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Alleged Instances of Observed Speciation — Evolution’s Smoking Gun Is Still Missing

William A. Dembski

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Editor’s note: William Dembski and Jonathan Wells, leading figures in the intelligent design movement, are co-authors of The Design of Life: Discovering Signs of Intelligence in Biological Systems. Originally published by the Foundation for Thought and Ethics, this path-breaking work explores some of the most important arguments for intelligent design in biology. To celebrate the launch of Foundation for Thought & Ethics Books as an imprint of Discovery Institute Press, we will be publishing excerpts from the book here at Evolution News. Through July 8, we will also be making the book available for only $10 — that’s more than a 70 percent discount, and it includes both the full-color hardcover and an accompanying CD with additional materials. If you haven’t read this classic book, now is your chance! Order now, because this special discount won’t last long.

Despite the absence of evidence for the ability of reproductive isolation to harness the mechanisms of genetic change and thereby to produce new species, some Darwinists still claim that there are many instances of observed speciation.1 But most of these alleged instances are in fact analyses of existing species that are used to defend one or another theory of how they might have originated — such as the theories of allopatric and sympatric speciation, or the bottleneck and founder effects. Analyzing existing species to support one or another theory of speciation, however, is not the same as observing speciation in action.

There actually are some confirmed cases of observed speciation, but these are due to an increase in the number of chromosomes, or “polyploidy.” Such cases, however, are limited to flowering plants and result from hybridizing two species to form a new one.2 Furthermore, according to evolutionary biologist Douglas Futuyma, speciation that results from polyploidy (also called “secondary speciation”) “does not confer major new morphological characteristics . . . [and] does not cause the evolution of new genera” or higher taxonomic levels.3 Darwinian evolution, by contrast, depends on taking a single existing species and splitting off new species from it (called “primary speciation”), which then in turn diverge and split, diverge and split, over and over again. Only primary speciation, and not secondary speciation, could produce the branching-tree pattern required by Darwinian evolution.

Of the many instances of observed speciation alleged by Darwinists, only five come close to claiming observed primary speciation. First, in 1962, from a single lab population of Drosophila (fruit flies), J.M. Thoday and J.B. Gibson bred only those flies with the highest and lowest number of bristles (the insect equivalent of hair). After 12 generations, the experiment produced two populations that not only differed in bristle number but also showed “strong though partial isolation.” Yet Thoday and Gibson not did claim to have produced a new species. Furthermore, other laboratories were unable to reproduce their results.4

Second, in 1958 Theodosius Dobzhansky and Olga Pavlovsky started a laboratory population of fruit flies using a single female of a strain from Colombia. Crosses between that fly and several other strains produced fertile hybrids in the laboratory. In 1963, however, similar crosses yielded sterile hybrids. In 1966, Dobzhansky and Pavlovsky concluded that the strain they had introduced in 1958 had become “a new race or incipient species . . . in the laboratory at some time between 1958 and 1963.”5 But Coyne and Orr, writing in 2004, suspect their results were “due to contamination of cultures by other subspecies.”6 In any case, Dobzhansky and Pavlovsky reported only a “new race or incipient species,” not a new species.

Third, in 1964 biologists collected some marine worms in Los Angeles Harbor and used them to start a lab colony. When they went back to the same location 12 years later, the original population had disappeared, so they collected worms from two other locations several miles away, and these were used to start two new lab colonies. In 1989, researchers found that the two new colonies could interbreed with each other but not with the Los Angeles Harbor colony that had been started 25 years earlier. In 1992, James Weinberg and his colleagues called this an observed instance of “rapid speciation,” based on the assumption that the original colony had “speciated in the laboratory, rather than before 1964.”7 A few years later, however, tests performed by Weinberg and two others showed that the original population was “already a species different from” the two new colonies “at the time when it was originally sampled in 1964.”8 No speciation had occurred.

Fourth, in 1969 E. Paterniani reported an experiment on maize in which breeding was permitted only between individuals possessing two extremes of a particular trait. Paterniani noted the development of “an almost complete reproductive isolation between two maize populations” but did not claim that a new species had been produced.9

Fifth and last, in the 1980s William R. Rice and George W. Salt subjected a population of fruit flies to eight different environments. They then took the flies that preferred the two most extreme environments and allowed only them to breed. Within thirty generations the flies had sorted themselves into two populations that did not interbreed. Even so, Rice and Salt did not claim to have produced two new species. More modestly, they believed only that “incipient speciation” had occurred.10

So, of the five alleged instances of observed primary speciation, only one (Weinberg’s) claimed to have observed actual speciation — and it was later retracted. The other four (one of which could not be reproduced by other scientists and one of which was not controlled for contamination) claimed only some degree of reproductive isolation or “incipient speciation.”

What is “incipient speciation”? Darwin wrote: “According to my view, varieties are species in the process of formation, or are, as I have called them, incipient species.”11 But how can we possibly know whether two varieties (or races) are in the process of becoming separate species? St. Bernards and Chihuahuas are two varieties of dog that cannot interbreed naturally, but they are members of the same species. Maybe they are on their way to becoming separate species, or maybe not. The two varieties of Rhagoletis pomonella described in the previous section do not interbreed in the wild, but they look exactly alike and are still capable of mating in the laboratory. Like different breeds of dogs, they are still members of the same species. Calling them “incipient species” amounts to no more than a prediction that they will eventually become separate species. But maybe they won’t. Short of waiting to see whether the prediction comes true, we can’t really know. And given our limited lifespans, we don’t have time to wait (at least not by conventional evolutionary timescales).

Darwinists therefore discount the lack of observed instances of primary speciation by saying that it takes too long to observe them. But if it takes too long for scientific investigators to observe primary speciation, then there will never be anything more than indirect evidence for the first and most important step in Darwinian evolution. Darwinists claim that all species have descended from a common ancestor through variation and selection. But until they can point to a single observed instance of primary speciation, their claim must remain an unverified assumption, not an observed scientific fact. University of Bristol bacteriologist Alan H. Linton made precisely this point when in 2001 he assessed the direct evidence of speciation: 

None exists in the literature claiming that one species has been shown to evolve into another. Bacteria, the simplest form of independent life, are ideal for this kind of study, with generation times of twenty to thirty minutes, and populations achieved after eighteen hours. But throughout 150 years of the science of bacteriology, there is no evidence that one species of bacteria has changed into another. . . . Since there is no evidence for species changes between the simplest forms of unicellular life, it is not surprising that there is no evidence for evolution from prokaryotic [e.g., bacterial] to eukaryotic [e.g., plant and animal] cells, let alone throughout the whole array of higher multicellular organisms.12

So except for secondary speciation, which is not what Darwin’s theory needs, there are no observed instances of the origin of species. As evolutionary biologists Lynn Margulis and Dorion Sagan wrote in 2002: “Speciation, whether in the remote Galápagos, in the laboratory cages of the drosophilosophers, or in the crowded sediments of the paleontologists, still has never been directly traced.”13 Evolution’s smoking gun is still missing.


(1) See Catherine A. Callaghan, “Instances of Observed Speciation,” The American Biology Teacher 49 (1987): 34–36; Joseph Boxhorn, “Observed Instances of Speciation,” The Talk.Origins Archive, September 1, 1995, available online (last accessed January 9, 2007); Chris Stassen, James Meritt, Annelise Lilje, and L. Drew Davis, “Some More Observed Speciation Events,” The Talk.Origins Archive, 1997, available online (last accessed January 9, 2007).

(2) See Justin Ramsey and Douglas W. Schemske, “Neopolyploidy in Flowering Plants,” Annual Review of Ecology and Systematics 33 (2002): 589–639; D. M. Rosenthal, L. H. Rieseberg, and L. A. Donovan, “Re-creating Ancient Hybrid Species’ Complex Phenotypes from Early-Generation Synthetic Hybrids: Three Examples Using Wild Sunflowers,” The American Naturalist 166(1) (2005): 26–41.

(3) Douglas J. Futuyma, Evolution (Sunderland, Mass.: Sinauer Associates, 2005), 398.

(4) J.M. Thoday and J. B. Gibson, “Isolation by Disruptive Selection,” Nature 193 (1962): 1164–1166. J. M. Thoday and J. B. Gibson, “The Probability of Isolation by Disruptive Selection,” The American Naturalist 104 (1970): 219–230. Coyne and Orr, Speciation, 138.

(5) Theodosius Dobzhansky and Olga Pavlovsky, “Spontaneous Origin of an Incipient Species in the Drosophila Paulistorum Complex,” Proceedings of the National Academy of Sciences 55 (1966): 727–733.

(6) Coyne and Orr, Speciation, 138.

(7) James R. Weinberg, Victoria R. Starczak, and Daniele Jörg, “Evidence for Rapid Speciation Following a Founder Event in the Laboratory,” Evolution 46 (1992): 1214–1220.

(8) Francisco Rodriquez-Trelles, James R. Weinberg, and Francisco J. Ayala, “Presumptive Rapid Speciation After a Founder Event in a Laboratory Population of Nereis: Allozyme Electrophoretic Evidence Does Not Support the Hypothesis,” Evolution 50 (1996): 457–461.

(9) E. Paterniani, “Selection for Reproductive Isolation Between Two Populations of Maize, Zea mays L.,” Evolution 23 (1969): 534–547.

(10) William R. Rice and George W. Salt, “Speciation via Disruptive Selection on Habitat Preference: Experimental Evidence,” The American Naturalist 131 (1988): 911–917. See also Coyne and Orr, Speciation, 138–141.

(11) Darwin, Origin of Species, 111.

(12) Alan Linton, “Scant Search for the Maker,” The Times Higher Education Supplement (April 20, 2001), Book Section, 29, available online with registration (last accessed January 9, 2007).

(13) Lynn Margulis and Dorion Sagan, Acquiring Genomes: A Theory of the Origins of Species (New York: Basic Books, 2002), 32.

Photo credit: © viperagp — stock.adobe.com.

William A. Dembski

Board of Directors, Discovery Institute
A mathematician and philosopher, Bill Dembski is the author/editor of more than 20 books as well as the writer of peer-reviewed articles spanning mathematics, engineering, philosophy, and theology. A past philosophy professor, he retired in 2014 from active research and teaching in intelligent design (ID) to focus on the connections between freedom, technology, and education — specifically, how education helps to advance human freedom with the aid of technology. Bill Dembski is presently an entrepreneur who builds educational software and websites. He lives in Iowa.