"not rocket science/not brain surgery"

[Sam Clements]

Nothing helpful in the archives about the origins of these similar phrases, which refer to how simple something is.

Usenet only comes up with the phrase(s) from about 1990.

Proquest offers a 1981 NYTimes review of books by Thomas Philbin, and an interview with him.  He says, in the interview, "I have more than the usual complement of thumbs.  I think of myself as a writer-editor of this stuff more than an expert craftsman.  But I can fix a screen.  I can fix a light.  This stuff is not brain surgery." 

Can anyone find an earlier example of "not brain surgery/not rocket science" to mean what it did in that interview?  

Was there an earlier phrase which defined the same sentiment?

Sam Clements

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