My take on widespread pyramid building is that without modern engineering, the only way to build large tall buildings is something like the pyramids with progressively smaller layers. That said I am a believer in pre Columbian contact. I just don’t think that pyramids per se are evidence of that
I asked perplexity ai about gene flows into pre columbian America. This was the answer.
Genetic studies of pre-Columbian America indeed show evidence of gene flow from Siberia and, to a lesser extent, from populations with Australasian (Melanesian) ancestry.
The primary migration from Siberia occurred around 23,000 years ago, during the last Ice Age. An international team analyzed genomes of ancient and modern Native Americans, concluding that the first Americans arrived in a single wave from Siberia no more than 23,000 years ago6. This Siberian ancestry forms the foundation of Native American genetics.
Interestingly, some studies have also detected traces of Australasian ancestry in certain ancient South American populations. A 10,400-year-old individual from Lagoa Santa in Brazil showed evidence of Australasian genetic signatures1. This finding is puzzling, as it appears to have “leaped over” North America, and the exact mechanism of this genetic contribution remains unclear.
Additionally, more recent gene flow from Siberia has been documented:
A migration around 4,000 years ago into North America3.
Another migration between 1,000-800 years ago, contributing to the contemporary gene pool in northern North America3.
These later migrations added to the genetic diversity of Native American populations but did not replace the existing populations entirely. Instead, they mixed with local communities, creating a complex genetic landscape1.
It’s important to note that while these genetic studies provide valuable insights into ancient migrations, they also raise new questions and hypotheses that require further research to fully understand the intricate history of human movement in the Americas.