I estimate the estimate is either high or low. Reliability of any estimate relies on validity of input. GIGO usually means garbage in, garbage out even though it could just as easily mean gold in, gold out other than the fact gold is seldom used for input.
By the way, folks talk about how European diseases wiped out so many in the Americas — and they are right. Nonetheless, it is noteworthy to consider that variations of those same diseases wiped out large percentages of the European population several times first.
Those alive today are simply the descendants of the few who survived each time — until the next time.
Darrin Bell and Theron Heir