Genetic disease or infectious disease?

Matt Ridley, writing in the Wall Street Journal, reports on the increased focus on pathogens as a cause of disease:

"The virus implicated in multiple sclerosis is called HERV-Fc1, a bizarre beast called an "endogenous" retrovirus. What this means is that its genes are part of the human genome. For millions of years, they have been integrated into our own DNA and passed on by normal heredity. It was one of the shocks of genomic science to find that the human genome contains more retroviral than "human" genes: some 5% to 8% of the entire genome.

Normally, the genes of endogenous retroviruses remain dormant, but—a bit like a computer virus that springs into action on a trigger—something wakes them up sometimes, and actual viruses are made from them, which then infect other cells in the body. The Danish scientists suggest that this is what happens in multiple sclerosis. Bjørn Nexø of Aarhus University writes that "retroviral infections often develop into running battles between the immune system and virus, with the virus mutating repeatedly to avoid the immune system, and the immune system repeatedly catching up. One can see the episodic nature of multiple sclerosis as such a running battle."

The possibility that you can inherit the genes of a virus blurs the distinction between a genetic and an infectious disease. 

The viruses have embedded themselves in our DNA.  Kind of freaky, right?

On the other hand, when was it ever different?  Mitochondria, the power plant of the cell, has its own DNA.  Before it got swallowed by a cell and played nice, it used to be independent bacteria a long, long, long time ago.

The difference between ancient and modern warfare

A long-time reader and member of the Army sent me an email on PTSD, and I'm including it in full because it's quite thoughtful.

John,

First I would like to say that I am a huge fan of Hunter-Gatherer. I found your blog when I first got into a paleo lifestyle over a year ago, and have always found your perspective on health and social issues to be informative and thought provoking. Recently, however, I was concerned by your post concerning Alexander the Great.

I found your dismissal of the possibility that Alexander was psychologically affected by his wartime experience to be troubling. I am an Infantry officer in the Army, and am currently preparing for my first deployment to Afghanistan. In the past 4+ years of training, both in ROTC and on Active-Duty, there has been a considerable focus on the effects of war and trauma on soldiers' mental function. The Army has spent considerable time preparing its newest leaders to deal with those effects both personally, and to help their soldiers. One of the biggest lessons they have given us is that PTSD can affect anyone, no matter their experience level. Yes, habituation and training can prepare the individual, and in fact the Army uses highly realistic training to inoculate soldiers to horrific wounds (http://www.militarymoulage.com/). However, nothing can prepare an individual for the reality of a combat situation, a fact which causes nervousness in all us unblooded soldiers. Also, previous experience of combat cannot inure someone to future stress. You need only to look at the currently developing story of the recent tragic killings in Afghanistan to see that. The accused Staff Sergeant was on his fourth combat deployment, and had received training as a sniper (traditionally a job that requires dissociation from emotion in combat) Link here. The specific events which can trigger PTSD, or other psychological trauma, are not always foreseeable.

In regards to the warriors of Greece I suggest you look at the Sophocles play Ajax. It has been performed recently around the country as part of a project called The Theater of War (Ajax). This play, written by a former Greek General, in the 5th Century B.C. depicts the psychological breakdown of a legendary Greek of the Trojan War after his friend Achilles dies. The project puts this play on in front of military audiences, and then opens a dialogue about the effects of war on the psyche which include the audience. Even in the era of perennial warfare faced by the Greeks at the time of Sophocles' writing the great warriors seem to have had psychological problems stemming from their combat experience. 

I am motivated to write to you because I believe your blog is an important resource with an audience who listens to your viewpoints. I think it is dangerous, and even irresponsible, to broadcast such a broad dismissal of the possibility that experienced warriors can have PTSD. The stigma of mental health problems, and the unwillingness to seek help, are obstacles the military is working hard to overcome since we have been at war these past eleven years. Anyone can be affected by PTSD, and simply being aware of that fact makes our armed forces better prepared to deal with the fallout of their experiences.

Thank you for your time. I hope that you will consider what I have written. I continue to enjoy your writing, and I believe you are doing a good job of showing new perspectives on important issues of psychology, health, fitness and society.

Respectfully,

Lane Pratt

I agree with Lane on a lot of points, so let me clarify my stance.  I'm not saying that great warriors can't be affected by violence.  I'm not saying that "real men" don't get PTSD.  I was trying to make a specific point to illustrate a general point.

The specific point was that Alexander the Great's change in mood has a far simpler and more coherent explanation than PTSD.  Alexander wanted to keep killing his enemies.  His soldiers mutinied.  Then he got vindictive and irritable.  Sounds like he wanted to keep killing his enemies.

I'm reminded of this quote by Genghis Khan:

“The greatest happiness is to scatter your enemy, to drive him before you, to see his cities reduced to ashes, to see those who love him shrouded in tears, and to gather into your bosom his wives and daughters.”

I see no reason to doubt him.

The broader point I was attempting to convey is that PTSD is probably more common today than it was in the past precisely because we have increasingly deactivated some of the key psychological adaptations that make humans so murderous.

Homo sapiens is a naturally violent species.  Hunter-gatherers kill a lot.  Herder-farmers kill a lot.  Heck, chimpanzees kill a lot.  It would be odd if humans didn't have psychological adaptations to be fully capable of killing.  As I mentioned in my Alexander post, two of those faculties are exposure and dehumanization.  I'm sorry, but playing Call of Duty, watching Transformers, or even undergoing basic training just aren't the same as actually hacking off people's limbs with a sword from a fairly young age -- and being encouraged to revel in it.  Furthermore, it's just not acceptable to dehumanize our enemies as much as was done in the past.

That's moral progress.

At the same time, we've made it psychologically more difficult for soldiers to deal with combat because they aren't as accustomed to violence, know that they're fighting other humans (not vermin), and face unprecedented constraints on their behavior towards the enemy (a tacit acknowledgement of their humanity).

Lane's reply:

"I think that today's society is in many ways preferable to the violent lives of our ancestors. Being more susceptible to PTSD might be one of the costs our society pays for a generally peaceful existence."

I agree.

For (star) dust you are...

The most astounding fact about the universe, as told by Neil DeGrasse Tyson.

Thanks to Bryan for the link.

Syndicate content