Garden of Joining Paths

Here's Robert Heinlein in 1942:

One thing alone was evident to the uninstructed eye: the two upper charts, Hamilton's and the girl's, contained twice as many chromosome patterns -- forty-eight to be exact -- as the charts of the gametes underneath them. But the chart of the proposed offspring contained forty-eight representations of chromosomes -- twenty-four from each of its parents.

Back when he was still funny, Michael Crichton coined the Rule of 48, which states that All Scientists are Blind (and became the guiding principle of his later books):

For years it was stated that men had forty-eight chromosomes in their cells; there were pictures to prove it, and any number of careful studies. In 1953, a group of American researchers announced to the world that the human chromosome number was forty-six. Once more, there were pictures to prove it, and studies to confirm it. But these researchers also went back to reexamine the old pictures, and the old studies -- and found only forty-six chromosomes not forty-eight.

This is only true for values of "American researchers" that include Joe-Hin Tijo and Albert Levan of the University of Lund in Sweden, and values of "1953" that include 1956, but NEVER MIND.

Clyde's Theory of Alternative Pasts explains this phenomenon in terms of multiple timelines that converge and join like trainlines as you approach the station. In one reality, Homo sapiens evolved with 23 pairs of chromosomes while in another reality there were 24; the two timelines collided around about December 23, 1955, with the latter coming to dominate, but the former reality was not erased completely and traces linger in the form of recollections of outmoded scientific theories. This theory also explains how the Frau Doktorin and I might hypothetically have an argument about "who said what" at some point in the past, and even though she is right, that doesn't mean that I am wrong.

It turns out that human beings are not the only mammal species with a fluctuating chromosome count. Darren Naish and his commentariat inform us that möøse have either 34 or 35 pairs, while wild boar have 36, 37 or 38 chromosomes. Clearly some of those chromosomes are NOT DOING ANYTHING. Parasites.

Only 7% of boars from the Netherlands had a chromosome trisomy but 27% of boars from Tennessee. Tact prevents me from commenting or drawing conclusions.

"Usually the number of chromosomes is constant in a given species, although it may vary between different species even of the same genus. In man the chromosome number is forty-eight...." [Human Genetics and its Social Import, by S. J. Holmes (1936), p. 8. The illustration above appears on p. 9.] "... the number of chromosomes is in general constant for any given species. Thus in each cell of a human being there are 48 chromosomes (24 pairs)...." [Principles of Heredity, 3rd. ed., by Laurence R. Snyder (1946), p. 26.]