asked if I was <comfortable> and I said I make a living. [Joke?]

[mycityofsky]

From NPR(American audio):

And now, strictly in the interests of evolutionary psychology, the nurse asked me to sit down and asked me if I was comfortable and I said, well, I make a living.
(LAUGHTER)

1. What's the meaning of "in the interests of evolutionary psychology"? Does it mean "to improve the evolutionary psychology"? Such as in the interests of justice / safety / efficiency etc? But if so, I could figure out the meaning of "strictly" in the context.

2. It seems to be joke, but I couldn't figure out why it is funny. If someone asks me if I was comfortable, I would answer "yes/no". The answer of "I make a living" seems not to correspond to the question at all. And given that "make a living" only means "do something to earn money to make you alive", I didn't see anything funny. Can anyone explain why it is funny?

Thanks in advance.

SOURCE: How To Tell When A Laugh Is Real: The Answer Is In A Breath

 

[JamesM]

If someone is "comfortable" in relation to finances it means that they have more than enough money for all their needs; the person is not extremely rich but has enough money to have luxuries. The joke is that he answered the other meaning of the question even though he knew the expected answer from the context. Humor is often about surprise or an unexpected twist. His answer was surprising but familiar in a different context.

 

[mycityofsky]

@JamesM. So if a person "makes a living", does it mean that he earns just enough money to live, but no more to buy luxuries?
And does "in the interests of evolutionary psychology" simply mean "in the field of evolutionary psychology"?

I'm very appreciated your help.