Imagine a researcher from the Alpha Centauri system charged with writing a report on Human Beings for the Department of Alien Studies at the Interplanetary University.
Previous researchers equipped with unpleasant medical devices have already provided the department with thorough information on human physiology. So now the faculty has decided it wants to know about human behavior and values. What do humans want? What makes them tick?
Unfortunately, a turf war with the Department of Linguistics has stalled all attempts to translate Human Languages, so our researcher must base his conclusions, not on what he hears humans say, but on what he sees them do.
Fortunately, however, the Theory of Evolution, developed by the great Selrahc Niwrad, Father of Centaurian Biology, and elaborated by his many successors, provides our researcher with a helpful guide to what he should look for and what he should expect to find.
And, sure enough, he finds what he is looking for:
Evolutionary theory tells him to expect individual human beings to compete aggressively for the scarce resources needed for survival and reproduction. Check.
But evolutionary theory also tells him to expect certain important exceptions to the general rule of aggressive competition.
In the first place, it tells him to expect human females to sacrifice lots of personal advantage for the sake of their few, precious offspring. Check. And it tells him to expect human females to demand of human males that they offer convincing assurance that they will do the same, as a condition of sexual access. Check. And it tells him that human males will do their best to make their assurances of fidelity to wife and child as convincing as possible. Check. (Though mileage may vary, once sexual access is granted. Check.)
In the second place, it tells him to expect humans to sacrifice personal advantage for the sake of their kin. Not only do parents, especially mothers, give up a lot for their children, but brother and sisters help each other out, at some cost to themselves, and cousins, at somewhat lesser cost, and so on. Check.
In conditions of great, short-term, collective danger, such sacrifices may extend to very distant kin, indeed: my clan against their clan, my tribe against their tribe, my people against their people, my race against their race. Check. Check. Check. Check.
In the third place, it tells him to expect humans to sacrifice (immediate) personal advantage for the sake of ongoing, mutually beneficial, cooperative relationships with unrelated folk - a.k.a. "reciprocal altruism" - though such relationships may be very fragile, and may collapse at the first sign of "cheating."
As for unrelated folk with whom they are in no position to enter into any sort of "ongoing, mutually benefical, cooperative relationship," because they don't encounter them regularly, humans' attitudes range from the benignly indifferent to the violently hostile - depending on circumstances.
* * * * *
So our researcher sends back his report, saying, more or less, that humans are exactly as one would expect them to be, given their biology and their evolutionary history - no surprises, here!
* * * * *
But, in the meantime, the Department of Alien Studies and the Department of Linguistics at Alpha Centauri's Interplanetary University have at last resolved their differences, quickly resulting in the successful translation of all major human languages.
And what do they find? They find that, while there may be no surprises about the things humans do, the things they say are another matter entirely. Why, one might almost argue that the things they say about their values contradict the way they actually live their lives at just about every important point!
But how can that be? What's to be made of it?
* * * * *
And so our hapless researcher must return to the dreary planet Earth - but armed, now, with an implanted translator that enables him to understand every word he hears or reads...