In a previous career, Brian Thomas was once a high-school biology teacher. I believe I’ve already expressed my horror at that.
His latest article – Single Mutation Makes Melanesians Blond – doesn’t help. There are, at my count, at least two HS biology concepts that the article suggests he is completely ignorant of. Let’s go look:
Solomon Islanders have very dark skin. Most also have dark hair, but about one in ten of them have strikingly blond hair. How is this blond trait inherited, and do the people of the Solomon Islands inherit it the same way that other blond populations do?
“How is this blond trait inherited”? What he means in this third sentence is to ask if the genetic underpinnings for blond hair are the same in Oceania as they are in Europe, but it comes off as if inheritance should be added as a third item on the list.
If appearances change slowly and gradually like Darwin taught, then it seems unlikely that the human “races” originated at Babel as recently as the Bible indicates. And if traits are conferred to creatures by their environments performing natural selection, then why would a single environment select multiple traits in the same creature? A fascinating study recently discovered the genetic basis behind blond Solomon Islanders, and the results shed light on these issues.
The first of the concepts, however, is the idea of discrete verses continuous variation. Continuous variation is like height, in that you can get a whole range of heights, while hair colour is comparatively discrete (it certainly is in this situation, but I’m getting ahead of myself). Discrete variation – an example commonly given is tongue rolling, a binary can-or-can’t do trait, though in reality nothing is that simple and mendelian tongue rolling appears to be a myth – has to jump dramatically from phenotype to phenotype. Height, on the other hand, can “change slowly and gradually,” though the “like Darwin taught” (seemingly phrased to contrast with ‘like Jesus taught’) seems to be a little off. At the time it was generally believed that species didn’t change, though admittedly there were some competing views around like saltationism that could potentially justify the comment. More important, however, is the discrete variation thing – that’s the first of the two.
The paper is Melanesian Blond Hair Is Caused by an Amino Acid Change in TYRP1, from Science (abstract only is freely available), if you want to check it out. Brian doesn’t link to a press release or news article today, but Science Daily has an article on it: Key Contribution to Melanesian Blonde Hair Color Discovered. Back to Thomas then:
The research, led by Stanford University’s Department of Genetics, zeroed in on the precise genetic differences between dark-haired and blond-haired Melanesians. They discovered that their blond hair is primarily caused by a single DNA base change that results in a single amino acid difference in an enzyme that helps build melanin—the darkly colored pigment molecule—in hair follicles.
Researchers described how the mutation likely destabilizes the enzyme, making it less efficient at its part in building melanin. The study further states that European blonds do not share that same mutation. Their blondness is conferred by an entirely different mutation.
In other words, a point mutation with major effects. It’s curious that he doesn’t mention that this mutation would have been ‘degenerative’, i.e. that it involves a loss of function, but he’s allowed to avoid the usual arguments for once.
How long does it take for dark-skinned individuals to develop blond hair? One dark-skinned British couple discovered as they marveled at their blond-haired baby that it can happen in one generation.
Again with the discrete variation – how can it take more than the one generation for this change to happen?
Actually, it can. The gene for blond Melanesian hair is recessive, which means that the mutation need not have taken place at the generation that it was first expressed. This technically means that you can count the change as ‘taking’ the several generations in between. However, we don’t know how long the mutation that caused the effect discussed in the earlier DpSU referenced here – Blond Baby from Black Parents a Genetic Mystery (oddly, he incorrectly says that he published it on “July 28, 2012″) – had lain dormant in the baby’s ancestors before it was expressed, so we can’t actually say how long it ‘took’ using the above logic.
In addition, it looks like natural selection had little or nothing to do with generating or retaining the blond hair trait in Solomon Islanders. The Science study authors wrote, “Furthermore, we found no evidence for recent gene flow from Europe nor a strong signature of recent positive selection.”
The second concept that Brian doesn’t seem to understand is genetic drift, another process capable of modifying gene frequencies in a population. Instead, he seems to think that because natural selection was not involved it must have been a Designer what dun’ it.
Natural selection itself, of course, actually makes a third highschool biology concept that Brian doesn’t seem to understand (how could it have something to do with “generating” a trait – that’s not what it’s about), but we already knew that.
Peculiarities among human traits happen quickly today, so it stands to reason that they happened quickly in the past. The observation that blond Melanesians differ from their dark-haired close relatives by only a single DNA base change must now be unnaturally and forcibly reconciled with the contradictory Darwinian doctrines; these evolutionary teachings claim that nature selected trait variations and that nature required eons to do it. Instead, science shows that trait variations like blond hair and even skin color occur in just a few generations. Plenty of time has passed since people were clustered at Babel—time for them to have expressed trait variations by design, not by nature.
That first sentence is confusing in that B.T. is apparently endorsing uniformitarianism. As for the “Darwinian doctrines,” Brian has no idea that this is nothing special and does not go against anything we already knew. There is nothing stopping point mutations with significant phenotype effects taking place, nor randomly becoming more prevalent in the population via genetic drift.
Not all variation is as simple and bible-friendly – mere point mutation + genetic drift – as this, however. The hair colour story in Europe, for example, is much more complex. And there will be other genes that differ in multiple loci, and all the rest.
The last sentence has a footnote, which says:
Even in the case where a random mutation caused a trait variation, as may have occurred in blond Solomon Islanders, the person’s designed genetic and cellular mechanisms interpret and express the trait variations so that the organism, not nature, deserves credit.
Really? If I wrote a novel, who deserves the credit – me or my laptop? What about if genetic engineering was done on a cell – surely it is the engineers, not the cell, that get the ‘credit’? Certainly, if it had been God that had made the mutation Brian would have credited Him with it. But if you remove the designer, and replace it with a random mutation, it is suddenly the organism that is responsible?
His poor students…