Remember the point in The Matrix where Agent Smith explains that he’s decided that humans are actually viruses (“Human beings are a disease, a cancer of this planet. You’re a plague and we are the cure“). Here’s even more to support his point of view:

When, in 2001, the human genome was sequenced for the first time, we were confronted by several surprises. One was the sheer lack of genes: where we had anticipated perhaps 100,000 there were actually as few as 20,000. A bigger surprise came from analysis of the genetic sequences, which revealed that these genes made up a mere 1.5 per cent of the genome. This is dwarfed by DNA deriving from viruses, which amounts to roughly 9 per cent.

On top of that, huge chunks of the genome are made up of mysterious virus-like entities called retrotransposons, pieces of selfish DNA that appear to serve no function other than to make copies of themselves. These account for no less than 34 per cent of our genome.

All in all, the virus-like components of the human genome amount to almost half of our DNA. This would once have been dismissed as mere “junk DNA”, but we now know that some of it plays a critical role in our biology. As to the origins and function of the rest, we simply do not know.

Remember that little scene in The Matrix where Agent Smith is sharing some of his philosophy with a captured Morpheus?

I’d like to share a revelation that I’ve had during my time here. It came to me when I tried to classify your species and I realized that you’re not actually mammals. Every mammal on this planet instinctively develops a natural equilibrium with the surrounding environment but you humans do not. You move to an area and you multiply and multiply until every natural resource is consumed and the only way you can survive is to spread to another area. There is another organism on this planet that follows the same pattern. Do you know what it is? A virus. Human beings are a disease, a cancer of this planet. You’re a plague and we are the cure.

Well, he was close: we’re apparently part-virus:

People may not be quite the humans they think they are. Or so suggests new research showing that the human genome is part bornavirus.

Bornaviruses, a type of RNA virus that causes disease in horses and sheep, can insert their genetic material into human DNA and first did so at least 40 million years ago, the study shows. The findings, published January 7 in Nature, provide the first evidence that RNA viruses other than retroviruses (such as HIV) can stably integrate genes into host DNA. The new work may help reveal more about the evolution of RNA viruses as well as their mammalian hosts.

“Our whole notion of ourselves as a species is slightly misconceived,” says Robert Gifford, a paleovirologist at the Aaron Diamond AIDS Research Center, affiliated with Rockefeller University in New York City. Human DNA includes genetic contributions from bacteria and other organisms, and humans have even come to rely on some of these genes for basic functions like fighting infections.

In the new study, Japanese researchers found copies of the bornavirus N (for nucleoprotein) gene inserted in at least four separate locations in the human genome. Searches of other mammalian genomes also showed that the gene has hitched rides in a wide variety of species for millions of years.