z***c
发帖数: 2959 | 1 有人要问订婚钻戒的问题了，我偷下懒，直接转载解释如下。有点长但值得读，因为本
版关于订婚戒指的一些常见说法可以得到印证，实在偷懒可以只读前一半然后跳到最后
一页。
Dr Peter Sozou and Professor Robert Seymour from University College London (
UCL) have developed a mathematical model that shows how expensive but
worthless gifts may help facilitate courtship.
Reporting in the journal Proceedings of the Royal Society of London B they
analysed the function of a courtship gift and what the characteristics of a
'good' gift are.
They show that gifts can act as a signal of a man's intention. Offering an
expensive gift may signal a long-term commitment but the man must be wary of
being exploited by a gold-digger who intends to dump him once she gets the
gift.
By modelling courtship as a sequential game, they show that an extravagant
gift, which is costly to the man but worthless to the woman, may solve the
problem.
A costly gift signals the man has long-term intentions but by being
worthless to the woman, gold-diggers are deterred.
The researchers also show that a modified form of the model may apply to
species where males do not help to raise the young.
Dr Peter Sozou, of UCL's Centre for Mathematics and Physics in the Life
Sciences and Experimental Biology, says:
"Gift-giving by males is a feature of human courtship and mating systems in
a number of species. Females invest more resources than males in offspring
and so must take care to pick the best partner possible, something that's
not always easy to gauge from general cues such as appearance.
"In humans, a girl wants a guy who is attractive to her and will help raise
their children. The worst pay-off, reproductively, is if she hooks up with
an unattractive male who, literary, leaves her holding the baby.
"Guys are less likely to offer expensive gifts to females they don't have a
long-term interest in. And girls won't be impressed by cheap gifts. By
offering expensive but worthless gifts, such as dinners and theatre trips,
the male pays no cost if the invitation isn't accepted. Girls that don't
find a guy attractive are less likely to take up the invitation because it
would mean spending time with a person they aren't interested in.
"In other species the deciding factors for a female is whether she's in a
sexually receptive state and the male is in a good condition. Males offer
gifts which may signal their condition. Those in a poor condition can't
offer the same quality of gift."
The researchers constructed two versions of the game with different
biological assumptions based on whether the male is involved with parental
care.
Attractiveness is relevant to human courtship (model 1). Male condition and
female receptiveness are the deciding factors in non-parental care species (
model 2). In both cases these were represented as binary variables.
Factors in the game such as whether the male and female found each other
attractive were given a probability and the possible outcomes of the
interaction, either positive or negative for each player, were given scores
to represent the consequences of their decisions.
上面的分析还只是停留在理论对现实的描述上，后来的分析则发现这个理论和历史的结
合非常完美。虽然钻戒在二十世纪三十年代早已出现，但那之前基本没有人用钻戒作为
订婚必备的，而之后对钻戒的需求则大大增加。
为什么会有这样的变化，分析发现，本来美国许多州的法律曾经规定，如果未婚夫在婚
前毁约，女方可以起诉男方，而且惩罚力度很大，但从1935年开始，16个相继州废除了
这个法律，这样导致了必须出现一种制度安排使得男方不能轻易毁约而不受惩罚，从而
导致女方受到伤害。在这样的背景下对钻戒的需求开始增加。
有兴趣的可以参看完整的分析 http://homes.chass.utoronto.ca/~siow/332/rings.pdf
对钻戒需求的变化是一个把理论分析和经验分析很好地结合到一起的一个例子。
有趣的是，结婚戒指则相对简单，不需要钻石，因为法律规定婚后的财产由夫妻共享，
这个对于婚后家庭出现分裂已经是非常大的约束，涉及到的财产价值远非一颗钻石可比
，因此也就没有必要在结婚戒指上带钻了。 | z***c
发帖数: 2959 | 2 好像有人问过，如果订婚后一方毁约，是不是要退还钻戒，现在根据这里的信息，应该是
如果男方毁约，就不用退，女方毁约还是应该退的。
另外就是到底需不需要男方花2-3个月的薪水来买，根据这个理论其实很好回答，对男
方没信心的就应该坚持，有信心的就不必那么在乎。当然爱面子的女生，和爱花钱的男
生可以
例外。
道理都很简单，世界也很简单的。
(
a
【在 z***c 的大作中提到】
: 有人要问订婚钻戒的问题了，我偷下懒，直接转载解释如下。有点长但值得读，因为本
: 版关于订婚戒指的一些常见说法可以得到印证，实在偷懒可以只读前一半然后跳到最后
: 一页。
: Dr Peter Sozou and Professor Robert Seymour from University College London (
: UCL) have developed a mathematical model that shows how expensive but
: worthless gifts may help facilitate courtship.
: Reporting in the journal Proceedings of the Royal Society of London B they
: analysed the function of a courtship gift and what the characteristics of a
: 'good' gift are.
: They show that gifts can act as a signal of a man's intention. Offering an
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