> The Serpent Mound is believed to have been built by the Native American Adena peoples around 320 BCE, and then either added to or repaired by the Fort Ancient peoples around 1100 CE.
T̶h̶e̶ ̶p̶r̶e̶v̶i̶o̶u̶s̶ ̶u̶n̶c̶o̶n̶t̶r̶o̶v̶e̶r̶s̶i̶a̶l̶ ̶l̶o̶w̶e̶r̶ ̶b̶o̶u̶n̶d̶ ̶w̶a̶s̶ ̶b̶e̶t̶w̶e̶e̶n̶ ̶1̶2̶.̶8̶k̶ ̶a̶n̶d̶ ̶1̶3̶.̶5̶k̶.̶ (This hasn't been a lower bound for a while, see below.)
It's my understanding this is an active area of debate. To give a tentative upper bound, the Cerutti mastodon kill - who's anthropogenic origins, while they seem compelling to me (a nonexpert), are hotly debated, have a date of 130k years ago.
(I suspect GP meant to reference the Cerutti Mastodon site, rather than Serpent Mound?)
(And of course, much of this is referenced in the article, I'm busted for reading the comments first! Interesting article that says it far better than I, worth reading.)
The current uncontroversial bound is roughly 15kya--as the article notes, the White Sands fossil footprints are still controversial. The Clovis First hypothesis has been considered thoroughly discredited in the academic community for about 20 years now.
The Cerutti Mastodon site is not compelling to me, because a date of 130kya would put it before any other site of homo sapiens outside of Africa. Being so far out of line with other evidence means that the evidence in favor of hominids needs to be exceptionally rock solid, which it isn't.
For sure, thanks for keeping me honest. I'm a decidedly a nonexpert, I just watch some documentaries and such.
I would submit we should be cautious with metaobservations like, "this is much older than other sites," because we should be trying to prove ourselves wrong, whereas these sorts of metaobservations amplify confirmation bias. I'm not saying skepticism is unwarranted, just that we need to be careful with this sort of reasoning.
As a side note, I've seen people strike through stuff out on HN, and I'd like to strike through this claim to emphasize there's a correction; it's not in the undocumented features repo[1], and I've tried a few standard things like ~this~ and ~~this~~ and -this- and --this-- and have never figured it out. Can anyone tell me what the markdown is?
> I would submit we should be cautious with metaobservations like, "this is much older than other sites," because we should be trying to prove ourselves wrong, whereas these sorts of metaobservations amplify confirmation bias.
Both 'we should be trying to prove ourselves wrong' and 'Being so far out of line with other evidence means that the evidence in favor of hominids needs to be exceptionally rock solid' can both be valid at the same time. The base rate of a 'false positive' for extraordinary claims that conflict with an existing body of evidence is typically much higher so confidence in the evidence would need to quite strong for that piece of evidence to move the consensus.
I'd consider myself largely a frequentist but the relevant xkcd [1] comes to mind
I'd argue that ignoring that aspect can amplify one's susceptiblity to confirmation bias if one is predisposed to believing in a very early American hominid story for whatever reason.
Cerutti being real doesn't mean it's H. Sapiens tho does it? It could be an older hominin, an other descendant of H.Erectus (after all as far as we know H. Neandertalensis did not evolve in africa, and H. Erectus reached the sea of china and the pacific ocean)
Although Fuyan also shows H.Sapiens may (its datation is also disputed) also have reached out of africa much earlier than otherwise supported.
The problem of cerutti's dating is that the archaeological record of hominids in the high Arctic begins <50kya, 80k after the hypothetical dating. There's some middle paleolithic stuff in southern/central Siberia, but also few options to get to the new world without boats or beringia (which was submerged during previous interglacials).
Does that make sense for them to continued to have existed for thousands of years during the ice age where nothing grew? Or if the dating is even accurate at all?
Furthermore the LGM event started around 33000 BCE, reached its peak around 25000 BCE, and the deglaciation started around 19000 BCE with a significant acceleration around 15000 BCE.
I wasn't the one insisting that Mexico and Central America were ice-free. The glaciation blocked off many high-altitude passes like the paso de cortes. Most of the taller ranges along the American cordillera had some level of glacial activity during the LGM and that meaningfully impacted regional climates throughout the Americas.
Well, the ice age[1] was everywhere right? Our ancestors would've had trouble surviving most anywhere, why not California? It's not that literally nothing grew, otherwise what were the mastadon & other animals in the kill site eating?
Another possibility is that this was another group of hominids, not homo sapiens, and that they did in fact die out.
But honestly I'm not qualified to say much more in the subject than I have, I think it's a fascinating hypothesis & that the evidence that the bones were broken apart by being impacted with stones, in a similar manner to how bones are broken up to extract marrow, is compelling. And that the further isotopic evidence suggesting it was the stones found around the site, rather than construction equipment, is also compelling. But I'm not an archaeologist, and when the debate settles, I'll accept the conclusion they come to.
[1] Not to be pedantic, just to note because I find it fascinating, but the current ice age hasn't ended, this was the "last glacial period". Between ice ages there can be things like palm trees and turtles living at the poles. We're currently in an interglacial period of an ongoing ice age.
Most of the world was not iced over; mainly just higher latitudes like where European geologists come from. People in the tropics experienced big climatic shifts -- green Sahara, Amazon savannah, and the Java Sea, South China Sea, Yellow Sea, and Persian Gulf all lush bottom land -- but mostly not ice.
Yeah worth mentioning, to put a fine point on it - geological ice ages are millions of years long and include alternating glacial and interglacial periods. In popular use of the terms, ice ages are those shorter glacial periods.
> The Serpent Mound is believed to have been built by the Native American Adena peoples around 320 BCE, and then either added to or repaired by the Fort Ancient peoples around 1100 CE.
So maybe 2k years?