Question

How have the physical characteristics of the Andes affected the native population of the Andean countries

Answer 1

We can look at this from two perspectives, the affect on the physical features of the native people in this region, and the ethnic composition and foreign influence on it.
1. The physical features of the people are heavily affected by the environment, the skin is very resilient to sunlight due to the higher UV received in the high altitudes, the nose is bigger and wider for better and easier intake of oxygen which is more sparse in here, people are shorter and stockier for better bearing of the low temperatures and lower nutrition, the lungs capacity is higher etc.
2. The ethnic composition is relatively homogeneous, the mixing with the newcomers had been small, so these people had kept their native ethnic core due to the harsh region which has been evaded by the newcomers.

Answer 2

How have the physical characteristics of the Andes affected the native population of the Andean countries?

         The Andean Indians have larger hearts and lungs than other inhabitants.

l really thought this was an absurd answer but apparently 'GeoPanther' said it in #1

"The physical features of the people are heavily affected by the environment, the skin is very resilient to sunlight due to the higher UV received in the high altitudes, the nose is bigger and wider for better and easier intake of oxygen which is more sparse in here, people are shorter and stockier for better bearing of the low temperatures and lower nutrition, the lungs capacity is higher etc."