So today, I was doing an assignment for my winter class and I ended up learning a lot about conditions that spring up in genetically isolated areas.
Here’s a Few Interesting Ones.
One of the more famous ones we’ve seen so far this year is the Dominican Republic village, where boys (called Guevedoces) don’t have visible testicles until they start undergoing puberty. This is the result of both a founder effect and the remoteness of the village. One of the original colonizers had the gene, and because of interbreeding in an isolated area, the gene propagated itself within the population.
But that’s not the only thing that can happen in an isolated area. Qatari natives (not the people who’ve recently moved into the area) have a 5.2% rate of hearing loss, because of Cosanguinity. Cosanguinity is where one marries their cousins. And prior to 1950, there were only about 50,000 Qatari natives. Now there is closer to 278,000 Qatari natives. This was also due to, not just consanguinity, but also the fact that the natives have large families, which increases the chance for that particular gene to be spread around.
This is Where the Research Gets Cool.
However one of the most visible examples of the kind of genetic phenomena, is the rate of twinning. In the Brazilian town of Candido Godoi (pop. 6,700), 1/10 births are twins. In a 1.5 square mile area, there are 44 sets of twins.
In the Nigerian town of Igbo-Ora, a town of approximately 60,000 or so people, 1/22 births are twins. In India, the village of Kodinhi, home to 2000 families, 250 sets of twins were born.
Hell, even in the Honduras, there is a small school with 23 pairs.
Inverclyde, Scotland has 72 sets of twins, in primary schools alone.
Hell in one grade in Illinois, there are 24 sets of twins in one grade, at one school.
So Why Does This Happen?
Well again, this has heaviliy to do with genetics. What the twinning towns all have in common are their relative isolation for most of their existence, for one. Then, you have a homogeneous population, that is rarely mobile and rarely moves away. Next, have a specific trait in the population. Give it time, and the trait will propagate itself.