Evolution of Communication - Volume 4, Issue 2, 2000

This paper reports a phenomenon supporting the hypothesis that the emergence of structure in the evolution of language was a staged process. To develop a grammatical structure it seems necessary to first have discrete constituents which can be the building blocks of a hierarchical system. By analysing observed speech we show that the development of a linear sequence of grammatical constituents has its own advantage, before a possible next stage when constituents are integrated into a hierarchical structure.A stream of speech sounds has to be segmented to allow for breathing. This segmentation has further developed in a certain way that makes it easier for the hearer to decode than if it were not segmented, or if it were segmented in an arbitrary manner. Well known tools from Information Theory are employed to analyse the ease of decoding speech. Segmentation depends on prosodic discontinuities, such as pauses and intonation marked by tone unit boundaries. These discontinuities usually mark groups of words with some syntactic cohesion, such as phrases and clauses. We show that in a modern corpus of spoken language observed segmentation facilitates the effective transfer of information, while lack of segmentation or arbitrary segmentation imposed on a stream of words makes decoding less efficient. This supports the hypothesis that the necessary constituents of a grammatical structure may have evolved as a consequence of developments favouring more efficient decoding of a linear stream of spoken words.The source material for this investigation is taken from the prosodically marked up Machine Readable Spoken English Corpus (MARSEC).

High levels of sex hormones may lower immunocompetence, making it difficult for a person’s body to fight off infections. Facial characteristics that reveal high levels of sex hormones might signal the presence of a robust immune system. In men, high testosterone levels are associated with prominent cheekbones, wide jaw, and long chin. In women, high estrogen levels are associated with prominent cheekbones, narrow jaw, and short chin. We examined whether facial features associated with immunocompetence positively covary with health. Participants from 2 groups of university students (67 women, 34 men, in total) completed daily measures of psychological, emotional, and physical health over a one-month period. Physiological fitness was assessed via cardiac recovery time following exercise. A facial photograph of each participant was rated along several personality dimensions, activity level, and attractiveness. Using the photographs, we measured participants’ jaw width, chin length, and cheekbone prominence. Results provide unimpressive evidence for the hypotheses that (1) women displaying an estrogenized face and (2) men displaying a testosteronized face are physiologically, psychologically, and emotionally healthier. Discussion highlights directions for future work on whether facial structural characteristics might communicate information about underlying health.

Chimpanzees (Pan troglodytes) give both food barks and pant hoots upon encountering food and regulate their calls based upon such factors as food quantity, quality, and possibly divisibility. Although it has been determined that several species, both primate and non-primate, regulate their food calls based upon the presence or absence of an audience, this has not been systematically explored with chimpanzees. Group-housed chimpanzees were given access to either large or small quantities of food when they had either visual access to companions (Audience condition) or were visually isolated (No Audience condition). We predicted that chimpanzees would call more for larger quantities of food and more in the presence of an audience. As expected, food calling was greater for large quantities of food than small quantities. The effect of an audience was more complex. A visible audience increased the rate of food calling for a large, sharable quantity of food, yet decreased the rate for a small, non-sharable quantity. These results are consistent with the hypothesis that chimpanzee vocal expression is sensitive to social context, and that they are able to regulate the information made available to others in accordance with predicted future interaction.

We investigated the vocal repertoire of a Malagasy primate: the black lemur (Eulemur macaco macaco). The first study allowed the characterization of 16 different vocal signals on the basis of acoustic parameters. Black lemurs emit sparse harmonic sounds, dense harmonic sounds, spectrally structured noise (Beeman, 1998) and a wide variety of grunts. The second study focused on the behavioral context of emission of these signals and used the pre- and post-event histogram method (Douglass and Sudd, 1980; Preuschoft, 1995a). It provides statistical demonstration of the association between a signal and other behaviors of the emitter, thus giving insight into the latter’s motivations. Four signals are linked to affiliative and agonistic interactions. Three signals express a state of alarm, and two appear related to discomfort. Most grunts are linked to contact and signal precisely the emitter’s level of vigilance. Other interdisciplinary communication studies could benefit from methodology and software used here.

The article presents the outlines of an integrative theory of meaning based on the concept of value, understood both as a biological and as a socio-cultural category, synthesizing ideas from evolutionary and developmental psychology, semiotics and cybernetics. The proposal distinguishes between four types of meaning systems, cue-based, associational, mimetic and symbolic, forming an evolutionary and epigenetic hierarchy. The theory is applied to phylogenetic and human ontogenetic development, pointing out significant parallels between the two processes, involving both continuity and discontinuity between the different levels. Since one of the basic tenets of the theory is that only living systems have intrinsic value, which is a necessary and sufficient condition for possessing the category meaning, negative implications are drawn for the meaning potential of (current) artificial systems.