When Stephen Hawking, the Cambridge University astrophysicist and cosmologist, passed away earlier this month, tributes poured in from around the world.
His story was a remarkable one. Diagnosed at the age of 21 with a rare motor neuron disease that is normally fatal after just a few years, Hawking lived for another 55 years, despite having to battle an illness that devastated his body and eventually removed his ability to speak.
Despite seemingly insurmountable physical disabilities, Hawking eventually gained worldwide acclaim for his theories of black holes, relativity, and The Big Bang. He was also known for his unique gift for articulating the complexities of science and the universe in language that reached ordinary people.
In a lecture he delivered in 1996 called "Life in the Universe," Hawking talked through his theories of the origins of life in the universe, from the Big Bang to the creation of DNA and RNA. After summarizing the three and a half billion-year process that led to the emergence of humans, Hawking then makes a remarkable observation about the impact of written language on human evolution:
...With the human race, evolution reached a critical stage, comparable in importance with the development of DNA. This was the development of language, and particularly written language. It meant that information can be passed on, from generation to generation, other than genetically, through DNA.
There has been no detectable change in human DNA, brought about by biological evolution, in the ten thousand years of recorded history. But the amount of knowledge handed on from generation to generation has grown enormously...The total amount of useful information in our genes, is probably something like a hundred million bits...By contrast, a paper back novel might contain two million bits of information...So the amount of information handed down in books, is a hundred thousand times as much as in DNA.
Beyond the sheer volume of information that can be encoded in books as compared to DNA, Hawking then describes one other significant difference between written language and DNA in the process of evolution:
It has taken us several million years to evolve from the apes. During that time, the useful information in our DNA, has probably changed by only a few million bits. So the rate of biological evolution in humans, is about a bit a year. By contrast, there are about 50,000 new books published in the English language each year, containing of the order of a hundred billion bits of information.
So what does all this mean for human evolution? Hawking explains:
We are more than just our genes. We may be no stronger, or inherently more intelligent, than our cave man ancestors. But what distinguishes us from them, is the knowledge that we have accumulated over the last ten thousand years, and particularly, over the last three hundred. I think it is legitimate to take a broader view, and include externally transmitted information, as well as DNA, in the evolution of the human race.