Tuesday, 30 June 2009

Decision making efficiency

I have been studying opinion formation for some time now, with a few papers published or to be published. Generally, my outlook on the capacities of human species to make rational - no, OPTIMAL - decisions is rather bleak.

Hunting through papers written on the subject I found one written by Amé, J.-M.; Halloy, J.; Rivault, C.; Detrain, C. & Deneubourg, J. L. Collegial decision making based on social amplification leads to optimal group formation, Proceedings of National Academy of Sciences, 2006, 103, 5835-5840.

And there is hope! we have founs at least one species capable of:
This experimental and theoretical study of shelter selection by cockroach groups demonstrates that choices can emerge through nonlinear interaction dynamics between equal individuals without perfect knowledge or leadership. We identify a simple mechanism whereby a decision is taken on the move with limited information and signaling and without comparison of available opportunities. This mechanism leads to optimal mean benefit for group individuals.

So, the old SF joke about cockroach surviving after we demolish the world with atmo bombs has a good, scientific basis. They are, collectively, smarter. Because I can not recall many examples when humans could take a good decision through interaction dynamics between equal individuals without perfect knowledge or leadership. A decision that would be taken on the move with limited information and signaling and without comparison of available opportunities. And turned out to be an optimal one.

Monday, 29 June 2009

Scare the public!!!

It seems that one of the duties of so called "science journalism" is to scare the general public witless. It is not so difficult, bearing in mind that the public is generally witless to start with, but let's focus on scaring them then.

What would you think when reading the following title: Caesarean delivery can alter DNA ? Monster mutants caused by cesarean birth? Permanent changes of DNA? ... Horror...

Yet this is the modern world: the title of the original publication is much less interesting: Epigenetic modulation at birth – altered DNA-methylation in white blood cells after Caesarean section
by T Schlinzig, S Johansson, A Gunnar, TJ Ekström and M Norman.
This does not sound so scary, does it?
And what you find in the abstract is
Aim: Delivery by C-section (CS) has been associated with increased risk for allergy, diabetes and leukaemia. Whereas the underlying cause is unknown, epigenetic change of the genome has been suggested as a candidate molecular mechanism for perinatal contributions to later disease risk. We hypothesized that mode of delivery affects epigenetic activity in newborn infants.

Methods: A total of 37 newborn infants were included. Spontaneous vaginal delivery (VD) occurred in 21, and 16 infants were delivered by elective CS. Blood was sampled from the umbilical cord and 3–5 days after birth. DNA-methylation was analyzed in leucocytes.

Results: Infants born by CS exhibited higher DNA-methylation in leucocytes compared with that of those born by VD (p < 0.001). After VD, newborn infants exhibited stable levels of DNA-methylation, as evidenced by comparing cord blood values with those 3–5 days after birth (p = 0.55). On postnatal days 3–5, DNA-methylation had decreased in the CS group (p = 0.01) and was no longer significantly different from that of VD (p = 0.10).

Conclusion: DNA-methylation is higher in infants delivered by CS than in infants vaginally born. Although currently unknown how gene expression is affected, or whether epigenetic differences related to mode of delivery are long-lasting, our findings open a new area of clinical research with potentially important public health implications.

Seems the effect is temporary, causes unknown and effects unknown as well. OK - I have nothing against the continued research, the topic may be important - but should Karolinska Institute really be involved in scaring everyone?

Or is it just my imagination that DNA is a dirty word? I remember the protesters holding up placards with "we do not want DNA in our tomatoes". Is this the time to ban DNA from our children as well?

Friday, 26 June 2009

Where do wars come from?

I have found - by a curious accident - a very interesting article by Samuel Bowles:
Did Warfare Among Ancestral Hunter-Gatherers Affect the Evolution of Human Social Behaviors?, Science, 2009, 324, 1293-1298,

Since Darwin, intergroup hostilities have figured prominently in explanations of the evolution of human social behavior. Yet whether ancestral humans were largely "peaceful" or "warlike" remains controversial. I ask a more precise question: If more cooperative groups were more likely to prevail in conflicts with other groups, was the level of intergroup violence sufficient to influence the evolution of human social behavior? Using a model of the evolutionary impact of between-group competition and a new data set that combines archaeological evidence on causes of death during the Late Pleistocene and early Holocene with ethnographic and historical reports on hunter-gatherer populations, I find that the estimated level of mortality in intergroup conflicts would have had substantial effects, allowing the proliferation of group-beneficial behaviors that were quite costly to the individual altruist.

In the light of Jared Diamond getting sued for writing about social strife in New Guinea by the very people who have told him the stories of the violence in the first place it is very risky direction of research. According to "politically correct" explanations wars are charactersictic only for white, aggressive and doministic western civilization. Savages are, by definition, noble. Fortunately for Bowles his work is based on field research done by others, so the chances of beinf sued for putting some tribe "in bad light" are slim. But who knows...

Seriously - what I have found important was a careful combination of theory/model and observations. As it should be in science.