I have posted a few times about “cryptids” and mentioned that the study of cryptids is called “cryptozoology”.  This has been very much a fringe science ever since its inception in the 1940s.  The disparagement has resulted from an over-reliance on anecdotal evidence and what some would call an “overabundance of credulity”.  What I am going to discuss here is not so much pure cryptozoology as the concepts that underpin it.

The heart of the unknown

It was Carolus Linnaeus who first started the systematic naming of living things in 1758.  People obviously already had names for many of these organisms, but they varied from place to place and did not always refer to the same creatures.  Linnaeus brought to prominence the “binomial classification” for species which had been around for some 200 years previously, and applied it rigorously in an attempt to standardise the naming process.  Since Linnaeus, many others have taken up the torch and a vast number of species have been named and classified into the current schema of evolutionary biology.  If you want to see how far we have come, go and look at Zipcode Zoo.  On that website, they have 2,646,557 web pages describing 1,296,614 animals, 1,105,429 plants, 193,534 fungi, 17,562 chromista, 16,529 protozoa, 16,112 bacteria, and 484 viruses (as of the time of writing).  Linnaeus brought us out of a nomenclative dark age where existing names were excessively long and convoluted or simply misapplied, but one can only wonder what a daunting task he was faced with at the outset.

How many species?

As researchers looked harder to define what a species was, two questions arose.  The first was “what is a species?”  This question, called the “species problem” is still not entirely resolved.  The definition that biologists have come up with is called the “biological species concept”, most championed by the late Ernst Mayr (although he acknowledges that the idea had been around since the 18th century).  In this definition, individuals of a given species are distinct from other species if they are unable to reproduce with members of that other species.  This leads to an isolation of genetic material.  However, while this is a useful distinction theoretically, it is very difficult to use the biological species concept to actually distinguish species from one another.

Given our uncertainties about where to draw the boundaries between species, the second question of “how many species?” becomes all the more difficult to answer.  Since Linnaeus, we have named somewhere between one and two million species.  Estimates for just how many species there are in total range hugely from 5 to 50 million.  Part of the uncertainty is that there are a lot of taxa which simply aren’t studied intensively.  Bob May, a noted evolutionary biologist and ecologist, noted that 1/3 of taxonomists work on vertebrates, which are less than 1% of all species, another 1/3 work on plants (around 10% of all species), and the remaining 1/3 work on the other 89-90% of taxa (hat-tip Jerry Coyne) (May, 2010).

As a way to illustrate this problem, here are some species discovery curves that I pulled out of online databases.  Data for the seven groups are from the following links: Mammals, Odonata, Fish, Bees, and Ephemeroptera.  The vertical axis is the number of species that have been discovered in total and the horizontal axis is time.  Each graph starts with Carolus Linnaeus in 1758.

What you can see from the plots is that even for the most obvious taxa (e.g. primates) the curves are still increasing at approximately the same rate that they have been doing since Linnaeus.  We have done a reasonably good job of maintaining that rate with increased intensity of surveying and description of organisms and this almost certainly masks the fact that we are having to try harder to find new species.  It is possible to attempt to extrapolate beyond these curves to predict how many species there should be.  This was tried by a group of researchers in 2007 and they found that, unless you have a group of organisms that has been almost completely described, the margins of error were huge (Bebber et al., 2007).

Whither cryptozoology?

So where do cryptozoologists fit into this problem?  Cryptozoology makes the very true claim that there are species out there yet to be discovered.  This much is obvious from the graphs that I showed above.  These individuals are driven to find unusual species and are employing ever-increasing levels of science and technology.  The trouble with cryptozoology is its obsession with anecdotal evidence about boring old vertebrates…  Wikipedia has a list of cryptids which illustrates this point: with a few exceptions (giant squid, for example), the list is entirely vertebrate.  It is a shame that a community of people with such great enthusiasm for nature and biodiversity choose to chase ghosts rather than the equally-fascinating real animals and plants that we are all surrounded by.

Perhaps even more important is the role that cryptozoologists could play in finding and identifying animals outside of their normal ranges.  “Alien big cats”, those species of large felines (thought by some to be cougar or puma) that have been reported in the UK, for example, are a good example of an almost-scientific application of cryptozoology.  However, using this approach to the detection of known species outside of their normal range will lead to an improved knowledge of climate-related range shifts and invasive species – two topics that are of the utmost importance in contemporary ecology.

In short, perhaps if the cryptozoologists focused their enthusiasm, knowledge and (more recently) their technology on issues that were closer to mainstream science then they could make a really valuable contribution.  Right now they are just chasing ghosts…

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References

Bebber, D.P. Marriott, F.H.C., Gaston, K.J., Harris, S.A. & Scotland, R.W. (2007) Predicting unknown species numbers using discovery curves, Proceedings of the Royal Society Series B, 274:1651-1658.

May, R.M. (2010) Tropical Arthropod Species, More or Less? Science, 329: 41-42.