Tag Archives: PNAS

word order

The origins of word order

A paper by Gell-Mann & Ruhlen in PNAS this week conducts a phylogenetic analysis of word order in languages and concludes that SOV is the most likely ancestor language word order.  The main conclusions from the analysis are:

(i) The word order in the ancestral language was SOV.

(ii) Except for cases of diffusion, the direction of syntactic change, when it occurs, has been for the most part SOV > SVO and, beyond that, SVO > VSO/VOS with a subsequent reversion to SVO occurring occasionally. Reversion to SOV occurs only through diffusion.

(iii) Diffusion, although important, is not the dominant process in the evolution of word order.

(iv) The two extremely rare word orders (OVS and OSV) derive directly from SOV.

This analysis agrees with Luke Maurtis‘ work on function and Uniform Information Density (blogged about here).

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/

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.

Bored birds, busy brains: Habituation to song initiates significant molecular changes in auditory forebrain of zebra finch

When we think of habituation, we tend to think of a process in which there is a decrease in psychological and behavioural response(s) over time following an organism’s exposure to a stimulus. Conceptualising habituation in this manner seems to imply the loss of something once an initial learning event has taken place. Although this may accurately describe what occurs at the psychological and behavioural levels, a study by a group of scientists from the University of Illinois (Dong et al. 2010), which examines habituation at the neurobiological level, shows that contrary to this conceptualisation, both initial exposure and habituation to song playbacks initiates a vast array of genetic activity in the zebra finch brain.

The systematic regulation of FoxP2 expression in singing zebra finches has been the subject of previous posts, but there is also a growing literature, of which Dong et al’s study is a part, documenting increases in ZENK gene (which encodes a transcription factor protein that in turn regulates the expression of other target genes) expression in zebra finch auditory forebrain areas in response to playbacks of song or the song of a conspecific. Studies showed that ZENK expression seems to mirror the typical decline in response associated with habituation in that after a certain amount of repetition, presentation of the song that originally elicited upregulation of ZENK no longer did so, and that ZENK returned to baseline levels – although upregulation of ZENK would occur if a different song or an aspect of novelty was introduced (i.e. the original song was presented in a different visual or spatial context).

What Dong et al. have demonstrated by conducting a large scale analysis of gene expression at initial exposure, habituation, and post-habituation stages however, is that unexpectedly profound genetic changes occur as a result of habituation in the absence of any additional novel stimuli following the surge of activity observed during initial exposure to novel song. Thus, the resounding merits of the Dong et al. (2010) study lie in the broadness of their approach, providing a true sense of magnitude with respect to genomic involvement in vocal communication and illuminating important influences that have gone unnoticed by studies with a narrower focus. I summarise the experimental design and findings of the paper below.

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Marc Hauser investigated for scientific misconduct

The Boston Globe reported today that Marc Hauser is on leave due to scientific misconduct . The Great Beyond summarises the article as follows:

The trouble centers on a 2002 paper published in the journal Cognition (subscription required). Hauser was the first author on the paper, which found that cotton-top tamarins are able to learn patterns – previously thought to be an important step in language acquisition. The paper has been retracted, for reasons which are reportedly unclear even to the journal’s editor, Gerry Altmann.

Two other papers, a 2007 article in Proceedings of the Royal Society B and a 2007 Science paper, were also flagged for investigation. A correction has been published on the first, and Science is now looking into concerns about the second. And the Globe article highlights other controversies, including a 2001 paper in the American Journal of Primatology, which has not been retracted although Hauser himself later said he was unable to replicate the results. Findings in a 1995 PNAS paper were also questioned by an outside researcher, Gordon Gallup of the State University of New York at Albany, who reviewed the original data and said he found “not a thread of compelling evidence” to support the paper’s conclusions.

Hauser has taken a year-long leave from the university.

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