I wrote this for my anthropology class and thought some people might be interested in reading it. - ameriwire

On the Origin of the Species Construction

INTRODUCTION

The most controversial topics in anthropology, surely, are any of those which relate to evolution, especially human evolution. Critiques of evolutionary theory launched from both religious and scientific (i.e., evidentiary) premises often pose challenges which are at least scientifically interesting enough to prompt extensive retorts from scientists from many disciplines, often in the arena of a peer-refereed scientific journal. Some scientists, the most culturally prominent of whom is Stephen Jay Gould, have even established their careers on the analysis, defense, and promotion of evolutionary theory and its nuances.

The anthropologist or evolutionary biologist engaged in her exhaustive attempt to present a straightforward answer to the enduring question,

‘What is the evidence that one species can in fact evolve from another?’

imposes upon herself an unnecessary burden. The overriding obstacle to acceptance of a Darwinian (or any updated, 'Neo-Darwinian') hypothesis of evolution is that the radical evolvement of the sort described by Darwin and his contemporaries has not been observed by mankind. That is, in the words of David Menton, PhD, of the Missouri Association for Creation,

Macro evolution . . . is a hypothetical process of unlimited variation that evolutionists believe transforms one kind of living organism into a fundamentally different kind such as the transformation of reptiles into birds or apes into people. Obviously, no one has ever observed anything remotely like this actually happen.

Before proceeding, it is worth pointing out that the passage above misrepresents the claims of evolutionary theory. Evolutionary theory claims that through mutation and reproduction, creatures whose ancestors were classifiable as "reptiles" are now themselves classified as "birds", and that the ancestors of those organisms now classified as "humans"—which are themselves taxonomically regarded as apes, of course—have ancestors which would be classified as "apes". Evolutionary theory would not support the idea that any individual organism underwent a "transformation".

The fossil record, relative dating and absolute dating techniques, and current observation of microbiological evidence—both in DNA mutation and the effects of mutation on microorganism speciation—collectively lend great weight to evolutionary theory. But scientific hypotheses are not proved; they are only disproved. In the absence of some paradigm shift effecting a drastic increase in the rapidity of the appearance of mutations underlying evolution, the reasons for doubt identified by Dr. Menton will always remain. That is, of course, unless the question, "What is the evidence that one species can in fact evolve from another?" is answered with, "Species? What’s that?"

A DEFINITION IS ABSOLUTELY ESSENTIAL

The scientist defending the hypothesis that one 'species' can evolve from another 'species' has agreed with her Creationist opponent to proceed on the common premise that there is, in the first place, such a thing as a 'species'. Her acknowledgement of species is the first and most important mistake she will make in the discussion.

As a self-identified 'human being' and member of a progressive Western culture which embraces the species concept, the contention is not that the author of this paper is unable to fathom what a species might possibly be. Rather, it is that there exists no essential definition of the concept (nor the word) species which withstands philosophical or scientific scrutiny.

It may be tempting to regard this appeal to linguistic and conceptual philosophy as tangential or entirely irrelevant to the matter of identifying what a species actually is. It is not difficult to find published considerations of this problem which dismiss it as largely semantic. (p.153) But the failure of evolutionary biology to define a term so central to its mission is a barrier to full acceptance of evolutionary theory by the scientific community, and the community at large. 3(p. 153) Further, dismissing the species definition problem as a mere detail is unacceptable, since evolutionary biology is built upon some concept of speciation. The problems encountered with defining the word species (or precisely bounding the concept of species) are vivid clues that expose the underlying fallacies of scientific taxonomy.

Incidentally, the person who is credited with trying to bring order to the web of species, Carolus Linnaeus, (p.506) may be the very person responsible for setting the stage for the scientific disaster that manifests today. The disaster referred to here is the tendency by well-educated scientists to accept (without evidence) that 'species' exist as discrete entities, that there are 'ancestral species' and 'modern species' – indeed, almost anything involving the species concept is formalized in the classification system invented by Linnaeus. He proclaimed that species had been absolutely fixed from the beginning of time, and aimed to document this in his evolutionary systematics. 4(p.506) Both evolutionary systematics and cladistics (the more modern system which analyzes characters more rigorously), aim to trace and document the evolutionary relationships between 'species'. These classification systems guide taxonomy in its effort to reflect these same evolutionary relationships in the names given for species. (p.199-201) In identifying an organism’s species, or naming a 'new species', evolutionary biologists and taxonomists make their determinations based upon the similarities and differences exhibited by the specimen in question. Here, a pivotal question presents: since a primary premise of evolutionary biology is in the first place that every organism is in some way ancestrally related to every other organism, what are the criteria that delineate a species? We will return to this question later.

Nothing is quite as frustrating (to the rejecter of the concept of species) as witnessing scientists turn to nature, the fossil record, DNA, or other observable data to help them determine whether, for example, 'Neanderthals' were the same 'species' as early man, or not. It can be likened to attempting to determine whether a Sport Utility Vehicle (SUV) is a member of the "truck" group, "car" group, or some other vehicle category by taking apart the vehicle and examining its parts to make this determination. Such examination and data- gathering will only help to determine how similar the specimen is to other specimens, which are themselves determined to be members of a certain category by virtue of their similarities to the other members of the group. If the correct classification is not obvious, then it is the classification concept—not the specimen—which needs examination. What is the gold standard to which questionable specimens should be compared?

The question above is posed rhetorically, because no ‘gold standard’ exists for any given ‘species’—not for the metaphor presented with cars and trucks, and not for ‘domestic dogs’, earthworms, any given bacterium, chimpanzees, or zebras. The meanings of these terms (and even their accepted scientific counterparts, such as, in the case of 'domestic dogs', (Canis lupus familiaris) are all malleable – and therefore, this author contends, overvalued by many evolutionary biologists.

Nonetheless, many attempts have been made to define and bound species. These attempts are noble, but troubling to the author of this paper, who views such attempts as evidence that so many biologists are ‘in the grip of the theory’ that species exist. Rather than the data leading the scientist to the evident conclusions, the process of defining species is a process in which the scientist attempts to reconcile the data with an a priori conclusion: that species do exist, and that the species concept merely needs to be properly defined. This approach is patently unscientific because the conclusion is not based on observations and/ or data.

The psychological phenomenon of species and the role the phenomenon of “fuzzy similarity clusters” plays in science is considered by psycholinguist Steven Pinker in his How the Mind Works.8(p.310) Pinker writes,

"Most biologists consider species to be lawful categories: they are populations that have become reproductively isolated and adapted to their local environment. Adaptation to a niche and inbreeding homogenize the population, so a species at a given time is a real category in the world that taxonomists can identify using well- defined criteria. But a higher taxonomic category, representing the descendants of an ancestral species, is not as well-behaved. When the ancestral organisms dispersed and their descendants lost touch and adopted new homelands, the original pretty picture became a palimpsest. "8 (p.310)

Indeed, some biologists are catching on to the fallacy of species. Most notably, a paper appearing in the prestigious Comptes rendus de l'Académie des Sciences Paris, Science de la vie (i.e., Reports of the Paris Academy of Science, Life Science), in 2000, documented and considered 92 different concepts and definitions of species , and ultimately rejected all of them. The paper was authored by Philippe Lherminer and Michel Solignac, the latter of whom is affiliated with the Société Française de Génétique ( French Society of Genetics). These are scientists, not philosophers. An excerpt from that paper’s conclusion, (translated into English) follows.

"Does there exist a taxonomic category made up by all the species and likely (to serve as a) general standard? . . . According to one point of view, there (should) be one definition for the zoologists, one for the botanists, another for fossils, for bacteria . . . and why not a definition of species which would be valid only for mushrooms, another for the drosophilas . . . and another for man . . . ?

Because one does not arrive at a definition of species, one has conceived doubt about its reality and exposed its evolution . . . ‘Species’ resists definition, but the spontaneous attempts by naturalists from all disciplines to construct the definitions testify that ‘species’ still remains the most universal guide to organize the diversity of living beings. 9 ( p.153 & 163)

In their conclusion, Lherminer and Solignac correctly point out that a species definition must be ‘constructed’. But species’ status as a construction does not mean that it is a useless construction. It is easy to see the practical benefit of indulging in speciative terminology in certain instances – and even, perhaps, in most instances. For example, a gastroenterological researcher or clinician wanting to convey information about the pathogenesis of certain stomach ulcers uses the term Helicobacter pylori to refer to a bacterial culprit. There is an immense practical need in this case to identify H. pylori as H. pylori insofar as such a species name has any meaning. It would do a clinician little good to say to his patient, “Well, you’ve been infected with a microorganism, but since species don’t exist, we can’t say anything more than that, and we have no idea which antibiotics would be appropriate. Good luck!” Clearly, this paper’s author does not advocate the outright dismissal of the species concept. Gastroenterologists need to identify H. pylori so that the correct antibiotics can be prescribed, rendering a cured patient.

But even this hypothetical gastroenterologist needs to keep in mind that species are constructed. At the molecular level H. pylori mutates when it reproduces – and very fast, at that. In fact, a report published in June, 2003 reports that, “Elevated mutation frequencies have recently been reported amongst natural populations of pathogenic . . . Helicobacter pylori ” and other bacteria.13 (Abstract) Even the practical-minded clinician must remember that what a given ‘species’ is today may be very different in a matter of months, and that the rapid mutations exhibited by many microbial species have potential implications for pathogenesis, treatment, and once recognized by the scientific community, even nomenclature.

THE PROBLEMS OF SPECIATIVE SELF-REFERENCE

While Lherminer and Solignac considered 92 definitions, we will briefly consider here two of the more common definitions in the field of systematics, and why they fail as scientific guides to speciation: the Biological Species Concept (BSC) and the Phylogenetic Species Concept (PSC).

BSC is the most widely used, and at first glance, seems to be a perfect approach to defining species. In the BSC, the essential definition of a species, cast in its strongest possible light, might look something like this:

species: a discrete set of organisms, the members of which each:

Is capable of producing viable offspring with other members of the set.

Is not capable of producing viable and fertile offspring with members of another species set.

But this definition fails when applied to ‘species’ which are “obligately asexual, organisms that lack males, groups with ‘ring species’. . . and organisms that hybridize.” 15

Eliminated from the definition offered above is another requirement of the BSC (as defined by its erstwhile champion, Ernst Mayr)16(p.372), which states that “reproductive isolation” (p.372) should be the guide for determining a species rather than ‘capability’. I have made this modification because reproductive isolation is often only behavioral,16(p.372) and therefore, the concept’s merit is enhanced by eliminating this stipulation. Furthermore, if Mayr’s standard definition of ‘reproductive isolators’ were to be used – i.e., “ biological properties of individuals that prevent interbreeding with populations belonging to different species”16(p.372)—we quickly run into a problem of circularity, because we must first know what a species is before we can determine whether it is reproductively isolated.

By the way, Mayr’s understanding of speciation has evolved considerably since he studied and published a comprehensive definition of the Biological Species Concept in 1942. 16(p.372) Since 1958, he has aspired to "ask the challenging questions (surrounding evolution and speciation) and try to answer them." 16(p.373)

The problem of circularity is not at all uncommon in discussions of speciation, and even prominent and intelligent biologists fall victim to the allure of circular definitions. For example, anthropologist Ian Tattersall, PhD appeared in a PBS-NOVA production, Neanderthals on Trial. In his fervent insistence that 'Neanderthals' and 'humans' are separate 'species', Tattersall declared that, "We couldn't interbreed with Neanderthals because we were different species." But is this so? Is it that we couldn’t interbreed with Neanderthals because we were different species, as Tattersall suggests? Or is it the reverse: that "we"— presumably by "we" Tattersall means 'humans', but this is problematic when we consider the speciation debate!—are a different species from Neanderthals because we couldn’t interbreed?

The example of 'ring species' is interesting because although this reproductive phenomenon is observed only in certain 'species', it may serve as a strong clue about how genetic diversity and ' species' have been established in nature in the first place. Consider this example (from the PBS online Evolution Library):

The various Ensatina salamanders of the Pacific coast all descended from a common ancestral population. As the species spread southward from Oregon and Washington, subpopulations adapted to their local environments on either side of the San Joaquin Valley. From one population to the next, in a circular pattern, these salamanders are still able to interbreed successfully. However, where the circle closes -- . . . in Southern California -- the salamanders no longer interbreed successfully. The variation within a single species has produced differences as large as those between two separate species.

This example demonstrates that 'species' exist on a continuum – that there are no 'discrete sets' of organisms except those created by the human mind.

BSC also fails to allow for: sexually immature organisms; the natural phenomenon of infertility; and, most interestingly, the example of Ficedula albicollis. Unlike the inter-group reproduction in 'ring species', and unlike hybridization in which offspring are generally infertile, the female Ficedula albicollis bird successfully and routinely mates with male Ficedula hypoleuca to produce fertile male offspring (along with several infertile female offspring). (Abstract) According to the BSC definition above, these female birds cannot be assigned to any species, because they are able to produce fertile offspring fathered by a male of another species.

Another alternative, the PSC, uses the phylogeny (evolutionary history) of an organism is the primary factor considered in determining the species designation of an organism. In the PSC, the individuals designated as a species comprise a set which contains all descendants of a 'single population of ancestors'. Members of a species are so identified because of their heritage, and are termed monophyletic20, meaning, according to Merriam-Webster Online Dictionary, "of or relating to a single stock; specifically : developed from a single common ancestral form."

The readily obvious problem with PSC is that it slyly declines to address the issue at all! The phrases, 'single population,' 'a single stock', and 'single common ancestral form' are all just ways to paraphrase the word species! PSC says, basically, that an organism is a member of the species group to which its progenitors belonged. Which begs the question: What is a species? How can one determine the species to which the progenitors belonged? Certainly not by applying the PSC, if PSC appeals to itself to achieve a definition! The PSC fails to account for the fact that there is only one known 'single population': life forms.

The failure of these two modern approaches should prompt a revisit to Darwin ’s original speciation model. Darwin wrote, "we shall be compelled to acknowledge that the only distinction between species and well-marked varieties is that the latter are known, or believed to be connected at the present day by intermediate gradations, whereas species were formerly thus connected ." 20 For the reasons detailed extensively above, Darwin’s approach is, by far, the strongest we have here considered. The time has come to revisit it.

CONCLUSIONS

The Darwinian Species Concept was abandoned by many scientists probably because it is, admittedly, impractical for many present-day applications of the species concept. I reiterate that there is nothing patently objectionable about using the name of a given 'species', or conceiving of a species – so long as the use of the term or concept 'species' is attended constantly in the mind of the scientist with the private, mental disclaimer,

"I am constructing this notion of species and using the word species to save myself time, and to help focus on my analytical or clinical endeavors. I realize that the term species is a sort of relative term, and that observations and data gathered from nature do not support me in regarding a species as a discrete set."

Cited References

1. Menton, David N. Is Evolution a Theory, a Fact, or a Law?: Or None of the Above? St. Louis MetroVoice, Oct 1993.

2. Based on definition offered by Merriam-Webster Online Dictionary, with significant editing. Accessed 19 Nov 2003, http://www.m-w.com .

3. Mohamed Noor. Is the Biological Species Concept Showing its Age?. Trends in Ecology and Evolution. Vol. 17, No. 4. April 2002. p.153-154.

4. Thomas Paul Thigpen. On the Origin of Theses: an Exploration of Horace Bushnell's Rejection of Darwinism. Church History. 57.4 (1988) p.506-513.

5. Robert Jurmain, Harry Nelson, Lynn Kilgore, and Wenda Trevathan. Introduction to Physical Anthropology. 8th ed. Belmont, CA: Wadsworth/Thomson Learning. 1999. 532 p.

6. This example borrowed and modified from Jurmain, et al. p.202

7. Entry for “Dog Family”. Microsoft® Encarta® Encyclopedia. 1993-2001. Microsoft Corporation.

Steven Pinker

How the Mind Works

C .R. Acad. Sci. Paris, Sciences de la vie / Life Sciences

Société Française de Génétique

Babelfish

12. Web site of the Helicobacter Foundation. Accessed 19 Nov 2003, http:// www.helico.com/, "Treatments" section.

Drug Resistance Updates

14. Christine K. Weldrick. The classification conundrum: species concepts and their applications in fisheries conservation. University of British Columbia Zoology Department Web Site. Published 3 Oct 2003. 6 p. http://www.zoology.ubc.ca/ ~etaylor/426www/tutorials/tutpaper.pdf. Accessed 22 Nov 2003.

15. Original source, (Turner) unavailable. Weldrick (see above), citing: Turner, G.F. 2000. What is a fish species? Reviews in Fish Biology and Fisheries 9: 281-297.

16. Ernst Mayr. Understanding Evolution. Trends in Ecology and Evolution. Vol. 14, No. 9 September 1999. p.372-373.

17. Nathan Hendrie, Ed. Neanderthals on Trial. Nova. Airdate: January 22, 2002. Quote from PBS Transcript published at: http://www.pbs.org/ wgbh/nova/transcripts/2902neanderthals.html. Accessed 18 Nov 2003.

18. Evolution Library Web Site. PBS ( Public Broadcasting System). Boston. http:// www.pbs.org/wgbh/evolution/library/05/2/l_ 052_05.html. Accessed 23 Nov 2003.

19. Thor Veen, Thomas Borge, et al. Hybridization and adaptive mate choice in flycatchers. Nature. 3 May 2001. 411, 45 – 50 (2001).

20. P. Calow, Ed. Species Concepts. Encyclopaedia of Ecology and Environmental Management. Blackwell Press. pp. 709-711. Republished with editing by James Mallet. Galton Laboratory, Department of Biology, University College London, at: http://abacus .gene.ucl.ac.uk/jim/Sp/speconc.html. Accessed 22 Nov 2003

22. Entry for “monophyletic”. Merriam- Webster Dictionary Online. While Merriam- Webster is not a scientific dictionary, the author has taken care to ensure that the definition offered here correctly defines the use of the word in the scientific literature .