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I've now had a chance to take a closer look at Caleb Everett's recent PLoS ONE article on the correlation between ejective consonants and altitude, and I think the ejectivedistribution is explainable on purely classical grounds, that is,common inheritance and areal diffusion. That is, it is NOT necessary to resort toan explanation in terms of altitude. The classical explanation is preferablesince the mechanisms of inheritance and diffusion are observable inplenty, whereas noone has yet observed the hypothesized mechanism wherebythe speakers start using more ejectives in response to moving to higheraltitudes.Here's why: The UPSID database via WALS contains 527 languages codedfor ejectiveness, with 87 with ejectives (having WALS value 2, 5, 6,or 8) and 440 without ejectives. The 87 languages with ejectivesbelong to 54 families (ejectives_families). The 54 families are not necessarilyindependent because some of them are geographically contingent. Igrouped the 87 languages into areas such that the languages within anarea could plausibly be connected by adjacency or via a path ofadjacent languages also known to have ejectives. There is some amountof leeway here but if there really is a causal link between altitudeand ejectives it should survive nevertheless. The 87 languages divideinto 19 areal groups (listed in ejectives_areal).Now if we pick languages such that no two of them belong to the same arealgroup or the same family, then there are arguably genealogically and areallyindependent. Since there are 19 areal groups (and 54 families) one cannotpick more than 19 independent languages, but it turns out that it ispossible to pick 19 languages which are indeed both areally andgenealogically independent. I picked a random such set, shown below,together with their altitude (as per the Shuttle Radar Topography Map attheir centre coordinate):Hadza [hts] 1049Yapese [yap] 0Hamtai [hmt] 1175Hausa [hau] 594Yuchi [yuc] 263Trumai [tpy] 312Southern Nambikuara [nab] 640Zuni [zun] 2009Itelmen [itl] 35Itonama [ito] 156Michoacan Mazahua [mmc] 3399Ona [ona] 117Tsimshian [tsi] 177Soqotri [sqt] 364Korean [kor] 158Shua [shg] 1057Wichi Lhamtes Guisnay [mzh] 208Abkhaz [abk] 0Central Aymara [ayr] 4298The mean elevation of these languages is 842.6 m and the median elevation 312 m. Isthis higher than expected for "random" languages? I took 1000 samples of19 languages from different families and checked their mean and medianaltitude. 56 of the 1000 random samples had a higher mean altitude than842.6 m and 296 of the 1000 random samples had a higher median than 312 m,giving p-values of 0.056 and 0.296 respectively. In other words, NOTSIGNIFICANT by conventional significance limits.So why does Everett claim to have controlled for areality and genealogyand still reports a significant correlation (in his Table 3 and associatedtext)? (The remainder of the significance results reported in his papertreats languages as independent, not controlling for areality/genealogy.)1. Everett doesn't measure the direct altitude of a language but theproximity to a "major region" of high elevation. What counts as amajor region is never objectively defined, and clearly there is somecheating going on when using the distinction "major/non-major" becausethe proposed theory (which has to do with air pressure etc) isoblivious as to whether the speakers are in a "major" or "minor"region of altitude. The difference is significant because it turns overmany datapoints, so that, e.g., the New Guinea Highlands is not countedas a high-altitude region!2. The division of the non-ejective languages into clusters "by assumingclusters contain ten languages each, in keeping with the approximate sizeof the clusters of languages with ejectives" is underspecified. This isa highly non-trivial step (there are *many* ways to divide non-ejectivelanguages into clusters containing ten each) and the fact that it is notexplained means that the experiment is not reproducible. If I was thereviewer I would never have let that through.3. There is arbitrariness with measures such as 200 km and 500 km from amajor region, and some comments in the paper suggest that data dredginghas taken place. That is, comments of the kind "only marginally furtheraway from high elevation at 380 km", might reflect that different thresholdshave been tried and 200/500 km are included in the paper because theyhappened to give the best results. If so, all p-values should be correctedfor multiple testing. Because of the irreproducibility (as of point 2 above)I cannot re-do the test with other thresholds than 200/500 km to check.One should perhaps also not forget that the UPSID database in the firstplace is not a random sample of the languages (or families or regions) ofthe world and therefore it is not legitimate to draw statisticalconclusions based on it. It would be better to re-check it on Steven Moran's orMark Donohue's databases.