C5. The U.S. Rate of Black-to-White Passing


Uploaded by frankwsweet on 28.02.2011

Transcript:
Sharpe: Good evening ladies and gentlemen. This is Karen Sharpe again, with Professor
Randolph Hemmings. Today Professor Hemmings will discuss the
rate of Black to White passing. Hemmings: Thank you Karen.
We will show how to compute the rate at which youngsters switch racial membership from Black
to White after high school. We will show that the rate has been steady
and continuous over the centuries. Every year, about 0.10 to 0.14 percent of
youngsters born into the African-American community change their racial self-identity
away from Black, to either Hispanic or White. There are several ways of measuring the annual
rate of Black-to-White switching. The most direct is to ask people their ethnic
self-identity, repeat the question every few years, and then count how many changed their
answer from Black to something else. The U.S. federal Departments of Labor and
of Health and Human Services do precisely this (along with many other questions) in
longitudinal studies meant to track life-long earnings and health, respectively, of large
numbers of Americans. The Department of Labor's NLS79 National Longitudinal
Survey has interviewed 12,686 young men and women yearly since 1979 to measure their career
progress. Each year they are asked the same hundred
or so questions. Between 1979 (when they were 14 to 22 years
old) and 1998, 1.87 percent of those who had originally answered "Black," switched to answering
the interviewer's race question with either "White," "I don't know," or "other."
This comes to 0.10 percent per year. Extrapolated to the Black census 2000 population
of 36 million, this comes to about 35,000 individuals per year.
A second approach is to start with the 0.7 percent African admixture found in the White
U.S. population today and work backwards. What rate of switching would have produced
the observed amount of genetic leakage through the color line.
Assuming a steady rate since 1710, it would have taken an average yearly injection into
the White community of the alleles from one person of one hundred percent African genetic
admixture for every 43,000 living White Americans. That is, 0.0023 percent.
In practice, people of one hundred percent African genetic admixture would not have been
accepted as members of White society, and so an adjustment is needed for the fraction
of African admixture in those Blacks who switched. Since some White Americans have as much as
1/4 African admixture, a reasonable estimate is that people who successfully switched from
the Black endogamous group to the White, had perhaps 1/8 African admixture.
To reach the observed admixture in White Americans today would have required one such person
per year switching self-identity for every 5,400 living White Americans. As a fraction
of African Americans, this comes to 0.14 percent per year for 300 years.
A third approach is to use the Philadelphia rate at which European-looking children are
born into the Black community (one out of every 500) and extrapolate this to the national
Black yearly cohort. This yields about 72,000 individuals as of
census 2000, or 0.20 percent per year. Most of these, of course, might choose not to switch.
Finally, Joel Williamson suggests a fourth approach.
It is based on the assumption that women are less likely than men to cross the color line
permanently. Approximately equal numbers of male and female
infants are born. But from age 16, millions of African-American
men disappear from the census, but women do not.
In 2000, this came to 2.77 million individuals. Where did they go?
The assumption of this method is that they redefined themselves as White.
This approach yields 0.10 percent per year or about 37,000 individuals per year as of
census 2000. The second method on the screen (working backwards
from today's observed admixture) assumed that the rate of Black-to-White passing has been
steady since 1691, when the endogamous color line was invented.
Is this a valid assumption? The Chesapeake colonies had been in operation
for nearly a century when intermarriage was outlawed in 1691.
There was much Afro-European intermarriage in British North America before then.
Perhaps there has been no Black-to-White passing ever since.
Could the African admixture found in White Americans today merely be an echo of the intermarrying
17th century, rather than evidence of the continual steady passing of biracials into
White society in the 18th, 19th, and 20th centuries?
Or perhaps it is the other way around. Could the African admixture found in White
Americans today be the result of intermarriage since 1967, when the U.S. Supreme Court ruled
that intermarriage was legal in Loving v. Virginia?
Well, there are three reasons to think that the African admixture found in today's White
Americans is the result of an ongoing process, and not the remnant of a one-time event.
First, as mentioned earlier, longitudinal studies show that the current rate of openly
avowed Black-to-White ethnicity switching would suffice to yield the observed admixture
had it always been going on. Second, if the White-to-Black gene flow that
has been going on for 400 years (in the children of interracial unions) had not been balanced
by an equal Black-to-White flow, Afro-Americans would have vanished by genetic assimilation.
For instance, although Spain and Portugal imported many thousands of African slaves,
Iberians of African appearance had vanished by 1700.
Similarly, African-looking Mexicans had vanished by 1800, and Afro-Argentines by 1900.
To see this, imagine the African-American community as a bucket of genes for Afro appearance.
Into the bucket falls a small inflow of genes for Euro appearance, the result of intermarriages
whose children join the Black community. If there were no outflow of genes for Euro
appearance, the African-American community would grow steadily Whiter looking.
Eventually they would vanish as a visible group. This is precisely what happened in
Spain, Portugal, Mexico, and Argentina. That a Black-looking population continues
to exist in the United States, despite the slow but historically documented intermarriage
rate, shows that genes for White looks have leaked out (in bodies of people who switch)
as fast as they have fallen in. Again, the computed outflow necessary to match
inflow is between 0.10 and 0.14 percent of the African-American population per year.
The third argument comes from molecular anthropology. It comes from observing linkage disequilibrium.
Chromosomes come in pairs. You have two copies of chromosome #1, two
copies of chromosome #2, two copies of #3, and so forth.
One copy of each chromosome came from your mother's egg cell; the other came from your
father's sperm cell. Consider the pair of chromosomes #5.
When your body wants to produce a gamete (a spermatozoon if you are male, an ovum if you
are female) it must place a single copy of chromosome #5 into the gamete.
Which copy does it choose? Does your body pick one or the other at random,
either the #5 copy from your father or the one from your mother?
Or does your body simply make up a new #5 never seen before?
Or does it blend together the material from your two copies, both the #5 copy from your
father plus the one from your mother, and mold a new #5 using only half of the resultant
mixture (otherwise the new #5 would be much too big)?
In fact, the process lays your two #5 chromosomes side-by-side, like two strands of yarn. It
then cuts them crosswise into matching pieces and swaps the pieces between strands.
The cut-and-swap process with two cuts yields one strand that is father-mother-father and
another that is mother-father-mother. One of the new patchwork #5 strands then goes
into the new gamete. This makes sense, because only thus can your
child inherit your mother's eyes and your father's chin.
The single #5 in the gamete is not a "blend" in the sense of being homogenized.
Instead, it has broad stripes from father and mother.
The width of the stripes is called linkage disequilibrium.
If one parent is European and the other is African, then the ancestry-informative DNA
markers will also fall into the same broad stripes.
The strands are cut and their pieces swapped at each subsequent generation. An individual
with barber-pole stripes of African and European DNA within the same strand must be at least
a second-generation biracial. A first generation biracial would have one
#5 from one parent with nothing but African markers, and the other #5 with nothing but
Euro markers. The chance that in the next generation, the
cut-and-swap will happen to hit the precise seams between existing stripes is negligible.
So the stripes of African and European DNA get narrower. Linkage disequilibrium diminishes
with each passing generation. A recent one-time wave of intermarriage, such
as since the 1955-65 civil rights movement, would result in uniformly high linkage disequilibrium
in admixed Americans. This is not observed.
An ancient one-time wave of intermarriage, as in the seventeenth century, would result
in uniformly low linkage disequilibrium in admixed Americans.
This is not observed either. An ongoing slow but steady genetic leakage
across the color line for 400 years would result in a distinctive pattern of linkage
disequilibrium distribution: stripes of every width occurring with equal frequency.
This is what is observed. In conclusion, as racialism scholar, Maria
P. P. Root puts it, "It is not uncommon that many individuals emerge out of college years
with a different resolution to their racial identity, than when they graduated high school."
And so, how common is it? It comes to about 0.10 to 0.14 percent, of
the African-American community per year. Thank you for listening.
Sharpe: Thank you professor. You make it sound as if White-looking children
born to mixed American families, routinely assimilate into White society.
But all of the novels and movies I have seen about this topic, depict it as shameful, or
even racial treason. I understood that Americans are quite harsh
about it. Hemming: Well Karen, all methods of estimating
the rate of Black-to-White identity-switching converge to the same numbers. So I am confident
in them. I think there are two different issues.
On the one hand, Americans seem quite serious in their demands that everyone choose a race.
On the other hand, they seem indifferent to which race you choose.
If you look White and claim to be White, nobody cares how your grandparents self-identified.
Sharpe: But given America's sharply defined color line, how difficult must it be for someone
to cut all their family ties? Hemming: Part of the problem is that the word
"passing" implies pretense. As far as I know, people who are comfortable
with multiple ethnicities make no secret of their partial African ancestry.
They just do not feel that this trivial fact should stop them from adopting a racial self-identity
that matches their appearance. There is no need to cut family ties.
I know many White families who take the children to visit their Black grandparents on holidays.
For instance, White Americans with openly acknowledged partial African ancestry abound
in the entertainment industry. Among these are blondes like Carol Channing
and Heather Locklear. At the other extreme are brunettes like Jennifer
Beals. Also, thousands of Hispanic entertainers,
such as Geraldo Rivera, Jimmy Smits, and Jennifer Lopez, proudly claim African as well as Spanish
roots through their Latin American heritage. The U.S. color line is sharply delineated.
But it is not completely impermeable. The numbers suggest that tales of cutting
family ties and deception more likely belong to the realm of fictional "passing novels"
than to the reality of America's notoriously mobile society.
Some Americans may see social mobility as treason, but I am convinced that most do not.
Sharpe: Thank you professor. Well, that is our time for today folks.
This is Karen Sharpe. Hemmings: And Randolph Hemmings
Sharpe: Goodbye until next time.