The linked chart is itself suspect since there weren't records back to 10,000 BC to support their 1 million headcount. But even so, 27 million in 2000 B.C. to 6 billion in a 4,000 year period, gives a growth rate of over 200x every 4,000 years.
Extrapolating back gives 135,000 in 8,000 B.C., 675 in 12,000 B.C. and 3 around 16,000 B.C.
The population growth rate of humans just doesn't support 6,000,000 years of history. Plus I think population growth has slowed in recent years. Extrapolating from that curve gives in my opinion ultra conservative results.
It's not logical that our population would only increase from 3 to just 675 in the first 4,000 years.
I have often thought the same thing. And I also wonder why we wouldn’t be much more technologically advanced than we are at this point. If you look at technology in the past 100 years, shouldn’t we be much more advanced at 6 million years?