Point: Counterpoint: High altitude is for the birds!

Birds arose from their dinosaur ancestors and took to the skies over 100 million years ago. Since that time, birds have become abundant at high elevation, they have acquired the ability to migrate over the world’s highest mountains, and they have even found reason to soar over 11,000 m above sea level (18). These anecdotal observations alone may convince some of an avian supremacy at elevation. Here, however, we provide physiological evidence for the superior ability of birds to adapt and thrive at elevation compared with mammals. Two lines of evidence are provided to support this opinion, showing that birds have 1) a greater tolerance of the hypoxia at high altitudes and 2) a greater capacity for exercise at high altitudes.