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Blue Eyes Are Obsolete

Category: Culture
Posted on: October 17, 2006 1:25 PM, by Jonah Lehrer

The danger of being a recessive trait:

Once a hallmark of the boy and girl next door, blue eyes have become increasingly rare among American children. Immigration patterns, intermarriage, and genetics all play a part in their steady decline. While the drop-off has been a century in the making, the plunge in the past few decades has taken place at a remarkable rate.

About half of Americans born at the turn of the 20th century had blue eyes, according to a 2002 Loyola University study in Chicago. By mid-century that number had dropped to a third. Today only about one 1 of every 6 Americans has blue eyes, said Mark Grant, the epidemiologist who conducted the study.

A century ago, 80 percent of people married within their ethnic group, Grant said. Blue eyes -- a genetically recessive trait -- were routinely passed down, especially among people of English, Irish, and Northern European ancestry.

By mid-century, a person's level of education -- and not ethnicity -- became the primary factor in selecting a spouse. As intermarriage between ethnic groups became the norm, blue eyes began to disappear, replaced by brown.

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Comments (4)

1

Ah, but as it goes on, we'll start seeing blue eyes showing up in dark faces ...

Posted by: The Ridger | October 17, 2006 2:37 PM

2

for a single locus recessive trait HW is

p^2 + 2pq + q^2. if frequency of blue eye genes (i believe the OCA locus in fact), the frequency of blue eye phenotype is q^2 assuming perfect dominance of brown eyes.

Posted by: razib | October 17, 2006 3:02 PM

3

Aren't we disqualified for HW because of immigration?

Posted by: Emily | October 17, 2006 6:10 PM

4

Aren't we disqualified for HW because of immigration?

yeah, you're right, but is the rate of change of frequency enough to account for deviation for HW over this time?

Posted by: razib | October 17, 2006 8:31 PM

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