Lecture+11+-+Language+origins

Language Origins: Gestural Communication in Earlier Hominins

Overview

• The discussion revolves around the gestural origins of language particularly in earlier hominins.

Objectives

• Introduce the argument for gestural origins of language.

• Present original and current models for the emergence of language in earlier hominins.

Ape Gestures

• Apes exhibit good communication skills through gestures rather than vocalizations.

• In lab settings:

  • Demonstrated ability to use icons and sign language.

  • Limited capabilities in vocal imitation and vocal communication.

• Extensive use of gestural communication observed in studies.

Gestures in Chimpanzees

• Wild chimpanzees utilize numerous gestures:

  • Examples of gestures used include those for grooming, communication between mother-offspring, and sexual signaling.

Meaning of Chimpanzee Gestures

• Chimpanzees have a rich gestural lexicon:

  • Same gesture can have different meanings.

  • Different gestures can represent the same meaning.

• High redundancy in gestures:

  • Over 60 distinct gestures identified but only around 15 meanings.

Features of Chimpanzee Gestures

• Interactions facilitated by gestures are primarily

  • Dyadic (one-on-one).

  • Imperative, often aimed toward achieving specific outcomes (e.g., "groom me" or "move away").

• Absence of 'gestural sentences' or syntax; gestures likely simplified versions of corresponding actions through a process called ‘phylogenetic ritualization’ (Lorenz).

Evolution of Gesture as Animal Signals

• Example of the 'acquire object' gesture illustrates evolutionary development:

  • Initially involved physical actions (e.g., dominant individuals taking objects) that evolved into communication signals to prevent aggression.

Origin of Ape Gestures

• Many gestures are shared among great apes, suggesting a commonality due to genetic factors and behavioral connections.

• Little evidence of social transmission or learned variation; implying gestures may have innate potential across individuals.

Gestural Origins of Human Language

• Implications arise that earliest hominin ancestors shared ape gesture systems.

• Early human ancestors likely possessed limited vocal capabilities similar to monkeys and apes.

• Theories propose gestural origins for human language.

Early vs. Late Origins of Language

• Historical debate on language origins revolved around a late origin (>300,000 years ago in Homo sapiens) focused on vocal speech.

• Alternative gestural models suggest much earlier origins in the genus Homo, possibly >2 million years ago (e.g., Homo erectus).

The Hand to Mouth Hypothesis (Michael Corballis)

• Proposes gestural language emerged in Homo erectus while speech developed in later species (Homo sapiens).

Transition: Hand to Mouth

• Increased hand dexterity influenced communication methods in early hominins.

• Many gestures were conducted by hands, necessitating their migration to orofacial gestures.

Neuroanatomical Evidence

• Broca’s area (in primates: area F5) influenced both hand and oral communications.

• Evolution of F5 toward controlling orofacial communication.

Hand to Orofacial Gesturing

• Association proposed between orofacial gestures and corresponding hand actions.

• Example: a hand gesture paired with a facial expression (e.g., open mouth) to enhance the communicative effect.

From Orofacial Gesturing to Speech

• Orofacial gestures often combined with vocalizations to augment communicative displays and intensity.

• Emergence of independent vocal signals proposed in Homo erectus and affirmed in Homo sapiens.

Evidence for the Hand to Mouth Transition

• The communicative shift from hand to mouth clarifies features of language and speech development.

• Enhanced motor control of orofacial movements seen in humans, with anatomical evidence pointing to thoracic spinal cord enlargement for speech.

Challenges to the Hypothesis

• Inquiries arise on how premotor areas adapt to become language centers that govern syntax.

• Competition for hand usage amidst tool-making and communication raises questions about language evolution's driving forces.

The Power Scavenging Hypothesis

• Presents adaptive reasoning for language emergence linked to communicative displacement in contexts of early hominin scavenging endeavors.

Displacement

• Typically associated with syntax in speech models but finds uniqueness in semantics for gesture-based communication.

• Example: Animal calls produce direct responses; human words can evoke meaning absent of their physical reference.

Foraging and Social Recruitment

• Waggle dances in bees as an example of communicating locations of resources, showing social recruitment dynamics.

The Power Scavenging Context

• Transition in diet and foraging tactics among hominins highlights conditions for linguistic displacement.

Cooperative Origins of Language

• The Power Scavenging Hypothesis explains gradual development of language within social contexts, emphasizing cooperation and information sharing.

Limitations of Power Scavenging Hypothesis

• Does not clarify why gestural evolution did not yield language in other species, even those employing cooperative tactics.

The Technological Hypothesis

• Suggests language developed from extensive tool-making practices as a necessity for skill transmission.

Tools and Early Hominin Niche

• Critical role of tools identified in the evolution of language, with significant cultural developments in tool usage predating linguistic complexity.

Early Lithic Technologies

• Overview of historical development of stone tool technologies and their efficiency over time.

Transmission of Tool-Making Skills

• Proposed that language arose as a utility for teaching tools, though the timeline of gestural language evolution remains under scrutiny.

Efficiency of Cultural Transmission

• Study comparing methods of teaching tool-making highlighted potential evolutionary steps towards language development.

Enhanced Tool-Making Skills

• Findings reveal gestural teaching as a particularly effective method; gestural language likely co-evolved with tool-making capabilities.

Gesture vs. Speech Alone

• Investigative questions around the efficacy of speech alone in skill transmission illustrated through comparative studies.

Speech Inefficiency in Tool Teaching

• Surprising results show that gestural teaching exceeds verbal teaching for imparting practical skills.

Rationale for Speech Emergence

• Acknowledges that while speech may not be superior for tool instruction, it likely evolved for broader social communication and complex cultural needs.

Conclusions

• A gestural origin of language aligns with existing primate data and archaeological records.

• The Hand to Mouth and Power Scavenging Hypotheses provide valuable insights but remain limited in offering full explanations for language evolution.

• The Technological Hypothesis emphasizes the interwoven nature of language and cultural evolution; both factors must be considered concurrently to understand the true origin of language.

Next Lecture

• Upcoming discussion on how human culture evolved in conjunction with language and cognition, highlighting aspects of natural and artificial intelligence.

References

1. Byrne, R.W., et al. Great ape gestures: intentional communication.

2. Corballis M. Did language evolve before speech?

3. Bickerton, D. & Szathmary, E. Confrontational scavenging and language.

4. Morgan et al. Experimental evidence for tool-making and language co-evolution.

5. Hobaiter C. & Byrne R. The meanings of chimpanzee gestures.

6. Cataldo D., et al. Speech, stone tool-making, and language evolution.