Gene variant may be responsible for human learning

Humans have a unique variant of a gene linked with learning and memory. This may help explain how we rapidly cut loose in intellect and language from our closest relatives.

The gene, KLK8, makes the protein neuropsin II, which in mice is vital for memory and learning. Bing Su and his colleagues at the Kunming Institute of Zoology in China had earlier demonstrated that neuropsin II is made by humans but not by lesser apes and old-world monkeys. Now they have shown that orang-utans and chimpanzees don't make it either (Human Mutation, DOI: 10.1002/humu.20547).

KLK8 is the first human-specific discovery of a "splice variant" - a gene that is roughly the same in different species but is "cut and pasted" differently when it is expressed, resulting in proteins with new functions. Su's team have shown that KLK8 arose through a single mutation in DNA when a thymine nucleotide was exchanged for an adenine.

This small change had a huge impact, causing 45 additional amino acids to be loaded into the protein that the gene expresses. The changes make humans' neuropsin...