…is this passage by Anthony Lane in the New Yorker:
In the seventeenth chapter of “The Voyage of the Beagle,” Charles Darwin turned to the mating habits of the giant Galapagos tortoise. “When the male and female are together, the male utters a hoarse roar or bellowing, which, it is said, can be heard at the distance of more than 100 yards,” he wrote. This is also the most accurate description that we possess of the duet performed by Mick Jagger and Christina Aguilera in “Shine a Light,” Martin Scorsese’s documentary on the Rolling Stones.
Anthony Lane, review, New Yorker April 14 2008.