A basic of science

I often find myself reminded of a post I made on just the third day in the life of FTSOS. It was about a media report on a recent study that said a certain pesticide found in anti-bacterial soaps may actually contribute to the development of antibiotic resistance by bacteria. It was a fine study, but it was far from conclusive. (The news article wasn’t so cautious in its assertions.) Perhaps it would be best if people only used regular old soap, what with that not really qualifying as a real sacrifice, but as for the science, I was far from ready to say that that pesticide was a contributor to antibiotic resistance among bacteria in any significant way in the given environment.

And the reason is quite simple: science does not rely upon individual studies. Of course, we may be able to point back to the results from one lab or one group of researchers as published in a single study as the linchpin that opened up a whole new branch of study. But that doesn’t mean we believe that paper as being conclusive on its own. It only works when we have a body of evidence. In most cases that means a number of studies looking at the same or a similar problem and coming to the same or very similar conclusions. For a single paper that proves itself a linchpin, that means we need a number of other studies which use its findings as their basis. For instance, green fluorescent protein, or GFP, was shown to work as a marker of gene expression in a pretty definitive study. It has about a bajillion (rough estimate) other studies on it, but no one needed to reproduce the study which won one research team the Nobel Prize in chemistry. But people did use that study as a basis for about a gagillion (rough estimate again) studies. If the original study was wrong or faked or otherwise limited, we would be well aware of that by now because of all those subsequent studies. That is one way to compose a body of evidence.

To put this another way, take the studies on intercessory prayer and its efficacy. We have some that show positive results. Look, God is here to help! But then we have others that show negative results. Oh, no! God must be angry! And then we have a whole bunch which shows a null result. Uh…God must be indifferent. So how do we interpret these results?

Remember, we need to be looking at the evidence as a body. As one of those intolerant, bigoted, hate-filled evilutionist atheists, I would find it humorous if prayer gave negative health results. But I don’t get to have that laugh. Instead, I have to conclude that prayer has no detectable effect on health. None of the studies are conclusive; they suffer from bias, or are statistically insignificant in either direction, or just show a blatant null result. The most likely conclusion is that prayer does nothing. No study has convinced me otherwise, and most of the studies have shown prayer to be inconsequential to the well being of people anyway.

What I hope this post enables readers to do is recognize a fundamental aspect of how science works so that next time they see a study which concludes a link between this or that, they know what to think. That doesn’t mean it is okay to just dismiss a non-bias confirming study (i.e., a study that doesn’t give a result one likes). It just means that it is always necessary to look at the entire body of evidence before drawing a conclusion.

Kin Discrimination and the Social Amoeba

Research recently published in PLoS Biology indicates that amoebas which are close to starvation will seek out genetically similar relatives.

We tested how widely social amoebae cooperate by mixing isolates from different localities that cover most of their natural range. We show here that different isolates partially exclude one another during aggregation, and there is a positive relationship between the extent of this exclusion and the genetic distance between strains. Our findings demonstrate that D. discoideum cells co-aggregate more with genetically similar than dissimilar individuals, suggesting the existence of a mechanism that discerns the degree of genetic similarity between individuals in this social microorganism.

It will be really interesting if/when a description of the mechanism discerning genetic similarity is given, and if there is any remnant of it still present in humans or to what extent it exists in other species.

Interestingly, this study seems to provide more evidence for the gene being the important unit of selection by nature. It is the very survival of these organisms that could explain what has been observed here on a genetic level: genes which are similar have evolved a mechanism for detecting one another because of the mutual (but ultimately selfish) benefit of doing so. The further from similarity they are, the more likely they are to discriminate in offering assistance, as was the case in this study. Aside from the reason of promoting different allelic versions of one’s self, one good reason for the evolution of this discrimination mechanism would be to weed out “cheaters”, or genes which take advantage of the ‘altruism’ of these genes to assist other amoebas in their time of need (starvation) by abusing their helpful nature. That is, if it is embedded in me, when I see a fellow organism of my species, ‘If starving, help fellow organism’, it will pay me to also have the command, ‘If distantly related, do not help’. In other words, if I see my brother and my 2nd cousin starving, it’s going to be worthwhile for my genes if I am able to detect which one is my brother since he shares more genetic material with me than my 2nd cousin. By helping him instead of the more distant relative, I am increasing the odds that my genes or genes very close to my own will be passed on to the next generation. My genes have limited interest in helping out other, distant genes.

By the by, the use of GFP makes this experiment all the more beautiful.