This paper suggests that somehow exposure to high G-forces results in more girls than boys being born. Faulty statistics, or does that really happen?
You heard it here first. Boy sperm get dizzy more easily than girl sperm.
I wouldn’t think that 62 pilots is statistically a very significant sample. The canonical example of this is Israeli fighter pilots, supposedly 80% or so of their children are girls. However, this might just be a random statistical clump (they happen), and both this figure and the report you cite might be a case of selective reporting.
The thing is, something prompted the researchers to go looking for the link in the first place, quite possibly the Israeli fighter pilots story.
This is very unlikely to be the reason, but girl sperms are a bit heavier than boy sperms due to larger x chromosome, and can be separated by high Gs in a centrifuge to some extent. Perhaps the same is happening in the urethra? Though I suppose you would have have to be having the sex while pulling 10 Gs, which might be abit uncomfortable
I performed a quick Fisher’s exact test to obtain a p value for their observations. Unfortunately, I can’t get the full text of the article so I had to make up the actual numbers.
The abstract stated that the probability of having a male child in 62 high G force pilots was 0.4. For the calculation, I assumed 2 children per pilot, therefore, they had 50 boys and 74 girls.
There were 220 men in the control group. I assumed 2 children per individual and a near 0.5 probability of having a male. I used 218 girls and 222 boys born to this group in the calculation.
The p value derived from a two-tailed Fisher’s exact test using these numbers is 0.0532. This means that 5.32 percent of the time a difference this large between the groups could be due merely to chance. The cut off value of statistical significance generally used in scientific discourse is 0.05.
Of course, I made up the numbers (based on reasonable assumptions). If the high G-force group only had one child each, the p value changes to reflect this and is 0.1387.
Did they compare fighter pilots with transport pilots? If not then they can hardly blame their results on G-forces. It is a common belief, based on anecdotal “evidence”, among pilots in general that they are more likely to have girls. Air transport pilots aren’t subject to any more Gs than anyone else.