There is no study which seeks to answer the question effectively. It’s rather pathetic and I make no bones about hiding my derision of those who practice - and report on - orthodox archaeology. The derision is well-deserved.
If North America was so awesome, why did the Nahuatl migrate south from Aztlán to found Tenochtitlán and become so successful there as the Aztecs?
Why did the Anasazi retreat to cliff dwellings?
Why were nearly all other tribes in NA - save for some east coast peoples - nomadic?
I think the answers reflect a general threat in NA which - by consequence - limited population. The ancient mounds - a nice little thorn in the side of orthodox scientists - reflect a knowledge of sky-borne catastrophe, some of which was likely volcanic in nature (Cascades & Yellowstone), never mind natural, persistent climate shifts/cycles which affected vast swaths of NA over millennia.
I believe that the human history of NA extends FAR longer than the accepted orthodoxy. This is a DEEP subject to those with open minds (a facet which doesn’t extend to ‘science’).
In the absence of conflicting hard data - dna or otherwise - I believe that the total indigenous population of NA was WELL under a half million by the arrival of our European ancestors. There is little to no evidence to suggest otherwise.
If these ‘normally intelligent’ so-called ‘scientists’ genuinely wanted to establish population trends, they would have performed a DNA study of remaining indigenous populations.
Thus, the logical conclusion is that they don’t want answers, just more controversy to fuel additional studies (i.e., “$$”).
To-wit:
“The new study also questions the inevitability of the conquest of the content. If Europeans had arrived a few centuries earlier and faced much larger Indigenous populations and well-organized tribal confederacies, the study authors conclude, “the history of North America might have been very different.””
Translated: “We’re intentionally provoking controversy.”
Estimates are that the Bering Land Bridge formed around 35,700 years ago during the last ice age when sea levels dropped sufficiently to expose the landmass connecting Siberia to Alaska across the Bering Strait. The land bridge between Asia and North America, known as the Bering Land Bridge, disappeared around 11,000 to 13,000 years ago as rising sea levels flooded the Bering Strait, caused by the melting of glaciers at the end of the last ice age.
Maybe the melting happened because the great Native American chief in what’s now called Alaska named Doneli-jont-Rump didn’t think that the Sabre-Toothed Smelt was worth saving, though it might have actually been wiped out by the poisonous dangerous fish some called the caring bass. And thus the sea level rose. A lot of family reunions between the Siberians and Alaskans to cook smelt had to be postponed due to the floods and then they lost touch with each other gradually and stopped trying to visit each other & eventually may have had some corrupt leaders who discouraged freethinkers to believing the oral legends about having relatives on the other side & all written records, whatever they had, were purged?
I’m just speculating, with a little satire.
But in all seriousness I think a lot of land bridges may have come and gone since Yellowstone’s last major eruption around 640,000 years ago until the land bridge formed over 35000 years ago. However, just like the Biden administration, there was lots of censorship that happened in human history so much was lost.
There have been DNA mutation rates calculated for several indigenous North American groups.
Range: 18,000 to 24,000 years of residency, which fits well with the land/ice bridge theory for crossing the Bering Strait.
From memory - peak Bering Strait ice has been calculated to 20,000 years ago.
North American DNA has been linked to several northeast Asian groups, including Japanese.
South American DNA has been allegedly linked to Pacific Island DNA, but I do not think that has ever been confirmed by world class science journals.
On the other hand, during peak ice, there were probably hundreds of habitable Pacific Ocean islands between South America and southeast Asia that no longer exist.