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How long have pandas been eating bamboo? At least 6 million years, study suggests
- Fossils unearthed in southwestern China show panda ancestors had ‘false thumb’ for grabbing food
- Researchers say the bears’ sixth digit never fully developed because it would have impeded walking ability
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Giant pandas might have started their bamboo diet 6 million years ago, according to a new study examining a thumblike digit that panda ancestors used to grip their food.
An international team of scientists based their analysis on a fossil of an Ailurarctos – an extinct ancestor of the modern panda – unearthed from Shuitangba in the southwestern Chinese province of Yunnan. The site dates back to the late Miocene period, or about 6 to 7 million years ago.
The fossil is the earliest example of an enlarged radial sesamoid – a bone that functions as an opposable thumb – in the panda’s lineage, according to the article published in the peer-reviewed journal Scientific Reports on Thursday.
Scientists have known about the animal’s “false thumb”, which allows pandas to survive on an all-bamboo diet, for more than a century. But previous research only found evidence of the sixth digit dating from 100,000 to 150,000 years ago.
The researchers found that the bone has stayed the same size since the late Miocene period and never evolved into a fully developed thumb.
The scientists proposed that the lack of elongation was the result of a compromise between the need to grab bamboo and the false thumb’s weight-bearing function.
When pandas walk, the bottoms of their paws touch the ground. If the sixth digit had grown longer, it would have compromised the bone’s dual functions – grasping and weight-bearing – and interfered with walking long distances.
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Panda urinates on tree while doing an impressive handstand
Panda urinates on tree while doing an impressive handstand
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