More likely, early humans simply killed off the large herbivores, and the large predators simply starved.
This happened in Australia. All the local megafauna disappeared rapidly once humans settled in.
This happened in Australia. All the local megafauna disappeared rapidly once humans settled in.
It's far more likely that people simply poked animals to death with sharp sticks.
We know from polar ice cores that the Americas were shrouded in dense smoke 12,800 years ago from fires started by the comet strikes at that specific time. Central and South America are certainly susceptible to massive wildfires, like anywhere shrouded with combustibles.
Why? Spears are extremely effective and deadly.
And it happened everywhere else. Megafauna also disappeared in Asia, as soon as humans appeared.
> People lived in the Americas for thousands of years without affecting them
In other words: animals existed for hundreds of thousands of years, but they disappeared within several hundred of years, right as human settlement waves moved across the Americas.
And continents are big, and people very unevenly distributed. 13kya there were few humans on any continent. It takes more than spears to eliminate mastodons, mammoths, short-faced bears, dire wolves, sabretooth cats, cheetahs, camels, horses, giant sloths in one blow.
Humans did not drive 30+ genera to extinction in the Americas all in under a century, after coexisting for millennia; and did not lay down a film of dust enriched with platinum over the whole continent, or torch it. They did not wipe out their whole material culture at the same time. Nothing Clovis, or any of those genera, are found anywhere above the layer of platinum-enriched charcoal and ash dust.
Horses and elephants did not become extinct in Eurasia, where people hunted far longer. You might notice Africa still sports plenty of megafauna.
It seems to be a pattern to this day. I view the flames as a kind of Asmovian terraforming.