Armchair: There is some possibility that in addition to the other answers there is a cascade affect. If some females respond by having sex, others may copy. There is evidence that females in other species copy each other's matings decisions. That might happen in humans as well.
Female Acorn Woodpeckers for example go to elaborate lengths to ensure that they are all breeding at the same time. The question of course is, if females copy each other in humans as well, why don't we see stronger birth patterns? I've copied a related abstract from an article in the American Naturalist that discusses the topic. JOURNAL. Pruett-Jones, S. "Independent Versus Nonindependent Mate Choice do Females Copy Each Other?" American Naturalist, v.140, n.6, 1992:1000-1009 Abstract: There is increasing evidence from both observational and experimental studies that females may copy each other's mating decisions. Female copying can be defined as a type of nonindependent choice in which the probability that a female chooses a given male increases if other females have chosen that male and decreases if they have not. The important characteristic of copying behavior that separates it from other similar processes is that the change in the probability of choice is strictly because of the actions of other females and not the consequences of those actions (e.g., male's behavior changing as a result of successful matings). A game-theory model suggests that the adaptive significance of female copying may depend primarily on the ratio of the costs to the benefits of active mate choice. Copying behavior, and more generally conspecific cueing, may be important in many behavioral processes beyond mate choice. ----- Original Message ----- From: Robin Hanson <[EMAIL PROTECTED]> Date: Monday, October 1, 2001 12:08 pm Subject: Re: Disaster Raises Happiness, Trust > Fabio Rojas wrote: > >An article in the LA Times discusses how high levels of stress > >change hormonal balances in the body causing, ahem, sexual arousal > >during times of stress. > > William Dickens wrote: > >Well that (if the LA Times got it right) is a very odd fact. Why > would we > >be programmed to make babies when we are under stress as opposed > to when > >we are fat and content? ... it really seems that such an impulse > would be > >counter productive. ... Perhaps our emotional/behavioral systems > simply > >aren't sophisticated enough to parse out different types of > arousal, but > >if that is true that should throw a lot of suspicion on the whole > >enterprise of evolutionary psychology since the mechanisms that > are being > >posited concerning sexuality and social interaction are usually > much more > >highly nuanced than this. > > One evolutionary psychology interpretation would be that when a > group is > suddenly threatened, its members are programmed to reassure each > other of > their affection and loyalty. Sex can do that. Babies may result, > but > perhaps other processes can reduce that effect when babies are > less desired. > > Robin Hanson [EMAIL PROTECTED] http://hanson.gmu.edu > Asst. Prof. Economics, George Mason University > MSN 1D3, Carow Hall, Fairfax VA 22030-4444 > 703-993-2326 FAX: 703-993-2323 >