If there’s some kind of show-stopper, such as a series of impacts (it’s pretty likely that impacts arrive in groups of at least two; the SL-9 impacts 13 years ago about now numbered more than 20), civilization will cease, and surviving human populations (y’know, after internal struggle and atrocities against one another) will be isolated from one another. Due to isolation, genes would get concentrated on a random basis and lead to pronounced ethnicities which don’t exist per se today — the same process by which we all got to where we are today.
Provided such survivors aren’t hunted out by a top predator, IOW, assuming the survivors preserve tools, or re-learn toolmaking skills, islands of genetically compatible groups will diverge from one another, but still be genetically compatible. There’s no way to predict what they’d look like, or whether they’d lose their wee-wee toes and earlobes.
“”””civilization will cease, and surviving human populations (y’know, after internal struggle and atrocities against one another) will be isolated from one another.””
There are so many possible scenarios - we should consider them all individually and in combination. TWC “It Could Happen Tomorrow” are interesting vignettes, but they are only regional, climate/weather related events, based on our current circumstances. They are relatively insignificant and make no mention of long-term effects, recovery or adaptation.
More remarkable is that our ancestors envisioned how life would ebb and flow - they must have reached the end of their imagination with the Apocalypse - total end - total destruction. Have we not projected anything more scientific? 6 billion people later and 6 billion people right now...with more on the way.
Bing - there’s another one - it’s a boy;)