The phrase "to have a cow" is defined as "to be very worried, upset, or angry about something" in Free Dictionary Online.
Other sources also define it to mean to react very strongly and emotionally. While it almost always is a negative response to stressful news or events, I imagine it might be used under other more positive circumstances.
Many may have become recently acquainted with this expression from "The Simpsons" TV show, as "Don't have a cow" is a catchphrase of the character Bart Simpson.
My interest was piqued when I was acquainted with some of Gertrude Stein's writings from the movie "Paris Was a Woman". In particular, "A Book Concluding With As a Wife Has a Cow: A Love Story", published in Paris in 1926, (Google Books) caught my attention. The analyses that I heard say that there is little doubt from the context that "to have a cow" equated to having an orgasm. One summary of that analysis appears here.
My question comes down to whether Stein's metaphor is the origin of the phrase as it is currently used. It seems possible that the meaning of "an extreme, emotional reaction" might fall somewhere in the evolutionary path between Stein's usage and the current one. (It's also possible that she simply created a double entendre from an existing phrase.) What I've covered so far doesn't necessarily mean there is a relationship between Stein's metaphor and the more current expression, but it does look like a possibility.
I don't have a good understanding how to pursue this question any further. What I have seen about the origins (as cited above) is that they don't seem to be very certain, and only agree to a possibility about its provenance.
Is Stein's usage related to the current meaning? If so, how did it evolve? How did it come to be associated more with negative reactions. If it originated before Stein used it, what is the source?