O U T L O O K O N E VO L U T I O N A N D S O C I E T Y doi:10.1111/j.1558-5646.2011.01511.x
HOW EVOLUTION GENERATES COMPLEXITY WITHOUT DESIGN: LANGUAGE AS AN INSTRUCTIONAL METAPHOR Michael R. Gillings1,2 1
Department of Biological Sciences, Macquarie University, Sydney, NSW 2109 2
E-mail:
[email protected]
Received April 7, 2011 Accepted November 1, 2011 One of the major stumbling blocks to understanding evolution is the difficulty in reconciling the emergence of complexity with the apparently undirected forces that drive evolutionary processes. This difficulty was originally framed as the "Watch and Watchmaker" argument and more recently revived by proponents of "intelligent design." Undergraduates in particular often attribute purpose and forethought as the driving force behind biological phenomena, and have difficulty understanding evolutionary processes. To demonstrate that complexity can arise solely through mutations that fix in populations via natural selection or drift, we can use analogies where processes can be observed across short time frames and where the key data are accessible to those without specialized biological knowledge. The evolution of language provides such an example. Processes of natural selection, mutation, genetic drift, acquisition of new functions, punctuated equilibria, and lateral gene transfer can be illustrated using examples of changing spellings, neologism, and acquisition of words from other languages. The examples presented in this article are readily accessible, and demonstrate to students that languages have dynamically increased in complexity, simply driven by the usage patterns of their speakers.
KEY WORDS:
Education, evolutionary concepts, intelligent design, language.
The concept of evolution by natural selection lies at the heart of understanding living things. Dobzhansky’s famous statement that “Nothing in biology makes sense except in the light of evolution” (Dobzhansky 1964) is perhaps even more important today than it was when he first made it. An understanding of evolutionary principles is critical for dealing with current environmental and social issues, such as global climate change, conservation of biological and genetic diversity, fisheries management, the problem of antibiotic resistance, or the rapid advances being made in biomedical science, to name but a few. Yet precisely at this time, acceptance of evolution may be declining in the United States, where one in three adults firmly rejects the very concept of evolution. In a recent survey of 34 developed countries, public acceptance of evolution was lowest in Turkey, and second lowest in the United States (Miller et al. 2006). C
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The rejection of evolution by citizens of the most economically and scientifically powerful nation in the world should be a cause for deep concern, because it implies that many of its legislators, managers, and decision makers are operating without any appreciation of the pivotal role that natural selection has in molding species and communities. The power and popularity of fundamentalist groups in the United States is clearly part of the reason for the prejudice against evolutionary ideas, but a lack of understanding of how evolution works is also a major factor. Consequently, there has been widespread discussion about how evolutionary ideas might be better taught, and of the challenges that face the teaching of evolution in public schools (Alberts and Labov 2004). A number of recommendations and new pedagogical strategies have arisen out of this discussion (Pennock 2003; Wilson 2005; Nelson 2008).
C 2011 The Society for the Study of Evolution. 2011 The Author. Evolution Evolution 66-3: 617–622
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One of the major barriers to understanding evolution is the difficulty in reconciling the enormous complexity of living organisms with the incremental and apparently undirected process of natural selection and genetic drift. This difficulty partly explains the widespread appeal of ideas such as “intelligent design” (ID). Various studies have shown that children tend to favor explanations involving purpose and intention when accounting for the origin of both animate and inanimate objects (Kelemen and DiYanni 2005), and it may be that such attitudes exhibit considerable inertia unless subjected to scrutiny. However, there has been some unwillingness on the part of teachers and biologists to critically examine ID in their classrooms, on the reasonable grounds that it legitimizes a narrow ideological viewpoint that has already been thoroughly refuted, both legally and scientifically (Good 2003; Pennock 2003; Forrest 2008). The history of ID and whether to explicitly address it when teaching evolution have been widely discussed (Langen 2004; Verhey 2005; Scott and Matzke 2007; Reiss 2009), but the larger issue is that of teleological thinking in general. The problems that confront educators are thus twofold: the specific question of improving student understanding of how evolution proceeds, and the more general question of how to deal with teleological notions of design as an explanation for complexity. These problems could be overcome simultaneously by using an analogy that demonstrates both complexity and evolution in an accessible manner. Evolutionary analogies are useful because they allow exploration of concepts and mechanisms without a detailed knowledge of biological systems (Pramling 2008). The principles of biological evolution have been applied to diverse fields, from culture to cosmology. Whether evolutionary theory is an appropriate paradigm for all these fields is a matter of debate (Derry 2009). However, the analogy between evolution and change in vocabulary is a particularly good one (Whitfield 2008). There is some disagreement whether languages actually arise and change according to evolutionary principles (Fitch et al. 2005; Jackendoff and Pinker 2005). Nevertheless, changes in language are successfully being treated as strictly evolutionary problems, using the tools developed by evolutionary biologists (Croft 2008; Lieberman et al. 2007; Oudeyer et al. 2007; Pagel et al. 2007; Fitch 2008). I propose using the dynamic nature of language as an explanatory metaphor for evolution, and as an instructional device. The ways languages change represent a good example of how complex systems can arise in the absence of design. Importantly, data on how languages change are accessible to those without biological knowledge, and may help in understanding evolution and natural selection. Here I outline examples of how changes in language might be used to illustrate evolutionary principles, thus helping students to understand the mechanism of evolution by natural selection, and to avoid teleological explanations of complexity.
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Comparing the Evolution of Organisms and Languages The similarities between the evolution of organisms and of language lie in the fact that both operate through coded information. In the case of organisms, the code consists of the order of nucleotides in genes, and in the case of spoken or written languages the code is respectively made up of phonemes or letters in words. Their similarities can be summarized as follows. Organisms contain genes, which collectively make up the organism’s genome. Each gene is composed of a sequence of nucleotides whose order specifies the order of amino acids in the protein it encodes. Proteins confer a phenotype on the organism. Mutations alter the nucleotide sequence of genes, which may then alter the amino acid sequence of proteins and consequently may alter the phenotype of the organism carrying the mutation. Languages contain words, which collectively make up the language’s vocabulary. Each written word is composed of a sequence of letters whose order specifies the order of sounds in the spoken word. The spelling or sound of the word confers a meaning to the reader or listener. Changes to the spelling or the pronunciation can alter the perceived meaning of the word.
Demonstrating the Role of Mutation and Selection in Evolutionary Change Evolution proceeds by the accumulation of mutations in genes, followed by natural selection, whereby organisms that possess those mutated genes replicate more successfully. Consequently, the mutated gene eventually becomes the most abundant gene in the population. Some genes are relatively conserved through time because most, if not all, possible mutations are deleterious, whereas other genes evolve more rapidly because the proteins they encode have less-stringent restrictions on their structure and function. These processes can be illustrated by analogy to the changes in spellings and meanings of words, as demonstrated by comparison between early English literature and modern-day parallel texts. For instance, in the Prologue to The Canterbury Tales (Chaucer about 1400), the section dealing with the Clerk partly reads as follows: Of studie took he moost cure and moost heede, Noght o word spak he moore than was neede, And that was seyd in forme and reverence, And short and quyk and ful of hy sentence; Sownynge in moral vertu was his speche, And gladly wolde he lerne and gladly teche.
A modern parallel text (http://www.fordham.edu/halsall/ source/CT-prolog-para.html) translates this as:
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Of study took he utmost care and heed. Not one word spoke he more than was his need; And that was said in fullest reverence And short and quick and full of high good sense. Pregnant of moral virtue was his speech; And gladly would he learn and gladly teach.
Clearly the spelling and usage of words has changed over 600 years, such that parts of the passage are difficult for the modern reader to understand. It should also be clear that there was no entity that planned these changes, but rather that they occurred incrementally across that time period. How and why did these changes occur? First, some words (of, he, and, than, was, that, in) have not changed in spelling or meaning over the last 600 years. These are the equivalent of highly conserved genes. These are words with fundamental meanings that are common in everyday speech and writing, just as conserved genes often encode fundamental and common functions. Changes to the spelling of these words may have been used, but were never adopted by the majority of English writers. Consequently, any changes that did arise in individual writings were selected against; these being the equivalent of lethal mutations whose use might render the word unintelligible. Second, some words now have different spellings than in the prologue, but are still generally understandable (studie, moost, heede, noght, spak, moore, neede). There are various mechanisms that fixed these and other words into their modern spellings (study, most, heed, not, spoke, more, need). One mechanism involves popular usage. The more people spell a word in a certain way, the more likely it is to become the current version of that word. This parallels the process whereby natural selection favors some new alleles, which then come to dominate the gene pool. This process is ongoing in the English language. At the present time, both scientific journals and word processing programs favor (favour) American spellings, so that word forms such as “analyzing” or “hybridizing” now dominate their Anglicized (Anglicised) counterparts, which may soon become extinct. Another mechanism for fixing spellings is the construction of dictionaries that codify and standardize (standardise) spellings. When dictionary spellings are widely adopted, this is the equivalent of a “selective sweep” that runs through the language, eliminating alternatives, and homogenizing spelling conventions. Hence, Webster’s American Dictionary marked the emergence and standardization of American English (see Atkinson et al. 2008). Dictionaries do tend to inhibit subsequent change in languages, unlike the gradual reappearance of genetic diversity after a selective sweep in biological systems. Finally, some words or word meanings in the Prologue have disappeared entirely from modern English usage (sownynge, sentence). These spellings and meanings fell out of favor. This means that they were no longer passed on from speaker to speaker (i.e.,
failed to replicate), and have become extinct. Their functions have been replaced by other fitter and more popular words. It should be apparent that the various rates of change in spelling and usage of particular words over time parallel the changes in nucleotide sequences of particular genes, some genes being highly conserved, others less so, and some becoming extinct.
Evolution by Natural Selection and Neutral Drift Illustrations of evolutionary processes in English are not restricted to spelling conventions, but are also recorded in pronunciation. English speakers from different countries have quite different accents. These accents are acquired by na¨ıve speakers in imitation of those from whom they learn the language. The adoption and retention of a particular pronunciation is then a matter of replication. The pronunciation used by the most individuals is the one most likely to persist and be passed on to new speakers. Even so, pronunciations do change over time (otherwise accents would not evolve). These changes are usually so gradual as to not be noticed over an individual speaker’s lifetime, even when the speaker’s own accent has changed. Nevertheless, ongoing changes in pronunciation can occur even on the timescale of generations (Wells 1999). Over longer time periods, significant and major differences can accumulate. For instance, in Alexander Pope’s (1688–1744) Essay on Criticism, we find the following: Good-nature and good sense must ever join; To err is human, to forgive, divine . . . .
In Pope’s day the words ‘join’ and ‘divine’ were pronounced in the same way, to make a good rhyme. He also uses pairs such as glass-place, lost-boast, and give-believe as rhymes, to give further examples (Baugh and Cable 1978). How did these changes in pronunciation taken place? There may be elements of two evolutionary forces at work here: natural selection and random drift. In some cases, the use of a particular pronunciation provides an advantage in communication (Nathan et al. 1998; Evans and Iverson 2007), and thus would qualify as natural selection. In other cases, pronunciation might drift for no particular reason other than the random adoption of variants. This phenomenon should be particularly apparent in small populations. One might then expect unusual accents to predominate in isolated communities, where communication with neighboring populations was difficult. This very phenomenon led to a proliferation of accents or “dialects” in the British Isles, where each county had a distinctive accent, and the origins of speakers could often be placed within small areas of individual shires (Wells 1970; Baugh and Cable 1978). Exactly this random process of drift is responsible for the accumulation and fixation of neutral (harmless) mutations in genes, and similarly, the role of such random or neutral genetic drift is much
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more apparent in small populations (Kimura and Crow 1964). Over comparatively short time spans, both word pronunciations and gene sequences can change, but there is no entity directing or planning these changes.
Language and Punctuated Equilibrium Evolution has traditionally been represented as a slow and steady process, whereby new species arise gradually out of old populations. This idea is called “phyletic gradualism.” However, the fossil record often reveals long periods of stasis, where no change is apparent in the morphology of species, followed by the geologically instantaneous appearance of new forms. Such occurrences are to be expected when long periods of environmental stability are followed by a rapid change, or when new species arise elsewhere and spread into the area represented by a fossil deposit. This notion of stasis, followed by rapid periods of observed speciation, is known as “punctuated equilibrium” (Eldredge and Gould 1972). It is often difficult to explain this notion, because nonbiologists tend to attribute such bursts of evolution to the influence of a designer. Punctuated equilibrium can readily be illustrated by analogy with contemporary English. For the last century or so, English language and grammar has largely been in stasis, due to the standardization of spelling, the uniformity of English language instruction around the world, and the dominance of the mass media. However, there has recently been a major shift in the language environment, precipitated by the widespread use of electronic communication. The use of the internet, e-mail, and short message services (SMS) as a means of communication has placed a premium on rapid and abbreviated messages. As a result, the face of literacy and its conventions on grammar and spelling are rapidly changing (Merchant 2001). This environmental shift has led to a burst of evolutionary change in English language communication, which will both enrich the language and become a permanent feature of its vocabulary. Sentences such as “hi m8 u k?–sry I 4gt 2 call u lst nyt-y dnt we go see film 2 moz” would have been virtually unintelligible a decade ago, but are now clearly understandable for many English users (Hi mate. Are you okay? I am sorry that I forgot to call you last night. Why don’t we go and see a film tomorrow?) (Prochasson et al. 2007; Plester et al. 2008). “Textisms,” as they are sometimes known, arise through a number of mechanisms including the rebus (b4 = before, C U L8R = see you later), consonant skeleton (txt = text, wnt = want), the acronym (LOL = laugh out loud, WUU2 = what you up to?), or by phonetic reduction (luv = love, nite = night) (Grinter and Eldridge 2003; Prochasson et al. 2007; Plester et al. 2008). The common theme in each of these instances is the reduction of elements of the alphabetical code while retaining the
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essential phonic information. In some ways, this is similar to gene reduction, where nonessential elements can be deleted from genes without affecting the activity of the final gene product (Robertson 2000). New textual inventions do arise in the hands of individual users, but their penetration into the general language and their persistence are a simple matter of replication. If a particular textism has utility and appeal, it will spread to a growing body of users. It may in time enter the lexicon and be formalized as a dictionary entry, and eventually replace the word or phrase it originated from. The history of English contains many examples of this process, for instance no one uses “perambulator” or “omnibus” when “pram” or “bus” will do. In any case, the principle of mutation of existing words, followed by their natural selection according to utility and fitness, is clearly illustrated by the adoption of textisms as an everyday part of the English language. Again, it must be stressed that there is no person or entity that enshrines these changes in the lexicon. Any changes that do occur are simply a result of the use and replication of new word forms by the whole body of English speakers. The end result is that the corpus of English words and phrases has become more complex. Recent work has shown that languages in general may exhibit punctuational bursts during key periods of cultural change (Atkinson et al. 2008).
Horizontal Gene Transfer In multicellular organisms, the acquisition of new gene function is usually a long stepwise process, involving incremental change to existing genes. In contrast, single celled organisms such as bacteria can rapidly gain new functions simply by acquiring genes from unrelated species. This process, known as horizontal gene transfer, is a major driver of bacterial evolution, and is one of the reasons why bacteria adapt to new circumstances so quickly (Ochman et al. 2000). This phenomenon is best illustrated by the rapid appearance of antibiotic-resistant bacterial strains in human pathogens. Resistant strains often arise from bacteria that acquire a resistance gene from some other bacterium in the natural environment (Martinez 2008; Stokes and Gillings 2011). The English language has evolved in the same manner by an ongoing process of acquiring words from other languages, and this may be part of the reason for the adaptability of English. Over time, English has borrowed words from almost every other language group, and has done so frequently and consistently. While English belongs to the Germanic group of languages, half its vocabulary is borrowed from Latin, French, Italian, and other Romance languages. The acquisition of “loanwords” is so common that they are unlikely to be identified as foreign words unless their origin is examined in an etymological dictionary. Some examples from particular languages include: measles, brandy, wagon
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(Dutch); piano, umbrella, volcano (Italian); caravan, divan, sherbet (Persian); or cartoon, dentist, routine (French). These are but a few examples of the huge corpus of loanwords adopted by English (Baugh and Cable 1978). In many cases, these words were adopted because there was no equivalent word in English. The English language has thus gained new functions by acquiring foreign words in a manner analogous to bacteria gaining new functions by acquiring genes from other species. The survival of foreign words in English is dependent on their utility and their adoption by a critical number of speakers. Some loanwords that were common in previous centuries, such as cohibit (restrain) or demit (send away) have subsequently disappeared either through random drift or through their replacement with more popular words (Baugh and Cable 1978). This tendency for English to borrow words is now being reversed, with the penetration of many English words into languages worldwide, driven by the dominance of English speaking countries in areas such as science, the electronic media, and economics. Efforts to legislate against such “horizontal word transfer” have largely failed (Truchot 1997).
Generation of Genetic Diversity by Recombination New genetic diversity can be generated by recombining existing genetic elements. For instance, two genes each with a mutation in a different location can undergo recombination to generate a new gene containing both mutations (and its reciprocal product, containing neither). At a higher level of organization, comparatively small sets of modular genetic units can be assembled in various combinations to generate a vast diversity of potential gene products. This is how the enormous diversity of antibodies is generated, through recombination of a constant scaffold with a relatively small number of genes for different variable regions, to generate the final immunoglobulin genes (Tonegawa 1983). An analogous process occurs when words or word roots are assembled into new words with new meanings. This process is very common in some languages, such as German, but also occurs in English. To give one such example, Frankenstein’s monster is a well-known image, evoking feelings of the horrific, artificial reconstruction of life. Thus the word frankenfood was coined to express protest about genetically engineered crops. Subsequently, the prefix franken has been used with a growing number of suffixes such as -science, -fish, -fruit, and -fries to name a few (Thelwall and Price 2006). In each case, the intention of the word is clear to English speakers even though they may have never heard the word before. The point to be made here is that using a finite number of building blocks, an ever more complex and diverse set of words can be constructed, in exactly the same
way that gene recombination or fusion can generate new gene diversity.
Conclusion The languages we speak have grown from a few simple sounds into compound utterances, and from a handful of symbols into the complex written languages of today. Along the way, pronunciations have changed, spellings and meanings have altered, and words have come and gone. The processes that lead to the generation, survival, and spread of elements of language are very similar to the processes that occur in biological evolution. At the heart of these processes is replication. Unless words, spellings, and pronunciations are repeated, they do not survive, and unless genes are replicated, they too do not survive. It is abundantly clear that languages have become richer and more complex over time, and that this evolution is ongoing. It should also be clear that despite the increasing complexity of languages, there is no entity or body that plans and designs changes in language. Rather, these changes are a result of average usage patterns, analogous to the replication and selection operating in biological systems. These changes continue to occur despite attempts to impose orthodoxy on language (Truchot 1997). Using the evolution of language as a metaphor for explaining biological evolution should aid in explaining evolutionary principles to students. It may be particularly useful for humanities students, who will be more familiar with English literature than with the Biological Sciences, and it should be useful more generally to explain evolutionary principles to wider audiences. Illustrations using modern English, such as “textisms,” or the development of slang, in particular, should find resonance with the younger generation. After presenting the evolution of language as a general metaphor, students should then be encouraged to independently explore further parallels between genes and language. They should also be encouraged to reflect on the potential shortcomings of this metaphor, as should always be considered when using explanations that rely on analogy. Our students will become the teachers, administrators, policy makers, and thinkers of the next generation. Their ability to understand and explain evolution by natural selection will allow them to make rational decisions about biological phenomena, and then to explain these decisions to society in general, perhaps using the very same metaphors we have used here. Improving the biological and evolutionary literacy of all members of society is critical for dealing with many of the pressing environmental issues of our times, because “Nothing in biology makes sense except in the light of evolution” (Dobzhansky 1964). ACKNOWLEDGMENTS Thanks to A. Beattie, B. Curley, D. Frankham, D. Kemp, and M. Westoby for comments on draft versions of this manuscript.
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LITERATURE CITED Alberts, B., and J. B. Labov. 2004. From the national academies: teaching the science of evolution. Cell. Biol. Educ. 3:75–80. Atkinson, Q. D., A. Meade, C. Venditti, S. J. Greenhill, and M. Pagel. 2008. Languages evolve in punctuational bursts. Science 319:588. Baugh, A. C., and T. Cable. 1978. A history of the English language. Routledge & Kegan Paul, London. Croft, W. 2008. Evolutionary linguistics. Annu. Rev. Anthropol. 37:219–234. Derry, J. F. 2009. Darwin in disguise. Trends Ecol. Evol. 24:73–79. Dobzhansky, T. 1964. Biology, molecular and organismic. Am. Zool. 4:443– 452. Eldredge, N., and S. Gould. 1972. Punctuated equilibrium: an alternative to phyletic gradualism. Pp. 82–115 in T. Schopf, ed. Models in paleobiology. Freeman, Cooper & Co. San Francisco, CA. Evans, B. G., and P. Iverson. 2007. Plasticity in vowel perception and production: a study of accent change in young adults. J. Acoust. Soc. Am. 121:3814–3826. Fitch, W. T. 2008. Glossogeny and phylogeny: cultural evolution meets genetic evolution. Trends Genet. 24:373–374. Fitch, W. T., M. D. Hauser, and N. Chomsky. 2005. The evolution of the language faculty: clarifications and implications. Cognition 97:179–210. Forrest, B. 2008. Still creationism after all these years: understanding and counteracting intelligent design. Integr. Comp. Biol. 48:189–201. Good, R. 2003. Evolution and creationism: one long argument. Am. Biol. Teach. 65:512–516. Grinter, R., and M. Eldridge. 2003. Wan2tlk?: everyday text messaging. In Proceedings of the SIGCHI conference on human factors in computing systems. ACM, Ft. Lauderdale, FL. Jackendoff, R., and S. Pinker. 2005. The nature of the language faculty and its implications for evolution of language (reply to Fitch, Hauser, and Chomsky). Cognition 97:211–225. Kelemen, D., and C. DiYanni. 2005. Intuitions about origins: purpose and intelligent design in children’s reasoning about nature. J. Cognit. Dev. 6:3–31. Kimura, M., and J. F. Crow. 1964. The number of alleles that can be maintained in a finite population. Genetics 49:725–738. Langen, T. A. 2004. What is right with ‘teaching the controversy’? Trends Ecol. Evol. 19:114–115. Lieberman, E., J.-B. Michel, J. Jackson, T. Tang, and M. A. Nowak. 2007. Quantifying the evolutionary dynamics of language. Nature 449:713– 716. Martinez, J. L. 2008. Antibiotics and antibiotic resistance genes in natural environments. Science 321:365–367. Merchant, G. 2001. Teenagers in cyberspace: an investigation of language use and language change in internet chatrooms. J. Res. Read. 24:293–306. Miller, J. D., E. C. Scott, and S. Okamoto. 2006. Science communication: public acceptance of evolution. Science 313:765–766. Nathan, L., B. Wells, and C. Donlan. 1998. Children’s comprehension of unfamiliar regional accents: a preliminary investigation. J. Child Lang. 25:343–365.
622
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Nelson, C. E. 2008. Teaching evolution (and all of biology) more effectively: strategies for engagement, critical reasoning, and confronting misconceptions. Integr. Comp. Biol. 48:213–225. Ochman, H., J. G. Lawrence, and E. A. Groisman. 2000. Lateral gene transfer and the nature of bacterial innovation. Nature 405:299–304. Oudeyer, P.-Y., F. Kaplan, and ric. 2007. Language evolution as a Darwinian process: computational studies. Cognitive Processing 8:21–35. Pagel, M., Q. D. Atkinson, and A. Meade. 2007. Frequency of word-use predicts rates of lexical evolution throughout Indo-European history. Nature 449:717–720. Pennock, R. T. 2003. Creationism and intelligent design. Annu. Rev. Genom. Hum. Genet. 4:143–163. Plester, B., C. Wood, and V. Bell. 2008. Txt msg n school literacy: does texting and knowledge of text abbreviations adversely affect children’s literacy attainment? Literacy 42:137–144. Pramling, N. 2008. The role of metaphor in Darwin and the implications for teaching evolution. Sci. Edu. 93:535–547. Prochasson, E., C. Viard-Gaudin, and E. Morin. 2007. Language models for handwritten short message services. Ninth International Conference on Document Analysis and Recognition, 2007. ICDAR 2007, 1:83–87. Reiss, M. J. 2009. The relationship between evolutionary biology and religion. Evolution 63:1934–1941. Robertson, H. M. 2000. The Large srh family of chemoreceptor genes in caenorhabditis nematodes reveals processes of genome evolution involving large duplications and deletions and intron gains and losses. Genome Res. 10:192–203. Scott, E. C., and N. J. Matzke. 2007. Biological design in science classrooms. Proc. Natl. Acad. Sci. U.S.A. 104:8669–8676. Stokes, H. W., and M. R. Gillings. 2011. Gene flow, mobile genetic elements and the recruitment of antibiotic resistance genes into Gram-negative pathogens. FEMS Microbiol. Rev. 35:790–819. Thelwall, M., and L. Price. 2006. Language evolution and the spread of ideas on the Web: a procedure for identifying emergent hybrid word family members. J. Am. Soc. Inf. Sci. Technol. 57:1326–1337. Tonegawa, S. 1983. Somatic generation of antibody diversity. Nature 302:575– 581. Truchot, C. 1997. The spread of English: from France to a more general perspective. World Englishes 16:65–76. Verhey, S. D. 2005. The fefect of engaging prior learning on student attitudes toward creationism and evolution. BioScience 55:996–1003. Wells, J. C. 1970. Local accents in England and Wales. J. Linguistics 6:231– 252. ———. 1999. British English pronounciation differences: a changing scene. J. Int. Phonetic Assoc. 29:33–50. Whitfield, J. 2008. Across the curious parallel of language and species evolution. PLoS Biol. 6:e186. Wilson, D. S. 2005. Evolution for everyone: how to increase acceptance of, interest in, and knowledge about evolution. PLoS Biol. 3:e364.
Associate Editor: T. Meagher
