Is this what killed off the Clovis culture?
One of the oldest American Indian peoples are the Clovis people, recognized for among other things their distinctive spear points. They disappeared around 12000 years ago.
https://penetrate.blogspot.com/2009/01/what-killed-off-clovis-people.html has this quote:
"What killed off the Clovis people. Tiny diamonds found in the soil are "strong evidence" a comet exploded on or above North America nearly 13,000 years ago, leading to the extinction of dozens of mammal species, according to a study"
I just saw some news that may be related: a 19-mile wide impact crater has been discovered, under the Greenland ice cap. It apparently dates to around 12000 years ago. See https://www.theguardian.com/science/2018/nov/14/impact-crater-19-miles-wide-found-beneath-greenland-glacier
The timing seems interesting. Could this be what killed off this early culture? Could other cultures around the world have been affected at about the same time?
This kind of science is not my area. Are there DU readers who know this area who can comment here?
= new reply since forum marked as read
however recently clovis mans DNA was discovered in central/south american peoples. Clovis culture seems to have had a much wider range then just NA.
DNA from mammoths/horses dated at about 6k years ago has been found in permafrosts in central Alaska, and fossils/ frozen remains on western coastal NA islands, and along the land bridge from Alaska to Russia. So although that blast was HUGE it didn't totally wipe out animals that migrated with the seasons or 'clovis man'
really must have been quite an event, I read the impact caused wildfires coast to coast! and are what formed a lot of the east coast bays & islands.
edited to add this good read https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesis
and here's the actual report from the scientists in the field 
http://advances.sciencemag.org/content/4/11/eaar8173
A 1.5-kilometer asteroid, intact or in pieces, may have smashed into an ice sheet just 13,000 years ago.
IMAGE: NASA SCIENTIFIC VISUALIZATION STUDIO
A large asteroid struck Greenland in the time of humans. How did it affect the planet?
....impact would have been a spectacle for anyone within 500 kilometers. A white fireball four times larger and three times brighter than the sun would have streaked across the sky.
If the object struck an ice sheet, it would have tunneled through to the bedrock, vaporizing water and stone alike in a flash.
The resulting explosion packed the energy of 700 1-megaton nuclear bombs, and even an observer hundreds of kilometers away would have experienced a buffeting shock wave, a monstrous thunderclap, and hurricane-force winds.
Later, rock debris might have rained down on North America and Europe, and the released steam, a greenhouse gas, could have locally warmed Greenland, melting even more ice.......
http://science.sciencemag.org/content/362/6416/738
