Whisper of Gibbons - Essay Example

Introduction

According to researchers, the whispers of gibbons could be central to understanding the evolution of human speech. These studies have revealed the likely purpose of some of the distinct whispers by gibbons popularly known as 'hoo' calls. The animals use some particular whispers for specific events, something that could offer clues to researchers on how human speech evolved. Gibbons are distinguished from other primates due to their loud and conspicuous songs, but they can also produce soft calls referred to as 'hoos.'

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For a long time, due to their low volume, these whispers have been difficult to record and analyze. However, the availability of computer analysis and modern recording technology has made progress in this area possible in the recent past, revealing that distinct whispers are made in response to specific events. Some of these events include an encounter with neighbors, foraging, and encounter with different predators (Wiener, 1984). Their vocal repertoire has allowed scientists to study the evolution of complex vocal communication of human beings.

The acoustic variation recorded in gibbons is closer to human communication, whereby subtle acoustic parameters, particularly pitch, are essential tools for communicating meaning. Hence, this research is critical in the understanding of the evolution of human speech. One of the central objectives of the research is to highlight whether whispers of gibbons vary with specific events and predators. The other objective to be pursued by the research includes the contribution of whisper by gibbons to the evolution of human speech.

Vocal Repertoire Size and Size of Social Group

One of the most important revelations that scientists have unearthed through the study of gibbon whispers is that the development of repertoire is linked to the size of a social group. Because human beings are social animals, the evolution of human speech could closely be associated with how early populations interacted. One of the major findings of the studies whispers by the gibbons is that vocal communication system plays an important role in facilitating or constraining increase in the size of the group as well as the levels of social bonding within the primate social groups.

According to McComb and Semple (2005), speech plays a very important role in the evolution of social behavior. As a result, it is possible to estimate when human vocal communication started by estimating when they began to live in larger social groups. According to these authors, originally, speech evolved to cater to social relationships. The development of language became necessary as primate groups grew larger, making grooming alone inadequate for maintaining social relationships.

Hence, vocal repertoire facilitates social bonding in non-human primates, alongside the rudimentary grooming. Evolutionary changes in grooming are closely linked to repertoire evolutionary changes in terms of size because as groups grew larger, a more advanced method of social bonding needed to be developed, hence, the need for a more advanced repertoire (McComb & Semple, 2005). As a result, it is more likely that repertoire size coevolved alongside grooming to facilitate bonding in apes as observed.

In other words, increases in one created a selection pressure for the other. For example, as the size of the social group grew, there was pressure for the size of grooming to increase to cater to the needs of the expanding size. Consequently, speech grew as a way to compensate for the inadequacy of grooming alone. Ultimately, both speech and grooming grew alongside each other to facilitate social bonding.

Linda Wiener (1984) advances this field by explaining that just like human, gibbons are capable of using non-linguistic information to interpret the meaning of a signal. In particular, she explained that the monkeys use sound to distinguish members of their own group from those of other groups, perhaps alluding to the presence of different dialects in the evolution of human speech.

In her observation, Wiener (1984) noted that the gibbons acted aggressively to the recordings of vocalizations that originated from a different dialect area. Similarly, human beings use dialect to distinguish members of their geographical and social area from non-members. Hence, in both monkeys and humans, vocal systems diverge naturally, and the members use differences in the system as social cues. This revelation has huge implications on the understanding of human speech. For example, the observation of dialects among gibbons may indicate that the variation in dialect is the first thing to appear in the course of the evolution of human speech.

Context-Specific Nature of Whispers

Apart from the development of speech to serve social functions, the study of gibbons has alluded that speech may have evolved due to the need to communicate a message that is specific to the context. In the course of evolution, survival has hinged upon the ability to communicate a message that is specific to the needs of a certain group ranging from defense, cohesion, playing, directing others, and begging (Clarke et al., 2015). For example, the pitch for calling other gibbons for food has been observed to be different from the distress call uttered by a member when separated from the herd. For example, according to Clarke et al., measures of peak and low frequency shows that whispers given in response to raptors were lower than those given as part of a daily duet song for both females and males.

One of the most distinct whispers by the gibbons is the one referring to predators such as tigers and leopards. So distinct was the pitch that the researchers classified that whisper as predator-specific call variant. For example, inter-call intervals for whispers referring to tigers and leopards were found to be shorter than the intervals for raptor warnings.

In contrast, those given out for raptors that the gibbons view as of a lesser threat were observed to be widely spread out, of less intense, of shorter duration, smaller frequency span, and lower frequency than other whispers, making them the least audible of all whisper variants (Clarke et al., 2006). Hence, the gibbons give this variant because they perceive raptors as less threatening while at the same time not wanting to draw the attention of more threatening predators including tigers and leopards.

Linda Wiener (1984) further develops this argument by explaining that apart from warnings, the human communication system has a variety of other functions that human share with all primates including the expression of emotions, information transfer, recruiting, ritual greetings, and requesting. However, only human beings and chimpanzees are capable of lying and planning. According to Wiener (1984), chimpanzees are politically and socially sophisticated animals that they have learnt to lie, manipulate others, and plan for the future.

Besides, according to Clarke et al. (2015), the young gibbons make whispers of a different pitch from that made by adults when threatened by raptors. As highlighted, in general, gibbons give specific warming when confronted by the threat of a predator.

Using Pitch

However, Clarke et al. (2015) went a step further to explain that using pitch, researchers have been able to distinguish the whispers made by gibbons of different ages when faced with predators. Due to the relative sizes of their bodies, infant and juvenile gibbons are more threatened by raptors than adult gibbons. However, because raptors and cats do not threaten them with the same degree, the mature gibbons give a significantly different anti-predator response.

Therefore, there is a lot of inference that can be gathered about the human speech from the context-specific nature of gibbon whispers. The variation in pitch recorded in gibbon whispers may be the basis of vocal parameters similar to human speech. In humans, and in other primates, subtle acoustic parameters, including speech, are important carriers of meaning (Clarke et al., 2006). Due to the widespread nature of context-specific calling, it is highly likely that the ancestors of modern humans and primates used this behavior to communicate meaning widely.

Among primates, gibbons are of interest to scientists because they create songs and have greater control of their vocal tract than other primates. The comparison of the vocal tract control of gibbons with human speech is critical because of shared phylogeny. For example, after comparing the vocalization of human beings and gibbons, Clarke et al. (2011) came to the conclusion that the only difference is regarding production flexibility.

However, the comprehension capability between both parties is similar because like humans, gibbons can use pitch to communicate meaning. Despite their limited vocal repertoire, non-human primates, including gibbons, are capable of varying their pitch to widen the power of their communication.

Conclusion

In conclusion, all the authors are in agreement that the whisper of gibbons shows evolution is speech, helping researchers understand some pertinent issues about human speech and its evolution. As observed, gibbons reliably produce whispers that are context-dependent in different contests, including an encounter with neighbors, predator detection, duet songs, and foraging (Clarke et al., 2006). This meaning need not be vocalized by different phonemes but also through the pitch.

Moreover, differences in vocalization are not just between non-predator and predator but also within different classes of predators. Besides, different ages of gibbons communicate different levels of threats in response to the different predators. Hence, the gibbons have a complex set of subtle spectral parameters that discriminate contexts (Clarke et al., 2015). Besides, by understanding the interaction between these non-human primates, scientists are is a better position to understand how and why human language could have evolved.

References

Clarke, E., Reichard, U.H. & Zuberbühler, K. 2015. Context-specific close-range "hoo" calls in wild gibbons (Hylobates lar). BMC Evolutionary Biology 15.

Clarke, E., Reichard, U.H. & Zuberbühler, K. 2011. The anti-predator behaviour of wild white-handed gibbons (Hylobates lar). Behavioral Ecology and Sociobiology 66: 85–96.

Clarke, E., Reichard, U.H. & Zuberbühler, K. 2006. The Syntax and Meaning of Wild Gibbon Songs. PLoS ONE 1: e73.

Cowlishaw, G. 1992. Song Function in Gibbons. Behaviour 121: 131–153.

McComb, K. & Semple, S. 2005. Coevolution of vocal communication and sociality in primates. Biology Letters 1: 381–385.

Wiener, L.F. 1984. The evolution of language: A primate perspective. WORD 35: 255–269.