A reader brought up some interesting points and uncovered some details about Oxygen binding that I wanted to update. You can find the transcript of our discussion in the ‘Getting Oxygen Where It’s Needed’ post below.

What I wasn’t able to post there was a graph of an Oxygen dissociation curve comparing caucasians with Sherpas living at high altitude (+4000m) and those living at sea-level. Surprisingly, the advantage Sherpas have in binding Oxygen at low partial pressure is completely lost at sea level. (see below)

Oxygen dissociation curve of the blood of (A) Sherpa living at high altitude, (B) Caucasians, (C) Sherpas living at low altitudes.

Presumably,  caucasian blood came from those living at sea level. It would have been great to have data on caucasians (or anyone, else for that matter) living at both high and low altitudes.

For those unfamiliar with data presented in this way, the horizontal axis starts at very low Oxygen concentration on the left and increases to the right. The vertical axis shows the amount of the subjects’ blood binding oxygen at each particular concentration. If the curve rises quickly on the left side, it means that the blood is picking up Oxygen even when it is present at relatively low concentrations in the air.

Data from:

Sherpas living permanently at high altitutde: a new pattern of adaptation.