Today, when we look at a brain, we see an intricate network of billions of neurons in constant, crackling communication, a chemical labyrinth that senses the world outside and within, produces love and sorrow, keeps our hearts beating and lungs breathing, composes our thoughts, and constructs our consciousness.

Carl Zimmer

Categorized in : Heart Communication Breathing

About 1.2% of the human genome is made up of genes, things that encode for proteins, the stuff that we consider us. There is about 8.3% that's a virus. In other words we're probably about seven times more virus than we are human genes, which is kind of a weird way to thinking about yourself.

Carl Zimmer

thinking-about-you stuff way

Parasites are not only incredibly diverse; they are also incredibly successful. There are parasitic stretches of DNA in your own genes, some of which are called retrotransposons. Many of the parasitic stretches were originally viruses that entered our DNA. Most of them don't do us any harm. They just copy and insert themselves in other parts of our DNA, basically replicating themselves. Sometimes they hop into other species and replicate themselves in a new host. According to one estimate, roughly one-third to one-half of all human DNA is basically parasitic.

Carl Zimmer

dna half successful

There is some research that suggests that viruses like the flu are really actually kind of at the razor's edge when it comes to mutation. They're mutating so fast that if they mutated much faster they would actually develop a lot of harmful mutations that could slow them down and cripple them and eventually literally drive them extinct.

Carl Zimmer

mutation viruses research

The only kinds of ways we have to deal with viruses are old school, so vaccines for example are very effective, but the first vaccines were invented in the 1700's, so we're talking about technology that is over 200 years-old.

Carl Zimmer

old-school vaccines technology

If you're looking for your own idea of your own identity you know the human genome may not be the best place to look for it. You're just looking at a bunch of viruses.

Carl Zimmer

viruses identity ideas

One of the big challenges now is to figure out just how many viruses there really are in the human genome. So far the estimate is 8.3% of our genome is virus, but it actually could be a lot higher.

Carl Zimmer

viruses figures challenges

At long last, we may be returning to the original two-sided sense of the word virus, which originally signified either a life-giving substance or a deadly venom. Viruses are indeed exquisitely deadly, but they have provided the world with some of its most important innovations. Creation and destruction join together once more.

Carl Zimmer

origin-of-life two long

In 1494, King Charles VIII of France invaded Italy. Within months, his army collapsed and fled. It was routed not by the Italian army but by a microbe. A mysterious new disease spread through sex killed many of Charles’s soldiers and left survivors weak and disfigured. French soldiers spread the disease across much of Europe, and then it moved into Africa and Asia. Many called it the French disease. The French called it the Italian disease. Arabs called it the Christian disease. Today, it is called syphilis.

Carl Zimmer

kings christian sex

The hand is where the mind meets the world.

Carl Zimmer

mind science hands

Evolution has led to some populations of people being able to digest milk without much trouble when they're adults as well.

Carl Zimmer

population adults people

It used to be thought that only a certain kind of virus could get into our genome and it's called a retrovirus and that's a virus that might be HIV for example.

Carl Zimmer

hiv viruses example

I wouldn't be a very good hunter without these glasses. I'm not a very good hunter with these glasses, but I'd be even worse without them, so that would put a crimp in how many kids I could have, so all of these medical advances have at least in some parts of the world blunted natural selection.

Carl Zimmer

hunters glasses kids

Viruses don't just make us sick. They can actually sometimes end up in our genomes.

Carl Zimmer

viruses sick sometimes

We really depend on viruses for our complete survival.

Carl Zimmer

viruses depends survival

Medicine allows people to live who would otherwise die, so antibiotics will let people survive infections that they might be otherwise very vulnerable to and even little things might make a big difference, so I wear eyeglasses because my eyes aren't particularly strong, before there were eyeglasses someone at my age would probably not be good for much.

Carl Zimmer

medicine eye strong

Everybody can digest milk when they're little.

Carl Zimmer

milk littles

When you get sick with the flu you get infected with flu viruses and they make lots of new flu viruses, but those new viruses are not exact copies of the old ones. They have mutations in them. A lot of those mutations are harmful.

Carl Zimmer

mutation viruses sick

The reason that viruses are so hard to fight, the reason for example we need a flu virus every year is that they evolve very fast.

Carl Zimmer

fighting example years

We may be sucking in all sorts of viruses and we really don't know the full range of them. Maybe we've got flu virus inside of us. That's a possibility. Maybe we're part flu.

Carl Zimmer

viruses flu may

We have Borna virus genes. We're part Borna virus, which is weird, but apparently our cells and our genomes in a weird way might actually be grabbing these viruses, grabbing genetic material from the viruses that are infecting it and pulling them into their own genome.

Carl Zimmer

viruses cells might