KUNMING -- Chinese researchers have decoded the molecular mechanism behind birds' ability to tolerate highly acidic foods, a trait that has long puzzled scientists.

Published in the journal Science on Friday, the study reveals that a key mutation in the sour taste receptor OTOP1 gene enables songbirds to consume acidic fruits without aversion.

Lai Ren, a researcher and the corresponding author of the paper at the Kunming Institute of Zoology, Chinese Academy of Sciences, said his team found that a single amino acid change in OTOP1 enhances sour tolerance in songbirds, likely aiding their dietary expansion and species diversification.

The team also discovered a potential co-evolutionary link between birds' sour tolerance and sweet perception, Lai said, adding that this synergy allows them to not only withstand fruit acids but also precisely detect sugars, enhancing their ability to exploit fruit resources efficiently.

"The study is the first to systematically uncover the molecular basis of avian sour taste perception and its evolutionary role, proposing the 'songbird sour-sweet co-evolution' hypothesis, offering new theoretical insights into how complex sensory systems adapt synergistically to environmental challenges," he said.