The differential biology reader

November 07, 2008

Genome scan for the major dimensions of personality


An association study of 4000 people with an almost equal number of replicates uncovered genes associated with each of the 5 major personality dimensions. Most of the associated genes are linked to various neurological disorders, so they seem to be in the right territory, though it would not surprise me if personality is linked in to a lot of other non-psychologicl traits. The problem of course is that so little of the variance (~1%) is being explained. 

Terracciano et al. Genome-wide association scan for five major dimensions of personality. Mol Psychiatry (2008) pp. 10 doi: 10.1038/mp.2008.113

Comments [0]



October 28, 2008

Predator–prey experimental evolution

If you were not in your field, what else would you like to specialize in? I toyed with doing experimental evolution before I fell in with the primatologists. 

Richard Lenski's lab has been on the forefront of this work.  Their latest paper is on the evolution of predator behavior. I love this picture


The prey patches just look so like what you see in theoretical ecology textbooks.

Hillesland et al. Experimental evolution of a microbial predator's ability to find prey. Proc Biol Sci (2008) doi: 10.1098/rspb.2008.1098

Comments [0]



October 21, 2008

Lived Day Analysis in Japan

So you’re extraverted, conscientious, and neurotic. What difference does this actually make in your daily life?

This is the question posed by Lived Day Analysis, first articulated in Barker and Wright’s (1951) in One Boy’s Life. Patient observers followed little Raymond Birch around and recorded his every move, down to which sock he put on first (Mehl, Gosling, and Pennebaker 2006).

As part of its census, the Japanese Statistics Bureau equips a sample of its citizens with notebooks to record their daily time budgets （社会生活基本調査・生活時間編）.Soma has lovingly visualized this data:

More high-tech research uses Electronically Activated Recorders (EAR), digital voice recorders or PDAs that sample sounds from your environment. The records are later analyzed to chart what the hell you spend your time doing. This can be compared with your personality to tell, for instance, that extraverted women really do spend more time in group conversation (Mehl et al. 2006).

Such observational sampling is common in research on other animals but more difficult with humans. However, technology is finally catching up with our desire to collect this kind of data and may bend research back to thinking about personality in terms of behavior rather than in terms of adjectival traits (cf. Mischel 1968).

or consider, Are Mexicans More or Less Sociable than Americans?

we measured self-reported sociability using a personality questionnaire, and behavioral sociability using the Electroctronically Activated Recorder (EAR) in Mexican and American students. The results showed that Mexicans saw themselves as less sociable than Americans, but they behaved more sociably in their everyday lives.… Whereas Mexicans socialized more often in public environments and by interacting with a person who is immediately present, Americans socialized more in private environments and by interacting with remote persons.

Mehl et al. (2006) Personality in Its Natural Habitat: Manifestations and Implicit Folk Theories of Personality in Daily Life. J Pers Soc Psychol 90. 862-877. doi:10.1037/0022-3514.90.5.862

Mischel, W. (1968). Personality and assessment. New York: John Wiley and Sons.

Ramirezesparza et al. (2008) Are Mexicans More or Less Sociable than Americans? Insights from a Naturalistic Observation Study. Journal of Research in Personality. doi: 10.1016/j.jrp.2008.09.002

Comments [0]



October 16, 2008

Their genes are your environment


Peromyscus maniculatus, PeroMHC

When we start accounting for all the things that influence your behavior, the first basic division is between differences in genes and differences in environments. 

But environments are not gene-free: your environment if filled by the genes of everyone you interact with. These are termed indirect genetic effects (IGEs, Moore 1997). 

Wilson et al. set up a series of bouts between absolutely adorable deer mice (Peromyscus maniculatus). They modeled the factors influencing each animals aggression, starting with their and their opponents identities and then breaking this down into additive genetic and permanent environment effects (the later including non-additive genetic effects as well as early experiences that shaped each animal's aggressiveness). Finally, they added an indirect genetic effect from the opponent to the model. They found

in general, those genotypes that directly cause higher than average aggression in the focal individual also increase the aggressive response indirectly when expressed in the opponent. 

Moore et al. Interacting phenotypes and the evolutionary process: I. Direct and indirect genetic effects of social interactions. Evolution (1997) vol. 51 pp. 1352-1362

Wilson et al. Indirect genetic effects and the evolution of aggression in a vertebrate system. Proc R Soc B (2008) doi: 10.1098/rspb.2008.1193

Comments [0]



October 16, 2008

Smart, steadfast kids live longer

The associations of childhood intelligence and dependability with adult mortality were examined in 1,181 people who were representative of the Scottish nation. Participants were born in 1936 and were followed for mortality from 1968 through early 2003. Higher intelligence and greater dependability were independent, significant predictors of lower mortality…Children in the lower half of the distributions for intelligence and dependability were more than twice as likely to die compared with those who scored in the top half for both these measures.

But what are the life-history trade offs? What do you get in return for being dense and unconscientious?

Deary et al (2008) More Intelligent, More Dependable Children Live Longer: A 55-Year Longitudinal Study of a Representative Sample of the Scottish Nation. Psychological Science 19 (9) 874–880. doi 10.1111/j.1467-9280.2008.02171.x

Comments [0]



October 11, 2008

Junk drawers, personal space, and personality

Paho Mann 
2001 
Junk Drawer, Albuquerque NM 
22.5 × 27 Inch Archival Inkjet Print

Paho Mann’s photographs of Junk Drawers & Medicine Cabinets “force the viewer to contend with the natural desire of humans to collect, categorize, and by doing so, manage to give clues about their personality and identity.”

Indeed: Sam Gosling’s personality psychology of everyday life reveals the physical manifestations of our personality. Your room, office, and desk are clues to your personality.

Gosling, S. D., Ko, S. J., Mannarelli, T., & Morris, M. E. (2002). A Room with a cue: Judgments of personality based on offices and bedrooms. Journal of Personality and Social Psychology 82, 379-398.

Comments [0]



October 09, 2008

Scanning the genome for personality in young twins

The number (726) and type (microsatellite) of the markers isn't great, but you do what you can do:

We report the first genome-wide scan of adolescent personality. We conducted a genome-wide scan to detect linkage for measures of adolescent Psychoticism, Extraversion, Neuroticism, and Lie from the Junior Eysenck Personality Questionnaire. Data are based on 1,280 genotyped Australian adolescent twins and their siblings. The highest linkage peaks were found on chromosomes 16 and 19 for Neuroticism, on chromosomes 1, 7, 10, 13 m, and 18 for Psychoticism, and on chromosomes 2 and 3 for Extraversion. 

Marker density is a real problem because a lot of genes lie within a 5 cM region (these are outbred people, not F2 crosses, after all). I would have preferred to see scores from the NEO, since we've seen quite a few genes reliably related to novelty seeking, and I'm curious to see what else associates with Openness.

Gillespie et al. (2008) A genome-wide scan for Eysenckian Personality Dimensions in adolescent twin sibships: Psychoticism, Extraversion, Neuroticism, and Lie. J Pers 76 (6) doi:10.1111/j.1467-6494.2008.00527.x

Comments [0]



October 05, 2008

Rodentology: epigenetics of behavior

Even identical twins, who share all of their genes, differ slightly in their behavior even when they are in the same environment. Besides sequence-level differences, genomes differ in a number of other ways that effect gene expression. This is your epigenome. 

Alter et al. tie large-scale differences in gene expression level to open field behavior in mice. Being handled after birth has long been known to influence anxiety levels and behavior and goes back to Seymour Levine's work with rats in the 1950s. Rodents that are handled as infants end up being more bold. 

Despite sharing the same genes, identical twins demonstrate substantial variability in behavioral traits and in their risk for disease. Epigenetic factors–DNA and chromatin modifications that affect levels of gene expression without affecting the DNA sequence–are thought to be important in establishing this variability. Epigenetically-mediated differences in the levels of gene expression that are associated with individual variability traditionally are thought to occur only in a gene-specific manner. We challenge this idea by exploring the large-scale organizational patterns of gene expression in an epigenetic model of behavioral variability.

To study the effects of epigenetic influences on behavioral variability, we examine gene expression in genetically identical mice. Using a novel approach to microarray analysis, we show that variability in the large-scale organization of gene expression levels, rather than differences in the expression levels of specific genes, is associated with individual differences in behavior. Specifically, increased activity in the open field is associated with increased variance of log-transformed measures of gene expression in the hippocampus, a brain region involved in open field activity. 

The only thing I don't quite follow in this study are their quality control measures. One problem with these experiments is that large differences you see between microarrays can be due to how much fluorescent dye you happened to squirt on them. You then attempt to control for this variability. Of course the authors make a number of references to the MicroArray Quality Control Project, which means everything is OK, right?


Comments [2]



October 04, 2008

My subjects in the wild

I finally saw red deer (Cervus elaphus) in the wild. They do exist!

We spotted a harem about a kilometer away. The deer saw us long before we noticed them.

   

Click here to download:
My_subjects_in_the_wild.zip (134 KB)



This sighting was in the context of hillwalking, so there was no time for deerstalking or any sort of ad lib data collection.


 

Comments [0]



September 24, 2008

Let my people see, and analyze

Along the lines of mycrocosm, DAYTUM brings Nicholas Feltron’s visual style to the world of micro-infographics.

Both tools are worth playing with for drafting lifecharts. DAYTUM, the prettier of the two, relies on too many mouse clicks for data entry. Mycrocosm’s text-based data capture is quicker but is not robust against typos. What both tools really need is an API so that we can pull our data into more brawny statistics packages.

Many Eyes has been pushing the goal of data democratization for several years. Many Eyes is attempting to crush much larger data sets than the two micro sites but still ultimately relies on our own visual competencies.

Plotting data is essential. Essential but only the first step (although as readers know some folks skip even this step). Many Eyes may guide you nicely from data to visualization, but it does not help you to conclude anything beyond what your eyes tell you.

Why don’t we demand more analytic oomph from these tools?

I studied statistics in high school but it did not stick. It was not until graduate school that I found a use for statistics. This is wrong.

Undergraduates in my department are required to take statistics but most of them (according to the professors) never use it after they graduate. This is sad.

Everyone having a basic literacy in statistics might not solve any problems, but it is damn worth a try.

Comments [0]