How Much DNA Is There on Earth?

What if the Earth was a computer?

Well then it would be able to tell us the Ultimate Question of Life, the Universe, and Everything, as anybody who has ever read Douglas Adams' aptly named Hitchhiker's Trilogy knows!

The Earth would also have a computational power of approximately 1015 yottaNOPS (yotta equaling 1024), which is about 1022 times faster than China's Tianhe-2, the most powerful supercomputer in the world. This, we know, thanks to a fascinating analysis just published to the journal PLoS Biology.

The Earth is brimming with life, and within that life, is information, stored in strands of deoxyribonucleic acid: DNA. This information constitutes instructions that tell life how to grow and function. In a multitude of analyses, scientists have tabulated the biomass present on Earth: the blood, the guts, the bark, the leaves, all biological material that makes up life. Yet, curiously, nobody previously attempted to measure the sheer amount of information present within that life. University of Edinburgh researchers Hanna Landenmark, Duncan Forgan, and Charles Cockell just did.

By using prior estimates of biomass, cellular abundance, and average genome size, they calculated the amount of DNA on Earth from all domains of life: 5.3 × 1031 megabases, a mind-boggling amount.

"This quantity corresponds to approximately 5 × 1010 tonnes of DNA," the researchers say. "[T]his... is equivalent to the volume of approximately 1 billion standard shipping containers... By analogy, it would require 1021 computers with the mean storage capacity of the world’s four most powerful supercomputers to store this information."

Taking the rate of DNA transcription as an analogy for processing speed, they further estimated Earth's computational power: 1015 yottaNOPS.

The researchers' calculations are part of a new, informational approach to understanding life on our planet.

"In this way, the biosphere can be visualised as a large, parallel supercomputer, with the information storage represented by the total amount of DNA and the processing power symbolised by transcription rates. In analogy with the Internet, all organisms on Earth are individual containers of information connected through interactions and biogeochemical cycles in a large, global, bottom-up network," the researchers say.

They draw further analogies.

"For example, mass extinctions can be considered to be similar to physical hard drive damage in a computer."

One pressing question Landenmark and her colleagues did not answer: Does the Earth run on Mac OS X or Windows?

Source: Landenmark HKE, Forgan DH, Cockell CS (2015) An Estimate of the Total DNA in the Biosphere. PLoS Biol 13(6): e1002168. doi:10.1371/ journal.pbio.1002168