Against parachute skepticism

Parachute use did not reduce death or major traumatic injury when jumping from aircraft. (Yeh, 2018)

From (Smith, 2003), the great paper on parachute use.
The inimitable XKCD.



From (Lafuente, 2019)
From here. The ideas here date back to (Promislow, 1990).
Developmental Plasticity II: The Revenge!
In response to stress, the adrenal gland produces the hormone cortisol. More on that in a second.

Neonatal Circumcision — the Experimental Evidence

From Gunnar (1981). Note broken y-axis.

Consistent with the life-history theory, we hypothesize that adults who underwent neonatal circumcision, compared to those who did not, will display alterations in socio-affective processing conforming to the fast life-history strategies, namely, decreased reliance on social environment and increased perceived stress and sexual activity.

Specifically, here we test whether early-circumcised men, compared to men who did not undergo neonatal circumcision, display higher attachment insecurity and emotional instability (i.e., impaired functioning in emotional, motivational, and social domains), lower empathy and trust, higher sexual libido and unrestricted sociosexuality (i.e., preference of short- over long-term mating), as well as higher stress and risk taking attitudes.

Note Miani (2020) look at sensation-seeking as a proxy for risk-taking attitudes; the two are closely related.
Effect sizes are small. That doesn’t affect the argument in this article at all, but it may affect what you think about circumcision.
All the theoretical predictions were in the correct direction, although the results for trust and empathy were not statistically significant.

Parachute Skepticism

Partisans … systematically denigrate, depreciate and counterargue evidence that is contrary to their political views but accept uncritically the supportive evidence.

Only the Grinch could be skeptical of this parachute.



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