Category: Evolution

Reconstructing linguistic phylogenies – a tautology?

ResearchBlogging.org

So I thought I should begin my first post on here with a nice and gentle introductory sentence, but I realise that pointing out the increased use of computational phylogenetic tools on cultural and particularly linguistic data to the avid readers of this blog is probably a pretty pointless exercise.

There is of course a lot to say about parallels between biological and cultural evolution, and some of the work using computational tools has given us new insights into yet unanswered (and even hitherto unasked!) questions regarding language and language change. But today I’d like to share some thoughts on a particular “application” of phylogenetic tools, the methodology of which I find a bit odd, even though it is arguably the simplest evolutionary analogy of them all: using computational phylogenetics to reconstruct linguistic phylogenies.

Continue reading “Reconstructing linguistic phylogenies – a tautology?”

James Hurford: Animals Do Not Have Syntax (Compositional Syntax, That Is)

After passing my final exams I feel that I can relax a bit and have the time to read a book again. So instead of reading a book that I need to read purely for ‘academic reasons’, I thought I’d pick one I’d thoroughly enjoy: James Hurford’s “The Origins of Grammar“, which clocks in at a whopping 808 pages.
I’m still reading the first chapter (which you can read for free here) but I thought I’d share some of his analyses of “Animal Syntax.”
Hurford’s general conclusion is that despite what you sometimes read in the popular press,

“No non-human has any semantically compositional syntax, where the form of the syntactic combination determines how the meanings of the parts combine to make the meaning of the whole.”

The crucial notion here is that of compositionality. Hurford argues that we can find animal calls and songs that are combinatorial, that is songs and calls in which elements are put together according to some kind of rule or pattern. But what we do not find, he argues, are the kinds of putting things together where the elements put together each have a specified meaning and the whole song, call or communicative assembly “means something which is a reflection of the meanings of the parts.”

(Link)
To illustrate this, Hurford cites the call system of putty-nosed monkeys (Arnold and Zuberbühler 2006). These monkeys have only two different call signals in their repertoire, a ‘pyow’-sound that ‘means’, roughly, ‘LEOPARD’; and a ‘hack’ sound that ‘means’, roughly, ‘EAGLE’.

Continue reading “James Hurford: Animals Do Not Have Syntax (Compositional Syntax, That Is)”

Degeneracy, Evolution and Language

Having had several months off, I thought I’d kick things off by looking at a topic that’s garnered considerable interest in evolutionary theory, known as degeneracy. As a concept, degeneracy is a well known characteristic of biological systems, and is found in the genetic code (many different nucleotide sequences encode a polypeptide) and immune responses (populations of antibodies and other antigen-recognition molecules can take on multiple functions) among many others (cf. Edelman & Gally, 2001). More recently, degeneracy is appreciated as having applications in a wider range of phenomena, with Paul Mason (2010) offering the following value-free, scientific definition:

Degeneracy is observed in a system if there are components that are structurally different (nonisomorphic) and functionally similar (isofunctional) with respect to context.

A pressing concern in evolutionary research is how increasingly complex forms “are able to evolve without sacrificing robustness or the propensity for future beneficial adaptations” (Whitcare & Bender, 2010). One common solution is to refer to redundancy: duplicate elements that have a structure-to-function ratio of one-to-one (Mason, 2010). Nature does redundancy well, and is exemplified by the human body: we have two eyes, two lungs, two kidneys, and so on. Still, even with redundant components, selection in biological systems would result in a situation where competitive elimination leads to the eventual extinction of redundant variants (ibid).

Continue reading “Degeneracy, Evolution and Language”

Cooperation and Conflict Colloqium papers

Papers from the “In the Light of Evolution V:  Cooperation and Conflict” edition of the Sackler Colloquium are now available in the early edition of PNAS:

http://www.pnas.org/search?tocsectionid=In+the+Light+of+Evolution+V:+Cooperation+and+Conflict+Sackler+Colloquium&sortspec=date&submit=Submit

Some papers such as “The cultural niche: Why social learning is essential for human adaptation”, “Genomic imprinting and the evolutionary psychology of human kinship” and “Evolutionary foundations of human prosocial sentiments” may be of interest to the reader of the blog.

 

You can read the earlier “In the light of Evolution” collections here:

In the Light of Evolution IV: The Human Condition: http://www.pnas.org/content/107/suppl.2

In the Light of Evolution III: Two Centuries of Darwin: http://www.pnas.org/content/106/suppl.1

In the Light of Evolution II: Biodiversity and Extinction: http://www.pnas.org/content/105/suppl.1

In the Light of Evolution I: Adaptation and Complex Design: http://www.pnas.org/content/vol104/suppl_1/

Laryngeal Air Sacs

So, I got a request from a friend of mine to make an abstract on the fly for a poster for Friday. I stayed up until 3am and banged this out. Tonight, I hope to write the poster justifying it into being. A lot of the work here builds on Bart de Boer’s work, with which I am pretty familiar, but much of it also started with a wonderful series of posts over on Tetrapod Zoology. Rather than describe air sacs here, I’m just going to link to that – I highly suggest the series!

Here’s the abstract I wrote up, once you’ve read that article on air sacs in primates. Any feedback would be greatly appreciated – I’ll try to make a follow-up post with the information that I gather tonight and tomorrow morning on the poster, as well.

Re-dating the loss of laryngeal air sacs in hominins

Laryngeal air sacs are a product of convergent evolution in many different species of primates, cervids, bats, and other mammals. In the case of Homo sapiens, their presence has been lost. This has been argued to have happened before Homo heidelbergensis, due to a loss of the bulla in the hyoid bone from Austrolopithecus afarensis (Martinez, 2008), at a range of 500kya to 3.3mya. (de Boer, to appear). Justifications for the loss of laryngeal air sacs include infection, the ability to modify breathing patterns and reduce need for an anti-hyperventilating device (Hewitt et al, 2002), and the selection against air sacs as they are disadvantageous for subtle, timed, and distinct sounds (de Boer, to appear). Further, it has been suggested that the loss goes against the significant correlation of air sac retention to evolutionary growth in body mass (Hewitt et al., 2002).

I argue that the loss of air sacs may have occurred more recently (less than 600kya), as the loss of the bulla in the hyoid does not exclude the possibility of airs sacs, as in cervids, where laryngeal air sacs can herniate between two muscles (Frey et al., 2007).  Further, the weight measurements of living species as a justification for the loss of air sacs despite a gain in body mass I argue to be unfounded given archaeological evidence, which suggests that the laryngeal air sacs may have been lost only after size reduction in Homo sapiens from Homo heidelbergensis.

Finally, I suggest two further justifications for loss of the laryngeal air sacs in homo sapiens. First, the linguistic niche of hunting in the environment in which early hominin hunters have been posited to exist – the savannah – would have been better suited to higher frequency, directional calls as opposed to lower frequency, multidirectional calls. The loss of air sacs would have then been directly advantageous, as lower frequencies produced by air sac vocalisations over bare ground have been shown to favour multidirectional over targeted utterances (Frey and Gebler, 2003). Secondly, the reuse of air stored in air sacs could have possibly been disadvantageous toward sustained, regular heavy breathing, as would occur in a similar hunting environment.

References:

Boer, B. de. (to appear). Air sacs and vocal fold vibration: Implications for evolution of speech.

Fitch, T. (2006). Production of Vocalizations in Mammals. Encyclopedia of Language and Linguistics. Elsevier.

Frey, R, & Gebler, A. (2003). The highly specialized vocal tract of the male Mongolian gazelle (Procapra gutturosa Pallas, 1777–Mammalia, Bovidae). Journal of anatomy, 203(5), 451-71. Retrieved June 1, 2011, from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1571182&tool=pmcentrez&rendertype=abstract.

Frey, Roland, Gebler, Alban, Fritsch, G., Nygrén, K., & Weissengruber, G. E. (2007). Nordic rattle: the hoarse vocalization and the inflatable laryngeal air sac of reindeer (Rangifer tarandus). Journal of Anatomy, 210(2), 131-159. doi: 10.1111/j.1469-7580.2006.00684.x.

Martínez, I., Arsuaga, J. L., Quam, R., Carretero, J. M., Gracia, a, & Rodríguez, L. (2008). Human hyoid bones from the middle Pleistocene site of the Sima de los Huesos (Sierra de Atapuerca, Spain). Journal of human evolution, 54(1), 118-24. doi: 10.1016/j.jhevol.2007.07.006.

Hewitt, G., MacLarnon, A., & Jones, K. E. (2002). The functions of laryngeal air sacs in primates: a new hypothesis. Folia primatologica international journal of primatology, 73(2-3), 70-94. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12207055.


Sound good? I hope so! That’s all for now.

Recall dependent on language?

A new study has been published in Current Biology which offers evidence to suggest that monkeys have the capacity for both recognition and recall of simple shapes.

The study showed that rhesus monkeys can recall shapes from memory. This was shown using an experiment which had the monkeys reproduce shapes on a computer touch screen. These findings suggest that the memory of humans and old world monkeys may be more similar than we previously suspected.

Recall is separate and special in comparison to recognition as it shows an ability to remember and visualise things which are not present in the moment. This is an ability which is implicated in skills such as planning and imagining. This is also thought to enhance things like navigation and social behavior. In the past it has thought that an ability to recall none present items is dependent on language. This has been suggested in the past by prominent linguists such as Charles Hockett who thought that the ability of displacement was facilitated by language and was a driving force behind its evolution.

Because of a lack of demand for recall in the lives of monkeys they will not use their recollection skills very often in the wild. In the press release, Benjamin Basile, who lead the study said:

“Maybe it’s often just easier to recognize the monkey, the food, or the landmark in front of you. What we do know is that they do seem to have the ability to recall information in the lab.”

Experiments with humans have shown that recall and recognition require different types of memory. This has been difficult to show with other primates as recall tests are difficult to devise for monkeys because they can’t draw or talk.

The experiment used five rhesus monkeys who were trained on a recall test in which they had to reproduce a simple figure on a touch screen from memory. The shapes were made up of large pixels or boxes on a screen. The monkeys were shown these shapes and then, after a delay, were presented with part of the shape in a different location. The monkeys had to replicate the rest of the shape by touching where the other pixels should be.

The monkeys remembered less in recall than in recognition tests which is the same case in humans. However, the recall performance deteriorated more slowly over time. The monkeys were also able to transfer their ability to recall shapes to novel shapes as they were shown to be able to recall shapes which weren’t used in training.

This ability has probably been present since our last common ancestor with old world monkeys some 30 million years ago and is probably not facilitated by language.

The study hypothesises that:

“Recollection and familiarity likely evolved because they solved functionally incompatible problems. For example, familiarity does not support detailed memory for context, but it is quick and resistant to distraction. Recollection is slower and more vulnerable to distraction but supports a more detailed and flexible use of memory. Familiarity might better allow rapid responses to foods and predators under distracting conditions, whereas recollection might be necessary to access knowledge of distant food locations or past social interactions for planning future behavior.”

References

Benjamin M. Basile, Robert R. Hampton. Monkeys Recall and Reproduce Simple Shapes from Memory. Current Biology, 28 April 2011

 

The path to empathy

Published online at Plos one yesterday a study done at the Yerkes National Primate Research Center by Campbell and de Waal (2011) has found a link between social groups and empathy in chimpanzees as demonstrated by involuntary yawning responses.

The study is based on the psychological concept of ingroups and outgroups. In humans ingroups are those we see as similar to ourselves and outgroups are those we perceive as different.

Biases involved in ingroup-outgroup discrimination in know to even extend to involuntary responses which includes empathy for pain. This has never been tested in other animals though.

Contagious yawning is thought to be linked with empathy. The study used this assumption to test if chimpanzees’ ingroup-outgroup biases would effect how contagious a yawn can be. In other words if contagious yawning is linking to empathy and empathy is linked to ingroup-outgroup biases within chimpanzees then the chimpanzees should yawn more in response to watching ingroup members yawn than outgroup.

The study used 23 chimpanzees from two separate groups and they were made to watch videos of familiar and unfamiliar individuals yawning. Videos of the same chimps not yawning were also used for control. The chimpanzees yawned more when watching the familiar yawns than the familiar control or the unfamiliar yawns, demonstrating an ingroup-outgroup bias in contagious yawning.

The authors have suggested that these result may be more magnified in chimpanzees than it is in humans as chimpanzees live in much smaller communities than humans and are generally very hostile to those outside of their small social group. Ingroup-outgroup biases are therefore probably much more absolute in chimpanzees.

This study adds empirical evidence to suggest that contagious yawning is subject to empathy. This may have further implications for studying the evolutionary foundations of empathy which obviously has implications for things like theory of mind which is pretty high up on the list for preadaptations for language.

References

Campbell MW, de Waal FBM (2011) Ingroup-Outgroup Bias in Contagious Yawning by Chimpanzees Supports Link to Empathy. PLoS ONE 6(4): e18283. doi:10.1371/journal.pone.0018283

The adaptive value of age, co-operation (and secret signals)

More elephant based news!

A new study from the Proceedings of the Royal Society B, published today, has found that elephants pay attention to the oldest female elephant in their group when a predator is approaching.

The research, carried out in Kenya, used recordings of roars from both male and female lions and monitored the reactions of groups of African Elephants. It has been known for a long time that elephants social groups are formed around a matriarchy. The experiment found that groups of elephants with matriarchs quickly organised themselves into defensive bunch formations after appearing to stop and pay attention to their female leader. These groups were also much more likely to approach the loud speaker producing the roar in an aggressive manner.

Male lions present a greater threat to groups of elephants as they are much more likely to attack elephants when alone and are usually much more successful than females who will only attack when part of a group. The elephants showed an ability to differentiate between male and female lions. The study also showed that matriarchs who were much older were much more likely to react in the appropriate way to roars made by male lions which is thought to be the result of experience.

The signals which allow the Matriarch to elicit this co-ordination among her group are still largely unknown due to the lack of loud vocalisations and Karen McComb and Graeme Shannon, who lead the initial study, are now looking into finding quieter, less obvious vocalisations and posture cues.

The study provides the first empirical evidence that within a social group, individuals may gain benefits from paying attention to an older leader because of their abilities in making decisions when under threat. This generates insights into selection for longevity in cognitively advanced social mammals.

Elephants give each other a helping trunk

A study published on PNAS.org yesterday has shown that elephants might have shared goals which gives them the ability to co-operate.

An experiment was done using the classical 1930s cooperation paradigm used to test the co-operative abilities of monkeys and apes. This paradigm is used to explore the cognition underlying coordination toward a shared goal. This explores what animals know or learn about the benefits of cooperation and also tests their ability to comprehend a partner’s role in cooperation.

The experiment comprises of 2 animals who need to work together to pull 2 ends of the same rope in order to pull a platform towards them which holds a reward such as food.

Experiments such as this have never been done on animals apart from primates before. Plotnik et al. (2011) subjected this experimental paradigm to elephants and have shown that elephants can learn to coordinate with a partner. The elephants also delayed pulling he rope for up to 45 seconds if the arrival of their partner was delayed which showed that they comprehended that there was no point to pulling on the rope if their partner lacked access to the rope. The elephants learnt that this was the case much more quickly than has been shown in Chimpanzees in other studies.

Observations from the wild suggest that in nonhuman primates these co-operative abilities exist but experimental results have been mixed. Plotnik et al. (2011) claim that convergent evolution may have lead elephants to have reached a level of cooperative skill equal to that of chimpanzees.

You can see a video of the elephants doing the experiment here: http://news.bbc.co.uk/earth/hi/earth_news/newsid_9417000/9417308.stm

References

Plotnik, J. M., R. Lair, w. Suphachoksahakun & F. B. M. de Waal (2011)
Elephants know when they need a helping trunk in a cooperative task. PNAS 2011 : 1101765108v1-201101765.