What if the Andean Indians domesticated the Capybara, while it live mostly in East of Andens, it seem to live some rather close to it, so interaction shouldn't be hard. Domestication is possible, it has been done later, and it seem wild Capybara is easy to tame, and quite peaceful from natures hand. Domestication also result in bigger litters, normal is 4 twice a year in good condintion. They take 2 years to mature, they live mostly of aquaplants and grass. Likely with a few centuries of domestication they can become primary grass eaters.