"Study catches 2 bird populations as they split into separate species (7/17/2009)":
The question of whether these two populations are on the road to speciation comes down to sex. When two populations stop exchanging genes-that is, stop mating with each other-then they can be considered distinct species. Uy and his team wanted to see if these flycatchers were heading in that direction. [. . .]

That males from the two populations no longer view the other as a reproductive threat is a good indication that not much mating is taking place between the two groups. Their evolutionary paths are diverging, Uy and his team found-all because of a change in plumage.

The researchers then went a step further. They looked into the birds' genomes to see what genes may have played a role in the different plumage pattern. They found only one: the melanocortin-1 receptor gene (MC1R). The MC1R gene regulates the production of melanin, which gives skin and feathers their color. The all-black and chestnut-bellied birds had different versions of the MC1R gene, which gave rise to the plumage change.

That change appears to have been enough to create a reproductive barrier for flycatchers. Not every species is so picky, so a color change doesn't always drive speciation. Nonetheless, these results suggest that it can take as little as one gene, in the right spot in the genome, to cause a fork in the evolutionary road.
Richard Dawkins (in The Ancestor's Tale):
As I said, zoologists define a species as a group whose members breed with each other under natural conditions — in the wild. It doesn't count if they breed only in zoos, or if we have to use artificial insemination, or if we fool female grasshoppers with caged singing males, even if the offspring produced are fertile. We might dispute whether this is the only sensible definition of a species, but it is the definition that most biologists use.

If we wished to apply this definition to humans, however, there is a peculiar difficulty: how do we distinguish natural from artificial conditions for interbreeding? It is not an easy question to answer. Today, all surviving humans are firmly placed in the same species, and they do indeed happily interbreed. But the criterion, remember, is whether they choose to do so under natural conditions. What are natural conditions for humans? Do they even exist any more? If, in ancestral times, as sometimes today, two neighbouring tribes had different religions, different languages, different dietary customs, different cultural traditions and were continually at war with one another; if the members of each tribe were brought up to believe that the other tribe were subhuman 'animals' (as happens even today); if their religions taught that would-be sexual partners from the other tribe were taboo, 'shiksas', or unclean, there could well be no interbreeding between them. Yet anatomically, and genetically, they could be completely the same as each other. And it would take only a change of religious or other customs to break down the barriers to interbreeding. How, then, might somebody try to apply the interbreeding criterion to humans? If Chorthippus brunneus and C. biguttulus are separated as two distinct species of grasshoppers because they prefer not to interbreed although they physically could, might humans, at least in ancient times of tribal exclusivity, once have been separable in the same kind of way? Chorthippus brunneus and C. biguttulus, remember, in all detectable respects except their song, are identical, and when they are (easily) persuaded to hybridise their offspring are fully fertile.


David Smith said...

“Today, all surviving humans are firmly placed in the same species, and they do indeed happily interbreed.”

A lot of people grossly underestimate the scope of interracial relationships today because they focus primarily on interracial marriage. They think that miscegenation is not a major problem because not many White Americans marry outside of their race. However, this view is deeply flawed because interracial dating is immensely more prevalent than interracial marriage. One study in particular found that 35.7 percent of White Americans had interdated. Based on my own personal experiences I would say that if that number is an overestimate it isn’t by much.

From the study:

“Yancey collected a sample of 2,561 adults age 18 and older from the Lilly Survey of Attitudes and Friendships, a telephone survey of English- and Spanish-speaking adults conducted from October 1999 to April 2000. He found that 35.7 percent of white Americans had interdated, along with 56.5 percent of African Americans, 55.4 percent of Hispanic Americans, and 57.1 percent of Asian Americans. Men and those who attended racially or ethnically integrated schools were significantly more likely to interdate.”

n/a said...


I've posted before on miscegenation. What ultimately matters is births, and there the picture is worse than I would have guessed before running the numbers, but in the bigger demographic picture cross-racial breeding remains a relatively small part of our problem at the moment. (Though in the long run even low rates of racial mixing make eventual mongrelization inevitable and racial preservation requires territorial separation.)

David Smith said...


As I’ve mentioned before I just discovered your blog, so I haven’t read hardly any of your older posts. Besides, your older posts don’t really address the point I was trying to make in my comment: that interracial dating is extremely common and perfectly mainstream. Indeed, I would say that it is starting to get to the point where you are viewed as uncool if you don’t date someone of another race.

I disagree with your assertion that miscegenation remains a relatively small part of our problem at the moment. Indeed, your own post about births strongly suggests otherwise. Also, if 35.7 percent of White Americans have interdated (or even if the number is somewhat smaller) that shows that White racial consciousness is absolutely non-existent. Furthermore, how are we ever going to convince Whites to join a ‘pro-White movement’ so to speak if such a huge proportion of them date outside of their race? And it’s pretty laughable to think that someone who has interdated could ever be convinced of the merits of racial separation.

Moreover, there is more to the issue of miscegenation than just intermixture. To put it bluntly, the sight of it being so common is a disgrace.

But I agree with you when you say that the picture is fairly problematic for births. Indeed, if that large of a percentage of births to Whites are of mixed race then that just further illustrates my main point: that miscegenation is one of the biggest problems (if not the biggest problem) that we face at the moment.