Friday, February 17, 2012

More on the black-white difference in sexual dimorphism

Reader Fenris suggests that if I am interested in black-white differences in sexual dimorphism, I shouldn't look at indirect measure like life expectancy, but should investigate height differences. I thought I had done it previously, but turns out that it was blacks and Asians that I compared before.

To make the best comparison, it makes sense to look at populations with environments that are as equal as possible. How about young blacks and whites measured recently? In fact, the data indicate that racial differences have reversed in the U.S. over time. I used Fenris' source and also found a newer one.

Here is the black sex difference in height minus the white sex difference for different age groups and periods:

Ages 40-59 (1988-94) -1.4 cm
Ages 20-39 (1988-94) -.2 cm
Ages 20-39 (2003-06) +.7 cm

As conditions have improved for blacks, their sexual height difference has changed from being smaller than that of whites to becoming larger.


Jim Bowery said...

How did you decide that it couldn't have been on-going development that changed the heights with age?

Also, it would be interesting to see data from subsaharan Africa with breakout for genetically different groups (bantu vs sann vs...).

Anonymous said...

Strangely, the data shows that black females 20-39 are slightly shorter than black females 40-59. All other groups got taller. (white male, black male, white female)

Anonymous said...

Nothing much there, really. Nothing to suggest sexual dimorphism at any rate.

I believe the US government in its infinite wisdom counts "Hispanics" as "whites". Is the white average being dragged down by millions of five foot tall brown people?

Ron Guhname said...

Both whites and blacks are non-Hispanic in these studies.

Anonymous said...

Perhaps I'm missing something here, but if the topic is "sexual dimorphism" then measuring black/white difference is meaningless.

If there is more sexual dimorphism among blacks then we would expect to find that either black males are significantly larger than black females, or that black females are significantly larger then black males.

Comparing the height of the typical black person in America to the height of the typical white person in America tells us nothing at all about sexual dimorphism.

Now, you could compare the male-female delta among both blacks and whites and see if one is significantly greater than the other. Of course that data would only apply to Americans amd not to blacks and white more generally, but Africans don't take the GSS.

Fenris said...

Nice, I like the idea of constraining it by age, but a .7 centimeter difference seems rather negligible and a somewhat odd finding considering the fact the 20-39 year old female co-hort is shorter then the 40-59. I don't see much here in the way of evidence for any major difference in dimorphism.

RR said...

As conditions have improved for blacks, their sexual height difference has changed from being smaller than that of whites to becoming larger.

Could it be that 'condtions' have worsened for whites?