuinely new. At least, certain expressions like "what does that even mean?" and "how does that even work?" have recently become common, and I can't find clear examples of them that are more than about 15 years old. But perhaps we should see this as rolling the clock back to the 16th century, and taking things up where they left off when even began a five-century detour as a scalar particle.
According to the OED, even started out meaning "flat, level, uniform", passed through related notions like "equal, coincident, balanced, exact", and eventually came to be used "in weakened senses as an intensive or emphatic particle", which might be "Prefixed to a subject, object, or predicate, or to the expression of a qualifying circumstance, to emphasize its identity". Thus
a1616 Shakespeare Tempest (1623) iii. i. 14 These sweet thoughts, doe euen refresh my labours.
This version of even was used hundreds of times in the King James bible, for instance
Gen. 34:29 And all their wealth, and all their little ones, and their wiues tooke they captiue, and spoiled euen all that was in the house.
We have no record of anyone complaining about the striking loss of literal precision.
At some point in the 16th century, even developed the OED's sense 9,
Intimating that the sentence expresses an extreme case of a more general proposition implied (= French même). Prefixed (in later use often parenthetically postfixed) to the particular word, phrase, or clause, on which the extreme character of the statement or supposition depends.
This use, now the prevailing one in Eng., is foreign to the other Germanic langs. It is rare in purely dialectal speech, and (though a natural development of 8) seems not to have arisen before the 16th c. Cotgrave 1611 does not give even among the equivalents of French mesme.
This is the "scalar particle" sense whose modern analysis was initiated by Larry Horn's 1969 paper "A Presuppositional Analysis of 'Only' and 'Even'", CLS 5, and fully developed by Lauri Karttunen and Stan Peters, "Conventional Implicature", 1979. K&P consider the sentence
Even Bill likes Mary.
and argue that besides asserting that Bill like Mary, this sentence presupposes that
(a) Other people besides Bill like Mary; and
(b) Of the people under consideration, Bill is the least likely to like Mary.
This points in the direction of a formal reconstruction of the idea in the OED's observation that this sense of even is "intimating that the sentence expresses an extreme case of a more general proposition".
(We'll pass over the formal part, and also ignore for now the fact that even associates with focus, so that e.g. "Kim even taught Leslie Tibetan" means something different from "Kim even taught Leslie Tibetan", where boldface denotes intonational focus.)
This same scalar-particle analysis of even works with verbs, as in the title of Slavenka Drakulic's book How We Survived Communism and Even Laughed. Thus this presupposes that there are other things besides laughing that we did (or might have done), and that of the activities under consideration, laughing is the least likely (or at least is well out towards the edge of likelihood).
But there's a class of (I think) recent uses of even that resist this sort of treatment as "intimating … an extreme case of a more general proposition", and instead seem to be purely emphatic. I associate this with the speech of young women, as in this passage from Rhoda Hayter, The Witchy Worries of Abbie Adams (2010):
How'd you like to be innocently walking in the door one day with an armload of books for your kitten and hear this in your head: "Father's going to owe me a lot of dimes soon"? How random and creepy is that ???? What does something like that even mean???
But like many such stereotyped associations, this one seems to be false.
Randall Munroe, the author of xkcd, is relatively young but not female:
And judging from his picture as well as his C.V., Owen J. Flanagan, the James B. Duke Professor of Philosophy at Duke University, is neither young nor female, but p. 265 of his 2002 book The problem of the soul: two visions of mind and how to reconcile them contains this passage:
And we might have the urge to say it is objectively true that friendship, love, kindness, and compassion are great goods. But what does this even mean?
An unusual auction began late yesterday on eBay. I’m selling my “right to regain weight.” Why would anyone in their right mind be willing to pay me cash to buy this right? What does this even mean?
Indeed, one of the earliest examples that I've been able to find of phrases like "what does that even mean?" is in a quote from a Chicago Bears linebacker (Marc Morehouse, "Bears' defense blitzed again", Dubuque Telegraph-Herald 11/13/1995):
Chicago linebacker Vinson Smith, who blitzed to collect two of the Bears' three sacks Sunday, questioned Favre's questionable status going into the game.
"He was not hurting," he said. "No way. You can't tell me that."
The Packers said Favre missed the entire week of practice. And Favre admitted Sunday that he didn't even go to practice.
"I'm hoping to get out of it again next week," said Favre, who finished 25 of 33 for 336 yars and no interceptions.
"Now he knows I know his ankle is getting better," Packers coach Mike Holmgren said. "So, we'll have to negotiate."
Smith as still unconvinced.
"That was bullcrap from the beginning," he said. "What's that even mean? He must have been practicing at night" when nobody was paying attention.
The earliest example that I've been able to find is Carl Herko, "It's time for some serious fun", Buffalo News 11/25/1993:
The Top 10 adult toys? Now, that is a holiday gift category full of (heh-heh) possibilities! And (nudge-nudge) peril.
What does that even mean, adult toys? It's not an easy term to define, like kids' toys or pornography, where you know it when you see it.
No sirree, an adult toy is something altogether different. To some adults, it might be nothing more than a parlor game big people play; Trivial Pursuit, perhaps.
The specific phrase "what does that even mean?" has become fairly common in the news media and in books, but most of the hits are from the past decade. Since it's used by older people like Ayres and Flanagan, you might think that it was around 50 years ago — Flanagan was born in 1949 — but I don't remember this expression from my youth, and I can't find any convincing examples before the 1993 quote given above. No doubt there are some out there, but it does seem that the spread of this variety of even is relatively recent.
Cecania's question, "How the heck will Kinect Swimming even work?", shows that this use of even is not limited to inquiries about what things mean. Some other web examples that seem similar to me:
How do you even spell that?
How do you even pronounce Ophiuchus?
Why are you even bothering me?
If she has children then it will be because she wanted to and I don't see how that's even entertaining to anyone.
I have no idea who that even is.
but has anyone even considered how that even happened?
I can't even stand this thing anymore.
As far as I can tell, this purely-emphatic version of even is a polarity item, in that it only works in a range of contexts including negation and questions.