THE practice of aborting female foetuses is found mostly in China and other Asian countries. But it is prevalent in the Caucasus, too. Two new studies look at why—and suggest the practice may spread.If nature takes its course, 105 boys are born for every 100 girls. Boys are more vulnerable to childhood diseases, so a slight preponderance of them at birth ensures equal numbers at puberty. But in Armenia and Azerbaijan more than 115 boys are born for every 100 girls and in Georgia the ratio is 120. These are bigger distortions than in India. In all three the figure has risen sharply since 1991 (see chart). In 2010, reckons Marc Michael of New York University’s Abu Dhabi campus, the number of girls born was 10% lower than it would have been had the ratio been normal. The gap is second only to China’s.The sex ratios in the Caucasus are especially distorted when a second or third child is born. In Armenia, among first children, there are 138 boys for every 100 girls. If the first child is a son, the next is more likely to be a girl than a boy (ie, reverse sex selection). But if the first child is a girl, son-preference goes off the scale. When the first child is a…