Not any great surprise, a particular gene expression profile1 correlates strongly with late in life fecundity. Interestingly the author studied Ashkenazi Jews and the genes in question are associated with apoptosis (cell death) and DNA repair mechanisms. He has found a similar profile among Bedouin women who conceived late in life. Surely there are some correlated responses that serve as “trade-offs” for this predisposition.2 This is of course the sort of thing that could make genetic testing early in life really be relevant to the choices an individual makes.
1 – From what I can tell there is a tacit assumption that the gene expression profile is inherited in the conventional sense and always expressed, but what about the possibility of epigenetic responses due to environmental and developmental inputs?
2 – One could argue that in premodern conditions the selection coefficient would not be as high as today because life expectancy was lower, so any short term trade-offs early in one’s reproductive career would be more detrimental to fitness than today when a far higher frequency of women make it to 50 healthy, hale and with husband.
I picked up the book as I had a day to give over to light reading, and a history of the so-called Nobel Prize Sperm Bank (actually Robert Klark Graham’s Repository for Germinal Choice) seemed like a good way to fill it; after all, I was curious to see what this curious cadre of noble sperm spawned. But instead of a group of interesting biographies, the reader gets a characterization of Graham (and his most infamous donor, William Shockley) as a eugenic, racist loons, whose ideas were the epitome of the word preposterous; a half-assed history of eugenics and the Repository, full of the obligatory -ist adjectives every other paragraph; a myriad of Plotz’s opinions about everything from artificial insemination to how parents expect too much from their children–many of which contradict each other; and, in between all this, a few plodding biographical sketches of the offspring and donors.
What struck me the most were two things. First, is Plotz’s inconsistencies: He insists that Graham’s ideas were coo-coo, yet later he concedes that they were good enough to forever shaped the sperm donation/artificial insemination industry. After all, when shopping for sperm today, who would purposefully go after semen from a man with a sub-average intelligence, sub-par health, and noticeable lack of morality. Perhaps serendipitous, but that is what Graham set out to do in the first place: set up a way to allow for positive eugenics; that is, trying to improve mankind’s intelligence, health, and morality via selective breeding. Moreover, Plotz implicitly condemns the thought of producing better babies (on purpose), yet later says that it is now common practice (although more at an individual level). Throughout the book, he leads the reader to believe that a kid’s environment is what causes him/her to be intelligent, personable, and successful, but at other points he admits that they are all influenced genetically. All in all, he takes no position (well, not for long anyway), and his ambivalence is tiresome.
In between his own diatribes, he gives a few glimpses of what the Repository kids are like: one is a reclusive “genius” in college, another a precocious, buoyant girl who is likely to enter in Marine Biology (following, ahem, her biological father’s footsteps, who was a chemist). One is a teenage father, although fervently struggling to go to school and take care of his family, while another (his 1/2 brother by the same Repository dad) is a “gifted” pianist/artist…..although remarkably similar having never seen, or heard of, each other and only having 1 parent in common. While only a handful of the 215, all in all, not too motley a crew, despite Plotz not-always-flattering picture of them.
But what really strikes me about the book is, despite Plotz implications to the contrary, the kids turned out to show the potency of genetics. Quantitative genetics would predict that if you take a group of sperm donors who are “above average”1 in intelligence, health, and morals, you would get, in return, a group of kids who, as a group, are above average. If a father’s trait, say, IQ, is 140 (not a far-fetched figure for the Repository) and assume that the heritability for IQ is .40 (an underestimate), then if the mom’s IQ is 85, then the average value for the kids will be 105; if the mom’s IQ is 120 (a more sensible estimate for the moms seeking Repository sperm), the average value for the kids is 112, and you can interpolate as high or low as you want.2 On average, the kids won’t attain the parents’ values, but they will be above average. While Plotz does his best to paint a dismal picture of the whole Repository, and tries to convince the reader that it is the kids’ environment that one should worry about the most, he can’t help but adding evidence to the genetic theory: “In short, they are certainly above average as a group, but the range is wide”…exactly what quantitative genetics would have predicted about genetically-influenced traits.
In sum, the book is little more than a collection of essays showing Plotz’s ambivalence and ostensible lack of knowledge in quantitative (behavior) genetics, with a few anecdotes about the Repository thrown in for good measure; in other words, read the local library’s copy.
[1] According to Plotz, even though Nobel laureates donated, none of their sperm fertilized an egg carried to term. The sperm that did was from other donors, who were sans Nobel.
[2] Y_hat = X_bar + (h^2){([Mom’s Score + Dad’s score]/2)-X_bar}, where X_bar is the population average.
This article in The New York Times about kids who are “picky eaters” is interesting and makes a tacit nod to evolutionary thinking by offering the option that picky eating might have been optimal in the EEA (that is, if you ain’t a picky eater you will put bizarro stuff into your mouth). But, the story could have benefited from the research which suggests that variation in sensitivity to bitter tastes might color a parent’s perception of a child as “picky,” particularly if the parent is the individual who is insensitive while the child is sensitive. Recently I munched on some raw tea leaves. I could taste the mild bitter flavor, but a friend of mine was physically retching from the bitterness. Some of this is likely due to heritable genetic differences, I am a PTC nontaster, a group less likely to be bitter sensitive. But there is also the gene-environment correlation aspect, I have spent many of the past 20 years increasing my tolerance of hot peppers to extreme levels through graduated escalation, exaggerating my relative insensitivity to capsaicin. Who knows if this rubbed off on other aspects of my taste perception?
Those of you with a biological education know well the λ phage and its host E. coli and the various life-history pathways that characterize interaction between the two.1 So, I was surprised to see this article in PLOS today, Population Fitness and the Regulation of Escherichia coli Genes by Bacterial Viruses (those of you more in the know are surely not surprised). One of my favorite sayings is J.B.S. Haldane’s “fitness is a bugger,” as it expresses to me the difficulties of the concept, and the issues with talking about it without being swamped by a swarm of qualifications, caveats and provisional conjectures. The authors in the paper above suggest that during the lysogenic phase the λ repressor factor, cI, might actually bind to regions of the E. coli genome and so downregulate transcription of products which have metabolic implications. In short, in some environments infection might increase the “fitness” of a bacterial lineage (measured in doubling time). The authors point to a clustering of homologous regions to the λ operator sites as evidence for positive selection (one is a coincidence, but seven?).
Obviously stuff like this is relevant in the abstract as understanding a “simple” organism like E. coli and its relationship to its pathogens can flesh out broader principles that are important in understanding “higher” organisms. Additionally, it seems that humans have an an order of magnitude more bacteria within their bodies (mostly the gut) than they have somatic cells!2 Some of the parasites infecting us are most peculiar, for instance, the bizarre cat parasites which seem to alter individual behavior….
1 – For those of you who don’t want to google, λ infects E. coli and either goes “lytic,” where the infection is virulent and the bacteria dies to release the next generation of phage, or “lysogenic,” where the λ inserts itself into the bacterial genome and hangs around until an opportune time to make a break. It is a canonical biological system that elucidates the complexities involved even in the genetic and physiological interaction between virus and its host bacteria.
2 – Bacteria are important in digestion too, there are certain vitamins, like B12 and K, that don’t seem to get produced in “sterile” organisms, so they need nutritional supplements.
Someone just forwarded me this email from Howard Metzenberg:
Razib:
You edited out the many of the comments in the Bad Science thread, including the one in which Henry says “for chris___ Gregory, stop being so arrogant.”
It appears to me that you are not really playing the role of a neutral moderator of these forums.
Howard Metzenberg
Well Howard, the reason you can’t find that comment in that thread isn’t because I deleted it, it is because it is in another thread. Hey jack, for your information, I’m not even a moderator because I’m barely reading the threads in question. Now stop telling me how to run my blog.
Variation is one outcome of sexual reproduction. Not only does recombination usually disrupt linkage disequilibrium in a population over time, but the law of segregation means that siblings will often receive different alleles from the same parent.1
As an illustration, click here. Sometimes nature just puts all its eggs in one basket….
1 – If the parent is homozygous, that is, carries two copies of the same allele, then obviously this isn’t so.
Of late I have expressed some reservations about what I term Evolutionary Psychology™, the model proposed by John Tooby and Leda Cosmides, which implies certain theoretical commitments that many sympathetic to a synthetic treatment of human nature that includes biological parameters dissent from. Nevertheless, it is important to understand Tooby and Cosmides’ model because it is to some extent the reference point for good faith rebuttals. So with that in mind, I link to Evolutionary Psychology: Conceptual foundations (a lengthy PDF). Also, if you have some time to kill I highly recommend Steven Pinker’s So How Does The Mind Work, a rejoinder to Jerry Fodor’s harsh critique (later expanded into a book) of Pinker’s weighty How The Mind Works.
“We’ve shown we can generate primordial germ cells. These are the cells that go on to form either the sperm or the egg depending on the gender of the individual,” said Professor Harry Moore, a reproductive biologist at the University of Sheffield in England.
“In culture, we’ve been able to show, using human embryonic stem cells, that some of those cells develop further to a later stage of sperm development,” he told Reuters.
Possible cure for infertility? In addition to making babies, eggs are the raw material for making new embryonic stem cell lines. The application of this work to making eggs could eliminate the problems of limited egg donation. It also will raise issues for the anti-embryonic-stem cell position: do embryos made completely from in vitro grown cells still count as “human life”?
After nearly 2 years I think PLOS has come really far. We link to their papers often, and some of their reviews by freelance journalists have been really informative. In any case, just so you know next month PLOS Genetics premiers. They have a preview of an interview with Dr. Neil Risch up. Risch is notable for two reasons, 1) he defends the idea of race as a genetically coherent concept (this is alluded to in the preview) and 2) he has put forward the standard model that diseases like Tay Sachs are the result of genetic drift cranked up due to extreme founder effect within Jewish populations.
, and, curiously, that is what the reader (at least this one) comes away feeling after completing the book: a lot of effort exerted, but with a highly disappointing result.