No scribe recorded it. This comes from genetic science. There is no evidence in the human genome that the number of individuals ever dropped to a single breeding pair.
Reposting what I have written before, I am a theologian, not a scientist myself. For scientific questions I rely on the work of countless scientists, including geneticists. In everything I have read, and in everything I have heard in papers at numerous conferences (including theology conferences), I have learned that humans evolved as a group. Some paleontologists and anthropologists assume this group was large and widespread; others assume it was smaller (in the tens of thousands). None assume it was smaller than 3,000 - 10,000 breeding pairs dating back several million years.
Humans never suffered a genetic bottleneck as did cheetahs, which may have been reduced to a few hundred pairs and suffered severed genetic constriction. There was the event of the eruption of Mt. Toba around 70,000 years ago, but that did not reduce the human species to two individuals named “Adam” and “Eve”:
“According to the supporters of the genetic bottleneck theory, between 50,000 and 100,000 years ago, human population suffered a severe population decrease—only 3,000 to 10,000 individuals survived—followed eventually by rapid population increase, innovation progress and migration. Several geneticists, including Lynn Jorde and Henry Harpending have proposed that the human race was reduced to approximately five to ten thousand people. Genetic evidence suggests that all humans alive today, despite apparent variety, are descended from a very small population, perhaps between 1,000 to 10,000 breeding pairs about 70,000 years ago.”
en.wikipedia.org/wiki/Toba_catastrophe_theory
StAnastasia