One of the most important and contentious subjects in today's American society is that of race, or is it ethnicity, or is it color, or ....? There are good, natural reasons to want to belong to a group, whatever name you use for it. It can give you a feeling and the protection of solidarity. It can help you form alliances. It can get you legal entitlement rights. It can be a path to status (high or low depending).
But the term race also has biological connotations, of genetic continuity, or even genetic inherency (if one thinks of traits like hair form or skin color). Viewed, as many have done, in evolutionary terms, natural selection will have favored better traits within the evolution of each race (whatever that is), and by the very same reasoning, must have also favored values of one race vs another. That's because natural selection picks what's 'best' at any given time, and it's unlikely that, relative to any societal value today, all groups (whatever they are) would have evolved to be identical today. That doesn't mean differences would be great, of course.
Race was central from Darwin's time through WWII in the form of eugenics, a scientific movement concerned with these evolutionary issues. The term was due to Darwin's cousin Francis Galton. Scientists, generally from the privileged parts of society, expressed long-standing concerns about the masses of the less-worthy (a concern Darwin's inspiration Thomas Malthus, and Darwin himself shared).
The Nazi regime used mass eugenics to justify its tyranny, but thousands of other people were incarcerated, sterilized, or even killed because of the supposed characteristics of their race -- that is, in what the Germans called racial 'hygiene', individuals were picked on because of the assumption that any member of a race had the traits of that race. That was not the whole story, of course. Individuals within a society who were its 'worst' were also picked out for similar treatment. Invoking Darwin and natural selection, eugenicists piously presumed to be able to help evolution along by deciding who shall thrive and who shall not, and trying to make policy accordingly.
An important question besides concern about having to pay to support the starving lower class was the threat seen coming from immigrants into the advanced European societies. Our best and most respected scientists viewed races as real, evolutionarily determined, biological categories. They were treated just like classical 'type' specimens in biology. Every person was assumed to be a member of a pure race, or someone admixed among pure races. This, of course, assumes there are, or were such things as pure races to be admixed from. And that assumption was certainly and explicitly made.
Mixing of different types was considered important. In its classical form, inbred marriages were not legal of individuals closer than first cousins. In the US there were even laws against two epileptics marrying. From a genetic and evolutionary perspective,too, it was natural to think that if members of two races mixed, their hybrid offspring would bear some of the genes--and hence traits--of their inferior-race parents. Inter-racial marriage was illegal. and believe it or not, how much mixture should be tolerated became a serious topic of interest.
In our age in which genetic ancestry estimation from DNA sequence is a major recreation (with some legal entitlement elements that may be quite serious), the subject is certainly alive and well in all of its senses. Immigrants now, as then, were viewed as a potential source for the degradation of society. Somebody had to bar the door! But what criterion would be used?
It's too big a subject to go into in this post, but Jennifer Wagner, a colleague of ours who is a lawyer currently writing a doctoral thesis on her specialty interest, human rights law and concepts of genetic ancestry, has provided a summary of some of the slippery legal (court-related) issues in regard to defining who can immigrate, who can become a citizen. That formalized the rather informal writings of eugenicists, and gave related policy the ability to be implemented. We'll put up Jen's guest post tomorrow, and it's worth checking back for, as she is very thoughtful and knowledgeable on this subject (among others!).