It seems to be human nature for humans to expand their population until they have reached (or exceeded) the limit of natural resources to sustain them. However, when NA was first discovered it had abundant natural resources that were not yet being fully exploited by the indigenous population. Since this appears to be true when NA was first discovered, I don't think the introduction of new diseases accounts for a reduction of pressure on natural resources--that happened later.

Did the population simply not have the time to expand to meet the constraints of resources in the 10K years NA had been settled? Were they actually at sustainable levels due to the level of technology of resource gathering? Or is there some other explanation (population growth restricted through artificial/cultural mechanisms).

Thanks!