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.
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.
8. Steven Pinker. How the Mind Works.
New York: W.W. Norton & Co., 1997. 660 p.
9. Philippe Lherminer and Michel
Solignac. "L’espèce: définitions d’auteurs". C
.R. Acad. Sci. Paris, Sciences de la vie /
Life Sciences 323 (2000) 153–165.
10. Solignac’s name is listed as a
contact for a bulletin associated with the
Société Française de Génétique. SEE: http://
www.infobiogen.fr/services/chromcancer/
Associations/sfg.html. Accessed 21 Nov 2003.
11. Translation accomplished with help
from Altavista’s Babelfish free online
translation service. www.babelfish.altavista
.com. Accessed 21 Nov 2003. Additional
Translation by my own knowledge.
12. Web site of the Helicobacter
Foundation. Accessed 19 Nov 2003, http://
www.helico.com/, "Treatments" section.
13. Ian Chopra, Alexander J. O'Neill and
Keith Miller. "The Role of Mutators in the
Emergence of Antibiotic-Resistant Bacteria."
Drug Resistance Updates. Volume 6, Issue 3.
June 2003. Pages 137-145.
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
.
(c)2003, ameriwire