My Answer to Thaler’s Question

THALER’S QUESTION

The flat earth and geocentric world are examples of wrong scientific beliefs that were held for long periods. Can you name your favorite example and for extra credit why it was believed to be true?

For years it was a given fact that humans had 24 chromosomes; e.g., as late as 1954, cytologist L. Sachs stated, “the diploid choromosome number of 48 in man can now be considered as an established fact.”

But in 1956, Joe Hin Tjio and Albert Levan discovered that there were in fact only 23 chromosomes. They even went back to look at old photographs in books and counted 23 pairs even though the captions said there were 24.

From their paper: “For instance, we think that the excellent photomicrograph of Hsu published in Darlington’s book (1953) is more in agreement with the chromosome number 46 than 48, and the same is true of many of the photomicrographs of human chromosomes previously published.”

Joe Hin Tjio, Albert Levan. The Chromosome Number of Man. Hereditas; Vol., Issue 1-2, pages 1–6, May 1956.

The “established fact” was making scientists blind to what was before their eyes. Perhaps part of the reason why this belief was held on to for so long is that all the other great apes have 24 chromosomes. Man being the only one with 23. That may have clouded the initial judgments, and once established, no one thought to question it.