my thought: this premise implies an assumption that if the Eurasians settled in NA shortly before the peak of the ice age, the projectile must also be found where the Eurasians came from; but if Eurasians settled in NA long before, say 500 years, there might be a chance that the projectile could not be found where the Eurasians originally cames from due to reasons like erosion or moved by animals.

no, because whether use it or not it does not change the fact that simple carb would lead to more fat (compared to non-simple carb food resources)

I wish they add the function that saves the past results and allows retakes.