In genetics we can look at genetic diversity in everyone and everything and find common genetic traits which would indicate a significant reduction in a given population. This is done by finding and identifying genetic traits that only a small breeding population would have in common and would be subsequently carried down through subsequent generations. If the story of Genesis and Noah were true, we would see genetic bottlenecks showing a breeding population of a very limited number and we would be able to identify roughly when it happened; but this is not the case at all.
If you don’t know what a genetic bottleneck is, it is a sharp reduction in the size of a population due to environmental events (such as earthquakes, floods, fires, disease, or droughts) or human activities (such as genocide). Such events can reduce the variation in the gene pool of a population; thereafter, a smaller population with a correspondingly smaller genetic diversity, remains to pass on genes to future generations of offspring through sexual reproduction. Genetic diversity remains lower, only slowly increasing with time as random mutations occur. In consequence of such population size reductions and the loss of genetic variation, the robustness of the population is reduced and its ability to survive environmental changes can be reduced.
Our last genetic bottle neck is estimated to have occurred over 100,000 years ago and even then there were still thousands of genetic variances belonging to a few thousand individual ancestors. In 2000, a Molecular Biology and Evolution paper suggested a transplanting model or a ‘long bottleneck’ to account for the limited genetic variation, rather than a catastrophic environmental change. This would be consistent with suggestions that in sub-Saharan Africa numbers could have dropped at times as low as 2,000, for perhaps as long as 100,000 years, before numbers began to expand again in the late stone age.
Now with that being said, we would see this same genetic bottleneck in every animal on earth happening at the exact same times if the bible was accurate, and yet there is zero evidence to support these ridiculous conclusion. What is so frustrating to scientists is that creationists think that the only evidence for evolution is fossils and educated conclusions. This is entirely incorrect since evolution is also written in your genes and thus not only debunks the story of Noah, but the Genesis story as well. This is yet another reason why we know evolution is a fact and that the bible is not factual by any scientific standard.
Hawks J, Hunley K, Lee SH, Wolpoff M (January 2000). “Population bottlenecks and Pleistocene human evolution”. Molecular Biology and Evolution 17 (1): 2–22. doi:10.1093/oxfordjournals.molbev.a026233. PMID 10666702.