Thanks very much for the additional background material. I agree wholeheartedly that The Atlantic article fails utterly to capture the essence of her thesis, b

Thanks very much for the additional background material. I agree wholeheartedly that The Atlantic article fails utterly to capture the essence of her thesis, but I also think she's seeing a co-evolutionary causation where it's merely a strong correlation. Those same environments with higher density of vipers also play host to the widest variety of plant life. In many fruits and leaves, the differences between positive identification and edible vs. inedible have more to do with color and texture than scent. Additionally, in a canopy environment fraught with the hazards and complexity of 3 dimensional navigation, and lack of a constant "ground scent-base", food source identification via sight would seem to be a more caloric-efficient approach. That's the strategy employed by most tropical birds and they have an even greater freedom of movement amongst the branches. It's also worth pointing out that exclusively ground-dwelling tropical birds such as Kiwi, Kakapo, Cassowary, and the Ocellated turkey all forage by scent and all have undergone reverse evolutionary trade-offs in visual acuity.