DISCUSSION 
Parkes: It depends on whether or not an equal number of 
males and females fail for some reason to get married. But in 
any case the sex-ratio, as you say, is not very catastrophic at 
present. It certainly wouldn’t set up social pressures of a kind 
which would change the whole social system and lead to 
polyandry. But we are not at the end of the tendency for more 
and more males to survive to marriageable age. 
Haldane: What happens if you make allowance for the fact 
that on the whole husbands are three or four years older than 
the wives? I think it would even out much of the excess of 
males. On the one hand there will be more females surviving 
to a younger age, and secondly, there will be the effect of 
the expanding population at the present time. Perhaps our 
habit of marrying a woman slightly younger than ourselves, 
or a husband slightly older, may be an adaptation to this 
excess of males, and have the effect of approximately balancing 
it. 
Parkes: The custom of marrying a wife slightly younger is, 
according to my understanding, of quite ancient origin, and 
certainly was common during the last century when there was 
an overall excess of females of marriageable age. Of course, 
this tendency may now be increased by the present slight 
excess of males of marriageable age, and, according to the 
demographers, that is going to become a vicious circle as the 
excess of males increases. 
Trowell: ‘There is a very long history behind this practice 
of men marrying women younger than themselves. It also 
occurs in polygamy and most areas of the world were poly- 
gamous until a few thousand years ago. In polygamy the excess 
of married women over married men is only possible if women 
marry at a younger age. This is still true in Africa. 
Coon: Have you considered the racial difference in sex- 
ratio? Among Berbers it used to be that the children of a man 
with four wives showed a much higher sex-ratio than those of 
the man with three wives, and so on down. But south of the 
Sahara the Africans, who were equally if not more polygynous, 
had a low sex-ratio. Does that mean that in the future the 
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