I recently came across the statistic that there are only 3 billion bits of information in DNA. This is a rather shockingly small number.
If we factor out the “junk” (viruses, non-coding regions, etc.) that leaves about 300 million bits of information or about 40 mega bytes. This means that you can probably squeeze nearly 1000 people on a single hard disk.
If we wanted to preserve a large variety of humans in data format we could probably concoct a compression algorythm that would be fairly effective since we probably have large sequences of data in common. I’m guessing we could get another factor of 10.
So that means 10,000 people per disk. Let’s be paranoid, however, and suggest that the amount of compression we get is smaller and the amount of “junk” DNA we can really be eliminated is less. Let’s say we can get 1,000 people on a disk.
That’s with current technology. Things you can just walk into the store and buy.
New technologies push this limit back on a regular basis. A recent breakthrough on slashdot suggests that we can store 12-13 peta bytes per cubic centimeter. This means that we could store one billion people in about 3 cubic centimeters.
One gallon is 3785 cubic centimeters, probably enough room to store the human race (every individual living person) plus a large selection of plants and animals. Conceivably an electronic version of Noah’s ark could be very small indeed.