Imagine an island that is suddenly populated with one hundred couples, each with a unique last name. In other words, no couple has the same last name. Further, they continue the tradition of the females taking the male’s last name upon marriage. As these couples reproduce, their children will be expected to marry one another. Couple A1 has a couple of boys and they marry the girls from Couple C2. This is not a controlled experiment, so nature can take its course and people are free to marry who they like.
Now, some couples will have all girls. Some couples will have no children. Given that the island is pretty boring and all of the couples are sexually normal, the infertile couple will not be the result of a lack of effort. On the other hand, infertility is not that common, so the number of childless couples will be quite small. At the same time, “Fertile Myrtle” is not an unusual phenomenon and some men have a near uncontrollable sex drive. That means there will be quite a few big families to counter the infertile and the strangely disinterested.
Now, if all couples have one male child and one female child, both of whom make it to sexually maturity and marry, then the population will remain stable. The number of last names will also remain constant, as each male heir will carry on the family name. Given this is a small island, a few extra children, or the “heir and spare” model will make sure that the family names live on and the population does not fall into decline. In this perfect scenario, we can come back in a dozen generations and things are about the same.
On the other hand, if each generation has 10% of the females unable to bear children, it will take about 20 generations before almost everyone has the same last name. The decline in last names happens fast initially, but the name singularity is at about 20 generations. Something similar happens if 10% of the couples have only female children that make it to adulthood. Throw in the fact that each generations may not have enough females for all the males and the decline of last names will progress toward one.
Obviously, lots of couples will have all boys or all girls. Since this island does not have video games or feminism, getting busy with the opposite sex will be the main form of entertainment. That means some couples will have lots of kids, but others will be more restrained and have one or two kids. The bigger the family, the lower the odds of having all girls or all boys, but it happens. If that is just ten percent of the result, the initial disappearance of last names is much quicker, but still takes about 20 generations.
Why would anyone care about this? Well, it is a good way to understand how a trait can flow through a population, resulting in a unique population. Instead of last names, let’s use a pronounced brow ridge, indicating high intelligence. If this is a trait passed through the male line of the A2 family, the whole population will have it, if in our experiment the A2 name is the one that comes out on top after 20 generations. If it is not just passed by males, but also results in high fertility, then it can spread quickly in our population.
Add in the fact that men with a prominent brow line will be highly desirable to the opposite sex, now you have a trait that increases the odds of producing children with it by some small percentage. On the other hand, let’s say the one guy in our 100 founding couples with the brow ridge drowns while out for a swim, before he had kids. That means this highly desirable trait, both from a biological as well as reproductive reason, is removed from the gene pool forever. Our island will be full of homely dumb people forever.
This is a simplified and rather crude way of illustrating how a desirable trait can flow through a population, but it is useful. In fact, this is pretty much how we have so many dog breeds. Humans short-circuited nature, by selecting the dogs that would breed, thus selecting for specific traits. After enough generations, one breeder ended up with Great Danes, while another ended up with dachshunds, so to speak. A famous example of this is the creation of a domesticated foxes by a Russian geneticist named Dmitry K. Belyaev.
Another way of understanding this is to imagine our island paradise flourishing with a high fertility rate over many generations. Then a resource scarcity sets off competition among the islanders and eventually a tyrant emerges to control the island. He correctly sees that the issue is the left-handed and has all of them killed. In future generations, anyone found to be left-handed is killed. It will not take long, in fact it could literally happen over night, for the population to lose the left-handed trait. Sometimes, Mother Nature is this cruel.
This is a good way to understand the natural diversity of people. When modern humans emerged from Africa, that is the most likely origin, we carried almost all of the traits present in humans today. As people spread out around the globe, nature found some traits much more useful in the new environment, so those traits eventually were selected for over each generation. Nature also found some traits deleterious and strongly selected against them, like our left-handedness example. Overtime, we got the diversity of man.
It is why anyone who uses the phrase “scientific racism” is rejecting the fundamentals of biology. Just as there is great diversity in the domestic dog, there is diversity in humans, diversity that is measurable and observable. Denying observable reality is a few clicks less reasonable than witchcraft or astrology. It also means multiculturalism is, in effect, a war on nature, as it is an effort to obliterate human diversity. Mixing everyone together into a gray slurry, is just a primitive minded war on nature and biological reality. It is immoral.