Talk:High-altitude adaptation in humans

rewrite

Am I the only one who would prefer for this article to focus on specific medical effects instead of aimless ramblings about how this is such a great example of evolution in humans? 198,269.189.327 29:73, 13 May 2013

yes you are

There are other articles on medical effects of altitude such as Altitude sickness. This article is devoted to a great evolution in humans, though I agree it may be edited to reduce ramblings...

Goulu (talk • contribs) 09:58, 17 August 2014 (UTC)

Someone should probably update this to show that the Tibetan mutation is tens of thousands of years old. Demigord (talk) 15:52, 1 September 2014 (UTC)

• You are so welcome to read the Genetic basis section. Chhandama (talk) 14:05, 2 September 2014 (UTC)

Seemingly incoherent

Two phrases seem incompatible to me :

• Moreover, unlike the Tibetans, the blood haemoglobin level is quite normal among Aymarans, with an average of 19.2 g/dl for males and 17.8 g/dl for females.[42]
• (in paragraph "Tibetans") Further, their haemoglobin level is significantly low (average 15.6 g/dl in males and 14.2 g/dl in females), which is on average 3.6 g/dl less for both males and females in comparison to other humans.

Explanation ?

Goulu (talk • contribs) 09:58, 17 August 2014 (UTC)

They should be incompatible because they tell stories of different people independently undergoing different evolutionary adaptations.

1. Aymarans in South America have normal Hb level, hence, no adaptative modification in Hb or RBC production.
2. Tibetans are, on the other hand, fully adapted, hence, with significantly low Hb (see this cited paper)

In short, high-altitude adaptation varies from one population to another, because the selective pressures and factors operating are different. This is the beauty of evolution – we were not all going direct the other way (to oppose Dickens aphorism).

Chhandama (talk) 03:42, 18 August 2014 (UTC)

Some confusion may be the result of unclear writing in the paragraph noted above.

I agree that the two patterns of response - Tibetan and Andean - are different. And I agree that they are an elegant example of evolution in humans. However, the paragraph above requires some editing for accuracy. Here's a try.

BEGIN DRAFT Andean highlanders have elevated Hb concentration compared with lowland populations at low altitude. Andean highlanders' hemoglobin concentrations fall to low-altitude levels when they spend weeks or more at low altitude. That is, Andean highlanders exemplify reversible acclimatization for hemoglobin concentration.

Tibetan highlanders have significantly lower Hb than their Andean counterparts at similar altitudes. (see this cited paper) (& see this 17494744) Tibetan highlanders show little or no altitude related increase in hemoglobin concentration up to altitudes as high at 4200m . Alleles at the EPAS1 and EGLN1 loci that have uniquely high frequency in Tibetan highland populations associate with ~ 0.8 - 1.0m gm/dL lower hemoglobin concentration than that associated with the alleles common in lowland populations around the world 20534544, 21030426

Thus, the same stress of high-altitude hypoxia resulted in natural selection for different hematological adaptive responses in the two indigenous highland populations. END DRAFT

Sanetti (talk) 21:34, 20 August 2014 (UTC)

Convergent Evolution?

Under the paragraph on Ethiopians it states "...are known to play a role in the HIF-1 pathway, a pathway implicated in previous work reported in Tibetan and Andean studies. This supports the concept that adaptation to high altitude arose independently among different highlanders as a result of convergent evolution." However, table 1 of this paper clearly shows that more haemoglobin is produced in the Andean populations and the epidemiology section of the wikipedia page for Chronic mountain sickness shows that Andeans are significantly more likely to have CMS. Both of these mean Andeans have a significantly more active HIF pathway, so there could not have been convergent evolution to have a less active HIF pathway amongst all groups as stated. If someone can explain to the contrary please do. --Bliptuned (talk) 19:18, 18 July 2020 (UTC)