Mitochondrial Bottlenecking
In every eukaryotic cell, there’s prokaryotic mitochondria that has it’s own DNA separate from the DNA of the eukaryotic cell host. The eukaryotic cell has DNA from both mom and dad, but the mitochondria has DNA only from mom that doesn’t experience any genetic recombination from dad. This lack of recombination makes it easy to measure genetic drift and “carbon date” the age of a species, or at least how far back you have to go to find a common mother for every member of that species.
For example, my siblings and I all have clones of my mother’s mitochondria. If I had a half-sister on my dad’s side, she would have different mitochondria than I do. One could figure out how far back we have to go to get to a common mother by comparing the mitochondria DNA sequencing, count the number of mutations, and divide that by the rate of mutation (about 1%/million years according to scientists).
In a 2018 article uploaded to bioRxiv, M.Y. Stoeckle and D.S. Thaler point out that within each species (and they studied a database that contains mitochondrial DNA from over 90% of the known species), the mitochondrial DNA differs by about 0.0 to 0.5%, for an average of 0.2%. This is not what you would expect if the species were tens of millions of years old; you’d expect mitochondrial DNA to differ by many percentage points. The best estimates for the rate of mitochondrial DNA change is about 1%/million years, and so scientists arrive at this conclusion that nearly every species descended from a mother of that species around 200,000 years ago.
Although the article stops short of this (and there’s an addendum at the top where the authors expressly deny this conclusion, even though their data is congruent with it), this is the exact phenomenon you would expect if there were a global flood in the recent past that wiped out all but a single mother of each species.
What’s more interesting, if the empirical calibration of mitochondrial substitution rates discussed in another blog post is to be admitted, then not only did the MCRA of all species live at approximately the same time (due to a global bottlenecking point), but that bottlenecking event occured much more recently than suggested in this article. The actual bottlenecking event may have occured as recently as ~6,500 years ago. This is on the rough order of time as either the flood or creation (for species where only a male and female were on the ark, this bottleneck would be the flood. For species were there were 7 of each on the ark, this would go back to creation).