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The Effects of Altitude on Phenotypes
Lately I’ve been wondering on the effects of high elevations on phenotypes and thus decided to study populations living under such conditions and see how they compare to one another. For that, I’ve mainly read about the Alpinid, Dinarid, Tibetid, Andid and Central Ethiopid (which according to humanphenotypes.com is the Ethiopid variety inhabiting the Ethiopian highlands) phenotypes.
INTRODUCTORY CLASSIFICATIONS
Let’s see what the SNPA and humanphenotypes say about them.
Alpinid: Named by Ripley (Alpine), the Alpinid is an important western and central European Europid type, short- to medium-statured, brachycephalic, characteristically round-headed and -featured, broad-faced, and of intermediate to dark pigmentation. Alpinids predominate in central parts of France, and are common in southern Germany (especially Bavaria) and the Alps. the central European Alpinid is probably derived from Cro-Magnoids through a process of alpinization (cf. Borreby, Gorid).
Alpinization: An evolutionary process or tendency involving reduction, brachycephalization and infantilization, possibly an adaption to a low energy, sedentary existence. Some alpinized or partially alpinized Europid populations (Alpinoids), are Alpinid, Borreby and Gorid.
Andid: Indianid type. Andids are small, stocky meso-brachycephals of the Andes (Quechua, Araucanians), the Ecuadorian coast, Peru and Chile. They are characterized by particularly strong eye-folds (but not particularly Mongolid eye features), a striking medium-broad, relatively high-rooted straight or convex nose, smooth hair and medium brown to brown skin
Of note’s the affirmation it’s characterized by a short body and large thorax as an adaptation to high altitudes.
Dinarid: Central and southeastern Europid, named with reference to the Dinaric Alps. The Dinarid is considered a Taurid, being a product of the dinaricization of an ancestral population of uncertain affiliation (a Borreby-like Cro-Magnoid type has been suggested). Dinarids are typically brachycephalic and planoccipital, long-faced and long- and convex-nosed, and intermediate to dark in pigmentation. They are most common in the Balkans, especially in the region of former Yugoslavia, and a Dinarid "belt" extends from France through southern Germany, the Alps and northern Italy, terminating in the western shoreline populations of the Black Sea. Cf. Norid.
Dinaricization: An evolutionary process involving brachycephalization, flattening of the occipital region, and development of a long and prominent nasal apparatus, typically of extreme convexity. Dinaricization, whatever its precise nature, could be an adaptation to life in mountainous regions, and is allegedly correlated with herding populations. The Eurasian Taurid types (including the European Dinarid) are classic examples of dinaricization, but a tendency may also be observed outside of the Europid group, e.g. in certain Indianid populations. Based on observations made by the budding physical anthropologist Byron O. Hughes in his doctor's thesis (The Physical Anthropology of Native Born Armenians), Coon explained the special set of features as the divergent outcome of interbreeding between Alpinid and Mediterranid populations of certain proportions (2/3 Mediterranid, 1/3 Alpinid; see The Races of Europe, Photographic Supplement, plate 35). It has also been suggested that brachycephalized Cro-Magnoids and/or similar strains have been involved in the various formations.
What catches my attention the most is that Alpinid and Dinarid are European populations with quite distinct features (though both are brachycephalic) and both are thought to have been affect by living on mountains. Not only that, but it’s also suggested that both might have been formed by the same ancestral population (Cro-Magnoids) living under those conditions. There’s also the hypothesis that the Dinarid type’s a blend of Alpinid and Mediterranid, thought some questions still persist such as how the Dinarid type came to be taller than both of them. Could it be the effect of living on mountains? Let’s study that possibility, but first we shall continue the classification of the proposed types left.
As it’s not specific to the Central Ethiopid phenotype, let’s see what humanphenotypes has to say about Ethiopid proper and Central Ethiopid:Ethiopid: Negrid subtype of northeastern Africa. Aethiopids are dolichocephalic, tall and slender, with generally narrow features, highly variable skin color and hair texture. The nose is high and narrow, and not seldom convex, and the chin is often strong. Whether these arguably Europoid features of the Aethiopid physique are the result of significant Europid (Mediterranid, Arabid) influence, or of divergence within the Negrid stock, is a much debated and so far unresolved issue.
One interesting observation to be made is that compared to the definition by SNPA for general Ethiopid, the one found on the highlands seems to be mesocephalic, not dolichocephalic, thus having a higher cephalic index (as seen in the table below, Reference 1) when compared to lowland types, just like the process described by Alpinization and Dinaricization.
Furthermore, while humanphenotypes says Ethiopid proper has a tall and slender stature (what could be labeled as ectomorphic) it says Central Ethiopid’s ectomorphic to mesomorphic, thus stockier.
It’s also stated Central Ehiopid’s brachyskelic, and the following image on the distribution of hyperbrachyskelic individuals when compared to the distribution of Ethiopid and Central Ethiopid shows that Ethiopid populations to the West of Central Ethiopid are more commonly hyperbrachyskelic, i.e. possess longer legs and are taller than Central Ethiopid. It apparently corroborates that Central Ethiopid got stockier.
It’s also described as having high and narrow noses, and while Ethiopid proper’s also said to possess those chaarcteristics it can be said to have narrower noses than at least Western Africans.
Last but not least, Tibetid:
Qiangid/Tibetid: The Mongolid subtype of the Tibetans - a blend of mostly Middle-Sinid with Tungid (Kumid subtype) and low-level Europid elements.
Comparing it to its constituent parts:
Sinid: The most numerous of the Mongolid varieties, characterized by a high and narrow skull and face (however the face is lower than that of the Tungid type), mesognathy, a high frequency of epicanthus, coarse and straight black (sometimes blue-black) hair, and darker skin and thicker lips than Tungids. Sinids are found in China, Tibet, and Korea. Subtypes: North-Sinid, Middle-Sinid, South-Sinid.
Kumid: Tungid subtype of Turkestan and Mongolia and the surrounding regions. Kumids are characterized by a low and wide skull (sometimes higher than with the Taigid subtype), high and wide face with somewhat smaller malars than the Taigid subtype, high frequency of epicanthus (however less so than with the Taigid subtype), and high and often rather large nose, of little projection. The hair is coarse and black, the eyes are dark, the skin is darker than with the Taigid subtype, and beard growth is scant (but stronger than with the Taigid subtype.
Tibetid seems to have a higher probability of having convex noses when compared to Sinid and Kumid but to be slender (ecto- to endomorph and macroskelic to mesoskelic) than Kumid/Aralid (endomorph and macroskelic).
With all of that, the mountain populations appear to have a higher cephalic index, to be stockier (except Dinarid and Tibetid) and generally to have more high-rooted and convex noses (except Alpinid) than their lowland counterparts.
TRADITIONAL ANTHROPOLOGICAL LITERATURE
Haddon in The Races of Man and Their Distribution said the Alpine race could be present in the Himalayas, which border the Tibetan Plateau
He also links the Dinaric type to the Anatolian/Armenian, though the first’s presented as taller than the latter.The Brachycephalic Cymotrichi may be conveniently included under the term Alpines or “Alpine Race." This race consists of a short and a tall variety. The race occurs mainly in the plateaus and mountains that extend from the Himalayas, through Asia Minor, the Balkan Peninsula to Central France and Brittany.
In Human Races, Garn defined Tibetans asDinaric or Adriatic: A tall variety, stature 1.68-1.72m. (5ft. 6-7 ¾ in.), which is probably an offshoot from the Anatolian. Anatolian or Armenian: The former name may be given to the tall variety of Asia Minor. The Armenians appear to be the modified representatives of an ancient Hittite stock. They are characterised by a tawny white skin; stature 1.63-1.69m. (5ft. 4 ¼ - 6 ½ in.); the body is heavy, with a tendency to corpulency; brachycephalic head, which is very flat behind (index 85-87); aquiline nose with a depressed tip and large wings is very characteristic.
Which goes against the expectations of high-elevation types being smaller than in lower altitudes.ruggedly-tall (and often big-eared) […] The taller, more linear, quite nasal peoples of Tibet, extending northward to Mongolia.
In Races of Man Cole attributed the round-headed element to other highlands regions, also linked Dinarics to the Middle East and said Tibetans have narrow faces, being the result of the mixture between the archaic white stock and fully evolved mongoloids.
A suggestion of the similarity of formation of Ethiopian and Dravidian races is given by Montadon in La Race, Les Races: Mise au point d’ethnologie somatique.The Alpines. The people discussed so far all had long or medium-length heads. The round-headed Alpines are in other respects very similar to Mediterranean peoples. This round-headed element re-emerged not only in the Alpine region but also in the Caucasus, Anatolia, the Syrian highlands and the Armenian plateau. These areas were not important highways for movements of Mediterranean peoples, but refuge areas. Dinarics and Armenoids. The well-known hooked nose, sloping forehead, eye-brows meeting in the middle, and heavy beard represented in Bronze Age sculptures and other forms of art of the Middle Eastern civilizations is a type which must have been ancestral to the present Dinarics and Armenoids. These people are characterized by round heads, artificially flattened in the occipital region as a result of ‘cradling’ of infants by strapping them to a cradle-board. The Dinaric type is believed to have originated in the Middle East around 2000 B.C., whence it spread to Spain and became associated with the Bell Beaker culture of Early Bronze Age times; this culture was later diffused to the Rhineland and central Europe. The Armenoids are closely related to the Irano-Afghans and both may possibly have acquired their round head from crossing with Alpines.
[…]The mountain people of Tibet (Fig. 25), Nepal (Plate VI, left), Sze-Chuan and northern Burma appear to be the result of mixture between the archaic White stock and fully evolved Mongoloids. The Tibetan face is narrower than that of the Classic Mongoloid and is less padded with fat, while the nose is typically prominent, resembling that of some American Indians.
FURTHER LITERATURELa race éthiopienne, en Afrique, et la race dravidienne, en Asie, paraissent être des produits de métissage du type méridional, moins différencié qu'aujourd'hui, avec des éléments divers du type septentrional.
Reference 2 gives good insights on the process of altitude adaptation:
Such an observation confirms what was stated by traditional anthropologists and is in accordance with the descriptions of some phenotypes, although the question remains as to why the Dinaric type is so tall.Newman and Collazos and, more recently, Baker (3) report that in the Peruvian Andes growth and skeletal maturation is retarded; the consequent relative stunting is possibly an advantage. Chest measurements do not follow this trend toward small dimensions, however; Indian boys in the high mountains of Peru, while developing more slowly than coastal dwellers in other respects, develop a larger thorax and greater lung capacity.
Reference 3 makes an important observation on the situation of Europe:
Which makes us question if European populations have inhabited mountainous regions for enough time to become significantly physically adapted.There are at least five sources of evidence by which adaptation to high altitude may be assessed. One is simply the presence of populations that have long resided at high altitude, conventionally defined as > 2500 m (8250 ft) as that is the altitude at which arterial O2 saturation begins to fall. Of the four major high-altitude regions of the world (Fig. 1), Native Americans resided seasonally at high altitude for millennia but permanent populations, largely of European origin, only for the past 150 years and hence not the longer time horizons required for genetic adaptation.2 Of note, there are no permanently inhabited communities at altitudes >2500 m in Europe. Archeological evidence for human occupation on the Andean Altiplano extends back as far as ~14,000 years (Rademaker et al., 2014), ~30,000 years on the Himalayan Plateau (Malasse and Gaillard, 2011; Jeong et al., 2014), and from 500 to ~70,000 years in the Ethiopian Highlands (Huerta-Sanchez et al., 2013), although the permanence of such residence continues to be debated (Capriles and Albarracin-Jordan, 2013; Rademaker et al., 2016) and yearround residence was probably not possible until plant and animal domestication was complete (Aldenderfer, 1999; Prates et al., 2013; Dong et al., 2016).
However, Reference 4 makes it clear some phenotypical adaptations can occur even within just one generation:
It also elucidates that not all highlander populations will be similar, as their characteristics depend on genetic influences. We can infer their attributes are dependant on the lowland populations they derive from, even if altitude adaptation may force certain similar physical adaptations. The reverse can also occur, i.e. the loss of adaptation or acclimatization when going to the lowlands. Because of that, we can say the same phenotype can possess different anthropometric values for people in different altitudes.An increase in chest dimensions has been described in high-altitude populations. Stinson (467) found that European children raised at high altitude have smaller chest dimensions relative to stature than the Aymara children living at the same altitude.
Reference 5, on the study of Ethiopian populations, found that highlanders are heavier but also taller than lowlanders.Comparisons between Andeans and Asians have given the general impression that the Andeans are “barrel chested” and that the Asians are not. Pawson (379), reviewing the Ethiopian, Peruvian, and Nepalese studies of growth and development in high-altitude populations, considered that genetic influences may play a significant role in the different chest dimensions found between Andeans, Ethiopians, Nepalese, and Tibetans. The complexity of these differences in chest growth has been analyzed by Beall (54), who concluded that the allometry between chest and body size throughout development and maturity differed in the Andeans and in the Tibetan population of Mugu, Nepal (3,800 m). The population comparisons are influenced by age and sex due to contrast in height-growth patterns as well as contrasts in height-weight relationships.
There’s also an excerpt which may explain a few things for other phenotypes as well:[…] clear evidence that the indigenous highlanders, and the highlanders that migrated to the lowlands, are heavier than the indigenous lowlanders.
[…] In the female sample there is also some statiscal evidence that highlanders are taller than the lowland people.
[…] It is to be noted, however, that there are fewer significant differences in height than in weight […].
It may explain why Dinarics and Tibetids don’t seem to be smaller than surrounding populations, as they don’t appear to be particularly rich in subcutaneous fat, in opposition to the Alpines and Cro-Magnoids, whom they might’ve derived from.[…] it is well known that measures of respiratory function are dependent upon body size, and, as has been shown, Ethiopians tend to be very light in body weight, though not particularly short in stature.
It is interesting that, whereas other studies (Cotes 1965) have clearly indicated that stature variation shows the closest relationship with respiratory function, in Ethiopians it would appear that the prime correlations are with body weight. This apparently anomalous situation probably arises because of variation in body composition. Certainly all the Ethiopian groups have very low measures of subcutaneous fat, and if this reflects overall fat levels, it’s probable that body weight is a better indicator of active biomass than stature or any function of stature.
Also on Ethiopian population, Reference 6 states the following about noses and stature.
This might explain why most of the phenotypes studies present long and narrow noses, which are thought to be better for low-humidity environments, similar to the ones in the Levant and Arabian Peninsula. The Alpine’s a bit distinct but still not very wide. It also affirms highlanders might be actually higher than lowlanders, which explains why some of those phenotypes are tall. That might be due to the lower atmospheric pressure, which also causes astronauts to grow taller in space.At a lesser level of certainty the differences in nose-shape may correspond to differences in atmospheric humidity, but without detailed knowledge of meteorological conditions it is impossible to be certain on this point.
[…] Perhaps the major phenotypic difference is the reduced rate of maturation of lowlanders as evidenced by skeletal development and numbers of teeth erupted. Hence it might be expected that lowlanders would tend to be smaller than highlanders in most physical dimensions and this is confirmed to some extent by the fact that differences in the parameters of regression of the various measurements tend to be less when skeletal age is the independent variable.
Reference 7 demonstrates there are some inconsistencies between populations in south America and Saudi Arabia:
While it observed highlanders were lighter-skinned in both places, it doesn’t seem to hold true universally, as Andids, Tibetids and Ethiopids apparently aren’t lighter than their lowland populations. As Sun radiation’s stronger in higher elevations, one could also expect darker skin to be more adapted to them.When analyzing the data, we observe that in general, women at high altitude are slightly lighter and slightly taller than women from the lowlands, nevertheless, high altitude men are significantly shorter and lighter than low altitude men (Fig. 4). Our findings are similar to those reported in Bolivia by Leatherman et al. in 1984. This study conducted an anthropometric survey among 138 men from rural mountainous areas of Bolivia (3,700 m) and concluded that high altitude men are shorter and lighter than their low altitude counterparts(31). Among Quechuas, a similar native group from Peru, Toselli et al., in 2001 found shorter individuals at high altitude in relationship to their corporal mass(32). In contrast to earlier findings, however, no evidence of these results was detected by Khalid et al., in 1995 when he showed that high altitude residents from Saudi Arabia were significantly heavier and taller than the low altitude control group(33). These differences between two populations (the Andean and the Saudis) could demonstrate differences in terms of adaptation, something that has been described extensively before (6, 19, 20, 34, 35).
The following table from Reference 8 shows some authors’ thoughts on the effects of altitude, climate and other elements on human physique. There was little agreement.
CONCLUSIONS
Some results were quite inconclusive given all studies. One can affirm high altitudes are responsible for increased torax circumferences (which isn’t to say it increases fatness) and probably higher cephalic indices. Noses found across populations in those environments tend to be to the narrower side. How skin color and height are affected was conflicting.
Anthropometric investigations of the analysed populations (as well as others) conjointly with genetic studies may provide more translucent interpretations.
Thoughts?
REFERENCES:
[1] Fernanda Catharino Menezes FrancoI; Telma Martins de Araujo; Carlos Jorge Voge; Cátia Cardoso Abdo Quintão. Brachycephalic, dolichocephalic and mesocephalic: is it appropriate to describe the face using skull patterns?
[2] Lasker, G. W. (1969). Human Biological Adaptability. Science, 166(3912), 1480–1486. doi:10.1126/science.166.3912.1480.
[3] Moore, Lorna G. (2016). Human genetic adaptation to high altitudes: Current status and future prospects. Quaternary International, (), S1040618216305936–. doi:10.1016/j.quaint.2016.09.045.
[4] Monge, C.; Leon-Velarde, F. (1991). Physiological adaptation to high altitude: oxygen transport in mammals and birds. Physiological Reviews, 71(4), 1135–1172. doi:10.1152/physrev.1991.71.4.1135.
[5] Harrison, G. A.; Kuchemann, C. F.; Moore, M. A. S.; Boyce, A. J.; Baju, T.; Mourant, A. E.; Godber, M. J.; Glasgow, B. G.; Kopec, A. C.; Tills, D.; Clegg, E. J. (1969). The Effects of Altitudinal Variation in Ethiopian Populations. Philosophical Transactions of the Royal Society B: Biological Sciences, 256(805), 147–182. doi:10.1098/rstb.1969.0040.
[6] Clegg, E. J.; Pawson, I. G.; Ashton, E. H.; Flinn, R. M. (1972). The Growth of Children at Different Altitudes in Ethiopia. Philosophical Transactions of the Royal Society B: Biological Sciences, 264(864), 403–437. doi:10.1098/rstb.1972.0015.
[7] Anthropometric and Body Composition Differences Among Genotype Controlled Indigenous Adult Kiwcha Natives Living at Low (230 M) and High Altitude (3,800 M) in Ecuador. https://assets.researchsquare.com/fi...f?c=1654258624
[8] BERNICE A. KAPLAN (1954). Environment and Human Plasticity. , 56(5), 780–800. doi:10.1525/aa.1954.56.5.02a00050
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Originally Posted by PaganPoet
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