Sherpas are genetically better....

Interesting stuff right here.

http://edition.cnn.com/2015/11/11/health/sherpas-superhuman-mountaineers/index.html

it doesn't really explain whether it's a genetic or physiological adaptation though...

SteveMarshall wrote:it doesn't really explain whether it's a genetic or physiological adaptation though...

That poses an interesting question. As I have a limited knowledge of physiology I'm not sure where the line is drawn. Is it genetic if your DNA changes or you have "evolved" over time?

Epigenetics

physiological differences can be the result of either adaptation (training/living at altitude) or genetic changes (DNA changes/inherited traits). or both. (edit: as Kevin mentioned, epigenetics study)

the hard part is figuring out which specific DNA differences relative to non-Sherpa populations might be responsible for the physiological manifestations. if, indeed, it's genetic adaptation.

Scott McMahon wrote:Is it genetic if your DNA changes or you have "evolved" over time?

yes. your DNA doesn't change while you are alive. it is something you are born with.

the question is, are they better because genetic traits among sherpas have been naturally selected over generations for high altitude performance?

or are they better because they spend their life living at a high altiude and thus have adapted to it better than most people?

probably a combination of both. but impossible to tell which.

SteveMarshall wrote: yes. your DNA doesn't change while you are alive. it is something you are born with.

That brings in the question of addiction changing your DNA.

A quick search shows that its still not known, but evidence suggests that it is a genetic adaptation.

As for DNA changing while you are alive, sort of. You have your DNA and that does not change(normally). On top of the DNA you have a control structure called epigenetics. Your epigenetics are like your DNA in that you receive them from your parents, but over time you can slowly modify your epigenetics code.

The Sherpa probably have multiple things that have helped them adapt to the region. From DNA, epigenetics, diet, culture, and just plane old living at altitude from birth.

Living at altitude from birth through your formative years has been proven to have more of an adaptive effect than an adult who moves from sea level to 7000 feet and live there for an extended time. The Sherpa physiology also has an interesting effect on how their bodies have adapted to altitude.

There have been a few papers written on the behavior of the EPAS1 Gene, which regulates the red-blood cell count in the body, and how Sherpas are better able to acclimate. This site explains it really well.

evolution.berkeley.edu/evol…

Also, there is some really neat work showing that the Sherpa genome contains a relatively large Denisovan component, absent from European genomes. One of the genes of Denisovan origin in Sherpas is EPAS1, which is linked to haemaglobin production and regulation. Potentially, this provides a plausible mechanism for a heritable adaptation to higher altitude that is absent in most other lineages (is present in some han chinese). As pointed out above though,there are many epigentic and environmental factors that will be major contributors to high altitude adaptation and you can't draw conclusions like this from genetics alone. Still... super amazing to think that traits that evolved separately in now extinct species of human may still be visible and providing advantage today. Biology just does my head in sometimes...

In case of interest:
nature.com/nature/journal/v…

A) Anyone on the planet who moves to a higher altitude will adjust to living there.
B) When you live at a high altitude anyone who has better genetics for living in that area will do better and likely reproduce more instead of dying younger.

This is more common sense than anything else... Just like people who scuba dives for years can stay down on a single tank of air at 100ft longer than someone who has never done it. But they didn't magically create new DNA they just lost DNA that wasn't good for where they live.

ViperScale wrote:This is more common sense than anything else... Just like people who scuba dives for years can stay down on a single tank of air at 100ft longer than someone who has never done it. But they didn't magically create new DNA they just lost DNA that wasn't good for where they live.

Obviously not common sense.

ViperScale wrote:Just like people who scuba dives for years can stay down on a single tank of air at 100ft longer than someone who has never done it. But they didn't magically create new DNA they just lost DNA that wasn't good for where they live.

Not entirely correct. In this case, the gene(s) in question were obtained by interbreeding between two species of human. As they proved advantageous for Sherpa people living at higher altitude they have been retained in the Sherpa genome. Selection such as this happens over many, many, generations. Not in a single lifespan such as your scuba example. Unfortunately (for some), you are stuck with the genes you were born with. Or, in other words, its not the genes you have but how you use them...

Nicholas Howell wrote: Not entirely correct. In this case, the gene(s) in question were obtained by interbreeding between two species of human. As they proved advantageous for Sherpa people living at higher altitude they have been retained in the Sherpa genome. Selection such as this happens over many, many, generations. Not in a single lifespan such as your scuba example. Unfortunately (for some), you are stuck with the genes you were born with. Or, in other words, its not the genes you have but how you use them...

Scuba was example of part A where you live somewhere you naturally adapt in a single lifetime. The DNA is something that changes over multi generations, the DNA they have isn't magic. Humans all over the planet have the same DNA, just image having thousands of parts with a grade of 0-10. They just happen to have 10s in all the parts that make it better for living up there after years of living there and those with 3 or less dying off etc.

Point is even with their genes if one of them was to be born and move to say the east coast of the US, even with the genes they would not be able to do what those who grow up living at altitude their entire life.

Imagine being born with all the perfect genes to physically give you a great body for climbing but never training to climb. You may be able to still onsite a 5.10a but if you had trained you would be doing 5.14+. But if you are born with crappy genes you may only be able to onsite a 5.6 without trying and with tons of training be at best maybe a 5.12 on a lucky day.

Always annoys me in schools when they try to tell kids they can do anything if they just try... but it isn't true. You are born with certain DNA and if you try you can make yourself better but you can't just do anything.