So, I just found out that Sayyed Qaboos bin Sa’id Al ‘Bu Sa’id, the Sultan and autocrat of Oman, is a homosexual. Not that there’s anything wrong with that! But that got me thinking, are there any other homosexual heads of state* out there? Please post a reference if you submit a candidate.
* Prime Ministers count in a parliamentary democracy.
Rich Lawler has an insightful comment:
It’s interesting to note that a few of the most insightful observations about the evolutionary process were first promulgated verbally, then later proven mathematically (unlike H-W equilibrium). These include runaway sexual selection (first adumbrated by Fisher, then shown mathematically possible by Lande and Kirkpatrick), the handicap principle (first adumbrated by Zahavi, then–finally–shown to be mathematically possible by Grafen), and, of course, natural selection (first adumbrated by what’s-his-face, then formalized by Wright, Fisher, and later Price, among others). And of course, all of these topics were debated back-n-forth until the math made them more clear.
I think the key here is the reference to evolutionary process, dynamics which span time and space beyond intuitive conceptualization. Verbal “lock & key” models are often sufficient to communicate the biophysical processes at work when an enzyme and substrate interact. A graphical illustration of a biophysical process is clear as the visual mapping is can be precise and accurate; the primary actors here are material. Not so for something as abstract as “fitness.” Verbal descriptions of moments about distributions of abstract concepts are not sufficiently precise to allow for fruitful theoretical inference beyond the most elementary level. Of course, a non-mathematical idea can, and usually does, serve as the seed for future growth of formal theory. But when the subject is by its nature complex formalism is often simplest route.
Looking for Nm* values for humans I stumbled across an interesting paper, Estimating sex-specific processes in human populations: Are XY-homologous markers an effective tool?:
…To test this idea, we analyzed XY-homologous microsatellite diversity in 33 human populations from Africa, Asia and Europe. Interpopulation comparisons suggest that the generally discordant pattern of genetic variation observed for X- and Y-linked markers could be an outcome of sex-specific migration processes (mfemales/mmales ~ 3) or sex-specific demographic processes (Nfemales/Nmales ~ 11) or a combination of both….
Basically the authors were looking at diversity on homologous markers on the X & Y chromosomes. Previously researchers had compared mtDNA (female) and Y (male) lineages, but the authors point out that the comparison using these two regions of the genome might be problematic (e.g., mtDNA is subject to its own peculiarities such as high mutational rate, and might not be as neutral as we assume). The diversity across the markers that they focused on implied two general dynamics:
1) female biased migration or 2) female biased sex ratios
The authors do note data which is locally contradictory, but the overall trends fit our expectations from other data, males usually exhibit more reproductive skew which drives their effective population down vis-a-vis females. Additionally, both common chimpanzees and H. sapiens seem to exhibit a tendency toward patrilocality & patrilineality which is somewhat anomalous among mammals (think of the matrilineages which are focus of social life among whales and elephants). But what is the balance between the two? The models above were presented as extreme cases, holding sex ratio or male and female migration even. It seems that a skew of 1 to 11 is a bit high for most populations, so likely the female migration rate is somewhat higher than the male one. But if history is a guide it may also be that male and female migration tend to follow different tracks, the former being rarer long distance movements and the latter much more common deme-to-deme exchanges. The Arab enslavement of women from black Africa is the main example I can think of long distance migration of females as opposed to males (black males in much of the Arab world were castrated). In contrast, we have many cases of groups of males founding new hybrid populations. The mestizo populations of the New World and the peoples of Madagascar are two prominent cases where males traveled over long distances and left a dominant genetic imprint (in the case of Madagascar the female lineages tend to be from the adjacent African continent).
* N = population size and m migration rate between populations.
Evolgen and Popgen Ramblings have put up posts where they criticize a parameter of the acceleration paper. John Hawks responds in the comments. But I thought this line was priceless:
Nah, you’re not a dirty anti-adaptationist! All these labels are nonsense; all that is important is understanding the math involved — something Gould never really seemed very interested in. The problem with purely verbal arguments is that there is no scorekeeper.: it’s like Olympic ice dancing, or something.
A lot of the formalism in population genetics isn’t that mentally taxing (although the derivations may be!). For example, the famous (or infamous) Hardy-Weinberg Equilibrium, p2 + 2pq + q2 = 1, requires about a middle school level of mathematical knowledge (grade 7 or 8). And one can describe it in words, but by doing so one removes its algebraic utility and clear precision of communication. A non-formal Hardy-Weinberg Equilibrium could never have become one of the pillars upon which population genetic theory was built, to use programming terminology, verbal arguments are often far less extensible than mathematical ones. In the short term verbal description of population genetic theory is much clearer to those who are not used to thinking in terms of variables, but over the long term they leave a lot to be desired in generating a contingent & systematic model. I also think that when scientists communicate and debate it wastes a lot of time when you argue in words because without any magnitude placed upon the implicit variables people easily talk past each other and generate mountains of repetitive prose.
Update: See comments for a clarification.
Laelaps has an excellent post up, Evolution’s Arrow, which you should read. Set some time aside, it is long. I don’t know enough about paleontology to comment with great insight on the many of the topics which Laelaps alludes to, and some of them get a bit philosophical for my own taste (that is, issues turn on the interpretation of words), but there is one point which I might assert is somewhat muddy:
…Looking at the hominid evolutionary bush pictured below [see here, it’s clear that we are but a single surviving twig of a group that once had a much greater diversity, australopithecines (including the “robust” forms in Paranthropus) seeming to be a much more successful type of hominid even if they are presently extinct. Given that our own species has only been in its modern form for little more than 200,000 years and we are daily poisoning our own well in terms of the global environment, I don’t know if we can rightly say that we are any better or worse than any of the related forms that came before. The extinction of so many different hominids begs the question of why they are no longer around to join us if their forms were so good. If so many hominids so close to us could go extinct, doesn’t that reflect that evolution is more contingent than directed towards a certain number of forms?
First, regarding the other hominid groups. Certainly some of them had some longevity on their side, but, it is important to note we are considerably more numerous. One could integrate across the time period that these species flourished and sum up total numbers to compare a raw count and use this as an estimator of “success.” But as I said, much hinges on words such as successful. But the second point is that I think there is a strong likelihood that other hominids no longer exist because we marginalized them (or absorbed them) through direct competition or destruction of their habitat. Look at what we are doing the other extant homonoids. We are co-opting their ecosystems for our own use, and on occasion we even hunt and consume them. It seems likely that they have been saved so far because they tend to inhabit biomes which our species has exploited to a lesser degree until recently. This emphasizes the fact that adaptation and response to other organisms, evolution’s arms race, is a critical parameter which expands the scope of the discussion beyond the interface of the environment and the phenotype of a given species.
John Hawks, Bruce Lahn, and company have a fun paper in Trends in Genetics on the role of introgression of adaptive alleles from archaic Homo species in human evolution. The key point:
[A]n allele with a 5% advantage has a 10% chance of fixation. In fact, selected alleles in an exponentially growing population have a slightly higher probability of fixation, augmented by twice the intrinsic rate of growth. Because each copy of an introduced allele has this fixation probability, only a small number of matings between archaic and modern populations would ensure the eventual fixation of a large proportion of the adaptive archaic alleles. For example, for any and all advantageous archaic variants with s = 0.01, a 95% probability of fixation requires only 74 archaic-modern matings, each introducing a single copy of the allele into the modern human population. Widespread introgression of selected alleles would occur with a minimal level of interbreeding, which would leave a negligible effect on even large samples of neutral loci.
There are, of course, assumptions in these sorts of caculations–perhaps most importantly, the fitness advantage of an introgressed allele would probably be canceled out or reversed by the effects of hybrid incompatibility loci for the first few generations– but it certainly seems reasonable to assume that a number of alleles slipped through the species barrier.
The authors point to a number of candidate gene studies, and have some speculation about the types of alleles that might have been beneficial to the invasive Homo sapiens. To systematically find these alleles and be able to generalize about them, one needs large-scale genome sequencing. Luckily, this type of data is being generated, as I type, at genome centers across the world.
Since the previous post was about the tendency toward radical skepticism and subjectivism within cultural anthropology, I thought I would point to this piece in The Economist which highlights positive insights from various anthropological fields. The article emphasizes the possible role that population pressure and the quest for food might have had in spurring human innovation, from the atlatl to agriculture. An interesting point to note is the implicit suggestion that high rates of hunter-gatherer warfare might have constrained population pressure and possibly lead to relatively higher standards of living; something familiar from Greg Clark’s model. From a population genetic angle, I am curious as to whether the endemic warfare of cultures which were pre-state resulted in higher or lower Nm*?
* N = population, m = migration rate. Nm > 1 results in equilibration of allele frequencies across demes, while Nm < 1 tends to lead to divergence.
Genome Wide Association (GWA) Study for Early Onset Extreme Obesity Supports the Role of Fat Mass and Obesity Associated Gene (FTO) Variants. Even if this is true, these correlations between particular alleles and obesity hold for the modern German lifestyle. I guarantee you that population level diversity in weight correcting for height was sharply attenuated when all Germans were basically farmers and laborers. It seems possible to me that in pre-modern times “obesity alleles” might have been selected for something different in an environment where gaining a lot of weight and becoming subject to higher risk of various chronic diseases was not a plausible outcome. With the change in environment the whole phenotypic landscape shifted as the environment in which the genes expressed was radically altered.
Note: I’m skeptical that obesity alleles mark a much more efficient metabolism. After all, if LCT can nearly fix in northern Europe why not genes which allow you to more efficiently convert food into energy would not have been swept to fixation long ago? I suppose this could be balancing selection, but there’s only so much of that a genetic architecture can support.