Do bacteria communicate like primates?

Seemingly rare in occurrence, ‘combinatorial communication’ has been speculated a cognitively complex process, and thus considered an evolutionary forerunner of the human language. Researchers have now challenged this view by showing that such communication strategies exist even amongst unicellular organisms, casting a new perspective on the evolution of language.

The process of combining two signals with distinct meanings to generate a third signal that has a completely different meaning is a hallmark of the human language. Humans have evolved to utilize composite signals as an advantageous and efficient means of communication. Considering the ease with which emotions can be expressed by means of composite signals, ‘combinatorial communication’ is surprisingly rare in nature. Excepting the example of the putty-nosed monkeys, there are hardly any evidences for the existence of such a communication system in the animal kingdom. This rarity led to the belief that combinatorial communication exhibited by non-human primates could be the precursor of linguistic communication.  

Scott-Phillips et al. have now replicated an experiment, which was previously used to demonstrate combinatorial communication in putty-nosed monkeys, in the bacterium Pseudomonas aeruginosa. Bacterial cells utilize the quorum-sensing (QS) system to monitor their external environment and to communicate with each other. Using chemical signals, bacteria alter gene expression based on the environmental cues.

Two well-studied signaling molecules of P. aeruginosa thus formed the basis of their study. Through their cognate receptors, these molecules regulate distinct gene expression patterns. When combined, one would expect to obtain an expression that is a sum of the effect of the two molecules. However, the researchers observed an interestingly novel expression pattern, which led them to suggest that combinatorial communication may indeed be widely present in nature.

Instead of considering the implications of superficial observations of animal communication systems, they propose that the precise cognitive mechanisms that regulate the communication process should be dissected across species to truly study the evolution of human language. 

Cover image: Pseudomonas aeruginosa (Wikimedia).

References

Orginal article: Combinatorial Communication in Bacteria: Implications for the Origins of Linguistic Generativity, PloS One (2014)

Why is combinatorial communication rare in the natural world, and why is language an exception to this trend?, J. R. Soc. Interface (2013)

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Comments

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  Alen Piljić Wednesday, 21 May 2014 - 19:31 UTC

  Fixed the link in admin. Thanks Johannes!

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  Johannes W. Dietrich Wednesday, 21 May 2014 - 19:05 UTC

  Unfortunately, the full text link to the paper in PLoS One doesn't work. The correct URI is http://dx.doi.org/10.1371/journal.pone.0095929 .