Remote Ready Biology Learning Activities
Remote Ready Biology Learning Activities has 50 remote-ready activities, which work for either your classroom or remote teaching.
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Blondes: an endangered species?
In our small group (Prof Dalke's class) someone brought up the theory of blondes becoming extinct. This topic interests me as well and last semester I wrote a paper on it. I thought people might be interested in reading it so here it is: (I don't know if the punnet squares will work.)
It has already been determined by research that evolution changes the genetic makeup of organisms, and therefore, their appearance and abilities through natural selection. Darwin, the first to propose this realization, makes it clear that the process of natural selection allows for the organism with the strongest traits to succeed biologically. But it seems that all of this has happened millions of years ago and it’s hard to believe that changes are still happening all the time. The process of biological change is slow, but is it possible that in only a few generations people might be able to see the next stage of human natural selection?
In 2006 Canadian anthropologist Peter Frost published his theory on the origin of blondes. Frost proposes that the genetic alteration to the dark-haired gene occurred within 35,000-40,000 years after the original Homo sapiens migrated from Africa to Europe (10). The blonde trait was developed within certain females to compete for mates with the dark-haired women (6). Frost is quoted: "The increase in competition for males led to rapid change as women struggled to evolve the most alluring qualities." It is easy to mistaken a genetic trait for willed change. The trait appeared because it was what men preferred for mates, and their preference exponentially increasing the movement of the blonde gene into the next generations (10). But if the development of blondes was due to competition could there be the possibility that blondes could become extinct because of competition as well?
For decades now, scientists and observers have spoken of the disappearance of blondes, expecting the gene associated with blonde traits to become “extinct” within two hundred years from today. Since 1865 scholars and lecturers have hypothesized the demise of the blonde population for a variety of reasons including male preferences to brunettes or “bottle blondes” and the fact that the blonde trait is characterized by a recessive gene (1).
In 2002 several media reports stated that the World Health Organization (WHO) conducted a study in which they found that this gene will become obsolete within the next couple centuries due to the fact that there are too few people actually carrying the gene for blondeness. However, The WHO countered the media by denying the accounts of said study: “In response to recent media reports citing an alleged World Health Organization study predicting the extinction of the naturally blonde hair gene, WHO wishes to clarify that it has never conducted research on this subject. Nor, to the best of its knowledge, has WHO issued a report predicting that 'natural blondes are likely to be extinct by 2202'. WHO has no knowledge of how these news reports originated but would like to stress that we have no opinion on the future existence of blondes.” (3)
According to the Hardy-Weinberg Theory that measures the frequencies of alleles, the amount of genes never changes (7). The majority of scientists, today, when asked, stated that although there may be a slight decrease in the number of blondes, its percentages within the human population will remain consistent. There are a few number of blonde genes out there however. Interestingly, both blonde and dark-haired couples are able to give birth to blonde children (as long as both parents in the dark-haired couple contain one blonde allele). (9). These Punnett Squares show the second generations of both couples:
A = dark-haired allele a = blonde allele
Dark-haired parents with blonde genes (Aa and Aa):
A
a
A
AA
Aa
a
Aa
aa
Dark-haired parents without the blonde gene (AA and AA):
A
A
A
AA
AA
A
AA
AA
Blonde parents (aa and aa):
a
a
a
aa
aa
a
aa
aa
One dark-haired with blonde gene and one blonde parent (Aa and aa):
a
a
A
Aa
Aa
a
aa
aa
Because the blonde gene is a recessive gene, the only way it will show up is if there is no dark-haired gene to override it. Just because a person is dark-haired does not mean they do not possess the blonde gene, it simply means the dark-haired gene is more powerful genetically. As seen in the Punnett Squares, two dark-haired parents with a blonde gene have 25% chance of giving birth to a blonde child. Two dark-haired parents without any blonde genes have 0% chance of giving birth to a blonde child. Two blonde parents (with both genes being blonde) have a 100% chance of giving birth to a blonde child, and one dark-haired parent with a blonde gene and a blonde parent have a 50% chance of giving birth to a blonde child. In order for the blonde population to either increase or decrease, these probabilities would have to change, and as the Hardy-Weinberg Theory explains, they are not going to.
Frost’s theory seems to agree with Hardy and Weinberg. Once the gene for blondeness surfaced and was passed into the next generation, and then the next, and then the next, and so forth, blondeness became a prominent trait among women who would continue to give birth to children with blonde traits even if they were dark-haired (10).
It is hard to predict the outcome of any genetic evolution because it take such a long time to, first of all, establish a trait, and second of all, change. There are many traits that do not get passed on. In fact, people with six fingers or webbed toes are considered freaks of nature when in actuality blondes are a similar mutation that is just a bit more genetically popular. The human population today is huge. For blondeness or any other trait to be completely effected (negatively or positively) in the United States, yet alone throughout the world, would take unimaginably long, and preference from the majority of all people. Even though the World Health Organization did not, a completion of such a study regarding the demise of the blonde trait or any other gene would be really interesting.
SOURCES: