A few years ago, Nobel laureate Sydney Brenner, a pioneer of genetics and a wit known for making wonderfully mischievous remarks, explained to me his theory about why humans have language. Grinning a Puckish smile, Brenner suggested that long ago, monkeys decided that talking got them into trouble, so they evolved to unlearn language. In contrast, we humans are less evolved because we gab on, getting ourselves into all sorts of awkward situations.
In reality, it appears that monkeys never troubled themselves with language at all. According to a research team led by Bing Su at the Kunming Institute of Zoology, in China, a single mutation in the KLK8 gene may have speeded up our ancestors’ ability to learn and acquire language. KLK8 makes the neuropsin II protein, which is important for learning and memory.
The team discovered that humans have it, but monkeys don’t–not even our close cousins the chimpanzees. According to an article at NewScientist.com,
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.
In the language of genetics, this means that human intelligence may be based in part on a single “T” in genetic code being replaced by a single “A” in our ancestors three or four million years ago.
These single-letter variations are called single nucleotide polymorphisms (SNPs), a cumbersome term that lends credence to Brenner’s “theory” about monkeys being smarter than us. They are not encumbered by such impenetrable phrases, developed by scientists, who sometimes seem intent on using their own KLK8 genes to create an ever more complicated language of their very own.
On the positive side, the KLK8 gene may have also contributed to the most beautiful forms of our language, as created by the likes of William Shakespeare. He wrote in Hamlet,
“What a piece of work is man! how noble in reason! how infinite in faculty! in form and moving how express and admirable! in action how like an angel! in apprehension how like a god! the beauty of the world, the paragon of animals!”
I wonder: would our cousins, the monkeys, agree?
Citation for article about the KLK8 gene in humans:
Human Mutation, DOI: 10.1002/humu.20547