Stephen Hawking’s moving argument that human evolution has gone far beyond biology

Physicist and cosmologist Stephen Hawking died today (March 14) at 76. Hawking’s major achievements included developing the first theory of cosmology unifying general relativity and quantum mechanics, and some of the most essential research on black holes ever accomplished—but he was better known in popular culture for his ability to convey impossibly complex cosmological concepts to the masses.

In a 1996 lecture called “Life in the Universe,” Hawking delivers on the title of the talk, giving a brief history of just that. In one particularly compelling passage, he makes a case that our view of human evolution as simply biological is too narrow.

Biological evolution has been and continues to be slow. But as Hawking argues, humans have been able to evolve much more quickly, beyond the physical limitations of their biology, because of written language:

[Writing] 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.

By Hawking’s rough calculation, he measures the amount of useful information in human genes as 100 million bits, which means a novel might have 2 million bits of information. “So a human is equivalent to 50 Mills & Boon romances. A major national library can contain about 5 million books, or about 10 trillion bits,” he said, concluding, “So the amount of information handed down in books, is a hundred thousand times as much as in DNA.”

Further, unlike DNA, books—and now, digital information—can be changed and updated quickly. Said Hawking:

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 100 billion bits of information. Of course, the great majority of this information is garbage, and no use to any form of life. But, even so, the rate at which useful information can be added is millions, if not billions, higher than with DNA.

The kind of evolution that gave rise to humans, said Hawking, has now given away to “an external transmission phrase,” which he defines thus:

In this, the internal record of information, handed down to succeeding generations in DNA, has not changed significantly. But the external record, in books, and other long lasting forms of storage, has grown enormously. Some people would use the term, evolution, only for the internally transmitted genetic material, and would object to it being applied to information handed down externally. But I think that is too narrow a view. We are more than just our genes.

The argument is particularly poignant given that Hawking couldn’t have lived the life he did without that very speed of information transmission. Despite the motor neurone disease that doctors initially said would give him a two-year life expectancy, Hawking lived a full, mobile life. While he was confined to a wheelchair and computerized-voice communication from age 21 until he died at 76, through his books and lectures Hawking captured the imaginations of curious people around the world. His life was proof that the information we receive into our brains, process, and then broadcast out, makes us more than the sum of our genes.

Read next: Stephen Hawking, one of the world’s greatest minds, was an inspiration for atheists

home our picks popular latest obsessions search