Evolution of the Mushroom Symphony
The earliest suggested depiction of human mushroom use is represented in cave art found within the Tassili plateau in Southern Algeria, and is approximately seven thousand years old (Stamets, 1996). The artwork portrays a bee-headed figure with mushroom fruiting bodies for fingers, coupled with an outline also infused with fungal shapes. It has been suggested that the bee indicates that the mushrooms were preserved in honey during the Paleolithic times. All these things considered, one could further the idea that the psychoactive properties of certain mushrooms have been part of human knowledge for well over seven thousand years, which is in itself an interesting idea.
Nowadays, whilst our knowledge about mushroom biology has increased greatly over the past seven thousand years, our real understanding of the purpose behind the advent of psychoactive compounds, such as psilocybin, hasn’t shifted at all. We have many theories as to why, but none are particularly falsifiable, which can, if one is seeking an ultimate answer to this question, be both a hindrance and an encouragement. Moreover it could be said we are no closer to a satisfactory answer to this question than the Paleolithic person who painted the cave art in what would become Algeria seven thousand years ago; their guess is as good as ours!
Evolutionary biology is a subject that can be heretical to some, yet reality to others. What is for sure is that it is a subject of permanent fluidity, and nowhere is this statement more true than within evolutionary mycology. Evolutionary mycology is a subject that thrives, as does its subject matter, within the microscopic. Crucial differences lurk at mind-boggling magnification levels, which forever push the layman away as footnotes to the ongoing drama that unfolds. It’s best to just sit back and ride the information as it flows out from the laboratory, which we shall now do post-haste.
Recent studies, which saw research teams from the Guadalajara University in Mexico and the University of Tennessee combine, have succeeded in illuminating crucial genetical and morphological differences amongst species of mushroom that were once treated as components of the same genus: Psilocybe. This is in thanks to the work of Ramirez-Cruz, Guzman et al. (full pdf of research is to be found here: http://www.nrcresearchpress.com/doi/full/10.1139/cjb-2013-0070#.Uk1SEMY6NBg )
It is now considered that all Psilocybe mushrooms must contain the compound psilocybin, whose oxidation is responsible for turning the fruiting body blue when bruised by an impact, such as rough handling. All previously considered non-bluing members of Psilocybe were part of the genus Deconica. Prior to this research it had been thought that Psilocybe was a polyphyletic group (meaning that the group has similar characteristics, which must have evolved convergently, as both Psilocybe and Deconica were incorrectly thought to have had different common ancestors.) It can now be said that Psilocybe and Deconica exhibit synapomorphy (a trait that is shared by two or more taxa and inferred to have been present in their most recent common ancestor, whose own ancestor in turn is inferred to not possess the trait.)
Previous scientific investigations were based on analysing and comparing structures known as the basidiospore wall (a part of the fruiting body that produces spores and whose presence makes up the fungal phylum Basidomycota, within which Psilocybe and Deconica reside,) and the chrysocystidia (a large, and in this case, yellow-bodied cell located on the basidia, whose purpose is little known, yet whose presence can be used to indentify species, as cystidia colour and form are unique in both species and/or genus.) This allowed many of the Deconica species to be classified within the Psilocybe genus. This classification was originally ordered polyphyletically, but the study by Ramirez-Cruz, Guzman et al. has shifted the organization of the two genera into a monophyletical classification. The reason for this is that both genera in discussion do share a common ancestor in antiquity after all. For a practical example: the mushroom that used to be commonly known as the ‘mountain moss Psilocybe’ (Psilocybe montana), although having never been proven to contain psilocybin, was still was classified as a Psilocybe, can now be labelled by its more correct name: Deconica montana.
It may seem obvious that a Psilocybe mushroom should contain that famous compound which gives the genus its name, but it’s a very complex task to try and prove that a mushroom that is almost identical in morphology doesn’t appear in this or that particular genus. It is only by using modern DNA sequencing and detailed spore print analysis, coupled with support from previous works done on the subject, which gives confidence in allowing such a reclassification.
To put this into perspective: something happened to the common ancestor, which both Psilocybe and Deconcia evolved from. This ‘something’ gave rise to both lineages, which in some cases evolved in very similar ways, yet Psilocybe obviously began to manufacture psilocybin and Deconica did not. That biological stress which gave rise to the split, I feel, is the key to unlocking the reason behind the genesis of psilocybin. What is even more interesting is that many Deconica, such as Deconica montana, evolved within the presence of other certain Psilocybe mushrooms. This would indicate that the biological stress that forced the split, from their common ancestor, and thus established the two distinct new genera of Psilocybe and Deconica must have been localised.
I feel that such a bifurcation must of been born out of an ‘internal motivation’ within one of the two genera; one chose to produce psilocybin, the other chose decline this option. One thing we can be sure of is that complex compounds such as psilocybin are not fabricated without ‘good reason’, as evolution can only react in direct experience of a question posed to it by the surrounding area; evolution provides an answer, which as a corollary is inscribed with meaning, divulged from a continued will to exist. So the final cause of the genesis of psilocybin must have provided some kind of evolutionary advantage to the Psilocybe mushrooms to enable such an embarkation into the realms of organic chemistry.
Further ruminations can be extracted from the idea that psilocybin has evolved within 200 different species that span 13 separate mushroom genera (this, however, is a reflection for another day.)
Stamets, Paul . Psilocybin Mushrooms of the World. 1996. Ten Speed Press. Berkeley, California.