Cryptorchidism (over 90% in some studies). Even after orchiopexy, these may also affect sperm maturation and motility at an older age. The most common diagnostic dilemma in otherwise normal boys is distinguishing a retractile testis from a testis that will not descend spontaneously into the scrotum. Retractile testes are more common than truly undescended testes and do not need to be operated on. In normal males, as the cremaster muscle relaxes or contracts, the testis moves lower or higher ("retracts") in the scrotum. This cremasteric reflex is much more active in infant boys than older men. A retractile testis high in
Collapse: How Societies Choose to Fail or Succeed Collapse: How Societies Choose to Fail or Succeed Collapse: How Societies Choose to Fail or Succeed (titled Collapse: How Societies Choose to Fail or Survive for the British edition) is a 2005 book by academic and popular science author Jared Diamond, in which Diamond first defines "collapse": "a drastic decrease in human population size and/or political/economic/social complexity, over a considerable area, for an extended time." He then reviews the causes of historical and pre-historical instances of societal collapse — particularly those involving significant influences from environmental changes, the effects of climate change, hostile neighbors, trade partners, and the society's response