xkcd #3127: Where Babies Come From
Title text:
Historians: Contemporaneous documentation of the initial events is often sparse, and in fact people often get testy and uncooperative when we urge better documentation for the historical record.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3127/
I think this might be a joke similar to https://xkcd.com/2030/