Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

The Joke

A man is presenting a series of historical facts to another person, each one making the past sound progressively more alien and uncomfortable:

1. "Things were better back when men were men and women were women" -- but then he clarifies that the fertility rate increases as we go back through history, and historically there were more men marrying men and women marrying women ("because there are ladies and lads who are ladies, and lads are men").

2. "Fact: homosexuality in males is highly correlated with the number of older brothers from the same woman." The listener responds with just "Okay..."

3. "Thus, the further back in time we go, the gayer it gets."

The final panel shows the listener saying "My God" while looking at a framed picture, and a caption reads: "The past is a foreign and slightly gayer country."

The Humor

The comic takes the nostalgic conservative sentiment that things were better "back when men were men and women were women" and systematically demolishes it using actual demographic and scientific facts. The humor lies in the logical chain: larger families in the past meant more older brothers, and the fraternal birth order effect (a real finding in psychology) correlates number of older brothers with higher rates of male homosexuality. Therefore, by strict logical deduction, the further back you go in history, the higher the statistical rate of homosexuality -- the exact opposite of what the nostalgic traditionalist imagines.

The final line, "The past is a foreign and slightly gayer country," is a play on the famous opening line of L.P. Hartley's novel "The Go-Between" (1953): "The past is a foreign country: they do things differently there."

References

The comic references the fraternal birth order effect, a well-documented finding in developmental psychology showing that each older biological brother increases the odds of homosexuality in later-born males by roughly 33%. The closing line paraphrases L.P. Hartley's "The Go-Between." The opening phrase "back when men were men" is a common conservative nostalgic trope.