Book Club: Darwin’s Unfinished Symphony, 5, the evolution of language

LanguageWhy is it that only the species Homo sapiens has evolved language? Well, aside, possibly, for other, now extinct, species of our own genus. Despite much talk of animal communication, that’s just what other species do: communicate. Language is a very special, and highly sophisticated, type of communication. Characterized by grammar, capable of recursivity, inherently open ended. Nothing like that exists anywhere else in the animal world. Why?

That’s the topic of the eight chapter of Kevin Laland’s Darwin’s Unfinished Symphony: How Culture Made the Human Mind, which we are in the midst of discussing. A major problem here, as Laland points out, is not that we have no idea of the possible answer, but rather that there are too many explanations on offer, none of which seems to quite do the job. Here is a partial list. Language evolved:

  • To facilitate cooperative hunting.
  • As a costly ornament allowing females to assess male quality.
  • As a substitute for the grooming exhibited by other primate species.
  • To promote pair bonding.
  • To aid mother-child communication.
  • To gossip about others.
  • To expedite tool making.
  • As a tool for thought.

And of course it’s very possible that language evolved to fulfill more than one, or even all of those functions! The stumbling block isn’t the imagination of researchers, but rather the dearth of relevant empirical evidence (something, of course, that isn’t the case only in some areas of evolutionary biology).

Part of the difficulty stems from the fact that the evolution of language was a singular event, which precludes the use of one of evolutionary biology’s standard tools of investigation, the comparative phylogenetic method. Moreover, languages don’t leave much of a fossil record, thus taking out a second major tool from the biologist’s box.

Kevin proceeds by listing six criteria (and adding a seventh of his own) that a successful theory of language’s origin should meet in order to be further considered (I refer the reader to the chapter itself for more in-depth explanations concerning each criterion):

  1. The theory must account for the honesty of early language. (If words are easy and cost-free, why should anyone believe what others say?)
  2. The theory should account for the cooperativeness of early language. (Why should people, early on, have gone out of their way to help others by passing to them valuable information?)
  3. The theory should explain how language was adaptive from the onset. (As it is hard to imagine how it could have been a spandrel.)
  4. The concepts proposed by the theory should be grounded in reality. (That is, how did words acquire meaning in the first place?)
  5. The theory should explain the generality of language. (As opposed to the specificity characteristic of every other animal communication system.)
  6. The theory should account for the uniqueness of human language. (Why us and not anyone else?)
  7. The theory should explain why communication needed to be learned. (Why is it that language needed to be socially learned and capable of changing rapidly?)

Laland then concludes that no theory suggested so far meets all seven of these criteria, and I think he’s right. His preferred answer should, at this point in our discussion of the book, come as no surprise:

“[This] raises the question of why humans alone should exhibit a culture that ratchets up in complexity. Theoretical studies answer this question by showing that high-fidelity information transmission is necessary for cumulative culture, but then pose the supplementary question of how our ancestors achieved high-fidelity transmission. The obvious answer is through teaching.” (p. 183)

Kevin then proceeds in orderly fashion by comparing his preferred hypothesis — that language evolved in order to teach relatives — to the seven criteria just listed, finding that the language-to-teach scenario satisfies all of them.

At this point it will be good to step back for a second. To begin with, I’m sure that other students of the evolution of language will dispute both of Laland’s claims: (i) that no other hypothesis is a good fit for all seven criteria, and (ii) that only the language-to-teach hypothesis does a good job with the same criteria. Or perhaps (iii) someone will question the adequacy or necessity of one or more of the criteria in the first place.

For me, though, what makes this chapter the least convincing of those we have read so far is that even if we grant Kevin everything he is arguing for, we are still left, at best, with an hypothetical scenario that falls far short of empirical verification. Yes, maybe language evolved so that we could efficiently teach valuable information to our relatives, and things then went on from there. Or maybe there is a clever variant of one of the other hypotheses now on the table that will be even more convincing than the present analysis. Or perhaps there is yet another scenario that simply nobody has thought up yet. We just don’t know. And to be honest I don’t think we are likely to know any time soon, if ever. Precisely because of a major stumbling block acknowledged by Laland himself: the evolution of language was a unique historical event, and unique historical events are exceedingly difficult (though not impossible) to study.

While reading the chapter, I was reminded of some sharp, and I’m sure very much unwelcome words written by one of my scientific role models, the Harvard geneticist Richard Lewontin. In a book chapter entitled “The evolution of cognition: questions we will never answer,” he presents a critical analysis of the literature on the topic, making an argument that builds up to the following conclusion:

“I must say that the best lesson our readers can learn is to give up the childish notion that everything that is interesting about nature can be understood. History, and evolution is a form of history, [often] simply does not leave sufficient traces. … Form and even behavior may leave fossil remains, but forces like natural selection do not. It might be interesting to know how cognition (whatever that is) arose and spread and changed, but we cannot know. Tough luck.” (p. 130)

Seems to me that one could easily replace “cognition” with “language” and still be largely in the right. I’m sure Kevin will disagree, and I look forward to his comments.

_____

(Note to the reader: this commentary covers that major part of chapter 8, devoted to the question of the original function of language. The latter part of the chapter addresses a different, if related, question: how was it computationally possible for hominins to learn language, regardless of which selective pressured favored it? While interesting, I elected not to cover this bit, in order to focus discussion on what I think are the more crucial points of the chapter.)

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132 replies

  1. I’d recommend the recent, brief Chomsky paper linked to above for discussion of pretty much exactly
    the questions raised in response to my earlier comment. Here’s the link again

    https://www.sciencedirect.com/science/article/pii/S0149763416305796

    An extremely well-informed, and different, view is that of W.T. Fitch (who, with M.Hauser, was a co-author on Chomsky’s first article in the recent revival of interest in evolution of language in 2002). The last section of
    this paper is relevant (whole special issue, devoted to Lenneberg’s 1967 “Biological Foundations of Language” is worth looking at):

    http://biolinguistics.eu/index.php/biolinguistics/article/view/531/393

    And his paper ‘Empirical approaches to the study of language evolution’ in a special issue of the “Psychonomic Bulletin & Review” on ‘the biology and evolution of language’ develops this sort of
    material at greater length

    https://link.springer.com/article/10.3758/s13423-017-1236-5

    My apologies for merely linking and not elaborating.

    –RC

    Liked by 1 person

  2. The trouble is that language might have increased survival chances 50 different ways in one month for a particular group and then 50 other different ways the next month.

    And one of these many benefits might be something like “being more specific in warning about danger” which is something we would not expect to leave any evidence since the difference between the pre language “warning about danger” and the post language “warning about danger in a more detailed and specific way” is not something which is going to show up in a fossil record or on an examination of the remains of ancient settlements.

    And that might just be a benefit at some times. At others it might be to better charm a mate, or to better organise responsibilities in the group, being able to be more specific about the location of good areas for food, better cementing alliances, being able to agree hunting strategies in advance etc.

    It is plausible that all of these and much more could have been the original benefit of language because all of these would have been things that were already happening in the species and language could have enhanced them.

    Language rose in intelligent primates with an already reasonably complex social structure and language might have enhanced the social interactions in so many different ways which could have improved their effectiveness as a social group in hundreds of subtle ways.

    It seems to me that asking questions like “what was the original function or functions of language?” would miss this possibility that it simply made all of the social interactions, which already were necessary to the group survival, more effective.

    Liked by 2 people

  3. Robin,

    “The trouble is that language might have increased survival chances 50 different ways in one month for a particular group and then 50 other different ways the next month.”

    That may be a slight exaggeration, but yes, hence Leeontin’s comment.

    Like

  4. As language is of very general use, it seems likely that any one ‘adaption’ accounts for it. It helps with all.

    Liked by 1 person

  5. Cousin: “In Himmel das ist kein Bier…”

    Liked by 1 person

  6. E.g., someone with a gift for gab might outcompete someone merely big and strong for mates. One can only hope …

    Someone who ‘kissed the blarney stone’ can invent the Alpha Male in the Sky (A.K.A., God) and intimidate all those big guy, thus, the ‘weak inherit the earth.’

    Thus, spake Zarathrusta

    https://goo.gl/yoyynw

    </:-_)

    Like

  7. https://goo.gl/BeUwJT

    Im Himmel gibt’s kein Bier, Drum trinken wir es hier

    to be exact…

    Like

  8. Robin: “Language rose in intelligent primates with an already reasonably complex social structure and language might have enhanced the social interactions in so many different ways which could have improved their effectiveness as a social group in hundreds of subtle ways.”

    It seems beyond ironic that language provides a universal connection between all humans, and at the same time limits the connection through the diversity of different languages.

    It’s no more than a hunch, but I think this diversity may have emerged, in part, through interaction within families between parents and children. Children are linguistic geniuses with limited information, trying to forge communication with adults who are much better-informed, but considerably less creative. As the circle of communication widens to include neighbors and other tribes, the language expands and distinguishes itself from others.

    Like

  9. synred: Beef labeling monitoring delegation Act. (epic!)

    Liked by 1 person

  10. https://phys.org/news/2018-02-steady-brain-evolution-turtles.html

    Turtle’s on the road to bigger brains too, along with mammals and birds.

    Maybe some day ‘turtles all the way down’ – once we get out of the way —

    Like

  11. synred,

    I don’t think language is “way too expensive”. The genomic, developmental and metabolic costs are likely to be small if not highly irrelevant to the organism in question.

    The reason I mentioned non-adaptive hypotheses is because the reviewed chapter, and subsequent comments, remind me of the recent string/multiverse discussions. It seems that one can conjure up an endless series of plausible sounding stories to explain the evolution of language without ever being able to determine what actually happened.

    Against this background of possible permanent ignorance it is important – and sensible – to ask if this trait actually needs an uber-adaptionist explanation. I’ve no idea, but I suspect that drift is of considerable importance here.

    Like

  12. Zwique,

    “Against this background of possible permanent ignorance it is important – and sensible – to ask if this trait actually needs an uber-adaptionist explanation.”

    Right. But, again, you seem to be treating a non-adaptive explanation as a catch-all, whatever happens if there are no selective pressures. But in fact non-adaptive explanatins (plural) are hypotheses in their own right, which need to be articulated and tested. They don’t win by default just because it is difficult to articulate an adaptive scenario.

    Personally I have little doubt that language is adaptive, but I’m with Lewontin that the historical traces are so few and confused that we’ll probably never figure it out.

    Liked by 2 people

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