High in the Peruvian Andes, above 3,500 metres where little else can thrive, alpacas have been producing some of the world's finest fibre for thousands of years. Their wool — technically called fibre, since alpacas aren't sheep — has a reputation for exceptional softness, warmth, and durability. But does that reputation extend to sustainability? The short answer is yes, with some caveats worth understanding. Alpaca wool scores 87 out of 100 on the Fashion Sustainability Index