Sex ratio & preferences

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The New York Times has a story, Where Boys Were Kings, a Shift Toward Baby Girls:

…South Korea is the first of several Asian countries with large sex imbalances at birth to reverse the trend, moving toward greater parity between the sexes. Last year, the ratio was 107.4 boys born for every 100 girls, still above what is considered normal, but down from a peak of 116.5 boys born for every 100 girls in 1990.

Please note that the “normal” sex ratio is usually skewed somewhat toward males, around 105 to 100 (the explanation I received about this is that sperm carrying the Y are faster because they are smaller, I appreciate anyone to falsifying this if they know the “true story”). But I also found it peculiar that the article did not note that another East Asian society has switched from son to daughter preference in the past few decades, Japan. The moral of this story is, I think, that economic and social development are more critical in shaping these trends than laws enacted from on high. Japan developed earlier than South Korea, and the change in societal attitudes on this issue occurred earlier.

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16 Comments

  1. There seems to be a number of factors affecting the sex ratio but for some reason most people obsess on the alleged preference by (some) parents for male offspring. 
     
    For example, recent research suggests that lower blood-sugar levels might have something to do with it and Emily Oster seems to have found a correlation with Hep B levels in a population and excess males. 
     
    Another factor that is confusing to me is that historically (well, from the early to mid 1800s) Britain had more females than males, and this situation did not change until the 1960s or 1970s. Now, while WWI and WWII would have had impacts for a while, Britain was not at war for all of that time, although there might have been two factors causing a lot of the excess females (who seemed to turn up from around 18): excess male deaths and males spreading out into the empire (or former empire) to seek fame and fortune. 
     
    I wonder if it is possible, though, that the change in the sex ratio in Japan is simply due to bounce-back, because when there are fewer females, they become more valuable (although this is confounded by the fact that something approaching 50% or all males are of little to no interest to any female–when she has a choice). 
     
    However, given the different interests of males and females and the economic contributions of males and females, I think this change in the ratio is a portent of disaster for the Japanese economy.

  2. FRom the parents’ perspective, especially in East Asia, having a daughter darn near guarantees that you’ll have grandchildren, while having a son is not so much of a sure bet anymore.

  3. There seems to be a number of factors affecting the sex ratio but for some reason most people obsess on the alleged preference by (some) parents for male offspring. 
     
    in many asian societies the sons take care of parents and offer sacrifices on family alters. the lineage only goes through sons.

  4. FRom the parents’ perspective, especially in East Asia, having a daughter darn near guarantees that you’ll have grandchildren, while having a son is not so much of a sure bet anymore. 
     
    And who exactly is impregnating these females? Is East Asia now a hotbed of illegitimacy and roaming superstuds?

  5. I personally know a 26 year old woman who has already planned her life out in the following method. She plans to get herself pregnant through either artificial means or though sex with an otherwise platonic male friend. Either way, the child will not have an acknowledged father. In a world where the political climate allows women to operate in this manner having a girl will provide better chances for grandchildren (as mentioned above). 
     
    It seems important to keep in mind that people will probably use some sort of cost/benefit analysis when deciding which sex to prefer in offspring. If the cost of a grandchild through a male child is greater than the cost of a grandchild through a female child then people will tend to prefer female children.

  6. And who exactly is impregnating these females? Is East Asia now a hotbed of illegitimacy and roaming superstuds? 
     
    Older, divorced men, and increasignly more in years to come, Westerners.  
     
    That’s just a guess, anyway.

  7. Razib says: 
     
    in many asian societies the sons take care of parents and offer sacrifices on family alters. the lineage only goes through sons. 
     
    Well, this might be so, but as Bobbi S Low points out on page 122 of Why Sex Matters people’s stated preferences can be at variance with their actual preferences. For example, the Mukogodo in Africa state a preference for male offspring because that is the preference the Masai have, while the sex ratio and their differential treatment of female offspring vs male offspring demonstrate that their actual preference is for female offspring. 
     
    It is to be expected that people will do what is in their reproductive interests while stating that they are doing what society around them prefers. 
     
    Also, this all has the smell of a manufactured crisis, because the situation in China is actual far more complex than the simple claim that those nasty sexist Chinese are killing beautiful baby girls because they prefer boys, and Low points this out as well.  
     
    What is even more interesting is that a high male to female ratio is actually in female interests, since it is clear from recent data that females find a large proportion of males unsuitable. 
     
    PA says: 
     
     
    FRom the parents’ perspective, especially in East Asia, having a daughter darn near guarantees that you’ll have grandchildren, while having a son is not so much of a sure bet anymore. 
     
     
    Please read Low or indeed a number of Razib’s postings. It has never been the case for all parents that sons guarantee grandchildren. Indeed, for those far down the pole in society, females are a much better guarantee of grandchildren and always have been. It is only for high status families that males are a guarantee of grandchildren. 
     
    Moreover, with female offspring you can be damn sure that her offspring are your grandchildren; there is no such guarantee with male offspring. His wife might have chosen another man as the sperm donor (of course, this risk is low for high status males, somewhere around 2%, higher for medium status males, around 10% and really high for low status males, 30% or so).

  8. Also, Low claims that Guttentag and Secord in Too Many Women: The Sex Ratio Question that among Orthodox Jews the sex ratio is 147 males to 100 females. 
     
    It strikes me as more than a little odd, then, that outrage is directed only at places like India and China, however, I have not yet read the above mentioned book, so I can’t vouch for the veracity of Low’s claim.

  9. Indeed, in the Why Sex Matters, Page 172, Low says: 
     
    Occasionally, [in respect to China] an effect could be seen in first births: In two provinces in 1985, the sex ratio of children in single-child families soared to over 129. But it was primarily in later births that the sex biases became most pronounced (fig. 10.1). In a nationwide study in 1989-1990, the sex ratio of first births was 105.6, right at the worldwide average, but the sex ratio of later-born children depended on how many older brothers and sisters already existed. For example, the sex ratio of third-borns when there were two older sisters was 224.9 males per 100 females, and the sex ratio for third-borns with two older brothers was 74.1.  
     
    She cites Wen, 1993 for the two province data and Yi et al, 1993, for the China-wide one-percent census data.

  10.  
    Well, this might be so, but as Bobbi S Low points out on page 122 of Why Sex Matters people’s stated preferences can be at variance with their actual preferences. For example, the Mukogodo in Africa state a preference for male offspring because that is the preference the Masai have, while the sex ratio and their differential treatment of female offspring vs male offspring demonstrate that their actual preference is for female offspring. 
     
     
    right. a lot of the sex ratio stuff happens through affluence & elite emulation.

  11. You guys ought to be discussing the Trivers-Willard hypothesis here: 
     
    http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=4682135&ordinalpos=7&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum 
     
    The important point is the difference in variance between male and female reproductive success. A female is limited by the number of offspring she can produce in a lifetime, while a male is limited by the number of females he can impregnate. In polygynous societies (like the Mukogodo. …should credit Lee Cronk and not Bobbi Low with this work) parents should invest in males only when the male has a high probability of being a breeding male and females at all other times.

  12. JAH says: 
     
    In polygynous societies (like the Mukogodo. …should credit Lee Cronk and not Bobbi Low with this work) parents should invest in males only when the male has a high probability of being a breeding male and females at all other times. 
     
    It was not my intent to suggest that Bobbi Low should have credit nor that she did not credit Cronk, because right there in the text she does exactly that. 
     
    Here is a reference to a paper by Cronk which contains my point: Intention versus behaviour in parental sex preferences among the Mukogodo of Kenya
     
    What I was pointing out that was that what people say and what people do are two different things, and that their actions are more likely to be aligned with their reproductive interests. 
     
    In addition, even in (largely) monogamous societies, some people are better off to have daughters while others are better off to have sons.

  13. You guys ought to be discussing the Trivers-Willard hypothesis here: 
     
    well, that was implied when i spoke of elite emulation. also richard sharpe pointed to when it alluded to the african example (de facto TW, but de jure elite emulation).

  14. among Orthodox Jews the sex ratio is 147 males to 100 females 
     
    No way. I’d know about that.

  15. Here’s one piece of evidence I just Googled up: 
     
    The male to female ratio in newborns of grand grand 
    multiparous women was evaluated in 569 Jewish Orthodox 
    women and 28 Muslim women. A total of 882 babies was 
    born on the ù10th delivery; 460 (52.2%) were males and 
    422 (47.8%) were females (sex ratio J 1.06).

  16. please look at addison disease :((

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