Inheritance in cultural evolution

I recently reviewed a book anthology devoted to the application of phylogenetic methods in archaeology (see List 2016, PDF here). This book, entitled Cultural Phylogenetics: Concepts and Applications in Archaeology, edited by Larissa Mendoza Straffon (2016), assembles eight articles by scholars who discuss or illustrate the application of phylogenetic approaches in different fields of anthropology and archaeology.

The volume presents a rich collection of different approaches, covering various topics ranging from the evolution of skateboards (Prentiss et al.) to the spread of the potter's wheel (Knappett). The articles dealing with theoretical questions range from historical accounts of tree-thinking in biology and anthropology (Kressing and Krischel) to an overview of the impact of Darwinian thinking on archaeology and anthropology (Rivero). Although I missed a golden thread when reading the eight articles of the volume, it is definitely worth a read for those interested in evolutionary approaches in a broader sense, as most articles explicitly reflect differences and commonalities between biological and cultural evolution, providing concrete insights into the challenges that archaeologists face when trying to promulgate quantitative approaches.

It is clear that evolution in the general sense is much broader than merely evolution in biology, as I have often tried to illustrate in this blog when showing how phylogenetic approaches can be applied in linguistics. Provided that descent with modification holds — in a broader sense — also for cultural artifacts, it is obvious to search for fruitful analogies between biological and cultural evolution, in order to profit from methodological transfer in disciplines like anthropology and archaeology. It is also clear, however, that certain analogies between biological evolution and evolution in other fields should be considered with great care. Even in linguistics, this is clearly evident, and I have pointed to this problem in the past (see Productive and unproductive analogies...). The goal cannot be a to try to press biological methods into the anthropological template. Instead, we have to rigorously test our proposed analogies, and adapt the biological methods to our needs if necessary.

What surprised me when reading the book was that the majority of the articles did not really seem to care about the crucial differences between biological and cultural evolution, but rather tried to fit the feet and heels of cultural evolution into biology's shoes. Tree thinking dominated most of the articles (with Knappett as a notable exception), and the scholars tried hard to find a clear distinction between vertical and lateral inheritance in cultural evolution. While it is clear that this distinction is the basis for phylogenetic tree applications, where patterns that do not fit a tree are explained as instances of homoplasy or lateral transfer, it is by no means clear why one would go through all the pain to identify these patterns in cultural evolution.

Consider, as an example, the evolution of skateboards. At some point in the history of mankind (some late point!), people decided to put wheels on a board and to do artistic tricks with it. Later, other people merchandised this idea, and started to sell those boards with wheels. Later on, other companies jumped on the bandwagon and started to produce their own brands, thus instigating a fight for the "best" model for a certain kind of clientel. In all of these cases, ideas for design were clearly taken among groups of people, further modified by specific needs or trends, until the current variety of skateboards arose. But which of these ideas were transferred vertically, and which ideas were transferred laterally? Can we identify processes of "speciation" in skateboard evolution, during which new brands were born?

In biology and linguistics we have the clear-cut criteria of interfertility and intelligibility. They cause us enough problems, given that we have ring species in biology and dialect chains in linguistics, but at least they give us some idea how to classify a given exemplar as belonging to a certain group. But what is the counterpart in the evolution of skateboards? Their brand? Their shape? Their users? The analogy simply does not hold. We have neither vertical nor lateral transfer in topics such as skateboard evolution. All we have is a before and an after— a complex network in which objects were constantly recreated and modified, be it based on ideas that were inspired by other objects or people, or independently developed. It seems completely senseless to search for a distinction between vertical and lateral patterns here, as it is not even clear to what degree we are actually dealing with decent with modification.

It seems to me that the problem of inheritance needs to be addressed in cultural evolution before any further quantitative applications using tree-building methods are carried out. Given that ideas can easily be develop independently, the crucial question for studies of cultural evolution is whether similar ideas can be shown to share a common history. It is (as David mentioned in earlier in a blog post on False analogies between anthropology and biology) the general problem of homology that does not seem to be solved in most studies on cultural evolution. Here, linguistics has generally fewer problems, given that linguists have developed methods to test whether two words are homologous. In cultural evolution, however, the assessment of homology is far from being obvious.

I think that cultural evolution studies such as the ones presented in the book would generally profit from network approaches. By network approaches, I do not necessarily mean evolutionary networks (in the sense of Morrison 2011), as the problem of inheritance is difficult to solve. Instead, I am thinking of exploratory data analysis using phylogenetic networks (Morrison 2011), or some version of similarity networks (Bapteste et al. 2012). Phylogenetic network approaches are frequently used in biology, and are now also very popular in linguistics. Similarity networks are more common in biology, but we have carried out some promising studies of linguistic data (List et al. 2016). As all of these approaches are exploratory and very flexible regarding the data that is fed to them, they might offer new possibilities for exploratory studies on cultural evolution.

References

• Bapteste, E., P. Lopez, F. Bouchard, F. Baquero, J. McInerney, and R. Burian (2012) Evolutionary analyses of non-genealogical bonds produced by introgressive descent. Proceedings of the National Academy of Sciences 109.45. 18266-18272.
• Knappett, C. (2016) Resisting Innovation? Learning, Cultural Evolution and the Potter’s Wheel in the Mediterranean Bronze Age. In: Mendoza Straffon, L. (ed.) Cultural Phylogenetics: Concepts and Applications in Archaeology. Springer International Publishing: Cham and Heidelberg and New York and Dordrecht, pp. 97-111.
• List, J.-M., P. Lopez, and E. Bapteste (2016) Using sequence similarity networks to identify partial cognates in multilingual wordlists. In: Proceedings of the Association of Computational Linguistics 2016 (Volume 2: Short Papers), pp. 599-605.
• List, J.-M. (2016) [Review of] Cultural Phylogenetics: Concepts and Applications in Archaeology; edited by Larissa Mendoza Straffon. Systematic Biology (published online before print).
• Morrison, D. (2011) An Introduction to Phylogenetic Networks. RJR Productions: Uppsala.
• Prentiss, A., M. Walsh, R. Skelton, and M. Mattes (2016) Mosaic evolution in cultural frameworks: skateboard decks and projectile points. In: Mendoza Straffon, L. (ed.) Cultural Phylogenetics: Concepts and Applications in Archaeology. Springer International Publishing: Cham and Heidelberg and New York and Dordrecht, pp. 113-130.
• Rivero, D. (2016) Darwinian archaeology and cultural phylogenetics. In: Mendoza Straffon, L. (ed.) Cultural Phylogenetics: Concepts and Applications in Archaeology. Springer International Publishing: Cham and Heidelberg and New York and Dordrecht, pp. 43-72.
• Mendoza Straffon, L. (2016) Cultural Phylogenetics. Concepts and Applications in Archaeology. Springer International Publishing: Cham.

Can biologists learn from linguists?

Of course they can. Biologists who know nothing about linguistics can learn a lot about linguistics from linguists, including the most nerdy, the most boring, and the most interesting things.

However, it is obvious that the question in the title of this post implies a different object of learning, and a more precise title would have been "Can biologists learn about evolution from linguists?" As a linguist, I would of course also provide an affirmative answer, but I doubt that most biologists would agree. At the moment, we have a situation in which the majority of interdisciplinary papers state that linguists can learn from biologists. The opposite, that biologists can learn from linguistics, can rarely be found.

Biology to linguistics

An abundance of analogies between biology and linguistics has been noticed so far, and new analogies are regularly being proposed. When looking at the analogies that have been made so far, we find that most of them have never been really followed up. Languages, for example, have been compared with organisms (Schleicher 1848: 16f), species (Pagel 2009), microbes (Nelson-Sathi et al. 2011, List et al. 2014), mutualist symbionts (van Driem 2004), and populations (Mufwene 2001). Words have been compared with cells (Schleicher 1863: 23f), amino-acids (Zwick 1978), codons (Enguix et al. 2012, Jakobson 1973) and genes (Pagel 2009. Sounds (phonemes) have been compared with nucleic bases (Hruschka et al. 2015, Enguix et al. 2012) and atoms (Zwick 1978). Only a small number of these analogies have received broader attention, many have been rejected quickly after they were first proposed, and only recently has an explicit transfer of methods and models been initiated (Atkinson and Gray 2005).

The tenor of most recent studies, especially in the literature published during the past one to two decades, is often that we finally realize that language evolution is largely the same as biological evolution,  surprisingly (for a recent account in this direction, see Pagel 2016). As a result, it is claimed that we can easily use biological methods to study language evolution. We need to use them, since linguistics is in a poor state with no methods of its own, and linguists have never quantified what they know about the history of their languages. Then, finally, with these new methods developed in biology, we see light at the end of the tunnel, and we can draw nice trees of our languages and see how they evolved into their current shape.

I am in complete favour of increasing the objectivity in historical linguistics, making it a more data-driven and a more transparent discipline. I also advocate interdisciplinary transfer of methods and models, and there are quite a few things we can actually learn from biologists in linguistics. What I do not like is this tone, which suggests that biology is the discipline that saved linguistics, waking it up from its 200-year-long sleep in the ivory tower. At the same time, I also do not like the horror-scenarios in traditional linguistics, which state that quantitative approaches would deprive our discipline of all its wit (see the figure below as a not too serious attempt to visualize these two perspectives). In this context, it is quite interesting to look back in history and to recapitulate what actually happened.

The biological storm of bits and bytes: Will it destroy the ivory tower of historical linguistics
or ultimately help it to shine with a new gloss?

The discipline of historical linguistics is about 200 years old, starting with the legendary scholarly work of poeple like Rasmus Rask (Rask 1818), Jakob Grimm (Grimm 1822), and Franz Bopp (Bopp 1816). Using family trees to model language history goes back to the 17th century, pre-dating the first networks in biology by one century (see David's overview in Morrison 2016). The first explicit alignments showing homologous sounds across words occur at least as early as the beginning of the 20th century (Dixon and Kroeber 1919), cladistic frameworks date back to the second half of the 19th century (Brugmann 1886), and even algorithms for tree reconstruction based on distance data occur back in the 1960s (Dyen's comment in Hymes 1960).

The discipline of historical linguistics can look back on a remarkable history of excellent scholarship. Thanks to this scholarship, we have gained invaluable insights, not only into the history of the world's languages, but also into the mechanisms that trigger linguistic diversity. It is undeniable that methods from evolutionary biology have given us some fresh insights during the past 20 years, but their actual influence is often exaggerated. On the one hand, our experience (since the quantitative turn in historical linguistics) shows that in most cases we cannot use biological methods to analyze our data directly. Instead, we need to carefully adapt them to our needs in order to get the best out of them (as I have tried to show in more detail in List 2014).

On the other hand, there is no example during the past 20 years, that I would know of, where the modern biological methods have really revolutionized our insights into language history. They have undeniably shifted our attention towards data and quantification. They have exposed weak spots, in our argumentation, and they have forced us to restate questions that we had forgotten to ask. But no new language family has been detected, no deeper genealogies between existing languages have been proposed, and no deeper insights into human prehistory have been achieved by the use of biological methods alone. Historical linguistics has profited from evolutionary biology, but not as a small oasis in the desert that was given water and seeds by the lords of bits and bytes, but as a discipline in which scholars learned to make active and critical use of interdisciplinary approaches.

Linguistics to biology

This brings us back to the question of the title. Can biology learn from linguistics? It has done so undoubtedly in the past. Tree-drawing in biology, for example, was popularized by Ernst Haeckel who himself became influenced by the linguist August Schleicher (Sutrop 2012: 300). In the early days of genetics, a multitude of metaphors were borrowed from linguistics to describe biological phenomena with words like "alphabet", "word" (Gamov 1954), or "translation" (Crick 1959).

While not all biologists have been in favor of this tendency (see, for example, Shanon 1978), and the borrowing of terms does not necessarily imply methodological transfer, we also find examples for the explicit transfer of methods and theories from the linguistic to the biological domain. As an example, consider the theory of formal grammar (Chomsky 1959) which still plays a very important role in addressing certain problems in bioinformatics (Searls 1997), like RNA folding and protein structure analysis. Biological textbooks on sequence comparison still tend to include a chapter on formal grammars and their application in biology (Durbin et al. 1998).

Biology could also profit from linguistic insights in the future, and this becomes a bit clearer when we recall, what Schleicher mentioned 150 years a go (and what has been obviously forgotten since then):

Observing how new forms descend from old ones can be done more straightforwardly and in a larger scale in linguistics than in biology. For once, the linguists have an advantage over the natural scientists. (Schleicher 1863: 18, my translation)

The advantage of linguistics, which Schleicher points out, is the availability of very concrete, very detailed, very valuable data in linguistics. This data allows us to see evolutionary forces in a detailed way of which biologists can only dream. Written sources allow us to trace the history of whole language families like Romance (and to some extent also Chinese dialects) from their ancestral speech varieties down to today. Language change is fast enough to allow us to investigate it in action. Recent topics in biology, like the importance of invoking a system perspective in evolution, have been long since debated and discussed in linguistics (Tynjanow and Jakobson 1928, since they are so much easier to detect.

In the past, when I worked intensively on the implementation of the Minimal Lateral Network method (Dagan and Martin 2007, Dagan et al. 2008) on linguistic data (List et al. 2014, List 2015), I stumbled upon numerous examples showing the limits of tree topology as a predictor for lateral transfer events. Given that the same necessarily also holds for lateral gene transfer, I was asking myself whether these false positives and the false negatives in the analyses would simply not matter due to the large amount of data in biology, or whether it was ignored due to the lack of good data for algorithmic evaluation. Later, when I read David's post on Tardigrades and phylogenetic networks, where he pointed to two analyses on the same data that explained them once with lateral gene transfer (Boothby et al. 2015) and once with errors in the data (Koutsovoulos 2015), I became aware of the strong advantage of my linguistic data, since I could test it against written records, tracing the history of words through centuries, thus being able to spot errors immediately when looking up a data point.

The detail of our data in linguistics is both a blessing and a curse. It enables us to write detailed word histories without ever having heard of tree reconciliation methods. On the other hand, it seduces us to get lost in details, forgetting about the bigger picture, and the bigger questions that we could ask, if this data was properly digitized and formalized. In this regard, historical linguistics still needs to learn from biology, as we have failed to turn historical linguistics into a modern, data-driven discipline. With more and more detailed data becoming available, however, the day will come when Schleicher is proven right, and when biologists can learn from linguists about evolution.

References

• Atkinson, Q. and R. Gray (2005): Curious Parallels and Curious Connections: Phylogenetic Thinking in Biology and Historical Linguistics. Syst. Biol. 54.4. 513-526.
• Boothby, T., J. Tenlen, F. Smith, J. Wang, K. Patanella, E. Osborne Nishimura, S. Tintori, Q. Li, C. Jones, M. Yandell, D. Messina, J. Glasscock, and B. Goldstein (2015): Evidence for extensive horizontal gene transfer from the draft genome of a tardigrade. Proceedings of the National Academy of Sciences 112.52. 15976-15981.
• Bopp, F. (1816): Über das Conjugationssystem der Sanskritsprache in Vergleichung mit jenem der griechischen, lateinischen, persischen und germanischen Sprache. Nebst Episoden des Ramajan und Mahabharas in genauen metrischen Uebersetzungen aus dem Originaltexte und einigen Aabschnitten aus den Veda’s. Andreäische Buchhandlung: Frankfurt am Main.
• Brugmann, K. (1886): Einleitung und Lautlehre: Vergleichende Laut-, Stammbildungs- und Flexionslehre der Indogermanischen Sprachen [Introduction and Phonetics. Comparative Studies of Sound Systems, Stem Formations, and Inflexion Systems of Indo-European Languages]. Grundriß der vergleichenden Grammatik der indogermanischen Sprachen [Foundations of the comparative grammar of the Indo-European languages], vol. 1. Walter de Gruyter, Berlin, Leipzig.
• Chomsky, N. (1959): On certain formal properties of grammars. Information and Control 2. 137-167.
• Crick, F. (1959): The present position of the coding problem. The Brookhaven Symposia in Biology 12. 35-39.
• Dagan, T. and W. Martin (2007): Ancestral genome sizes specify the minimum rate of lateral gene transfer during prokaryote evolution. Proceedings of the National Academy of Sciences 104.3. 870-875
• Dagan, T., Y. Artzy-Randrup, and W. Martin (2008): Modular networks and cumulative impact of lateral transfer in prokaryote genome evolution. Proceedings of the National Academy of Sciences 105.29. 10039-10044.
• Dixon, R. and A. Kroeber (1919): Linguistic families of California. University of California Press: Berkeley.
• van Driem, G. (2004): Language as organism: A brief introduction to the Leiden theory of language evolution. In: Lin, Y.-c., F.-m. Hsu, C.-c. Lee, J.-S. Sun, H.-f. Yang, and D.-a. Ho (eds.): Studies on Sino-Tibetan Languages. Academia Sinica: Taipei. 1-9.
• Durbin, R., S. Eddy, A. Krogh, and G. Mitchinson (2002): Biological sequence analysis. Probabilistic models of proteins and nucleic acids. Cambridge University Press: Cambridge.
• Enguix, G. and M. Jimenez-Lopez (2012): Natural language and the genetic code: From the semiotic analogy to biolinguistics. In: Proceedings of the 10th World Congress of the International Association for Semiotic Studies (IASS/AIS). 771-780.
• Gamov, G. (1954): Possible relation between deoxyribonucleic acid and protein structures. Nature 173. 318.
• Grimm, J. (1822): Deutsche Grammatik. Dieterichsche Buchhandlung: Göttingen.
• Hruschka, D., S. Branford, E. Smith, J. Wilkins, A. Meade, M. Pagel, and T. Bhattacharya (2015): Detecting regular sound changes in linguistics as events of concerted evolution. Curr. Biol. 25.1. 1-9.
• Hymes, D. (1960): Lexicostatistics so far. Curr. Anthropol. 1.1. 3-44.
• Jakobson (1973): Six lectures on sound and meaning. Cambridge and London: MIT Press
• Koutsovoulos, G., S. Kumar, D. Laetsch, L. Stevens, J. Daub, C. Conlon, H. Maroon, F. Thomas, A. Aboobaker, and M. Blaxter (2015): The genome of the tardigrade Hypsibius dujardini. bioRxiv.
• List, J.-M., S. Nelson-Sathi, H. Geisler, and W. Martin (2014): Networks of lexical borrowing and lateral gene transfer in language and genome evolution. Bioessays 36.2. 141-150.
• List, J.-M. (2014): Sequence comparison in historical linguistics. Düsseldorf University Press: Düsseldorf.
• List, J.-M. (2015): Network perspectives on Chinese dialect history. Bull. Chin. Linguist. 8. 42-67.
• Morrison, D.A. (2016): Genealogies: Pedigrees and phylogenies are reticulating networks not just divergent trees. Evol. Biol. in press.
• Mufwene, S. (2001): The ecology of language evolution. Cambridge University Press: Cambridge.
• Nelson-Sathi, S., J.-M. List, H. Geisler, H. Fangerau, R. Gray, W. Martin, and T. Dagan (2011): Networks uncover hidden lexical borrowing in Indo-European language evolution. Proc. R. Soc. London, Ser. B 278.1713. 1794-1803.
• Pagel, M. (2009): Human language as a culturally transmitted replicator. Nature Reviews. Genetics 10. 405-415.
• Pagel, M. (2016): Darwinian perspectives on the evolution of human languages. Psychonomic Bulletin & Review . 1-7.
• Rask, R. (1818): Undersögelse om det gamle Nordiske eller Islandske sprogs oprindelse [Investigation of the origin of the Old Norse or Icelandic language]. Gyldendalske Boghandlings Forlag: Copenhagen.
• Schleicher, A. (1848): Zur vergleichenden Sprachengeschichte. König: Bonn.
• Schleicher, A. (1863): Die Darwinsche Theorie und die Sprachwissenschaft. Offenes Sendschreiben an Herrn Dr. Ernst Haeckel. Hermann Böhlau: Weimar.
• Searls, D. (1997): Linguistic approaches to biological sequences. Comput. Appl. Biosci. 13.4. 333-344.
• Shanon, B. (1978): The genetic code and human language. Synthese 39.3. 401-415.
• Sutrop, U. (2012): Estonian traces in the Tree of Life concept and in the language family tree theory. Journal of Estonian and Finno-Ugric Lingusitics 3. 297-326.
• Tynjanow, J. and R. Jakobson (1991): Probleme der Literatur- und Sprachforschung. In: Viehoff, R. (ed.): Alternative Traditionen.10. Vieweg: Braunschweig. 67-69.
• Zwick, M. (1978): Some analogies of hierarchical order in biology and linguistics. In: Klir, G. (ed.): Applied General Systems Research: Recent Developments & Trends. Plenum Press: New York. 521-529.

Directional processes in language change

Given that we are still in the process of beginning the new year, it seems to be in order to talk about directions — not in general, but rather in specific, namely, about directions in language change. This is important in so far as many processes in language evolution are directional. This means that they follow a specific direction from a state X to a state Y, and this is frequently attested across a large number of the languages of the world, while the opposite process, that state Y changes to state X, is extremely rare or even unattested.

In language evolution there are a lot of well-known and well-investigated processes with a strong directional tendency. In sound change, for example, a [p] can easily become an [f], whether it is in the Indo-European, the Austronesian, or the Sino-Tibetan languages. Yet the opposite process, that an [f] becomes a [p] is extremely rare. Similar tendencies hold for a [k] becoming a [ʧ], as in Italian [ˈtʃɛnto] cento "hundred", going back to Latin [kɛntum] centum "hundred", or a [g] becoming a [h], as in Czech [ɦora] hora "mountain", going back to Proto-Slavic *gora "mountain" (Derksen 2008).

In semantic change, unidirectional tendencies can also be observed, although it is often more difficult to identify them, let alone generalising them. Nevertheless, I think it is a rather safe bet to claim that words which originally mean "head" have a certain tendency to shift their meaning to denote "(the) first, the boss" or "the upper part, the top", while the opposite shift (that words which mean "boss" or "top" will be used to denote "head") is very unlikely to happen. Finally, in grammatical change, or, to be more precise, in grammaticalization (the process by which languages acquire new grammatical categories) directionality is one of the most important constraints (Haspelmath 2004).

Linguists usually know these tendencies very well, and they use them in their daily work, be it when trying to reconstruct the original pronuncation of words in unattested ancestral languages, when deciphering historical documents, or when tracing the semantic development of words through history. Directional changes are also important in evolutionary biology. Ratchet-like (that means: unidirectional) processes serve as a major explanans for constructive neutral evolution (Gray et al. 2010), direction is at the core of lateral gene transfer, and — as David mentioned in an earlier post — the usage of directional (non-reversible) models in phylogenetic reconstruction even provides an elegant way to root a tree (see also Huelsenbeck et al. 2002).

Given the active transfer of ideas from the biological to the linguistic domain in the last two decades, and the important role that directional processes play in both domains, it is surprising to me that methodological transfer has so far been almost exclusively limited to time-reversible models. The only approach known to me that explicitly makes use of linguistic knowledge of directions is that of Baxter (2006). In this paper, Baxter analysed phonological mergers in Chinese dialects within a framework of Camin-Sokal parsimony (Camin and Sokal 1965).

Phonological merger is a specific systemic process in language evolution. When sounds change (and they always change in some way), it may happen that two formerly distinct sounds are pronounced in the same way. As a result, words that formerly sounded different may suddenly sound alike, such as English write and right, which remain different only in their spelling not pronunciation. Mergers are a prototypical irreversible process. Once a merger has happened, speakers cannot go back, unless they recorded the original distinction and artificially tuned their language. But even this may be less easy than it seems — it is always easy to reduce distinctions. For example, most English speakers wouldn't have many difficulties in artificially pronouncing all instances of s as sh during a conversation. But being asked to pronounce a randomly chosen set of words with s as sh will turn out to be much more difficult. For this reason, mergers are an ideal data type for directional models of language change. Their drawback is, however, that they are difficult to determine, which may also be the reason why Baxter's approach has never been tested on other language families since then.

It may be justified to use time-reversible models for analyses that use lexical data, especially cognate sets, as in the approaches following Gray and Atkinson (2003), since it is difficult to determine the impact of directional processes on lexical replacement. Furthermore, due to the specific way the data is sampled, it is extremely difficult to determine directions. Yet in many other approaches that use different types of data, especially in those cases that model sound change processes (Hruschka et al. 2015, Wheeler and Whiteley 2015) or grammatical change (Longobardi et al. 2013), it might have a substantial impact on the results if directionality was explicitly modeled.

What does this mean for the directions for the New Year? I keep being surprised by the similarities between evolutionary biology and historical linguistics, be it the organization of information in genomes and languages, the processes that drive evolution, the philosophical questions underlying our investigations, or the quarrels among scholars in their fields. Unfortunately, much of the transfer from the biological to the linguistic domain is still very simplistic, often ignoring the specific differences between the two domains. On the other hand, many fruitful analogies are still out there but have not yet been properly investigated. So, as a direction for those who work in interdisciplinary domains in this New Year, I think we should try to avoid reinventing the wheel, and we should also pay attention to not putting wheels on sledges.

References

• Baxter, W. (2006): Mandarin dialect phylogeny. Cah. Linguistique -- Asie Orientale 35.1. 71-114.
• Camin, J. and R. Sokal (1965): A method for deducing branching sequences in phylogeny. Evolution 19.3. 311-327.
• Derksen, R. (2008): Etymological dictionary of the Slavic inherited lexicon . Brill: Leiden and Boston.
• Gray, R. and Q. Atkinson (2003): Language-tree divergence times support the Anatolian theory of Indo-European origin. Nature 426.6965. 435-439.
• Gray, M., J. Lukes, J. Archibald, P. Keeling, and W. Doolittle (2010): Cell biology. Irremediable complexity?. Science 330.6006. 920-921.
• Haspelmath, M. (2004): On directionality in language change with particular reference to grammaticalization. In: Fischer, O., M. Norde, and H. Perridon (eds.): Up and down the cline -- The nature of grammaticalization. John Benjamins Publishing Company: 17-44.
• Hruschka, D., S. Branford, E. Smith, J. Wilkins, A. Meade, M. Pagel, and T. Bhattacharya (2015): Detecting regular sound changes in linguistics as events of concerted evolution. Curr. Biol. 25.1. 1-9.
• Huelsenbeck, J., J. Bollback, and A. Levine (2002): Inferring the root of a phylogenetic tree. Systems Biology 51.1. 32-43.
• Longobardi, G., C. Guardiano, G. Silvestri, A. Boattini, and A. Ceolin (2013): Toward a syntactic phylogeny of modern Indo-European languages. J. Hist. Linguist. 3.1. 122-152.
• Wheeler, W. and P. Whiteley (2014): Historical linguistics as a sequence optimization problem: the evolution and biogeography of Uto-Aztecan languages. Cladistics 30.1. 1-13.