Friday, June 19, 2009

Height changes in Germany   posted by Razib @ 6/19/2009 07:33:00 PM

Growth and Puberty in German Children: Is There Still a Positive Secular Trend?:
In Germany, as elsewhere in northern Europe, the upward secular trend in height is slowing (ca. 2 cm/decade up to the mid-20th century, currently less than 1 cm/decade), and the age at menarche has stabilized at just under 13 years. It remains an open question whether the observed slowing will merely be temporary, or whether it indeed represents the near-attainment of an endpoint owing to relatively stable environmental conditions.


Friday, December 12, 2008

Height, weight, waist & BMI of Americans   posted by Razib @ 12/12/2008 09:59:00 PM

Steve has a modestly titled post up, Height and Weight, where he analyzes data from Anthropometric Reference Data for Children and Adults: 2003-2005 (PDF). This is government data on American men, women and children who are Non-Hispanic White, Non-Hispanic Black and Mexican American. I invite readers to peruse the raw data themselves. Steve did a little comparison of various parameters for males and females of the three populations. I thought it would be illustrative to plot the distributions of some the metrics so as to illustrate more intuitively the variation within the populations (the X axis are percentiles). Half Sigma pointed to Steve's post, and the discussion is unsurprisingly vibrant. I think it's safe to assume there is "structure" in something like weight within these populations due to geography and SES. You can see this even in New York City, just start from Bergdorf Goodman (especially around the Holidays) and walk north and east into the Upper East Side. Mean BMI starts dropping. In any case, like Steve I thought focusing on the 20-39 demographic was convenient, in part due to the nature of the readership of this weblog. Here's the CDC's BMI Calculator.

The data I used is here.

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Friday, October 17, 2008

Dark Age giants?   posted by Razib @ 10/17/2008 10:58:00 PM

From Barbarians to Angels: The Dark Ages Reconsidered:
Measurements taken on skeletal remains in cemeteries in southwestern Germany indicate that the average height for men was about five feet eight inches, for women about five feet four inches, statures well above those of late medieval and early modern times. Measurements taken on skeletons in other regions are comparable. In Denmark, for example, the average height for men was about five feet nine inches-just above those for southwestern Germany-and for women about five feet four inches. These average heights were not achieved again until the twentieth century. Compared with earlier and later populations in the same regions, these average measurements show that most people had adequate nutrition during most of their lives and their living conditions were generally good
This is in line with the charts I posted below. With the introduction of the three-field system, mouldboard plow and horse collar northwest Europe, in particular the regions of northern France, the Low Countries and the Rhineland, surpassed the Mediterranean as the population center of the continent (at least its western half). During the expansionary phase, i.e., 500-800, the span covered by Barbarians to Angels, the Malthusian pressures would have been relatively modest. The screws would have been tightened up to the medieval demographic peak before 1300.

In any case, remember my focus on morbidity vs. mortality? It might be apropos in this case. The uncertainty and political instabilities due to the collapse of the Pax Romana could plausibly have increased mortality as peasants were exposed to the erratic depredations of barbarian warrior bands. But as depopulation occurred, in part because of withdrawal from the frontiers in places like Gaul (France) an western Germany of most farmers, those who opted to remain and take on the risks would be relieved of some Malthusian pressures. I think the chart of European heights does point to this as well, you can discern a slight upward trend after the Black Death due to a radical population reduction. I've reedited one of the charts for clarity:

As for Barbarians to Angels, the author doesn't really make me reconsider. I've talked about my skepticism of the idea of revisionism in regards to the decline of Rome. The author argues that technological advances occurred during the Dark Ages, and that many cities remained active nodes in trade networks. But the author's treatment is highly qualitative where he had concrete examples of how complex society persisted after the collapse of the Pax Romana, and he repeatedly scolds the readers to not judge Dark Age societies by modern standards which would tend to align more with the priorities of Roman civilization (e.g., reading, writing, arithmetic, public architecture, basically what we might term civilization). If the author wants to strip the term "civilization" of any normative biases brought to bear due to the prejudice of moderns, the argument is won, amassing a large collection of ornate weapons with which one might be buried is just as Cultured as writing letters to your friends laced with literary references. A good cup of mead is at the same level as a Falernian.

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Human evolution & height?   posted by Razib @ 10/17/2008 12:52:00 PM

In the posts below I wanted to make clear my assumption that morbidity was likely more prevalent during the Neolithic than the Paleolithic. This does not mean of course that the Neolithic people were necessarily poorer than the Paleolithic peoples; Greg Cochran recently told me that people got healthier for obvious reasons during the Great Depression. I would not be surprised if the rate of mortality was somewhat higher than during the Paleolithic simply because the hunter-gatherer lifestyle had less buffering against disasters because trade and social networks were poorly developed so that environmental variation took a greater toll.

For me the biggest point to favor the idea of increased morbidity is that heights seem to have decreased after the Neolithic revolution. It seems plausible that nutritional shifts are the main reason that humans would shrink in size. Below the fold I have reproduced some charts from various papers for your reference.

The cite is Long Bone Dimensions as an Index of Socioeconomic Change in Ancient Asian Populations. Of course, height is not the only thing that changed. From Stature in Early Europeans:
...The sexual dimorphism creased in the more recent populations. Upper Palaeolithic humans not only were taller and had more robust bones in comaprison with the LInear Band Pottery Culture Neolithic people; they also had longer lims, a shorter trunk, and similar to modern African people, very long forearms and crural segments. The low brachial index is a very recently acquired characteristic of white Europeans.
... is interesting to note that, though moern humans have returned to the body structure of their Early Palaolithic ancestors, they retain the modern proportions with short forearms and short crural segments

Agricultural populations as a whole have shifted toward a less robust physique. The increase in height due to better nutrition doesn't seem to have resulted in a more robusticity or a Palaeolithic dentition. So there may be some biological evolutionary parameters at work here as well. The first paper notes that between region differences in height seem to persist over long periods of time (East Asians are smaller). Phenomena such as Bergmann's rule point to changes in body form and size correlating with climatic shifts, and certainly the rise of agriculture is coincident with our current Interglacial.

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Sunday, January 13, 2008

Another height gene   posted by p-ter @ 1/13/2008 12:57:00 PM

Following on the heels of HMGA2, another genome-wide scan for genes involved in height identfies a region near GDF5 and UQCC:
Identifying genetic variants that influence human height will advance our understanding of skeletal growth and development. Several rare genetic variants have been convincingly and reproducibly associated with height in mendelian syndromes, and common variants in the transcription factor gene HMGA2 are associated with variation in height in the general population1. Here we report genome-wide association analyses, using genotyped and imputed markers, of 6,669 individuals from Finland and Sardinia, and follow-up analyses in an additional 28,801 individuals. We show that common variants in the osteoarthritis-associated locus2GDF5-UQCC contribute to variation in height with an estimated additive effect of 0.44 cm (overall P < 10-15). Our results indicate that there may be a link between the genetic basis of height and osteoarthritis, potentially mediated through alterations in bone growth and development
It's worth noting that the loci currently identified as being "height genes" contribute less than 1% of the total variance in height in the population, while the total heritability of height is around 80% in developed countries.

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Sunday, January 06, 2008

Dwarfism and cell division   posted by p-ter @ 1/06/2008 09:36:00 PM

A simple, elegant paper published in Science maps a certain type of dwarfism to the PCNT gene:
Using genetic linkage analysis, we find that biallelic loss-of-function mutations in the centrosomal pericentrin (PCNT) gene on chromosome 21q22.3 cause microcephalic osteodysplastic primordial dwarfism type II (MOPD II) in 25 patients. Adults with this rare inherited condition have an average height of 100 centimeters and a brain size comparable to that of a 3-month-old baby, but are of near-normal intelligence. Absence of PCNT results in disorganized mitotic spindles and missegregation of chromosomes.
Perhaps the goal of genetics is to understand how genetic information becomes an organismal phenotype; I find this example fascinating. It appears that cells lacking pericentrin have abnormal chromosome segregation, which leads, in some fraction of cells, to arrest of the cell cycle and possibly cell death. Now as this happens from birth, the authors propose simply that fewer cells=smaller stature. It seems rather intuitive, but this is biology--intuition is not always the best guide to reality, and it's fun when things make sense.

The authors note that a number of genes involved in microcephaly (ie. ASPM, MCPH1, etc.) are also involved in cell division. There's not much comment on this, but it does make sense these sorts of phenotypes (small stature, small brain) be affected by the rate at which cells divide or die.

Finally, having put together this nice paper, the authors take the well-deserved liberty of a little speculation:
There is an ongoing debate as to whether the Late Pleistocene hominid fossils from the island of Flores, Indonesia, represent a diminutive, small-brained new species, Homo floresiensis, or pathological modern humans. We note that individuals with MOPD II have several features in common with Homo floresiensis, including an adult height of 100 cm, grossly normal intelligence despite severely restricted brain size, absence of a sloping microcephalic morphology, and a number of minor morphological features including facial asymmetry, small chin, abnormal teeth, and subtle bony anomalies of the hand and wrist. Given these similarities, it is tempting to hypothesize that the Indonesian diminutive hominids were in fact humans with MOPD II. With the identification of the genetic basis of MOPD II, this hypothesis may soon be testable.

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Sunday, November 25, 2007

Are tall women like Porsches?   posted by agnostic @ 11/25/2007 11:21:00 AM

We have already seen that female adult film stars are just average in height, while sexy celebrities are a half-sigma above-average. However, consider the heights of the 2007 Miss World contestants, whose median is 68.9 in (N = 106), a clearly significant difference from the US mean of 64.1 in. (where an SD = 3 in.), let alone the mean height of the second and third-world countries that most of the contestants come from. And though I can't find the original cite, many websites quote the Association of Modeling Agents as saying that female models should be at least 5'8. So, if tall women are not more attractive physically, as the first two data-sets suggest, but are more glamorous or prestigious, as the latter two suggest, there is a simple account of all of the data.

First, it's worth reviewing a few key facts about tall women and successful men, which come from Jensen & Sinha's (1993) excellent review of the physical correlates of intelligence. There is a positive correlation between height and IQ of roughly 0.2 -- however, all of this is due to between-family differences, as there is no within-family differences.

In other words, while members of tall families tend to be smart, within a given family, there is no relationship between height and IQ. Therefore, we can rule out some genetic causes such as pleiotropy, where a gene has effects on more than one trait; and genetic linkage, where genes for height may lie close to genes for IQ and be pulled along with them like teammates in a game of Red Rover. Common environmental causes like nutrition do not likely account for the pattern since most of the data comes from first-world populations not subject to much environmental stress, and also because the height-IQ correlation holds even among those with gifted IQs, who do no inhabit slums or want for basic nutrients.

Interestingly, the height-IQ correlation is entirely due to differences in leg length, since the correlation vanishes when sitting height is used instead of standing height. The simplest explanation that Jensen & Sinha propose is that there is cross-assortative mating between female leg length and male IQ. They summarize several studies which show that tall women, no matter what economic class they are born into, tend to climb the economic ladder more easily and marry higher-status husbands. That pools tall and smart genes into the same family, but any given kid of theirs doesn't get to pick and choose which parent he gets his height or IQ genes from, which explains why height and IQ are uncorrelated within families. Moreover, this is not a pattern only among the rich and bright: at every level of IQ, the pattern holds.

Jensen & Sinha suggest that men find tall women physically more attractive, and they mention the heights of Miss Universe contestants as support. But as we've seen, beauty pageant contestants and runway models are an entirely different group from adult film stars and sexy celebrities, who more accurately reflect what males find physically attractive. Therefore, to the extent that tall women are preferred as mates, it is probably so that the man can show her off as a hard-to-acquire status symbol, like a Porsche. This is an honest signal of high status since you don't have to conduct studies to know that a guy with a tall wife is far more likely to be a somebody than a nobody. That's especially true when the woman is not just tall, but taller than her mate, as shown in this gallery of famous shorter man / taller woman couples. We leave aside what makes a man high-status -- it could include wealth, power independent of wealth (as with Dennis Kucinich), and so on.

Broadcasting his status in this way might allow him to attract the attention of a large number of attractive onlooking females, who he may then seek on-the-sly copulations with. It may also allow him to be taken more seriously by his male colleagues and inferiors, and so to rise further in status: "Hey, that guy has a 6' tall wife -- he must be a real go-getter." Both of these effects serve to increase his reproductive fitness. And importantly, parading around your tall wife is a far less vulgar signal of status than, for example, driving up in an obscenely expensive car or sporting tons of jewelry. Consequently, the man does not suffer a loss of reputation as he would with those other signals, and because it is less conspicuous, he is less likely to draw the ire of those around him. He will provoke class envy in them, for sure, but he has to be careful not to enrage or offend them either, since social politics are central to his status.

Finally, because height is highly heritable, he may seek a taller wife more as a long-term wife than a short-term fling since he is concerned about the upward mobility of the children who he invests in. Mating with a tall woman will give his kids a leg up in the status competition. In the case of on-the-sly mating, he will not invest much in them later on, so he could be less worried about their social mobility -- just have a lot of them and hope some do well.


Jensen, A. & S. Sinha (1993). Physical correlates of human intelligence. In P. Vernon (Ed.), Biological approaches to the study of human intelligence, pp. 139-242.

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Heights of female adult film stars: Perfectly average   posted by agnostic @ 11/25/2007 12:04:00 AM

As a follow-up on a previous post about the heights of female sex symbols picked from the pool of celebrities, which found that they're about 1/2 SD above-average, let's now look at how tall adult film stars are. They're worth examining since they are chosen almost exclusively based on how attractive they are to the average male consumer, not how elegant or confident they appear. The website of the modeling agency that hosts the more elite stars -- LA Direct Models (NSFW) -- has height data for all but a couple of their members. If anything, these data are probably biased toward taller height since everyone lies in the upward direction.

Here is the frequency distribution of this sample of 121:

The mean is 64.5 in., the SD is 2.6 in., and the skewness is 0.24, which indicates it is weakly positively skewed (more of the points are bunch around the lower end). In a representative sample of the general population (see this PDF, p.10), females aged 20-29 have a mean height of 64.1 in. Because the adult film star sample could easily by biased by a half-inch, and because the means are close enough anyway, I won't bother running a t-test. If you really want to, feel free to post it in the comments, but it's clear that the adult film stars are not taller or shorter than the population at large.

Because the females are chosen only based on how physically attractive they are, this result goes against the hypothesis that long legs are in general physically attractive to men (although some men may find them sexy). There is another, non-physical reason why tall women may be preferred as mates, which I'll post about soon.

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Monday, October 22, 2007

Pedophiles are short   posted by Razib @ 10/22/2007 10:20:00 PM

Are Some Men Predisposed To Pedophilia?:
A difference in average height is a trait found in other illnesses with biological links. The average difference in height was two centimeters, which is similar to the shorter height associated with schizophrenia or Alzheimer's disease.

Further research is necessary, but this finding re-enforces evidence that pedophilia has a biological cause, possibly related to brain development before birth.

I'm really not that interested in the biological origins of pedophilia, instead my attention was drawn to the fact that such a height difference is known for a range of disorders. In The Mating Mind Geoffrey Miller hypothesized that variance in mutational load across individuals tracked beauty. This is basically a "good genes" model for why organisms exhibit sexual preferences. Miller was assuming a polygynous social system, but this makes me wonder as to the importance of "good health" due to provisioning in a monogamous species.

Though height is about 80% heritable in modern environments that still leaves an unaccounted for 20%; where does that come from? Possibly infection or developmental instability early on for whatever exogenous reason. In pre-modern contexts one assumes that heritability would be a bit lower because of the random stresses during pregnancy and during early childhood growth. In any case, adult height in males would surely be a good proxy for how healthy he is, and how productive a provider he might be. Additionally, good genes is still operative in a scenario where ability to resist and fight off infection is a proxy for fitness.

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Tuesday, August 28, 2007

Dutch Height (again)   posted by DavidB @ 8/28/2007 05:04:00 AM

As I have several times discussed the height of the Dutch (and other peoples) I was interested to come across a reference to this article. Unfortunately I don't at present have access to the full article (without paying $30), but the abstract says:

In the late-Middle Ages and at the onset of the early modern period, the Dutch population was taller than in the first half of the 19th century. This inference is partially based on skeletal evidence, mainly collected by the Dutch physical anthropologist George Maat and his co-workers. A spectacular increase in Dutch heights began in the second half of the 19th century and accelerated in the second half of the 20th century. At the end of the 20th century, the Dutch became tallest in the world.


Tuesday, August 14, 2007

Height and health   posted by Razib @ 8/14/2007 03:49:00 PM

Height, health, and development:
...This paper investigates the environmental determinants of height across 43 developing countries. Unlike in rich countries, where adult height is well predicted by mortality in infancy, there is no consistent relationship across and within countries between adult height on the one hand and childhood mortality or living conditions on the other. In particular, adult African women are taller than is warranted by their low incomes and high childhood mortality, not to mention their mothers' educational level and reported nutrition. High childhood mortality in Africa is associated with taller adults, which suggests that mortality selection dominates scarring, the opposite of what is found in the rest of the world. The relationship between population heights and income is inconsistent and unreliable, as is the relationship between income and health more generally.

From what I recall in modern countries height is about 80% heritable (the proportion of within population variation is controlled by genes). Obviously this is probably going to be lower in less developed nations.

Related: An article in The Washington Post talking about the tall Dutch again. Has anyone thought to check the height in the Dutch areas of southwest Michigan? Whites seem smaller in many east coast or southern cities than in the Pacific Northwest (e.g., Boston and New Orleans). I assume my perception has to do with the ethnic mix, since the Pacific Northwest has fewer "ethnic" whites than other parts of the country, and a disproportionate number of the ethnics are Scandinavian ("everyone in Ballard is Norwegian").

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Monday, May 14, 2007

Heights of comedians: Average Joes   posted by agnostic @ 5/14/2007 07:54:00 AM

Continuing the series on the maintenance of variation in human height, let's have a look at how comedians measure up. (See the previous entry in the series here, which has links to the other entries.) I could see their heights go either way: maybe they're shorter than average, and their comedy routine is their way of getting attention -- or maybe they're taller than average, since you might need a more commanding height to put hecklers in their place.

As explained in the previous entry on daredevils, females in general prefer a male who is taller than average. For a man who's average or below-average in height, then, he had better have something to make up for his unremarkable stature. Since a sense of humor is typically listed near the top of women's preferences (search this page for "humor"), perhaps perfecting comic skills could save a shorty from romantic oblivion. In a recent advice column for short guys, we read:

Bill, a 35-year-old publishing executive from Rochester, NY, who's 5'6", says he's had a good response online from women of all heights. "I have taller girls emailing me a lot, even though I don't meet the height they say they're looking for," he says, "They all tell me my profile made them laugh. I think the key is having something to capture their attention other than height. Humor's the best."

To investigate this possibility, I took a list of the Top 100 comedians as ranked by Comedy Central in 2004 [1], and looked up their heights at the CelebHeights website, for which I found 42 data-points. I then looked up the remaining individuals on Imdb, which gave me new total of 61 heights. But to correct for ubiquitous lying in self-reported height, I subtracted 1 inch from the heights listed at Imdb (a generous assumption). The means and SDs were not different for the group of 42 culled only from CelebHeights vs. the pooled group of CelebHeights plus Imdb data, so I used the larger sample to increase N.

I ignored the 8 or so females who made the ranking, and I left out individuals who were born before 1935, in order to make sure their height wouldn't have been affected by growing up during the Great Depression or anything like that [2]. See here (PDF) for data on a representative sample of male American height.

Below is a frequency distribution of heights in this sample of comedians:

The points show what percent of the group lies strictly above the next-lowest height and up to & including the height where the point is (e.g., 26% were above 68 inches and at most 70 inches). It's an almost normal distribution, and its skewness of 0.29 means that it's more or less symmetrical. Comedians here have a mean height of 69.5 inches (median = 69 inches), with one SD = 3.0 inches. If that sounds like a perfectly representative sample of the general population, that's because it is: a two-tailed t-test to test the difference from the population mean of 69.6 inches gives t = -0.26, which is nowhere near significant (p = 0.8). Out of curiosity, I checked whether height and rank in the Top 100 list were correlated -- they were not: Spearman's rank correlation = -0.06, but p = 0.64.

It's pretty clear that variation in height will not be eroded by female preferences for tall males, provided the average and short males have some way to compensate. Upon realizing that they are not cut out for most sports, hand-to-hand combat, executive positions, and so on, they carve out a niche where this flaw of theirs is unimportant. They still manage to do all right for themselves, and enjoy the side-effect that they are probably much better flirts than their competition. While not knowing much about the history of comedians, I still doubt that a person was able to earn a living as a comic until very recently, so I don't claim that the benefit of comic skills was in attaining high financial status and attracting a bevy of groupies like some modern comedians do.

At the same time, most comedians -- until they are very rich and famous -- typically hold down a day job and perform before an audience during their leisure time. So being a comedian would not have meant that you couldn't have earned a living some other way. And even if there weren't large audiences to tell jokes to, a first-rate comic would surely have acquired a reputation for his skills and would have impressed enough women -- either via reputation or by face-to-face flirtation -- that he would've earned distinction as a local star. After that, mating opportunities would have ensued.

So, there are at least four ways for men to compensate for unimpressive stature: as rockstars (and perhaps as musicians broadly), daredevils, and comedians. All involve cultivating a talent which one can display in front of an audience and which is difficult to copy (as anyone who's tried to make up their own jokes has quickly figured out). This increases their social status. The other way we've seen is to simply be a pretty boy -- no talent there, really, but it's conceivable that women would be attracted to pretty boys due to "good genes" selection. I don't think this necessarily says that short guys will tend to gravitate toward performance-based niches -- it's just that the CelebHeights website only keeps data on celebrities. It would require funding that I don't currently have in order to investigate what other pursuits are shorty-friendly.

Again, let this serve as "news you can use" for sub-tall men currently in the dating arena, or men who plan to have sub-tall sons but still wish for them to do well with girls.

[1] You can bicker about who should be where, but it's a representative sample of famous comedians.

[2] Actually, Jackie Mason's data-point (65 inches) made it into the first round of data collection, and I forgot to throw it out when I calculated the statistics, made the graphs, made these into images, and so on. Rather than waste another 30 minutes to correct all of these just to weed out this one point, I'll keep it in, since its exclusion wouldn't affect any of the results.

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Monday, April 16, 2007

Heights of daredevils: shorties get the girls   posted by agnostic @ 4/16/2007 08:46:00 PM

To expand on the findings of a previous post on shorter guys dominating the pretty boy and hip hop niches, itself inspired by a discussion at Steve Sailer's blog on short guys dominating the rockstar niche, let's now consider the average height of males who specialize in another show-off niche: daredevils. Since performing physically dangerous stunts must require a certain degree of athleticism, you might think that daredevils would tend to be taller than average, as in basketball, football, and other popular sports. On the other hand, perhaps what counts more than height or dominance are nimbleness, ability to maintain one's balance, and being a smaller target (e.g., when being charged by a bull or having darts thrown at one's body). To investigate, let's have a look at the heights of the main cast of the popular MTV daredevil show Jackass. [1] Examining just the hardcore, professional members:

Jason Acuña - 4'7
Bam Margera - 5'8
Chris Pontius - 5'8
Preston Lacy - 5'8
Ryan Dunn - 5'9
Brandon Dicamillo - 5'9
Steve-O - 5'10
Dave England - 5'10
Johnny Knoxville - 6'0.5
Ehren McGhehey - 6'1

Using the data at the excellent website, I could only verify the heights of Knoxville, Margera, and Steve-O (in the thread on Knoxville). The other heights are from their entries, and so are probably exaggerated by 1 inch or so (this is clear from comparing cast members when they stand side-by-side in stunts). Making no adjustments, and leaving aside the outlier of Jason "Wee Man" Acuña (a "little person"), the mean here is 5'9.7; while reducing the unverifiable heights each by 1 inch gives a mean of 5'9.1. For American males age 20-39 (see the PDF here, p.10), mean height is 5'9.6, based on a sample of 1441. I assume the SD for height of the general population is 3 in., though the test is not affected by any reasonable choice. We accept the null hypothesis of no difference in means between daredevils and a random sample of males, regardless of whether we use the unadjusted or adjusted data (both p greater than 0.6 using a two-tailed t-test). Even norming to non-Hispanic White height does not make the results significant (p ~ 0.3). Admittedly the n is small, and perhaps a larger dataset on professional daredevils would resolve the issue of whether there truly is no difference or whether the non-significant trend toward shorter stature here is actually significant.

Looking at a related group of elite athletes in "extreme sports" such as skateboarding and BMX (rather than the all-purpose daredevils of Jackass), I found this handy webpage for a star-studded event that includes height info. NB: Tony Hawk is actually ~6'2, not 6'3 as reported at the above website (let alone the claim of 6'4 at, according to several profiles (e.g., this one and this one), and by comparing him and Johnny Knoxville when they stand side-by-side in a stunt for Jackass Number Two. It's always safer to round down when we're talking about self-reported male height. Comparing the mean of these 15 males -- 5'9.3 -- with that of the aforementioned representative sample of American males, we again accept the null hypothesis of no difference in means (p greater than 0.7 using a two-tailed t-test). As with the stunts of "well-rounded" daredevils, those of the specialists too do not appear to demand taller or shorter than average height.

So, if daredevils tend to be of average height, why the insinuation in the title of the post that they qualify as "shorties?" In the mating arena, the minimum height for an American male to qualify as a "good blind date" is probably 6' or 6'1, so that men who are shorter than this must make up for it somehow. For example, a study of online dating outcomes (PDF) suggested that a 5'10 male would have to earn $32,000 more than a man of 6' in order to receive the same amount of attention from women. The idea is that females are more concerned with quality than quantity of mates, so that they focus on traits as proxies for quality. Since it's rare to find a male who scores highly on all desirable traits, most women face a trade-off between competing "almost dream guys."

Being a professional daredevil is a pretty easy way to signal your genetic quality -- only the truly blessed can perform one dangerous stunt after another without being disfigured, mamed, paralyzed, or killed (watch the bloopers reel for amateur daredevils and see). You need at least general intelligence, boldness and risk-taking, and physical deftness / coordination. So, this could be another instance of the Handicap Principle. Once the first few daredevils in history figured out that they could impress girls as sex symbols, they would have had more children than the population average, increasing the frequency of alleles implicated in the relevant traits. This logistic growth would have continued until their niche became saturated (i.e., when it would pay off more to specialize in some other niche than join the daredevils). Again, it's hard to attention-whore when everyone is exhibitionistic in the same way. [2] This show-off quality is what distinguishes the daredevil niche from others that might also preserve variation in daredevil-ish traits, such as that of young soldiers (cannon fodder). By hypothesis, daredevils are more narcissistic than soldiers.

These processes will maintain genetic variation in traits such as excitement-seeking and height when other pressures might want to erode such variation; e.g., females might in general want a 6' partner or a cautious father of her children. In the comments of a related post on the heights of female sex symbols, Jason asked whether the trend toward shorter male height was an effect of production companies wanting to minimize the height difference between male and female stars, preventing awkward shots. The data on daredevils suggests that this is not a reason, as they rarely appear kissing females on film, and the same is true of rockstars.

And returning to another post on the role of technology in preserving variation, new technology will help people to identify who is cut out to be a daredevil since most stunts involve taking punishment from some product of human artifice, taunting but escaping from a deadly predator using technology, and in general using technology to push the limits of human performance. Now, this is not to say that pre-industrial individuals were jumping off cliffs with a parachute, but the Spanish matador requires only a sword (and really a stick with a large, sharp arrowhead might do). Also, Jackass members Chris Pontius and Steve-O developed their own daredevil show, Wildboyz, in which they often don't use technology at all, but rely on withstanding assults from wild animals (e.g., having their buttocks stung repeatedly by scorpions or surviving a swim with killer sharks). So, there's no reason this dynamic could not have started tens of thousands of years ago, although surely recent history, during which human beings have radiated into a myriad of diverse physical and social environments, will have created different frequencies of such traits between populations. [3]

We now turn to the question of whether daredevils actually do manage to mate with top-choice females, since status per se isn't attractive (as Half-Sigma likes to point out w.r.t. World of Warcraft nerds). Here are some photos of the girlfriends / wives of the sub-6' daredevils:

Bam Margera's wife
Bam Margera's former fiance
Chris Pontius' wife
One of Steve-O's girlfriends (others)
Best example: Wee Man's girlfriend (see pics "w/ Trisha")
Dave England's wife
Dave Mirra's wife (in the middle)
Carey Hart's wife is singer Pink
Bucky Lasek's wife

Perhaps more important than quality is quantity of mates, since the latter is more of a limiting factor on male reproductive success. Steve-O says here that he often sleeps with groupies, and judging from the friends on the MySpace pages of the Jackass members, their groupies are plenty -- and plenty attractive. On a final note, the shorter male readers should take this into account when encouraging your sons to take up one activity or another: if you want them to be successful with females, they'd better train hard to enter a niche that's tailored to short or average-height guys.

[1] No student of human biodiversity can forever avoid pop culture icons, filled as their ranks are with freaks and deviants of all kinds. The only DVD I've ever bought is Jackass Number Two, which I highly recommend to all the young male readers, if you haven't seen it already. The DVD contains lots of bonus footage, too. It is easily one of the most hilarious movies I've ever seen. For those who are unfamiliar with the material, here are a few illustrative examples from YouTube (both NSFW): here and here.

[2] Another clear example of the exhibitionistic appeal of the Jackass members is that they frequently engage in very homoerotic behavior, although none are gay. This is like the increasingly large group of straight girls in college (and, I hate to think, high school) who conspicuously make out with each other at parties (leks) in order to monopolize the attention of the alpha males.

[3] One puzzle is why sub-Saharan Africans are not only underrepresented among daredevils, but are positively freaked out as a group by the idea. (Watch any black stand-up comic show long enough, and soon you'll learn that they love to joke about how insanely death-defying White people can be, in contrast to the sensible Blacks. Another frequent topic is that White people stick around to find out what's going on in a calamitous situation, whereas Blacks immediately get the hell out of there.) This is a puzzle because they are well represented in most other show-off niches such as dancers, singers, athletes, models, and so on. Two possible reasons for this are the aforementioned aversion to "danger in nature," as well as their group's mean IQ of 85. Again, part of the daredevil appeal is that you rely on smarts to avoid accidents. Linda Gottfredson recently argued that avoidance of accidents was part of the reason why human beings became more intelligent (her first paper under 2007). The Jackass members are smart enough to pass high school-level classes at least (though Chris Pontius dropped out); Steve-O attended the University of Miami for a time, and his father is a high-ranking business executive.

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Sunday, April 15, 2007

Female sex symbols: somewhat taller than average   posted by agnostic @ 4/15/2007 05:48:00 PM

A recent John Tierney blog entry cited a much discussed study of online dating behavior (PDF), which suggests that shorter than average women have it easier in the online dating market, with the ideal height being about 5'2 - 5'3, and taller heights incurring increasingly greater costs. [1] However, women clearly vary in height well outside this range, so something is responsible for so much variation in height being maintained. Here I examine a fairly obvious, partial reason: being somewhat taller than average pays off if a woman is specializing in a niche that depends on sex appeal, in particular sex appeal that incorporates a fair amount of moxie / aggressiveness.

To test this hypothesis, I used to determine the heights of the women listed in the Maxim 2006 Hot 100 ranking. It's somewhat of a "sample of convenience," but it's hard to argue that the women there aren't sex symbols or that Maxim has an irrational bias toward women of a certain height. I could only find data for 77 of them [2], which you can see below the fold. [3]

The above frequency distribution by two-inch blocks (up to and including the right endpoint) shows that the heights of sex symbols are approximately normal (skewness = 0.07, or essentially symmetrical), with mean = 65.6 in. and SD = 2.8 in. A representative sample (PDF p.10) of 1,371 US women aged 20-39 showed that their mean height is 64.1 in., making sex symbols on average 1.5 in. taller than the average American woman. Using any reasonable estimate of variance in the general female population, a two-tailed t test shows that this difference in means is significant (t = 4.5, p less than .0001 -- perhaps lower; my calculator cut it off there). Clearly, being a bit taller than average helps in becoming a sex symbol. But does it matter even within the sex symbol set? Not really. Here is rank in the list as a function of height:

The Spearman rank correlation coefficient between height and rank in the list is 0.14 but is not significant (p greater than 0.2). So, being a bit taller than average probably helps you get noticed, but it is not of central importance. Note, though, that the non-significant relationship is not due simply to a restricted range for height in this sample -- the SD of 2.8 in. is close enough to the commonly used estimate of 3 in. for the general population.

Having established the greater average height of such women, what accounts for this pattern? This tends to be the most bullshitty part of a report, so I'll just throw out some guesses, and readers can add their own two cents in the comments. (Apologies for not researching / citing this section, but my hunch is that it'd be easy to dig up a few references for and against each of the guesses, as the "why" is always harder to pin down.)

Conjectures that assume there's something sexy about tallness per se:

- Longer legs. My eyes feast upon other parts, so perhaps in the comments the leg men can explain the appeal of long legs.

- Greater height tricks the eye into seeing a thinner figure. Fatter is usually not sexier (unless it's fatter than Kate Moss), since it reflects poorer health.

Conjectures that assume height isn't sexy per se, but that it covaries with some sexy other traits:

- Greater height could reflect a higher degree of male-typical hormones, which would aid the female in projecting the less passive / "take what she wants" attitude that characterizes sex symbols.

- Greater height could reflect better nutrition and healthy development in general -- think of all those Midwestern model types who grew up away from pathogen- and- toxin-infested urban areas. Good health is sexy per se.

A conjecture that assumes height isn't related to sexiness at all:

- Greater height is necessary to stand out from the crowd and intimidate other women in the entertainment industry. Maybe the average guy couldn't care less about a woman's height, but to break through and survive in a cut-throat industry, sheer height helps.

Whatever the reasons turn out to be, it's clear that there are reproductively prosperous niches that taller than average women are suited to, so that some genetic variation in height will be preserved despite males' apparent greater interest in females who are 5'2 - 5'3. Presumably the same is true in the other direction: former rockstar Shakira says here that being petite (she is ~5'1) causes men to act protective around her. Petite women might have a more sprightly, giggly appeal; so, alleles for shorter height could be preserved either due to the sexiness of girly girls or due to their receiving more protection and investment from others because of their pedomorphic stature.

[1] Oddly, the authors phrase this as a trade-off of height vs. income -- i.e., how much more income would a 5'10 woman have to earn compared to a 5'4 woman in order to garner the same amount of male attention? This makes sense when looking at female preferences since most female online daters are concerned principally with the guy's height and income, and thus face a trade-off should a particular guy not excel at both traits. It makes zero sense to look at male preferences this way, though, since most men are interested in many other physical traits before height even enters their mind, and income and power are not sexy to most men.

[2] I coded the women by rank only, so if a reader wants to know which data are missing, I'll upload the Excel sheet, and they can see for themselves. Almost all of the missing data are from the bottom of the ranking anyway, so the more important points are accounted for.

[3] I took the cited height for granted if it was an integer; otherwise I browsed through the text of the entry and discussion to decide which number was most accurate, sometimes rounding up, sometimes down, and sometimes keeping it as is. (19 of 77 data-points are non-integers, so I didn't round indiscriminately.)

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Saturday, April 14, 2007

IQ, height & Crooked Timber   posted by Razib @ 4/14/2007 08:08:00 PM

John Quiggin @ Crooked Timber has a post where he moots ideas re: IQ & height. If you're inclined to give dkane a helping hand, swing on over! Just remember, the gang @ CT are much, much, smarter than you, so tread lightly....

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Monday, February 12, 2007

Dutch Height, Again   posted by DavidB @ 2/12/2007 02:18:00 AM

GNXP has carried several previous posts about the long-term increase in adult heights, for example my post here. Average height is said to have increased by several inches over the last century in most Western countries (and in post-war Japan and Korea), but the increase has been less in the USA, which started at a higher level, than in Europe. Some European countries have now overtaken the US, and the Western world's tallest people are now the Dutch.

There is apparently a new study confirming this trend, and analysing the reasons: see this report from the London Times. It may be worth mentioning a letter to the Times following this report, from one Philip Lawford, which attributed the increase in the Netherlands to the very high consumption of dairy products there, from cattle fed on growth-enhancing additives.

I doubt that this is the main reason, as the long-term trend started before the agricultural use of growth hormones, but it is worth considering as a possible marginal factor.


Sunday, January 07, 2007

Short guys: thank environmental heterogeneity   posted by agnostic @ 1/07/2007 05:49:00 PM

At Steve Sailer's blog, there's an interesting discussion on height in music stars, with some evidence that country singers are taller on average than rock musicians. The mean for rock stars is ~5'10", although personal observations in the comments suggest exaggerated heights among the shorter rock stars like Mick Jagger. I looked through the CelebHeights website for height data on "pretty boys" (e.g., Johnny Depp), and they too appear to be at or below the male population average of 5'10" (see list at the end of this post). If the apparent trend is real, it would be a nice illustration of why all males aren't the same ideal height: there may be some ideal height, but those falling on either side of ideal will still have some niche to fill. Thus, selection is likely more of the balancing type -- it keeps heights within a tolerable range, in this case normally distributed.

Just because you're within 1 SD of the mean on the below-average side doesn't mean you're doomed -- you can excel in areas where being short is more advantageous, such as bouncing around on stage as a musician, generating pretty boy / heartthrob appeal, or honing your skills as a dancer (which becomes more difficult as your center-of-gravity increases and your limbs become longer). This assumes the below-average individual possesses independent other appealing traits, which is why the height distribution isn't uniform -- guys who are 5'7 and otherwise unappealing will be selected against, so 5'7 males will be less frequent than 5'10 males, but enough of the former can rely on other qualities to find mates that their frequency won't be close to zero.

Now, it may sound strange to lump being a rockstar and being a good dancer into the same category, but that just proves the point: just one generation ago during the disco era, dancing skills were highly valued in males. Now, not really. Stochastic environments tend to result in a more diverse range of phenotypes -- unlike, say, the constant environment of oxygen in the air, which will weed out human lungs designed to process anything other than oxygen. So, it seems that predicting fitness based on a guy's height is chancy enough that non-ideal phenotypes aren't mercilessly purged from the genepool.

This scenario predicts that human height will show moderate-high heritability, since directional selection isn't at work and so doesn't exhaust genetic variance in the trait, and since height is not so fitness-neutral that there is nearly unconstrained variance among individuals. Sure enough, h^2 = 0.65 [see Note1]. All this said, I'm no expert on life history theory, so there are surely some subtleties that I'm missing.

As a final thought, complex modern societies open up many more niches to be exploited by yesteryear's outcasts (asocial introverts for one), and the accelerated pace at which aspects of social life change in such societies -- especially due to technological changes -- introduces greater environmental stochasticity. Aside from the disco example, consider the present-day greater fitness of lesser-IQ individuals compared to higher-individuals: in the mid-19th C., who could've rationally predicted that the less intelligent would turn the Darwinian tables on the more brainy? If we ended welfare state policies that support large families among lower-IQ individuals, the trend could snap back to the way it was in 1850. This greater unpredictability of life compared to that of hunter-gatherer societies tells us that phenotypic variance should have exploded not long after the transition to agriculture roughly 10,000 years ago. Concluding where we began with height, Greg Cochran coined a nice mneumonic for remembering the take-home lesson here: "The bow begat the Bushmen."

Pretty Boys

Gael Garcia Bernal 5'6.5
Tom Cruise 5'7
Wilmer Valderrama 5'7
Scott Wolf 5'7
Johnny Depp 5'8
Ryan Phillippe 5'8
Jon Bon Jovi 5'9
Jared Leto 5'9
Dave Navarro 5'9
Scott Baio 5'10
Orlando Bloom 5'10
Leonardo DiCaprio 5'10
Matt Damon 5'10
Colin Farrell 5'10
Jude Law 5'11
Brad Pitt 5'11
Mark McGrath 5'11
Jake Gyllenhaal 6'
Freddie Prinze Jr. 6'1
Gavin Rossdale 6'1
Josh Hartnett 6'3

Median = 5'10. Sex appeal doesn't tail off as height decreases in this sample: look who's 5'9 or shorter. I'm sure there are other data points, but I'm only going to tolerate looking up so much data on pretty boys in the interests of science. I randomly thought of as many as I could, then Googled websites showcasing pretty boys, so if anyone is going to add more data, try to make it random rather than only looking for confirming or disconfirming data points. I think I covered the real heartthrobs, though, which are the most important data. I invite those more inclined to study this -- such as our legions of teenage girl readers -- to pick up where I'm leaving off.

Note1: Falconer & Mackay give two references for heritability of human height, one of which is here, and the other of which is:

Huntley (1966). Heritability of intelligence. pp. 201-18 in Meade & Parkes (eds.), Genetic and Environmental Factors in Human Ability. Oliver and Boyd: Edinburgh.


Monday, October 17, 2005

Small Gains   posted by Jason Malloy @ 10/17/2005 05:58:00 AM

The New York Times Magazine queries - is an inch Worth $100,000? (The Short of it). I guess that depends where it goes . . .

Down the toilet is where, apparently, according to the article, which describes the modern trend for parents and doctors to favor expensive Human Growth Hormone treatment for young boys who happen to naturally develop at the extreme left-hand side of the height bell curve – completely normal males who won’t even hit the 5 foot mark. The parents and health professionals are under the reasonable impression that height below the 2nd percentile, must provide these boys with some significant social handicaps – handicaps which could eventually affect their mental health and major life outcomes (ability to acquire mates, wages, job security, etc.). Unfortunately, attempts to empirically verify the assumptions behind this treatment have all failed:

Several years ago, around the time the Food and Drug Administration was considering the use of human growth hormone to treat extremely short but otherwise normal children, researchers were working up the results of a large-scale psychology experiment involving hundreds of middle-school and high-school students in the Buffalo area - including some who were extremely short but otherwise normal. The students didn't know the study was about height. All they knew was that each of them had been asked to be the director of a class play. They were given thumbnail sketches of various characters in the drama - "a good leader," "teases others too much," "gets picked on" and so forth - and were then asked to cast the play by selecting classmates who best fit each role.

If short stature is a ticket to social prejudice and psychological purgatory, which has been the animating idea behind expanded use of growth hormone in the last 20 years, you would have expected the shortest children in the Buffalo study to be lining up to collect their Tonys in victimhood; they would have been nominated by classmates for every beleaguered role: being picked on, behaving shyly, acting withdrawn, being left out. But that, surprisingly, was not the case. A team of psychologists, led by David E. Sandberg at the University at Buffalo, concluded that a child's stature, whether tall or small, had "minimal detectable impact" on his or her social standing among schoolmates. At least in this setting, even extremely short children (those around the first percentile) made friends and earned the respect of their peers as easily as kids of average size.

Sandberg’s evaluations have found these kids at the 1st percentile to be emotionally, socially, and behaviorally normal, something replicated by similar research in England. This isn’t a trivial find considering that typical treatment runs about $20,000 a year for 4-5 years, and typical gains are only about 1-2 inches. And yet clinical comparisons between an HGH group and a control group found:

. . . no significant differences in the quality of life between young adults who had been treated with growth hormone as children and a control group of adults (equally short as children) who had not - except that adults who had taken the drug as children had a romantic partner less often than those who hadn't used it.

So the largest scientifically verified benefit of this $100,000 treatment is less sex partners! With treatments like these, as they say, who needs sickness?

I can see why it would be tempting, even prudent, for parents to disregard such results, though. We’ve all heard the one about the taller presidential candidate, and it’s not as if the literature isn’t full of examples of the woes of shortness. Even this article admits:

There is a considerable literature suggesting that taller men receive higher pay than shorter men, and one recent study concluded that economic discrimination against short adult males was equal in magnitude to racial or gender bias in the workplace.

Right, ‘considerable literature’, so then did the paper that followed the HGH “adults” measure things like job security and wages? If it didn’t look at these kinds of things then we have a poor study design (I’d bet subjects are still too young to catch the most important variables), but if it did and didn’t find any difference, we have results that can at least fairly be regarded by concerned parents as anomalous – at odds with the larger literature. Because of a number of safe study designs, like comparing the taller of two identical twins, Steven Landsburg noted that we know height is worth about $1000 per inch per year. Sadly these substantial returns wouldn’t even match the treatment costs after an entire adulthood of working, but shortness appears to be related to more than just money – long term mental health may also suffer in important ways:

In a study of records for nearly 1.3 million Swedish men, the investigators found that for every 2 inches a man gained in height, his suicide risk dipped by 9 percent. Overall, the shortest men in the study were about twice as likely as the tallest men to commit suicide.

So we have $2000 extra dollars a year and 9% less of a chance of killing yourself. On top of this, many other studies show that inches have a significant impact on romantic outcomes, both indirectly through greater income, and directly, as increased male height is considered more attractive. Taller males have more, and more attractive, sexual partners, are less likely to be bachelors or childless, and have more children compared with others who do reproduce. A burden humorously illustrated in this unscientific ABC News pseudo-study by some very heartless, um, ‘size queens’:

” ABCNEWS put together an experiment to test just how willing women are to date shorter men . . . To see if the women would go for short guys who were successful, ABCNEWS' Lynn Sherr created extraordinary résumés for the shorter men. She told the women that the shorter men included a doctor, a best-selling author, a champion skier, a venture capitalist who'd made millions by the age of 25.

Nothing worked. The women always chose the tall men. Sherr asked whether there'd be anything she could say that would make the shortest of the men, who was 5 feet, irresistible. One of the women replied, "Maybe the only thing you could say is that the other four are murderers." Another backed her up, saying that had the taller men had a criminal record she might have been swayed to choose a shorter man. Another said she'd have considered the shorter men, if the taller men had been described as "child molesters."

So given what we know about height, it’s not totally unreasonable for parents (who probably want grandchildren) to continue to want to boost their extremely short children at great expense, despite some of these more direct studies suggesting no pay-off – at least at the time of young adulthood.

A height skeptic might wonder if any of these correlations matter in the ways we assume they do, after all “correlation isn’t causation” and the precise relationship between height and income or height and suicide may have nothing to do with height by itself. To illustrate, men who are married make more money at sales, presumably because a third skill – influencing people – gave them an advantage at both finding a partner and making more sales. Therefore just because there is a correlation between marriage and sales, doesn’t imply that giving some sales failure a wife (from your harem, in the manner of a grateful Saudi sheik) will improve his sales ability. This sheik wife may be like HGH tallness.

I am not a height skeptic, in part because the path between height and at least some male outcomes (perceived dominance/attractiveness) is not completely mysterious (see the Landsburg link for a clever experiment to find the path from height to income). Still, I can think of reasons to doubt the cost/benefit analysis in favor of HGH treatment.

Even if the drug had some measure of proven benefit, other factors, such as the possibility of untested long-term effects for new treatments, have to be weighed in these decisions. Also most families don’t have $100,000 to blow; perhaps an equal amount of money put towards good college, a decent home, or something bearing interest for this wee lad would be a wiser investment than 1 inch of height.

Related: Tall Tale, How Much Taller?, Taller ~ Richer, On Height, Medieval Height, Asian Height Gaps.

Addendum from Razib: There is book, it is called Worldwide Variation in Human Growth, and it is searchable via Amazon and Google Print. This book has tables, it reports on studies. These tables and reports transmit facts. Facts are important, and many would contend, as would I, that they should precede opinions, rather than being rendered unnecessary by the presence of an opinion. One need not read the book above, one might even make recourse to a website called google, where one can find facts. If one has an allergy to facts, or lacks the cognitive aptitude toward the manipulation and deployment of facts, one should retreat from the plain of discourse. We aren't here to play Risk, some intellectual stakes are on the table....


Wednesday, October 12, 2005

Hellenic (Achaean) Height   posted by Razib @ 10/12/2005 03:45:00 PM

Since we've talked about height on this blog before, I thought the following might interest some...from The Aegean Bronze Age:

All the large samples have produced very similar averages of height...around 1.67 m [about 5'6] for men and 1.55 m [about 5'1] for women, but with a range that in both sexes spreads over 20 cm [a little under 8 inches] around the average...these averages are only half a centimeter lower than in modern Greece....

I don't know if the average for modern Greece is correct, the book dates from 1994, and many works of scholarship often use old data when drawing upon facts from outside of their discipline. Here are height tables for Greek boys and girls, even assuming that Athenians are taller (for whatever reason) than average the comparison to modern (21st century) Greeks is off. But, the legends of tiny ancients go back at least few centuries, so it doesn't exculpate scholars totally.

Here is some more from Mycenaeans:

...The skeletons of aristocrats in Grave Circle B show that the women were 1.58-1.61 [5'2-5'3] tall and the men were 1.61-1.76 m [5'3-5'9] tall, around 6 cm [2.4 inches] taller than commoners.
Zeta 59 [remains of an individual] was also a big man...he was 1.75 m tall [5'9].
Gamma 55 was another big man, 1.76 m tall....

These might not be giants on the march, but they are certainly more substantial than the 5'0 tall roman rankers described to me by one anthropologist. Certainly peasant farmers and (later) urban poor recruits are not necessarily equivalent to aristocratic warriors 1,000 years before their time, but, it suggests that one should take gee-whiz generalizations with a grain of salt.


Monday, September 19, 2005

Medieval Height   posted by DavidB @ 9/19/2005 02:38:00 AM

I have occasionally discussed the subject of long-term increases in average height, so I was interested to see an article in today's London Times, here. (Link may expire after a week for non-subscribers.) The drift of it is that average adult height in Britain, as measured from skeletal remains, has not changed very much since Neolithic times. Contrary to popular assumption, people in the Middle Ages were not much shorter than today. There has been a small increase (an inch or so) in recent decades due to better nutrition, but it's not such a big deal.

I think this may somewhat underestimate the increase since the 19th century. Most sources put this at at least a couple of inches. There in some evidence that average height fell in industrial areas during the harshest period of the Industrial Revolution, before rising again from the late 19th century onwards, so the increase since medieval times may indeed only be an inch or so.

While on the subject of press reports, I can't resist repeating the classic headline from Sunday's über-tabloid, The News of the World: 'Cocaine Kate's 3-in-Bed Lesbian Orgy'. (The 'Kate' is Kate Moss, in case you hadn't guessed.) Nothing to do with GNXP, but it's a dream come true!