As known because of the rarefied air, the blood in the mountainous regions is less saturated with oxygen. Because of this, the inhabitants of the lowlands who got there often feel weakness, malaise and other symptoms of altitude sickness, up to a change in consciousness.

Sherpas, a people living in the east of Nepal, in the vicinity of Everest, face these difficulties much less. They are perfectly adapted to the conditions of high mountains, they are hardy and therefore often serve as guides and assistants to climbers climbing Everest. In addition to endurance, Sherpas enjoy several other bonuses to the mountain habit, such as high reproductive success. This means that Sherpa women are more likely to successfully become pregnant and give birth to live children more often than representatives of other nations in the same conditions.

Sherpas are helped to adapt to the highlands, in particular, their blood. Highlanders generally produce more red blood cells (about 1.5 times) than lowland dwellers, which allows them to carry more oxygen, while Sherpas synthesize even more plasma, making their blood less viscous, which means that they can move faster through the vessels and thereby carry oxygen faster, as a result of which the load on the heart decreases.

However, starting from an altitude of 8000 meters (or any other altitude at which the atmospheric pressure is below 35.6 kPa (267 mm Hg), the oxygen level in the air is insufficient to support human life due to prolonged stay at such an altitude a person will need an oxygen balance.

And here we come to the essence of my question: how should the respiratory system of my genetically modified people be arranged so that they have the opportunity for a sufficiently long time without any health risks with a similar lack of oxygen in the air?

  • $\begingroup$ Not worth a full answer, but maybe you just need to have a more efficient lung. Normally you breath air with 21% of oxygen and exhale air with 17% oxygen. Modify your people to have more "dense" lungs to be able to capture more oxygen every single breath. And maybe make the lungs a little bigger $\endgroup$ – Gianluca Jan 20 at 22:30

Add one more muscle to change breathing from a "2-step" to a "4-step" procedure

Your lungs are already able to expand and shrink - if you mess with the timing and add the ability to seal them up as part of a breath, you can use that existing muscle to compress the air and boost that oxygen pressure such that as far as the blood / oxygen exchange is concerned, you're not in the death zone.

So add a "seal" of some form, a muscle which makes the lungs airtight. Either in the back of the throat, or upper lungs.

Your genetically modified creature:

  • Expands their chest muscles, pulling air into the lungs
  • Shuts a muscle within the throat or upper lung, sealing the lungs.
  • Pulls their chest muscles in, compressing the air.
  • Holds their breath for a few seconds, the blood circulates, oxygenating the blood and releasing CO2 into the lungs.
    • If your human wants to "hold its breath" this is where it occurs.
  • Releases the seal, which expels the air.
  • Repeat immediately.

Your lungs hold about 6 litres of air when full, and ~2L of air when empty. This implies your lung muscles can compress air up to a maximum factor of about x3 - at the absolute max. (I do not think you'll need to reinforce the lungs for this load but if you're already opening the genetic engineering can of worms can't hurt to strengthen it while you're in here.)

At 8000m you've got about 35kPa of air. 100kPa of air is about sea level. If you creature is able to multiple it's pressure in the lungs by a factor of 3, they'll be able to function at 8000m as well as a current human can at sea level, but realistically it only needs to increase the pressure enough that's it's no longer in the dead zone - even a 20% increase in pressure will allow your creature to summit Everest at 6500m of altitude in the lungs.

  • $\begingroup$ if the concentrantion in the blood stream is higher than in the lungs, the oxygen will move away from it. That means that as soon as it releases the "compression", the lungs will remove oxygen from the blood. or not? $\endgroup$ – L.Dutch - Reinstate Monica Jan 19 at 12:46
  • $\begingroup$ @L.Dutch-ReinstateMonica I don't know for sure, but that makes sense - leaving the lung seal open would long term drain oxygen from the blood, and the blood passing the lungs during an exhale would be underoxegenated - but I'd assume that'd average out. Us humans can pause our breathing at any stage of the cycle, if this creature has a pause in its cycle natively (at the high pressurised state), It would make sense that any conscious suppression of breathing would best occur at this stage. $\endgroup$ – Ash Jan 19 at 12:52
  • $\begingroup$ The amount of energy you would burn, compressing each lungful of air, will vastly outrank the added oxygen you obtain from that air.. By about 3 magnitudes. Compressing air is an incredibly energy-intensive action. $\endgroup$ – PcMan Jan 19 at 14:38
  • $\begingroup$ Calculator says: compressing one lungful of air (ambient 0.3bar) down to 1 bar, heats the air from 0C to 112.5C, consuming 187.5J of energy in the process. That's some HOT lungs!!! $\endgroup$ – PcMan Jan 19 at 14:45
  • $\begingroup$ "This implies your lung muscles can compress air to a factor of about x3" - no, this it not. It means that the chest/lungs have this volumetric capacity, not that the muscles can perform this kind of compression. I'm not saying this is impossible, just this is a more complex than just adding one extra muscle. $\endgroup$ – Alexander Jan 19 at 17:26

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