Here's a question that I've puzzled over for some time: how long
will it take different modern-day races and ethnicities to blend
and/or assimilate fully?  Reading through the Old Testament, for
example, we see mention of dozens of ethnicities which no longer exist
today: Babylonians, Assyrians, etc.  Of course their descendents live
on, but the Babylonian people no longer exists qua people.
In the modern world there is in many cases an increasing
inter-marriage rate, as well as a breakdown of racial prejudice at   
historically impressive speeds.  Taking all this together, how long
should we expect it will take the following ethnicities and races
to more-or-less be fully intermingled and no longer distinguishable?

1.  Jews and non-Jews.  I predict that the Jewish people will be
disappear almost entirely qua people in the next 200 years.  A handful 
of strict Jews may persist, but for the most part it seems that the
rate of intermarriage is sufficiently high in mixed countries (about
50% in the U.S.) and the level of prejudice is sufficiently low that  
the Jew qua ethnicity is unlikely to continue for too much longer.
Of course, Jews have persisted as an independent culture for several
thousand years, but it is only in the last 1-2 centuries that
intermarriage has become so widespread.  In a sense, it seems that
anti-Semitism is the woe of Jews but an important preserver of
Judaism as a distinct cultural identity.

2.  Asians and Caucasians.  I would predict about 500 more years.
Again, in mixed nations the inter-marriage rate is high and (I think)
still growing.  The result will be more of a blending than an
absorption.   I would expect that it will take longer both because
of the large initial population, and because of the degree of geographic
isolation.  Still, national borders will become less and
less important and travel easier; combined with the increase in inter-
marriage and the decline of Caucasian-Asian prejudice, my     
projection is quite reasonable.

3.  Causasians and Hispanics.  This one is harder to predict -- I
would say 500-1000 years for full intermingling.  Intermarriage is
still on the rise, but the level of prejudice between the two groups
is not clearly falling.  As with Asians, I would think that advances
in transportation and the declining importance of national borders will
break down racial distiction faster than many would expect.

4.  Caucasians and Africans.  This one will probably take the longest
for full breakdown -- I give it 1000-2000 years.  I believe that
inter-marriage, though rising, remains at low levels; and again,
the trend of prejudice between the two groups is unclear.  But    
the decline of national borders and the advance of transportation are
going to ultimately eliminate the distinction, perhaps to the surprise
of many alive today.

There are many other combinations to consider -- these
are merely meant to be illustrative. 

A final question one might ask is: Is this "abolition of race" a good
thing?  It seems clearly so to me.  I don't expect war and hatred and
prejudice to disappear when identifiable races and ethnicities no
longer exist, but ONE important factor contributing to these problems
will disappear.  It would be unfortunate if valuable cultural traits
disappeared, but there is no reason why a deracinated humanity could
not pick and choose the best elements of each of the cultures of the
present time.  I suppose that many find the prospect of humanity without
ethnic identity to be frightening and alienating, but I see it as
an exhilirating opportunity for individuals to define themselves as
they think best, freed from the dead hand of the past.  It will no
longer be possible to inherit one's identity; it will have to be chosen
for oneself.
                      --Bryan Caplan