Mount Everest climbs depend on Sherpa guides — the Nepali ethnic group renowned for years for leading teams of climbers up the world’s highest mountain peak. But a deadly avalanche last week has some Sherpas calling for better conditions — or at least greater rewards.Mount Everest climbs depend on Sherpa guides — the Nepali ethnic group renowned for years for leading teams of climbers up the world’s highest mountain peak. But a deadly avalanche last week has some Sherpas calling for better conditions — or at least greater rewards.