A discussion between Damien Neadle and Andrew Whiten regarding Neadle et al.’s CES 2021 talk on ape novel action copying

Here we present the current state of an exchange between Prof. Andrew Whiten and Dr Damien Neadle, following Neadle et al.’s talk on ape novel action copying at the Cultural Evolution Society’s (https://culturalevolutionsociety.org/) online 2021 conference – hosted by Dr Masanori Takezawa (Hokkaido University). Prof Whiten’s points/questions are presented in italics and Dr Neadle’s are below in each case. Note that this is an ongoing discussion – with plans to formalise it into manuscript formats. For the time being, the following is merely to make the current state of the debate accessible beyond the CES website’s lifetime.

Hi again Damien – I have many questions there was not time for in the live Q&A so I’ll add some now!. First, I think that Zanna’s study and yours are highlighting child-chimpanzee differences in what they are prepared to copy – this may be either the ‘overimitation’ difference Vicky Horner and I first reported back in 2005, or a difference in preparedness to copy a ‘gesture’ like Mike T and others reported back in 1997 – or both – so my first question is – do you think you might be able to disentangle these two?

Hi Andy, yes a shame we were not able to talk about these things face to face, alas I will do what I can to answer these here. I’ll respond to each paragraph in turn to aid in clarity and so that I don’t forget parts. I agree with you here, we are clearly highlighting a species difference (though note that this isn’t just a child/chimpanzee one – in fact Zanna & Claudio’s is child/bonobo and ours is essentially child/non-human ape). However, where we might disagree is with regards to your phrasing: ‘prepared to copy’; this is assuming that apes can copy a novel action under this kind of ‘action only’ paradigm (although note that answers to later questions will allow me to unpack this more).

Whilst the literature on overimitation to date (Hoehl et al, 2019) is clear, there is a difference between humans and non-humans in their propensity for overimitation – this appears to extend beyond just primates (I am referring to work here by Daphne Buchsbaum and colleagues that is as yet unpublished but I have been fortunate enough to read). Whilst I do not agree that you and Victoria  identified ‘imitation’ in 2005, as the task was not sufficiently novel to assume this (based on your criteria laid out in 1998 in the Journal of Comparative Psychology), the study is relevant here and that you found ‘over-enhancement’ maybe?. Also, the fact that there were environmental results present means that we cannot rule out other social learning mechanisms like enhancement or emulation (detailed critiques along these lines can be found in Clay & Tennie, 2017). Regardless, the study I presented in my talk does follow an overimitation paradigm – just as you suggest. The task we used was to copy actions that are not ”obviously” required – and this is also the reason why Clay & Tennie had the term overimitation in their title.

You ask about the begging gesture study (Tomasello et al., 1997) and its relation here, I briefly (due to the time constraints enforced by the conference) mentioned that I consider this study to be one of the three remaining pieces of relevant data to this ‘pure’ novel action copying debate (the others being Clay & Tennie, 2017 and Tennie et al., 2012). You will note that Tomasello et al 1997 considered theoretically that there might be ape social learning of their gestures, however based on the substantial variation in the performance of these gestures, they largely dismiss imitation as an explanation (presumably because of a lack of copying fidelity, even if these gestures are copied at all). However, when they later attempted to test specifically for action copying in a begging gesture context (study 2 in the 1997 paper) they came up with no evidence in the tested chimpanzees. So, this evidence is consistent with our findings and interpretation. While Tomasello et al. 1997 did indeed use a gesture copying paradigm, all other studies (including the one I presented) went beyond mere gestures. All three other studies used actions on tasks – i.e., actions that were designed to accompany solutions – that appeared necessary for solutions (and yet, novel and arbitrary – the first to test for human like copying; more on this below), the second to test for the copying of actions, rather than for copying of task structures etc. (achievable in principle via emulation).

In addition, we used two actions, to test additionally for anchoring effects. The ‘rub’ action is in contact with the box (probably more like overimitation tasks in general) and the rotate action is not (perhaps a bit more like gestural tasks) – see Clay and Tennie, 2017 for further discussion of this. So, we are testing for the ability to copy novel actions in technical tasks, and at the very least we achieve this with the anchored action. We are not attempting to fully disentangle these things here for our second action, and neither do we need to (as we have the other action, too).

Other puzzles and questions arise from your dismissal of all ‘two-action’ experimental designs for documenting action copying. This raises many questions, because I think virtually all of these methods’ many appearances in the animal social learning literature is typically offered as specifically used to distinguish copying (of one action form rather than the alternative action form) from simpler processes, notably stimulus or local enhancement; moreover in diffusion versions incorporating the two-action idea, the further interesting question is whether the different forms spread differentially in the experimental groups to become incipient traditions. So – second question – if what is of interest is a species’ capacity to copy in a way that sustains cultural transmission across multiple individuals – aren’t two-action experiments, and specifically two-action diffusion experiments, exactly what we need to test for that spread? (After all, your prediction seems to be that non-human animals, unlike humans, cannot copy different forms and so will not be able to reliably transmit different forms of action along cultural diffusion chains?)

Indeed, if we were just looking for social learning mechanisms that might or might not sustain behaviours for a while in a laboratory transmission chain then the ‘two action’ tasks (as you call them) are suitable. However, in this study we aren’t looking at this, we are instead looking at the capacity to copy novel actions in a technical task (under majority demonstrations). However you will note that when Dawson and Foss initially introduced the two action paradigm there was an error in their application, namely the mixing of actions (body movement/parts) with object movement (sadly, this was not disentangled). This error carries through (as also highlighted by Heyes before) in the literature. To this day, this means that it is possible to ‘succeed’ in the “two-action task”, without needing to actually copy actions at all. This is different from what we are testing for here and in other related studies. Which is why the name of ‘two-action’ task has been questioned previously, preferring to call them two-target tasks (Tennie et al., 2010).

In the study I presented it is important that we go beyond the baseline of the species concerned, for this a ‘two action’ task (at least how they have been implemented) were not suitable. This is because if we stay within the baseline we cannot even exclude individual learning playing a very large role (let alone other social learning mechanisms). This means that when the targets to copy are within the baseline capacity (as with all ape iterations of the two-target paradigm; Tennie et al. 2020 did a review of these) we can’t be sure that actions are copied and we know that something has been copied that did not go beyond baseline performance (begging the question whether this should even be called copying in a human sense) Therefore, these types of tasks aren’t useful to answer the question we pose. That is not to say that are not useful (e.g., to study social learning biases), just not here.

Your assumption about our prediction “that non-human animals, unlike humans, cannot copy different forms and so will not be able to reliably transmit different forms of action along cultural diffusion chains” is somewhat off. We are interested in the first part – we had negative data as to whether non-humans can copy novel actions (in suitable tasks). We wanted to try again (this time with a majority bias) – the transmission and diffusion would have been the next step (it would have been had we identified action copying). There is no need – no possibility – for us to test the latter until we can confirm the former. As I see it, we don’t have this data yet so cannot assume that this is the case (and indeed, the negative data pattern seems consistent by this point).

The types of cultures identified in the lab via the two target method remain real – but they remain within the realm of baseline performances. But again, we never denied that apes can and do sustain cultures made up of such latent solutions. 

Third, related question – for you and your colleagues, what counts as an ‘action’? You seem to want to limit that to only what goes on ‘within the skin’, like limb movements. But what about actions that employ tools, such as ‘poke stick into hole X’ versus ‘lift blockage with stick’ in the example of the pan-pipes you illustrated (Whiten et al, Nature 2005)? Aren’t they alternative ‘actions’? And involve differential know-how? It is not implausible that most of the culture we humans acquire concerning what we do with our hands involves forms of tool actions and manipulations of other objects? If so, don’t we need to include these in our tests of action copying? I hypothesise that chimpanzee action copying is relatively ‘pragmatic’ in that it is in play in tool use and other actions on objects, but does not extend to over-imitation nor copying gestures.

This is a continually interesting point that you raise. For us actions are the behavioural forms themselves not the results they produce. So, yes, tool use like this does contain actions. However, and as I said in response to your previous comment, to answer the questions we specifically set out to answer (do apes copy beyond their ZLS; in the current study specifically, do they copy actions beyond their ZLS) these actions must go beyond the individual capacity. This brings me to the pan-pipes. It has been claimed that these experiments might be the exception to the rule of ‘two-action’ studies not going beyond baseline. As you mention in the 2005 study the lift behaviour does not occur at baseline (the poke behaviour does also, in 1 subject in that study and others in other studies, if I recall correctly). However, what one would not be acknowledging here is that the ‘alternative action’ (i.e. alternative solution) was found in another group; i.e., lift was innovated in the poke seeded group (as pointed out in Tennie et al., 2020 citing Hopper et al., 2007 and Whiten et al., 2005). Therefore, it is not possible to assume that the apes have copied  (actions or other types of info) here anything novel – anything beyond their ZLS, if you will – as both solutions clearly are within the baseline level of ape performance (thus individual learning capacity) of the subjects concerned. Indeed, both of these behaviours have appeared in the baseline conditions of other studies using the pan-pipes (Tennie et al. 2020), showing once more that they are within the individual learning capacities of these species (their ZLS).

So, in sum, yes. We could include these kinds of behaviours, providing they

  1. Go beyond the individual/baseline capacity of the subjects
  2. Do not allow for the task to be solved by other social learning mechanisms that ultimately have to rely on individual learning (e.g., enhancement)
  3. Allow at least equal testing time for baselines and demonstration/live conditions (and tested with properly powered baselines (Bandini et al. 2020))

Your point about human culture is an interesting one, but our study does not set out to explain human culture in this way, we are interested in ape culture and the mechanisms underpinning it – in particular if they copy beyond their ZLS. If it were shown that modern human culture is not often or never based on action copying (I think we can all agree this is unlikely) then this raises other issues.

Then turning to your three criticisms of the power of two-action tests. From your slide: 1. “No baseline”. But in the example you illustrate, of the pan-pipes, in addition to the two alternative seeded actions groups, there was a third group that first experienced the pan-pipes with no model for an hour individually, then 4.5 hours as a group, without achieving any success, although they tried to apply the stick tool to the panpipes. Just to take diffusion two-action studies alone, as reviewed by Mesoudi and me just up to 2008, we tabulated 8 studies with this three groups design with birds and mammals, plus another 3 with baseline no-model conditions. (That review updated in Whiten, Caldwell, Mesoudi 2016). So question 4 is really – what do you mean by ‘no baseline’ in these studies?

See my above comment about the appearance of the target behaviours in baseline conditions of some iterations of the ‘two-action’ tasks. Clearly, my comments do not target any one study. I used the pan-pipes as a well-known, and well cited, example – and given that you yourself mentioned it above). I refer to general problems, with the application of the two target methodology as an inappropriate technique to identify action copying generally. So, some are not using novel actions,  allowing for social learning mechanisms other than action copying (including in some cases, even local enhancement) and yes, some lack a baseline. The 2005 pan-pipes study you refer to has a baseline but, as the behaviours can (and did) occur in the absence of a demonstration (see above) we cannot possibly assume that copying of novel solutions (solutions beyond the ZLS of apes) is at the heart of it. Furthermore, other iterations of studies like the pan-pipes one (using two-target methodologies) often have very underpowered and/or significantly shorter baseline testing time compared to the social learning conditions (even less than half the subjects/time). But, yes, perhaps ‘no baseline’ was the wrong terminology in my talk, I now would correct this to include target behaviours that can occur without the need for demonstrations (either in baseline or by occurring in an alternatively seeded group; see Tennie et al., 2020). 

As for other species, we do not deny that other species than apes may copy beyond their ZLS (again, the thing to look out for would be copying beyond baseline performance), our study here was on apes – our main study focus in general. And so, we would like to stick with the ape data.

Then you had 2. “Possibility of result-based (emulative) copying”. But the result for both pan-pipe actions, for example, is the same – a grape comes out of the lower pipe. But chimpanzees see either of two forms of action to achieve this, and they tend to copy the form they have seen and thus acquire the corresponding know-how. Perhaps more importantly, it is exactly this kind of match between what is done with a tool or performed on an object and what the observer then does that is the basis not only for what counts as copying, or more often the term is ‘imitation’, in the child literature generally, but in nearly all of the corpus of even that labelled ‘overimitation’. So question 5 – are you arguing that all these researchers are misguided in treating this as action copying, or as imitation? Remember also that in Horner and Whiten 2005, when the box was opaque, after watching the model do so the chimpanzees did tend to probe the stick in the top hole like children did, its just that they selectively did not when the transparent box revealed it was unnecessary, whereas the children persevered, later called overimitation by Lyons et al. And also remember that Buttelman et al,. with Tomasello as a co-author, described what chimpanzees matched a human doing with their head, or hands, or bum, on an object, as ‘rational imitation’.

As you have been very frank in your questions/critiques of our study here, I will do so too. In short, yes; we are arguing here that labelling the findings of these studies as ‘imitation’/action copying is incorrect. That is not to say imitation (action copying) did not occur, especially in the case of children (for which we have good independent evidence for action copying). However, we cannot exclude other social learning mechanisms in these tasks generally (we know this since Heyes critiqued them) and therefore to assume one mechanism over the others is not supported by data – this it is too soon to draw this conclusion.

Do we dismiss the utility of the ‘two-action’ task? No (see above) – but yes,we do dismiss it as a ‘gold-standard’ for identifying action copying because it lacks the precision required to separate the mechanisms at play. Again, this issue is not novel and we are not the first to suggest it. Cecilia Heyes has often said that these tasks contain confounds that cannot be overlooked (when used in this context) and Lydia Hopper’s had a study that identified copying in ‘ghost conditions’ in apes – where no actions were at all demonstrated. If imitation really were the only possible social learning mechanism at play here ‘ghost conditions’ would have to fail – clearly this is not the case. And again, in some such tasks used, even enhancement effects were not excluded (e.g. the two target locations at the pan-pipes were spatially separated).

The issue with the Horner and Whiten (2005) study is that the tested chimpanzees we not naïve to stick tool use, they were well aware that sticks were functional tools and could be used to solve tasks like this. This links to the ‘not always novel’ point below (it is not helpful to consider these as granularly as you have split them here, but nonetheless I have responded in the order you have raised the issues). As we know the chimpanzees in the 2005 study were capable stick users (as nearly all chimpanzees are) the only thing we can say (with certainty) that is ‘copied’ is the place where they inserted the stick (which is just local enhancement). That task, whilst perhaps still great for identifying social learning biases, falls short when attempting to identify imitation as you have defined it previously (1998 & 2004). Note that this critique has already been levelled in detail at this task by Clay and Tennie (2017), where it was explained how we cannot differentiate between social learning mechanisms.

Regarding the Buttelman study, this study used enculturated apes and therefore is not relevant to this debate. In the same way as I am dismissing Josep Call’s 2001 of imitation with an enculturated orangutan from this debate. Note that Josep was my examiner for my PhD and he had no issue with my dismissal of this data as not relevant to the arguments here.

P.s.  My commitment is to the data, you will note that I was perfectly happy publishing my data from 2020 that went to some degree against the ZLS account’s predictions (with caveats). Had the present study – the one I presented in my talk – identified action copying I would have published it and happily so. I was Claudio’s student, he is my co-author and collaborator, but if the data did not support his theory I would have no reservation in still publishing (and indeed, Claudio always encourages everybody to publish all data, and regardless of whether that data supports things he said before or not). Thus, just because Tomasello is on that paper it doesn’t make it any more or less relevant than any of the other studies that identified ‘imitation’ in enculturated apes.  

Then you had 3. “Not always novel”. Well in the case of the pan-pipes, for example, the chimpanzees had never seen a pan-pipes before, and of course they had not seen either the poke or lift technique on it before their model did it, and the no-model individuals did not do these actions. So fifth question – what more criteria for ‘not novel’ can reasonably be expected?

This fact is exactly why the pan-pipes were – initially – considered by Tennie et al. (2020) to be the possible exception to the ‘two-action’ tasks being dismissed as good evidence of anything approaching action copying. However, the issue comes back to that one I outlined above – attempting to breakdown my critique of the ‘two-action’ tasks in this way can lead to a misrepresentation of the argument. The pan-pipes failed to meet the standard, not because the task was not novel but because it proved possible for subjects to solve them without the need for social learning at all (lift in the baseline and poke in a lift-seeded group). And when tested with material tasks whose solutions lie outside the ZLS of the species, apes fail to copy (Tennie et al. 2009). So, my critique stands, some applications of the ‘two-action’ paradigm include tasks that are not novel to the subjects – pan-pipes are an example of this not being the case.  

In any case, let me suggest that if the research question is ‘is copying necessary to acquire action X?’ then a baseline or parallel no-model condition is indeed needed: but if the research agenda is instead ‘do these animals copy a technique they witness well enough for it to pass faithfully along a chain, or across a group, of cultural learners? then the key is a two-action design, and a no-model control group is in this case redundant – if the alternative actions diffuse within and even between groups like in our 2007 study, that is the interesting finding in relation to cultural transmission. Don’t you agree? Note, by the way, that when Emma Flynn and I reported a parallel pan-pipes study with children in 2010, we found the seeded alternatives also began to spread differentially in the groups, but soon with less fidelity than in the earlier chimpanzee study.

I agree with your first point. If we are to ask the question whether or not action copying (or indeed any social learning) is required or as I phrase it in my 2017 paper “necessary” for behaviour X then we need a baseline. This is the crux of the Latent Solutions testing methodology that Claudio has been championing for many years now. The issue that we have here is that often (not always, see Neadle et al., 2020 and Bandini & Tennie, 2018) primate behaviours do not require social learning to occur. They occur at baseline, therefore are not beholden to culture in the way that has been suggested. So yes, if we are asking this question that is correct. But, that is not the question here. Ours is can apes copy beyond baseline levels? We had planned baseline testing and a whole bunch of testing to figure out what exactly is going on (had they done it; see our preregistration of this study on the OSF for details: https://doi.org/10.17605/OSF.IO/GPV54).

Your point about fidelity has been addressed by other researchers (e.g., Claidière & Sperber, 2010), the “high” fidelity of the mechanism alone is not sufficient to explain culture in the way that is often suggested. It doesn’t matter to that argument whether or not imitation is identified in non-humans as Claidière & Sperber argue that it is not sufficient (they even go as far to suggest it is not in any case, we would not go that far). But, again, this is not the question here. Based on the data, we know that ape cultures (many aspects at least) do not seem to require action copying (or imitation however one terms it; or know-how/form copying), see the many Latent Solutions experiments that have been outlined by our group and beyond. There are still candidates that require additional attention (here I refer you to Claudio’s work with Alba Motes-Rodrigo and her related talks this year).

Regardless, the ape transmission studies that you suggest, following a ‘two-action’ paradigm, tested within the individual learning capacities (or ZLS) of the ape species tested for the reasons I have outlined extensively here. Therefore, this is not relevant to the question we are asking. That is not to say this data is uninteresting, just that this isn’t the topic at hand. As for the note about Emma Flynn and your study in 2010, biases in culture are common and this has been well championed by Sperber and his many students. The countless cultural traits and ‘know how’ that we support are maintained in spite of this (Motes-Rodrigo & Tennie, 2021).

So, if one is interested in explaining the patterns of wild ape culture that you (and many others besides) have identified, the questions you ask are relevant, and so are the two-target tasks so far performed on apes. However, we do not question whether apes have culture. You might recall that we had this very discussion at CES, in Arizona, last time. I have termed these types of culture ‘minimal culture’, that is where social learning plays a role in the facilitation of a trait that is however in the baseline possibility (the ZLS) of the species. I explained in 2017 how gorilla food cleaning falls into this category. This is where I think a sort of straw man has been erected over the years between your research group and the critics, including Claudio (but also Galef etc.). Moreover, Tennie, Call, Tomasello or any of their students would not ever deny the existence of some sorts of culture in apes. Quite the opposite, we acknowledge it and contrast it with our own (markedly different) culture to infer the answers to questions about the early evolution of our specific human culture (which consists mostly of ZPD) and the behaviours and cultures of early hominins.

So, to answer your suppositions of our research questions, I shall state them clearly (now here I speak only for Claudio, and sort of myself – though I confess in response to the politics in this research area I have begun to move towards other aspects of cultural evolution). We ask whether or not apes can spontaneously utilise now-how copying (including novel action copying) to ever go beyond their ZLS, therefore expressing culture dependent know-how and going beyond the ‘minimal’ culture that we all agree they definitely have. If this copying occurs, what social learning mechanisms are included in it and to what degree are they applied? Perhaps now it is clearer, how the methodologies you suggest do not match the questions we are asking.

I hope that my responses here answer at least some of the questions you have. It really is a shame we weren’t able to talk outside of the Q&A session at the conference. If you’d like to chat we can always Zoom, I’d be very glad to hear what you think about all this and how we can all work together to advance the cultural evolution literature even further. These kinds of debates are useful (in my humble opinion) to consider where we all stand and to ensure that we understand one another’s’ point of view. I think this misunderstanding is often the cause of the some more ‘heated’ debates in our field.

References

Bandini, E., Motes-Rodrigo, A., Steele, M. P., Rutz, C., & Tennie, C. (2020). Examining the mechanisms underlying the acquisition of animal tool behaviour: Sources of animal tool behavior. Biology Letters, 16(6). https://doi.org/10.1098/rsbl.2020.0122rsbl20200122

Claidière, N., & Sperber, D. (2010). Imitation explains the propagation, not the stability of animal culture. Proceedings of the Royal Society B: Biological Sciences, 277(1681), 651–659. https://doi.org/10.1098/rspb.2009.1615

Clay, Z., & Tennie, C. (2017). Is overimitation a uniquely human phenomenon? Insights from human children as compared to bonobos. Child Development, 89(5), 1535–1544. https://doi.org/10.1111/cdev.12857

Hoehl, S., Keupp, S., Schleihauf, H., Mcguigan, N., Buttelmann, D., & Whiten, A. (2019). ‘Over-imitation’: a review and appraisal of a decade of research. Developmental Review, 51(November 2018), 90–108. https://doi.org/10.1016/j.dr.2018.12.002

Hopper, L. M., Spiteri, A., Lambeth, S. P., Schapiro, S. J., Horner, V., & Whiten, A. (2007). Experimental studies of traditions and underlying transmission processes in chimpanzees. Animal Behaviour, 73(6), 1021–1032. https://doi.org/10.1016/j.anbehav.2006.07.016

Horner, V., & Whiten, A. (2005). Causal knowledge and imitation/emulation switching in chimpanzees (Pan troglodytes) and children (Homo sapiens). Animal Cognition, 8(3), 164–181. https://doi.org/10.1007/s10071-004-0239-6

Motes-Rodrigo, A., & Tennie, C. (2021). The Method of Local Restriction: in search of potential great ape culture-dependent forms. Biological Reviews, 9. https://doi.org/10.1111/brv.12710

Neadle, D., Allritz, M., & Tennie, C. (2017). Food cleaning in gorillas: social learning is a possibility but not a necessity. PLoS ONE, 12(12), e0188866. https://doi.org/10.1371/journal.pone.0188866

Neadle, D., Bandini, E., & Tennie, C. (2020). Testing the individual and social learning abilities of task-naïve captive chimpanzees (Pan troglodytes sp.) in a nut-cracking task. PeerJ, 2020(3), e8734. https://doi.org/10.7717/peerj.8734

Neadle, D., Chappell, J., Clay, Z., & Tennie, C. (2018). Testing the effects of conformity bias on great apes’ imitative abilities. https://doi.org/10.17605/OSF.IO/GPV54

Tennie, C., Call, J., & Tomasello, M. (2009). Ratcheting up the ratchet: on the evolution of cumulative culture. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 364(1528), 2405–2415. https://doi.org/10.1098/rstb.2009.0052

Tennie, C., Call, J., & Tomasello, M. (2012). Untrained chimpanzees (Pan troglodytes schweinfurthii) fail to imitate novel actions. PLoS ONE, 7(8). https://doi.org/10.1371/journal.pone.0041548

Tennie, C., Greve, K., Gretscher, H., & Call, J. (2010). Two-year-old children copy more reliably and more often than nonhuman great apes in multiple observational learning tasks. Primates, 51(4), 337–351. https://doi.org/10.1007/s10329-010-0208-4

Tennie, C., Hopper, L. M., & van Schaik, C. P. (2020). Consideration of the Role of Copying in Culture- Dependent Traits and a Reappraisal of the Zone of Latent Solutions Hypothesis. In S. Ross & L. M. Hopper (Eds.), Chimpanzees in Context: A Comparative Perspective on Chimpanzee Behavior, Cognition, Conservation, and Welfare. University of Chicago Press.

Tomasello, M., Call, J., Warren, J., Frost, T., Carpenter, M., & Nagell, K. (1997). The ontogeny of chimpanzee gestural signals: a comparison across groups and generations. In S. Wilcox (Ed.), Evolution of Communication (pp. 224–259). John Benjamins.

Whiten, A. (1998). Imitation of the Sequential Structure of Actions by Chimpanzees (Pan troglodytes). Journal of Comparative Psychology, 112(3), 270–281. https://doi.org/10.1037/0735-7036.112.3.270

Whiten, A., Horner, V., Litchfield, C. a, & Marshall-Pescini, S. (2004). How do apes ape? Learning & Behavior, 32(1), 36–52. https://doi.org/10.3758/BF03196005

Whiten, A., Horner, V., & Marshall-Pescini, S. (2005). Selective Imitation in Child and Chimpanzee: A Window on the Construal of Others’ Actions. In S. Hurley & N. Chater (Eds.), Perspectives on Imitation: From Neuroscience to Social Science: Mechanisms of Imitation and Imitation in Animals (Vol. 1, pp. 263–283). MIT Press.

How do animals learn tool use behaviours?

By Alba Motes Rodrigo

Several members of the “Tools and Culture among Early Hominins” lab have recently published an opinion piece in the journal Biology Letters entitled “Examining the mechanisms underlying the acquisition of animal tool behaviours”. Elisa Bandini, Claudio Tennie and myself, together with crow researchers Matthew Steele and Christian Rutz, teamed up to describe a methodology that allows to unravel the individual contributions of different learning mechanisms to the acquisition of tool behaviours in animals.

A summary of the paper can be found in the following thread:

https://twitter.com/elisa_bandini/status/1269295123462082561

Screen Shot 2020-06-08 at 11.11.18

The article can be accessed for free in the following link:

https://royalsocietypublishing.org/doi/10.1098/rsbl.2020.0122

Chimpanzees spontaneously reinnovate tool use behaviors: implications for early hominin behavior and culture.

by Alba Motes Rodrigo

Every one of us walks on the shoulders of giants: all human behavior is based on knowledge gathered by our predecessors. This cultural intelligence is what allowed us to be ubiquitous on this planet, and soon enough, outside of it.  But how did we end up here? When did we start collecting, modifying and accurately transferring the knowledge that constitutes modern human culture?

Technological artifacts (or tools) are currently considered the oldest instances of this special variant of culture. These tools come in three flavors: stone tools, bone tools and wooden tools (as well as marks left by tools, which are rare). If these tools are truly the product of modern-like cultural processes, this would mean that the knowledge about how to use or produce them needed to be acquired (copied) from someone else. Consequently, if these tools are “cumulatively cultural” (i.e., in the sense that we understand modern human culture today), no isolated individual could have spontaneously acquired the knowledge necessary to make and use these tools.

Members of our research group as well as researchers from institutes in Oslo (Norway), Linköping (Sweden) and Wisconsin-Madison (USA) conducted several experiments recently published in PLOS ONE and the American Journal of Primatology (AJP) with our closest living relatives, who also produce and use a multitude of tools: chimpanzees. In these studies we tested if we could find reinnovations (Bandini and Tennie 2017) of hominin and wild chimpanzee behaviors in naive captive chimpanzees i.e. those that had never performed or been exposed to these behaviors.

In the first set of experiments (Motes-Rodrigo et al. 2019 PLOS ONE), we tested the ability of two groups of chimpanzees to use tools to extract food buried underground. The results from these experiments are particularly important because this is the first time that this behavior (the use of tools to excavate buried food pieces simulating roots and tubers) has been directlyobserved and recorded. Previous reports of this behavior came from populations that are not habituated to humans, and therefore chimpanzees had never been directly observed excavating before. In this experiment, the chimpanzees also collected their own tools to excavate.

In the second experiment (Bandini and Tennie 2019 AJP), we tested the ability of several groups of chimpanzees to use tools to pound and extract food from a container. Without ever seeing another individual using the tools for these purposes, chimpanzees in most groups tested, spontaneously used stick tools to solve the tasks. As before, the chimpanzees collected their own tools and brought the to the testing area.

We can be certain that at least the first chimpanzee in each of the groups tested where the target behavior was reinnovated, did so spontaneouslyi.e. without the need to see any kind of demonstrations. That is, social learning of any kind (including action copying) proved unnecessary to explain the formof these behaviors! These results show that some hominin and wild chimpanzee behaviors do not rely on copying to be acquired by naïve individuals. These studies contribute new data to the growing body of evidence showing that many behavioral forms previously considered cultural (in the sense of modern-culture) can actually be acquired relying solely on individual learning. This does not exclude a role of social learning, however, as some non-copying variants of low fidelity social learning are likely to play an important role in the increase in frequency of target behaviors. That the chimpanzees in this study did not require to observe any models, further means that we should be more cautious in assigning cultural properties to all early hominin and wild chimpanzees technological behaviors. As more and more studies of this kind are published, it becomes clearer that chimpanzee, and  perhaps now also early hominin, cultures are actually likely different from modern-human cultures. Their cultures (like so many others in the animal kingdom) use social learning to increase the frequencies of behavioral forms – but the behavioral forms themselves do not require any variant of social learning mechanisms. This seems to be the strongest difference to human culture – where copying is necessary.

References

Motes-Rodrigo, A., Majlesi, P., Pickering, T.R., Laska, M., Axelsen, H., Minchin, T. C., Tennie, C. and Hernandez-Aguilar, R. A. 2019. Chimpanzee Extractive Foraging with Excavating Tools: Experimental Modeling of the Origins of Human Technology. PLoS ONE 14(5): e0215644. 

Bandini, E., & Tennie, C. 2017. Spontaneous reoccurrence of “scooping”, a wild tool-use behaviour, in naïve chimpanzees. PeerJ. 5, e3814.

Bandini, E & Tennie, C. 2019. Individual acquisition of ‘stick pounding’ behaviour by naïve chimpanzees. American Journal of Primatology. e22987 

Media coverage:

IFLS: https://www.iflscience.com/plants-and-animals/captive-chimps-learn-a-digging-behavior-once-thought-unique-to-humans-and-other-hominins/

New Scientist: https://www.newscientist.com/article/2204102-chimps-that-mash-potatoes-challenge-our-understanding-of-tool-use/?utm_term=Autofeed&utm_medium=SOC&utm_source=Twitter#Echobox=1558465877

The musings of a formerly confused cultural evolutionist

Written by: Damien Neadle and Claudio Tennie

Culture is all around us, from the device that you are seeing/hearing this on to the very words I am using. However, it is a rather slippery fish to grasp and it can be difficult to nail down exactly what culture is.

Thought exercise

When I say “culture” what do you think of? I expect that this will vary depending on who you are: a biologist might think of something close to the definition provided by the Oxford English Dictionary (2019):

“The cultivation of bacteria, tissue cells, etc. in an artificial medium containing nutrients”

An anthropologist might think of another part of the Oxford English Dictionary (2019) definition:

“The arts and other manifestations of human intellectual achievement regarded collectively; The ideas, customs, and social behaviour of a particular people or society”

A comparative psychologist, like myself, might envisage something altogether more simple. For example, when I hear culture, I think of a family of chimpanzees sitting together cracking panda nuts in Taï Forest, Côte d’Ivoire. These different ways to perceive culture – and their contrast to the way I think of culture – frequently presents a problem for me when I am talking to people about culture in non-humans.

My problem

I often find myself hesitating to even use the term culture at all because, for some, it is synonymous with human culture, which is special – human culture is “cumulative” (Tomasello, Kruger, & Ratner, 1993). Whilst there are debates as to whether at least some non-human cultures also qualify as cumulative (see, for example, Schofield, McGrew, Takahashi, & Hirata, 2017), most would agree, human culture is special – even if that means that it simply often is cumulative (instead of always).

Therefore, my coauthors and I found ourselves seeking another term for the interesting processes that chimpanzees (and other non-humans) engage in regularly; in this post, I will be talking you through our logic in selecting a term and the pitfalls and advantages that the possible definitions contain.

The options

In the nineties, there was a call for a distinction between cultures and traditions – the difference between these terms was a topic of significant debate (see Galef, 1992); Galef concluded that a tradition is a behaviour type that is somehow acquired, at least in part, by social learning mechanisms, other than imitation 1 or teaching. According to Galef, culture instead relies on imitation and teaching. Galef (and other early researchers e.g., Jane Goodall) should be applauded for their forward thinking “splitter” mentality – but, alas this distinction did not catch on as much as some may have preferred.

Somewhat expectedly, there is a degree of pushback within the field from what Galef termed “lumpers”, those who fail to see a distinction between cultures and traditions or may wish to attribute culture to non-humans. Culture, after all, has a nice ring and a high impact factor attached to it, and so, taking it away from many other animals has far-reaching consequences.

In a well-cited paper a group of field researchers from research sites across Africa sat down to compile their observations to generate a tentative list of the repertoire of wild chimpanzee behaviours; crucially, they divided up the repertoires by frequencies and by population (Whiten et al., 1999). This allowed them to produce a derived list from the behaviours themselves, namely a list of putative cultural traits of chimpanzees (see also Whiten et al., 2001). The logic being that population level (geographical) differences in behavioural repertoires might be due to cultural forces (this is similar logic to that employed in anthropology, for example, the different human cultures of eating food with hand, versus chopsticks versus cutlery etc). However, a factor missing from these reports (which was not identifiable with this so-called “method of exclusion”) was to pinpoint the exact underlying social learning mechanism(s). Indeed, even non-social learning mechanisms and that Galef would not even have counted as underlying traditions (let alone culture) often could not be excluded (Langergraber et al., 2011).

In using terms such as “culture” to describe these patterns of behaviour we, as a field, left these findings open to misinterpretation. In the original paper (Whiten et al., 1999, p. 685), it was directly claimed to be “difficult to see how such behaviour patterns could be perpetuated by social learning process simpler than imitation”, whilst useful, the data in this study do not allow the veracity of such a claim to be tested.

In examples like these, which are frequent, we can see how the current use of the term “culture” has become detached from that of Galef. Again: for Galef, for something to be called cultural it is required that the trait is indeed underlain by imitation. With this in mind, the evidence for chimpanzee imitation is all too often lacking; claims of imitation are usually misnomers or failures to control for variants of social learning other than imitation. Tests of ‘pure’ imitation (where a task cannot be solved by any social learning mechanisms other than one including action copying) reliably yield negative results (Clay & Tennie, 2017; Tennie, Call, & Tomasello, 2012; Tomasello et al., 1997). In other words, apes do not spontaneously ape (i.e., imitate). Hence, following the logic of Galef, the chimpanzee behavioural differences between populations are certainly interesting, but they are not cultural as they are not shown to be based on imitation – we would need to conclude that we have here evidence for chimpanzee traditions instead.

This debate has raged for some time, with adherents on both sides – and even we ourselves, one of the major objectors to ‘lumping’ are tired of it. But an alternative seems possible – and this is what we recently proposed (Neadle, Allritz, & Tennie, 2017). The solution is to simplify the definition of culture to the bone – we merely add qualifiers to the term, to not loose precision. That way, we hopefully can focus on collecting and comparing data rather than to waste resources fighting definitions.

Our solution

We proposed the most minimal definition of culture that would seem possible. The bar for any animal to become cultural has been set intentionally low by our definition. This is so as not to alienate researchers from the start (if you like your animal species to have culture – while empirical evidence is still necessary even in our definition – the empirical test can be very easily made) and to allow the widest possible net to be thrown out to find animal culture. Arguably the latter is the best approach to enable us to detect general evolutionary patterns.

We, therefore, proposed the “minimal culture” definition: This definition directly equates the presence of any variant of social learning mechanism in any species with culture (Neadle et al., 2017). “Minimal” is simply part of the name of the definition and need not be added in front of the term culture. And so, if you find social learning of any flavour in your study species – congratulations, you have found culture. Crucially, our definition does not require that a specific social learning mechanism (such as imitation) is at play. In fact, a behaviour can be considered cultural – under this definition, if social learning is shown to have any influence at all. For example, if a social learning mechanism is at play that merely facilitates/catalyses the expression/frequency of a behaviour – that’s fine, and is, therefore, culture (compare also Tennie, Call, & Tomasello, 2009).

But with this new, low bar, we have not only rid the debate of the need to show imitation before one can talk of (minimal) culture (others have done the same in their own definitions for similar processes: e.g. Socially Mediated Learning; Caldwell & Whiten, 2002). Here, we took the lesson from the past – these fights about what is and isn’t cultural proved unnecessary bonfires of resources. And so, we designed our definition to really and truly be minimal – there is no additional baggage. In other words, social learning is culture. Thus, by using our definition, there is no need to argue whether, additionally, the behaviour itself is copied, whether it lasts so and so long, whether it appears in at least these many individuals etc.

It’s pure and simple and that’s why we like it. We hope you do, too.

Now, can we please use all our concentration on actual data, and stop fighting over words?

1 In this context, imitation is the copying of actions (Whiten et al., 2004), this is distinct from copying only the results of these actions – termed emulation. Yes reader, I know, term overload, but bear with me here! I am going to focus on imitation in this post – teaching is a whole new kettle of fish!

References
Caldwell, C. A., & Whiten, A. (2002). Evolutionary perspectives on imitation: Is a comparative psychology of social learning possible? Animal Cognition, 5(4), 193–208. https://doi.org/10.1007/s10071-002-0151-x
Clay, Z., & Tennie, C. (2017). Is Overimitation a Uniquely Human Phenomenon? Insights From Human Children as Compared to Bonobos. Child Development, 00(0), 1–10. https://doi.org/10.1111/cdev.12857
Galef, B. G. (1992). The Question of Animal Culture. Human Nature, 3(2), 157–178.
Langergraber, K. E., Boesch, C., Inoue, E., Inoue-Murayama, M., Mitani, J. C., Nishida, T., … Vigilant, L. (2011). Genetic and ‘cultural’ similarity in wild chimpanzees. Proceedings of the Royal Society B: Biological Sciences, 278, 408–416. https://doi.org/10.1098/rspb.2010.1112
Neadle, D., Allritz, M., & Tennie, C. (2017). Food cleaning in gorillas: Social learning is a possibility but not a necessity. PLoS ONE, 12(12), e0188866. https://doi.org/10.1371/journal.pone.0188866
Schofield, D. P., McGrew, W. C., Takahashi, A., & Hirata, S. (2017). Cumulative culture in nonhumans: overlooked findings from Japanese monkeys? Primates, (0123456789), 1–10. https://doi.org/10.1007/s10329-017-0642-7
Tennie, C., Call, J., & Tomasello, M. (2009). Ratcheting up the ratchet: on the evolution of cumulative culture. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 364(1528), 2405–2415. https://doi.org/10.1098/rstb.2009.0052
Tennie, C., Call, J., & Tomasello, M. (2012). Untrained Chimpanzees (Pan troglodytes schweinfurthii) fail to imitate novel actions. PLoS ONE, 7(8). https://doi.org/10.1371/journal.pone.0041548
Tomasello, M., Call, J., Warren, J., Frost, T., Carpenter, M., & Nagell, K. (1997). The Ontogeny of Chimpanzee Gestural Signals: A Comparison Across Groups and Generations. In S. Wilcox (Ed.), Evolution of Communication (pp. 224–259). Amsterdam, The Netherlands: John Benjamins.
Tomasello, M., Kruger, A., & Ratner, H. (1993). Cultural Learning. Behavioral and Brain Sciences, 16, 495–552. https://doi.org/10.1017/S0140525X0003123X
Whiten, A., Goodall, J., Mcgrew, W. C., Nishida, T., Reynolds, V., Sugiyama, Y., … Boesch, C. (1999). Cultures in chimpanzees. Nature, 399, 15–18.
Whiten, A., Goodall, J., Mcgrew, W. C., Nishida, T., Reynolds, V., Sugiyama, Y., … Boesch, C. (2001). Charting Cultural Variation in Chimpanzees. Behaviour, 138(11), 1481–1516.
Whiten, A., Horner, V., Litchfield, C. a, & Marshall-Pescini, S. (2004). How do apes ape? Learning & Behavior, 32(1), 36–52. https://doi.org/10.3758/BF03196005

Conformity in wild vervet monkeys? Possibly not.

Comment on van de Waal, E., Borgeaud, C., & Whiten, A. (2013). Potent social learning and conformity shape a wild primate’s foraging decisions. Science, 340(6131), 483-485.

Written by:

Claudio Tennie, Julia Fischer, Daniel B. Haun & Bennett G. Galef

 

[This was written, submitted and appeared on Science magazine online at the time – but somehow its now lost there. So, rather than resubmit etc etc its now simply here]

 

The conclusion [1] that vervets exhibit “conformity” is, we believe, premature (even though methodologically this study is superior to a previous study making a similar claim in chimpanzees [2]).

Conformity – adjusting ones behaviour to that of a majority – characterizes human cultural learning. Consequently, conclusive evidence of conformity in a non-human primate would increase understanding of the evolution of human culture.

In [1], groups of wild monkeys were trained to avoid one of two different foods. Males subsequently migrating between groups with different food preferences reversed their food choices to match that of the group into which they migrated. The authors concluded that the migrants conformed to the majority [1].  However, socially induced biases other than conformity can account for the reported effect.

Norway rats trained to avoid one of two foods preferred that food after interacting with a single conspecific eating it [3]. Similarly, migrating vervet males might have copied the food choices of a few individuals (e.g females [4])– or even a single other individual (e.g. a dominant) rather than copied the majority. Consistent with the latter hypothesis, the single migrant that did not change food preference was immediately of highest rank in the group he joined [1]. In any case, there is no need to invoke “conformity” to explain the behaviour of migrating males [5, 6].

While it is indeed interesting that social learning can result in stable variation in food choices of vervet social groups, the mechanisms of such social learning may well differ from those supporting analogous behaviour in humans. “Conformity,” particularly normative conformity [7], remains to be demonstrated in non-human primates.

 

  1. van de Waal, E., Borgeaud, C. and Whiten, A. (2013). Science 340, 483-485.

 

  1. Whiten, A., Horner, V. and de Waal, F. B. M. (2005). Nature 437, 737-740.

 

  1. Galef, B. G. and Whiskin, E. E. (2008). Anim. Behav. 75, 2035-2039.

 

  1. van de Waal, E., Renevey, N., Favre, C. M. and Bshary R. (2010). Proc. R. Soc. B 277, 2105-2111.

 

  1. Haun, D. B., Leeuwen, E. J. V. and Edelson, M. G. (2013). Dev. Cogn. Neurosci. 3, 61-71.

 

  1. Leeuwen, E. J. V. and Haun, D. B. (2013). Evol. Hum. Behav. 34, 1-7.

 

  1. Deutsch, M. and Gerard, H. B. (1955). J. Abnorm. Soc. Psych. 51, 629-636.

Open Science Series – Open Access

Damien Neadle

Open science is a term that we hear a lot as academics, however, what exactly does it mean? In this blog series I will discuss some of the most important aspects of open science, including access, data and good practice. As our lab becomes ever more involved with the open science movement, we encourage open science (in all its forms) in our members and those we work with. We are keen to implement changes in our work as the movement progresses.

Open Access

This is probably the most common form of open science. One may often hear about people publishing Open Access, but what does this mean? Well, there are three (main) levels of Open Access:  green, gold and platinum.

Open access

Green is the “lower” level form of Open Access; usually articles with green Open Access are published in a more traditional (subscription or pay-to-view) journal. However, the author retains the right to place their work (or at least a non-final version of it) on some form of repository – institutional or subject specific – after an embargo period has passed. The OpenDOAR project allows you to search for a suitable repository for your paper (http://v2.sherpa.ac.uk/opendoar/). Green Open Access usually doesn’t come with any additional charges. Whilst this is a substantial “improvement” over the traditional journal model – as the science can be disseminated publicly for free – there are drawbacks. For example, as the version of the document that is permitted in the repository is not the published version of the manuscript, it can often lack the polishing and clarity that a formal copy editing process provides. See the SHERPA project for a bank of information of each journal’s self-archiving policies (http://www.sherpa.ac.uk/romeo/index.php). In addition, it may be that the version placed in the repository is not the final version (this is the so-called “pale green” option), so minor errors may still be present. Despite its drawbacks, there is really no reason why any journal/author should not facilitate green Open Access at the very least. It is a low/no cost (the only cost being to the repository) method of scientific dissemination.  However, some authors (myself included)  remain dissatisfied with the limitations of green Open Access, as a result, one may turn to gold Open Access.

Gold Open Access is (or at least was), as the name suggests, the gold standard in Open Access content. This is a form of Open Access where the onus is on the publishers themselves to host the articles in a manner where they can be freely accessed. The final article is usually published under a form of licence agreement that allows free dissemination, under creative commons licence. Journals that offer gold Open Access fall into one of two categories, pure Open Access journals and hybrid journals. A pure Open Access journal only publishes articles using gold Open Access; e.g., PLoS ONE. Meanwhile, hybrid journals are traditional (subscription model) journals that offer gold Open Access as an option. The drawback with gold Open Access is that it comes with a large fee that must be paid by the author. Do not despair though, many large universities have an Open Access budget that is designed to cover these fees – research suggests that as many as 88% of these charges are either paid by an institution or are waived by the journal (https://arxiv.org/abs/1101.5260).

One must recognise, that a large fee may limit which authors can publish using gold Open Access. As a result, the platinum option is more recently being incorporated into the models of many journals dedicated to open science. Platinum Open Access is referred to as a few different things – diamond Open Access, universal access and universal Open Access being a few examples – they are all the same model. Platinum Open Access is simply an evolution of gold, whereby the article processing fee is removed, the costs being covered by a 3rd party (often not for profit) or the journal themselves. This, therefore, allows the material to be published without barriers. Do not assume that all gold level Open Access publishers operate on a “author pays” model, there are many models that also allow the publishers to remove article processing fees (http://oad.simmons.edu/oadwiki/OA_journal_business_models). As many as 70% of pure Open Access journals charge no author fees (https://dash.harvard.edu/handle/1/4552050), however, the large, high impact, journals are yet to adopt this standard on a large-scale.

The full spectrum of Open Access.

Open access spectrum.png

A Proposal for Systematic Replication in Psychology

Written by Claudio Tennie and Richard Moore

This blog post is in response to a recent target article on the replication crisis

Zwaan, R. A., Etz, A., Lucas, R. E., & Donnellan, M. B. (2017). Making replication mainstream. Behavioral and Brain Sciences, 1-50. https://doi.org/10.1017/S0140525X17001972

In the face of the continuing so-called replication crisis, we must aim to fix the system, and to bring scientific research back on track – both with respect to the integrity with which it is conducted, and the faith that others have in it. We therefore strongly agree with the arguments and approach as presented by Zwaan et al. (2017 – see above). Here, we suggest a systematic extension of their proposed program – with a focus on the field of psychology.

We propose to extend the proposals of Zwaan et al. in three ways: (1) to mark differences between replicated and non-replicated work in writing, (2) to use patterns arising from systematic replication to reinforce a just system of reputation management in psychology, and (3) to describe an outline of how a systematic replication system could be installed.

(1) Given the unsatisfactory proportion of psychological findings that currently do not replicate, we as a field could mark this verbally in future manuscripts (and journals/editors could begin to require this). Where authors’ key claims rely on findings that have not (yet) been replicated, they should be encouraged to acknowledge this explicitly in in text citations (e.g. “Smith et al. 2000 – currently awaiting replication”). This system might be extended to count only replications from outside the original group (e.g. “Smith et al. 2000, 2001 – currently awaiting independent replication”). Additionally, where key claims have been subjected to failed replications of which the authors are aware, they should be expected to acknowledge this, and discuss the failure to replicate.

Journals should be encouraged to facilitate authors’ tracking of replication attempts, by systematically updating manuscript websites to link to ongoing, successful, and unsuccessful replication attempts. Successful replications could then be marked and flagged, so that authors could easily track the reliability of the findings they cited (where originals authors had contested unsuccessful replications, these too could be linked from online publication sources.)

(2) While we would like to emphasise the importance of replication attempts, authors should be protected from the possibly negative consequences of single/few failed replications – since inevitably, the findings of honest researchers will sometimes fail to replicate. By adopting a policy of systematic replication attempts, the field of psychology will benefit from both a more reliable exposure of persistent fraud (which we take as self-eminently the most harmful kind) and, at the same time, learn to downplay the role of occasional failures to replicate for personal careers. Where replications are systematic, only if an individual’s work systematically failed to replicate would their reputations suffer. Within such a system, researchers tempted to take shortcuts on their data sets would know they increase their risk of exposure (or reputation drain), and honest researchers would rest assured that overall the reliability of their work would shine through. Of course, underlying reasons for systematic failure to replicate might include unintentionalprocesses (e.g., where a whole field of study had adopted substandard research methods (as detailed by Zwaan et al. (2017))) – but systematic replications could here lead to the adoption of new, more appropriate standards of rigour. In such cases, replications failures would not automatically lead to suspicions of dishonesty, but instead would highlight methods in need of repair.

(3) We propose the ‘PhD Replication Project’. The most straightforward way to encourage systematic replication would be to assign a standard requirement for replicating one finding in the literature to every PhD candidate in psychology. From a centrally constructed database, students would be permitted to choose which currently unreplicated studies to attempt to replicate, as this related to their own research interests. Therefore replication attempts would nonetheless contribute to the foundations of their own PhD research, and young students would not be unfairly burdened with the task of rectifying others’ mistakes.

If this ’PhD Replication Project’ proposal were adopted systematically, individual PhD students would not suffer relative to others. Additionally, while replications in some fields likely take longer than in others, relative publications rates between subfields should not be affected. Of course, PhD student replications should be supplemented by larger replication projects, which could be used for particularly large and demanding replication attempts. But larger projects could also be broken down into smaller parts, suitable for replication attempts by multiple PhD students.

Pressure to make PhD-granting institutions comply with this system could come from grant agencies and governmental resources, who could make it a prerequisite of research funding that PhD scholarships participate in the replication project. If all PhD students were required to replicate, the foundations of any active field of research would rapidly be secured – with the more active fields benefitting most rapidly.

 

How clean is your food?

Written by: Damien Neadle

This post will serve as a brief taster and summary of the main conclusions for the following paper.

Neadle D, Allritz M, Tennie C (2017) Food cleaning in gorillas: Social learning is a possibility but not a necessity. PLoS ONE 12(12): e0188866. https://doi.org/10.1371/journal.pone.0188866

Everything around you right now is the product of culture, from the screen that you are reading this on to the chair that you are sat on; however, the key difference (arguably) between the culture that created these, and the culture that our non-human cousins display is the notion of accumulation (Tomasello, 1998). The concept of cumulative culture (outlined by Tomasello, Kruger, & Ratner, 1993) is one for another post, here we are interested in the culture displayed elsewhere in the animal kingdom.

In my recently (and first) published paper we provide evidence which challenges the notion that cultures require copying social learning to occur. Instead we suggest, in line with previous work from our research group (Bandini and Tennie 2017), that while social learning is responsible for the frequency of behaviours in a population, individual learning is responsible for the emergence of the form, at least in non-human primates.

To avoid confusion between traits that require social learning to emerge (i.e., culture-dependent traits) and those that do not, we introduced a new “soft” definition of culture that ascribes a lower level of culture to any behaviour where social learning is present, in any form. We apply this definition to our example of food cleaning, which had recently been dubbed a putative cultural trait. However, this soft culture concept can be applied to many other great ape behaviours such as algae scooping, a behaviour that is individually reinnovated, but which expression may be facilitated by social learning (Bandini & Tennie, 2017).

Given how common a behaviour such as food cleaning is in the animal kingdom (Neadle, Allritz, & Tennie, 2017), it was unlikely that social learning was required for its emergence. In fact, our data combined with that of Robbins et al (2016), show that all western lowland gorillas, in which food cleaning has been studied, have shown evidence of performing this behaviour. Consequently, food cleaning can be considered as a species universal (Whiten et al., 2001). Thus, our results show that even species universals (that are facilitated by social learning) are included in the “soft” culture definition.

The finding that social learning is not necessary for the emergence of food cleaning lends support to the Zone of Latent Solutions hypothesis (Tennie, Call, & Tomasello, 2009), and suggests that the null hypothesis for non-human animal behaviour should be redirected to assume that individual learning is the default explanation for the emergence of behaviors in primates.

Chimpanzees can reinvent their culture

Written by: Elisa Bandini

The following post was originally posted on http://www.evoanth.net/2017/11/02/chimps-reinvent-culture/ as an assessment of some of the misconceptions of our recent paper; Bandini & Tennie. 2017. ‘Spontaneous reoccurrence of “scooping”, a wild tool-use behaviour, in naïve chimpanzees’

Overview

One of the top 125 questions of our time, as outlined by Science (2005), is understanding the origins of human culture. Our culture has been argued to be one of the most defining features of what makes us human, and differentiates us from other animals. As we cannot go back in time to observe early hominin behaviour, our closest living relatives, chimpanzees, provide a valuable source of insight into how our culture may have started, and cognition behind the evolution of early human behaviour and material culture. Therefore, many researchers study chimpanzee behaviour to draw insights into our culture and that of other animal species. Despite the long-standing research effort into chimpanzee behaviour, debate still remains over how their behaviours (in particular tool-use) first emerge in naïve individuals. Our research focuses on experimentally testing the individual and social learning skills of both human and non-human primates in an effort to further understand how these behaviours emerge across the species.

Experimentally testing chimpanzee tool-use emergence

Our recent paper: ‘Spontaneous reoccurrence of “scooping”, a wild tool-use behaviour, in naïve chimpanzees’ published in the journal PeerJ this September describes the results of an experiment into the individual learning capabilities of chimpanzees. We provided naïve chimpanzees (who had never seen the wild behaviour before) with all the materials of algae scooping, a behaviour observed in wild chimpanzees in Bossou, Guinea.

The chimpanzees in our study were able to reinnovate the same technique as their wild counterparts, despite never having seen the scooping actions before. From these results, we concluded that ‘scooping’ is a behaviour within chimpanzees ‘zone of latent solutions’ (ZLS) or their pre-existing behavioural repertoire (Tennie et al., 2009). Behaviours within the ZLS of a species do not necessarily require social learning to emerge.

Chimpanzee culture

Since Jane Goodall’s (1985) first report on chimpanzee’s tool-use behaviours in the wild, many have argued that chimpanzees possess ‘culture’. The differences in tool-use behaviours observed across wild chimpanzee populations (mapped most extensively in Whiten et al., 1999; 2001) that cannot be explained via genetic or ecological differences have been heralded as evidence of chimpanzees socially learning their population-specific behaviours from each other, therefore suggesting that chimpanzee culture depends on social learning to emerge in naïve individuals.

Our recent paper on the individual learning of one of these presupposed ‘cultural’ behaviours sparked discussion as it goes against the current widespread theory that social learning is absolutely necessary for these behaviours to be reinnovated by naïve chimpanzees. However, one common misunderstanding about the ZLS theory and our paper is that whilst we argue that social learning is not necessary for tool-use behaviours to emerge, we by no means negate that chimpanzees have their own form of culture. Instead, what our paper suggests is that chimpanzees do not have to rely on culture, i.e. on social learning, for the latent behaviours that are expressed by naïve individuals. Thus, chimpanzees can (and, as we show, do) reinnovate tool-use behaviours when placed in the right ecology (amongst other factors) without having to socially learn the behaviour.

The role of social learning in chimpanzee culture

Although the behaviours do not depend on social learning, these processes (such as stimulus enhancement, where individuals are attracted to a specific object by observing another individual interacting with that, or a similar, object) help create the small differences in behaviours observed across chimpanzee populations in the wild.

For example, if a chimpanzee that has never scooped for algae before comes across the debris of another chimp’s scooping stick, social learning processes will make it more likely for the naïve chimpanzee to also use a stick for the same behaviour: the frequency of the behaviour is socially (culturally) increased. This does not, however, mean that chimpanzees cannot spontaneously pick up a stick to scoop algae without first seeing another individual practice the behaviour (as we demonstrated in our study).

One common assumption for chimpanzee (and indeed other animal) behaviours is that if there are multiple ways to reach a same end product, at least one of these ways has to be socially transmitted. We do not agree with this view. In fact, multiple ways of dealing with the environment can all be latent solutions. Again, social learning can then harmonize frequencies of one variant within a population (but it could also have been the other, if it had started differently). And so, small differences in tool choice (e.g. using a wooden or stone hammer for nut cracking) can be within chimpanzees ZLS, but social information influences which behaviour is more likely to be expressed.

The difference between human and chimpanzee culture

Thus, chimpanzees are also influenced by social information, and subsequently clearly possess culture. However, the big difference between modern human and chimpanzee culture is the degree of reliance on social learning: whilst modern human culture relies on high-fidelity social learning processes such as imitation and teaching (indeed, most of the products that surround us today, such as the technology you are reading this from, could not be reinnovated by a single individual on the spot), chimpanzee culture can be reinnovated on the spot by all individuals.

Although we argue that modern human and chimpanzee cultures are fundamentally based on very different mechanisms, it is important to note that humans also possess a ZLS. In fact, humans also have some basic tool-use behaviours that they can also reinnovate without social information. Reindl and colleagues (2016) presented children with novel tool-use tasks and found that the naïve children spontaneously used tools to solve basic problems (such as using a stick to retrieve pom-poms from inside a tube) without needing the solution to be demonstrated beforehand. However, the difference between our ZLS and that of other animals is that we can go (and have gone) far beyond our ZLS by imitating and learning from each other, ultimately creating the extraordinary and diverse culture that surrounds us today.

Elisa Bandini

References

Kummer H, Goodall J. (1985). Conditions of Innovative Behaviour in Primates. Philosophical Transactions of the Royal Society of London. Series B.

Reindl E, Beck SR, Apperly IA, Tennie C. (2016). Young children spontaneously invent wild great apes’ tool-use behaviours. Proceedings of the Royal Society B, 283. Doi: 10.1098/rspb.2015.2402.

Tennie C, Call J, Tomasello M. (2009). Ratcheting up the ratchet: On the evolution of cumulative culture. Philosophical Transactions of the Royal Society, 364, 2405-2415. Doi: 10.1098/rstb.2009.0052.

Whiten A, Goodall J, McGrew W, Nishida T, Reynolds V, Sugiyama Y, Tutin C, Wrangham W, Boesch C. (1999). Cultures in chimpanzees. Nature, 399, 682-685. Doi: 10.1038/21415.

Whiten A, Goodall J, McGrew WC, Nishida T, Reynolds V, Sugiyama Y, Tutin CEG, Wrangham RW, Boesch, C. (2001). Charting cultural variation in chimpanzees. Behaviour. 138, 1481-1516. Doi: 10.1163/156853901317367717.