London: We have larger brains and live longer than our closest relatives, the chimpanzees, but these advantages come at a cost.
A new study has found that only humans have brains that progressively shrink with increasing age.
Age-related shrinkage of large-scale brain structures such as the hippocampus and frontal lobes has only ever been observed in humans.
Now, scientists have confirmed that they do not even occur in our closest relatives, the chimpanzee. They appear to be uniquely human.
US researchers led by Dr Chet Sherwood, from George Washington University in Washington DC, carried out magnetic resonance imaging (MRI) brain scans of 99 young and old chimpanzees aged 10 to 51.
The results were compared with MRI scans of 87 humans over an equivalent age range of 22 to 88.
The scans showed a decrease in the volume of all major brain structures over the course of human life.
In contrast, ageing chimpanzees showed no significant age-related changes to their brains.
“Humans may be uniquely vulnerable to age-related neurodegeneration, pointing to compromises that have been struck in the evolution of an enlarged brain and an extended lifespan,” the Daily Mail quoted Dr Sherwood’s team as writing.
The findings were published in the journal Proceedings of the National Academy of Sciences.