Behavioral pathology in bacteria mismatched with their environment

A lovely article by Witze  in last week’s Nature  inspires thinking about how to get bacteria to behave as unhealthily as lines of humans drawn as if by magnets to burger joints.

Magnetic particles in bacterium.
From Chen, et al, 2012

The Nature article notes that the radioactive isotope iron 60 does not form on earth.  The tiny amounts found in seabed sediments come from supernova explosions.  The Munich physicists Shawn Bishop and Ramon Egli wondered if the event could be dated.  Sure enough, iron 60 was found only in sediments from exactly 2.2 million years ago (Bishop, S. & Egli, R. Icarus 212, 960–962, 2011, perhaps coming from a supernova in the Scorpius–Centaurus stellar association to be incorporated into magnetotactic bacteria in the sea.  By happenstance, these events occurred at the very time when modern humans were first emerging.   This is interdisciplinary science at its best!

But, doesn’t it make you wonder why some bacteria have special machinery to synthesize magnetic particles? One clue is that they tend to be anaerobic bacteria that live near a boundary with oxygenated water.   Their magnetic crystals align them with the earth’s magnetic field, so they can swim only along the earth’s magnetic lines.  How could that help, given that the earth’s magnetic fields go north and south?  In the northern hemisphere, the magnetic lines dip downwards into the earth, so by turning their flagella counter clockwise and swimming straight towards the pole, they can reliably dive to deeper depths where there is less oxygen.   In the southern hemisphere, the magnetic lines go up instead of down...so to get to the depths and away from oxygen, bacteria that evolved there swim away from the pole. 

More info at Chen, L., Bazylinski, D. A. & Lower, B. H. (2012) Bacteria That Synthesize Nano-sized Compasses to Navigate Using Earth's Geomagnetic Field. Nature Education Knowledge 3(10):30

Lucy's Lesson on The Fundamental Attribution Error

The fundamental attribution error is pervasive. On yesterday's walk, our black standard poodle, Lucy, simply would not heel. I held a dog biscuit in my left hand, usually a surefire cure for bad behavior, but she insisted on roaming to the right, where my wife was walking. I quickly came up with an explanation, "She's always liked you better." Margaret agreed, "Yes, I spend more time with her and I feed her."

I ran out of dog biscuits, so I asked Margaret if she had any. She gave me her bag of treats, tiny bits of liver biscotti, Lucy's favorite. Everything changed. Now Lucy paid no attention whatsoever to Margaret. She heeled perfectly, her eyes riveted to my left hand, waiting, salivating. Lucy's behavior had nothing to do with her love for Margaret, and everything to do with who held the liver biscotti.

Why do we so readily attribute behavior to enduring traits and neglect the power of the situation? I suspect it's because over the past few hundred thousand years, information about what individuals are like has been enormously useful. People, and dogs, have personalities that stay remarkably consistent for decades. Attending closely to what people are like, coming up with theories about their traits, and gossiping about them has been important. Using theories about persons to explain behavior comes naturally, so naturally that we routinely underestimate the power of the situation.

George Williams, 1926-2010

George C. Williams, 1926-2010

George C. Williams died on September 8, 2010 at the age of 84. One of the most important biologists of the 20^th century, his influence came not from big grants, flashy talks, magazine articles, or scores of graduate students. Instead, he pursued methodical thinking about important questions and distilled his conclusions into crystal clear prose. His approach was consistent. He would be struck by some apparent contradiction between fact and evolutionary theory, and work on it until a resolution emerged. Senescence, sex, menopause, and vulnerability to disease, all are hard to explain in evolutionary terms. In each case, he thought and thought, eventually coming up with a major contribution.

My tribute to his influence on the field and my life is in: Nesse, RM: Maladaptation and natural selection. Quarterly Review of Biology 80(1):62-70, 2005. In that article, I noted that he had a cognitive anomaly, I called it "Williams vision," that made it very difficult for him to blind himself to evidence that contradicted his ideas.

Short answers to big questions

John Brockman's Edge World Question Center has been an inspiration.
Below are some of the questions posed in recent years, and my answers.

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1998
What is the most important invention in the past two thousand years?...and why?
Text is special

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1999
What is today's most unreported story?
Is the Market on Prozac? (This was reported in hundreds of news sources just before the crash. The idea has been reinvented by others several times early in 2009. No one has tested the idea yet.)

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2001
What questions have disappeared?
Why is life so full of suffering- I ?

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2002
What is your question...and why?
Why is life so full of suffering- II

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2003
"What are the pressing scientific issues for the nation and the world, and what
is your advice on how I can begin to deal with them?" GW Bush
Finding out how relationships work

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2004
What's your law?
Nesse's Laws for deciding when it is safe to use drugs

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2005
What Do You Believe Is True Even Though You Cannot Prove It?
People gain a selective advantage from believing in things they can't prove

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2006
What is your dangerous idea?
Unspeakable Ideas

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2007
What are you optimistic about?
We will find new ways to block pessimism

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2008
What have you changed your mind about? Why?
Truth does not reside with smart university experts

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2009
What will change everything?
Recognizing that the body is not a machine

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Nature-Nurture, No Nonsense

As often noted, it is senseless to ask whether a trait is caused more by genes or more by environment. Like the length and width of a rectangle, both genes and environment are essential to the development of any trait. However, if the task is to explain variations in a trait, then the same analogy holds--the area of the rectangle changes only if its width or length (or both) changes. Variations among individuals can result only from differences in genes, differences in environments, and the interactions between them.

Why Constructive Engagement is Rare

Constructive engagement is rare, not just in political seasons, not just in our society, but always and everywhere, for good evolutionary reasons. Understanding those reasons gives us a fighting chance to avoid useless fighting and begin constructive engagement.

By constructive engagement, I mean people trying as hard as they can to express their own ideas clearly, to understand other people’s beliefs and their reasons for those beliefs, to understand the exact differences between the beliefs, and to specify and search out information that would resolve any differences. Far more common are two patterns of unconstructive engagement, which can be caricatured as the mutual admiration society and the war of the clans.

On reading Schopenhauer in Berlin

I have spent much of this year trying to understand why natural selection shaped a capacity for low mood. The evolutionary perspective is new, but the core idea is ancient—despair comes from unsatisfied desires. Schopenhauer (1788-1860) was preoccupied with the connection between desires and despair. Like many aging philosophers, he wrote a late essay giving advice on how to live: The Wisdom of Life (1851, translation by T. Bailey Saunders, Echo Library, 2006). The essay has much to say about the goals humans pursue. 

Evolutionary pharmacogenomics

Articles about evolution and medicine are spread so widely over the scientific landscape that no matter how much you read, you know you are missing things. The pleasure on finding them is, however, like finding a diamond in the sand. Such is the case with evolutionary pharmacogenomics (a phrase that turns up not one hit on Goggle!).

No genes for schizophrenia--What gives?

Ten years ago, most of us paying attention were exhilarated about the prospects for psychiatric genetics. Heritability is high for many disorders--80% of the variation in vulnerability to bipolar disorder and schizophrenia can be attributed to genetic variations. We thought we would soon find the responsible abnormal genes, and this would quickly reveal the biochemical defects that cause these disorders, and this would quickly lead to ways to cure, or at least dramatically alleviate, these terrible scourges.

Candidate genes were examined by the best researchers using larger and larger samples and sophisticated statistics; a few were identified as prime suspects. Most results could not be replicated, but a few loci were very suspicious based on multiple studies.

Now, in an article by in this month's American Journal of Psychiatry, Saunderset al. report on 433 SNPs associated with 14 candidate genes that were prime suspects for schizophrenia in about 1900 cases and 2000 controls of European ancestry. The results? Not one of the genes was significantly associated with schizophrenia prevalence.

Balancing selection--no answer for schizophrenia

Many have asked why genes that cause such a serious disease persist, and a number of evolutionary hypotheses have been inspired by the kind of balancing selection that explains the persistence of genes that cause sickle cell disease. A new article by Adriaens debunks such hypotheses. He offers a nice review of studies about the reproductive success of people with schizophrenia, although I think he discounts excessively the evolutionary significance of a 50% fitness decrease for male schizophrenics.

It seems to me that he is absolutely right, however,