Friday, November 4, 2016

Birds and landscape histories

Finds tongues in trees, books in the running brooks,
Sermons in stones, and good in everything.
I would not change it. 

Most traditional historians do not see much use for science but there are now growing branches of science that are essentially about determining histories. These include histories of climate, habitat connectivity, and the evolution of organisms. The field of phylogeography attempts to look at the distributions and evolutionary relationships of a cluster of inter-related species to see patterns in their diversification and examine timing and relationship to environmental or climatic changes. Past vegetation  can be guessed by the signs left by plants through pollen deposits in certain kinds of preserving environments like peat bogs. A cylindrical core can then be extracted from the bog and the deeper layers tell us something about the vegetation of the older period, the time itself can be established by carbon dating. Every organism has a book in the form of DNA and the lines in this book are constantly being edited with copy pasting as the organisms reproduce and accumulate mutations. By looking at the edit history of specific sections of DNA across sample individuals, it is possible to reconstruct a chronological sequence of the edits (the way to establish what is recent versus what is older requires a trick that requires prior knowledge of a script that is decidedly older - an individual known as an outgroup). In addition to regular nuclear DNA, there is DNA in the mitochondria which passes from mother to offspring and this is generally conserved with occassional changes caused by mutations. The history of these mutations can also be examined to reconstruct chronologies. There are of course little problems with these sources including possibly corrupt histories resulting from the possibility of DNA being inserted by viruses or bacteria that break the linearity. Histories of human movements have been found by examining DNA across peoples.

Histories at different scales and for varying epochs can be read from diverse sources. Igneous rocks tell the pressure, temperature and rate of cooling around them by the sizes of the crystals formed within them and their mineral compositions. Sedimentary rocks hold fossils in the leaves of their pages. Trees keep note of fires and environmental conditions in the rings. Bubbles trapped in polar ice have been the source of atmospheric composition history.

The sources for history therefore go well beyond what archaeologists and traditional historians would want to preserve. It is a pity however that these other sources get so little attention.
Few can read the significance of this specimen from Antharasanthe near H.D. Kote, Karnataka

I recently visited the Regional Museum of Natural History at Mysore along with Dr Robert Prys-Jones of the Natural History Museum at Tring and thanks to his presence, I was, reluctantly, allowed to go behind the scenes and take a peek at some bird specimens that Salim Ali had collected in the late 1930s. [I had been at the RMNH many years ago with the late S.A. Hussain when this collection was moved there and I have since always been irritated by the way government officials prevent access to such collections across India.] One of the specimens that caught my attention was of a black-headed babbler / dark-fronted babbler (Rhophocichla atriceps). It was collected by Salim Ali in 1939 from Antharasanthe. I have passed through Antharasanthe many times in recent years and for someone who knows the bird and the kind of location in which it is normally found, it is simply mind-boggling to realize that Antharasanthe once held dense forests with a dark and dense undergrowth. This is something that few can appreciate and it requires that they know something about the bird in question.

Clearly not all sources of history can be appreciated or understood by traditionally trained historians. There is a classic example of such ineptitude provided by Delhi-based historians Romila Thapar and Valmik Thapar who, in their book Exotic Aliens – The Lion and Cheetah in India, claim that lions and cheetahs in India were introduced from Africa in fairly recent times by local rulers. This of course can easily be dismissed by looking at DNA evidence and the book of course has since been dismissed by scientists.

In April 2016 I had the privilege of walking along a Himalayan hillside with Emmanuel Theophilus and S. Subramanya and we came across trees with curious rings on their trunks. Observing them closely showed that there were series of punctures made over these rings by woodpeckers. There are a group of woodpeckers in North America that are called sapsuckers - they all belong to the genus Sphyrapicus and have the habit of making punctures on trees and waiting for sweet sap to fill them up. They revisit these holes and sip the sap that collects. Now there is just one species in Asia that has the same habit - the rufous-bellied woodpecker and even called the rufous-bellied sapsucker (Dendrocopos hyperythrus) - and it evidently leaves a trace on the trees. Not a single individual but evidently generations of them. The trees which are at least a century old have rings that are tapped repeatedly and the calluses grow quite wide due to the repeated injury. Not all trees seem to respond to the damage in the same way and the most significant callusing was found in karsu oak and rhododendrons (they are massive trees here, worth mentioning for readers familiar only with rhododendrons from higher latitudes). Interestingly Green-tailed sunbirds (Aethopyga nipalensis) seem to be secondary sapsuckers and they hover and steal sips of sap.

Emmanuel Theophilus points to calluses on karsu oak Quercus semecarpifolia

Callus rings on a Rhododendron

Rings seen at a distance.
Close up of a ring showing a fresh line of punctures.

Perhaps there are places in the Himalayas where the woodpeckers have left their traces in the trees and vanished since and these are the histories that are lost perhaps to the timber trade.

There is then a case for historians to learn a bit of ornithology and there is of course a case to be made for ornithologists to know a little bit of history. The latter is probably harder considering that hordes of them can contribute to such systems a ebird but not put any effort to standardizing the recording of habitat conditions. Since such a standard that can be analyzed quantitatively has to be evolved locally, it involves democratizing citizen science websites and therein lies the problem. Perhaps history, even of humans, is important for the software designers.