Monday, 27 February 2017

How Science Works - Correcting Errors


Monarch butterfly (Danaus plexippus)



Tiger butterfly (Danaus genutia)
Monarch miscalculation: Has a scientific error about the butterflies persisted for more than 40 years? | Science | AAAS

How does a possible mistake in what was believed to be the number of chromosomes in the monarch butterfly validate scientific methodology?

Well, firstly, if you're looking for certainty, don't look at science - if you value certainty over truth, that is. Certainty and truth are not the same thing at all. The only certainty in science is that there are no certainties. Science is a human endeavour and as with all human endeavours the humans doing it make mistakes. Doubts, not certainties, are what drives science forward and the reason science continues to grow and develop and take us closer to a better understanding of the way things work.

By contrast, religion, and especially the extreme fundamentalist form we see in Bible-literalist creationism, depend on certainty and a complete absence of doubt. Allow in the slightest doubt; ask a difficult question and the whole thing could come crashing down and to make matters worse, the is no factual basis for those certainties so nothing neutral by which to alloy those fears and satisfy those doubts.

Once the doubts are there or the certainties have become uncertain, there is nothing holding it back. And fundamentalists know this, hence their refusal to acknowledge errors, even the glaring contradictions in the holy books. They can't be contradictions because the holy book is the source of all truth. How can they be contradictions?

Science is a search for truth, not a search for certainty, and certainly not an exercise in explaining away glaring errors in 'sacred' science texts. Truth itself is sacred, not beliefs or the wisdom of elders but never-the-less, mistakes are made and can perpetuated, sometime for many years, because humans have a tendency to take on good faith the work done and honestly presented by others, especially where there was nothing to be gained by falsehoods, and very especially where the mistake is minor and have very limited ramifications in the particular area of interest.

So, whilst an article in Science such as we have this week, explaining how a small mistake may have been made as long ago as 1975 and is still being perpetuated by gladden the heart of any creationist struggling to cope with the dishonesty of creationist certainty and the constant battle against cognitive dissonance brought about by reality not being what they would like it to be, it should gladden the heart of any rationalist even more - because it validates science as a methodology for discovering the truth.

The article explains how the 'accepted' number of monarch butterfly chromosomes - 30 - seems to be based on a single paper published by Indian entomologists in 1975. This was spotted by a post-doctoral researcher, Christopher Hamm. When reading up on the monarch butterfly, Hamm noticed that all recent papers dealing with chromosome number reference a single 2004 paper which in turn referenced the 1975 paper. So, Hamm checked by doing his own cell-squash analysis - the technique used by the Indian researchers, biologists N. Nageswara Rao and A. S. Murty of Andhra University, Visakhapatnam, India.

Monarch Butterfly chromosomes. 28 or 30?
Hamm examined the cells of 6 juvenile monarchs and found a consistent 28 chromosomes in all of them.

The 1975 mistake, if it was a mistake, could have been made in all innocence caused by the difficulty in distinguishing between difference related species of butterfly. The monarch, Danaus plexippus, is a notorious migrant species, holding the record fr the longest seasonal migration for any insect and it frequently gets blown off course, turnign up in Western Europe, including the UK. There is a small established colony now in southern Spain (I have seen monarchs in Puerto Benus near Marbella, Andalucia, Spain). However, it is highly unlikely that real monarchs would turn up in India.

But, there is a related species, the tiger butterfly, D. genutia, which is found in India and which, for many years, was regarded as the same species. It was only reclassified as a separate species in 1954 but is still sometimes referred to wrongly as D. plexippus. It is entirely possible that Rao and Murty simply caught some local D. genutia believing they were monarchs.

The 'mistake' has perpetuated and gone unnoticed or unchallenged because it really isn't very important in the grand scheme of things. No important decisions have depended on getting it right. It is of academic interest only and mostly to a small group of lepitopteran taxonomists.

So, that would appear to be an end to the mistake? 

Well, not entirely. No sooner had Hamm published his findings prior to peer-review on the online repository, bioRxiv, than some of his former colleagues also published their findings which appear to confirm the 1975 Indian paper. And this is the real strength of science - healthy disagreement! What we have now are two contradictory findings. (Note here the approach of fundamentalist religions to clear, mutually exclusive, contradictions in their holy books and sacred texts!)

Typically for science, Hamm's response is instructive. "I am glad that other researchers are skeptical and want to build on my minor contribution. There could be some interesting biology going on.”

One of the interesting pieces of biology going on could be that chromosome numbers differ in different local populations of monarch (as they do in some other species of butterfly). They could also vary from cell to cell. Or it could simply be that one or other group was wrong because the technique they used gave wrong results.

Whatever the answer, there is now doubt where once there was certainty and science will progress as a result. The real error was in being too dependent on one piece of research - too much certainty and trust (or 'faith', if creationists want to call it).

Yep, faith leads to fallacies! Certainties perpetuate them and cause stagnation.

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