Various theories attempt to explain how and why human language evolved. The social intelligence hypothesis posits that language co-evolved with our social cognitive abilities. The ecological dominance hypothesis argues that language helped humans adapt and spread across diverse environments. The genetic change hypothesis proposes that mutations affecting language areas of the brain occurred. Likely a combination of social, ecological and genetic factors drove language evolution.

Chapter 6 - Explaining Language Evolution 

Early humans likely started with emotional vocalizations like crying, laughing and grunting to express needs and feelings. Over time, the ability to control vocalizations and associate sounds with meanings developed. This gradual transition from emotional vocalizing to structured language poses the fundamental question this book explores: How and why did human language originate? Language sets us apart in its complexity, conceptual requirements and social nature. The origins of this unique ability are shrouded in mystery.

Chapter 1 - The Problem

While emotional vocalizations still predominated, the ability to point at and reference objects through gestures likely emerged first. Pointing allowed early humans to jointly attend to and communicate about objects in their environment. This led to the next breakthrough - making voluntary vocal sounds to label and name objects. Naming objects through learned vocal associations began the transition from emotion-driven to symbol-driven communication.

Chapter 3 - Pointing & Naming

Once individuals sounds became associated with specific meanings and functions as words, the ability to combine words into larger utterances emerged. Word combinations exponentially increased the expressive power of language by allowing the description of actions, qualities and relationships. However, early word combinations were likely holistic and lacked systematic syntactic rules.

Chapter 4 - Words & Combining Words

The book concludes by considering the ongoing evolution of language. Languages are constantly changing and new dialects and languages emerge. Advances in artificial intelligence may one day allow machines to develop vocabulary and combine words in a rule-based way, but true generativity and conceptual understanding remain challenges. The outlook for radically different future languages, either biological or artificial, remains an open question.

Chapter 7 - The Future Of Language 

The crucial step - developing recursive syntactical rules that allow words to be combined in an open-ended number of ways - enabled the true generativity of human language. Recursive rules allow an infinite number of grammatical and meaningful sentences to be generated from a finite set of words. This property sets human language apart and likely emerged gradually through cultural and genetic evolution.

Chapter 5 - Generativity & Recursion 

The roots of language lie in emotion and communication of needs. Proto-language likely began as involuntary emotional vocalizations like crying, laughing, grunting and growling. These helped strengthen social bonds and coordinate group activities. Over generations, some vocalizations became associated with specific emotions, objects or situations, laying the groundwork for referencing the world through sounds. However, early vocalizations were still largely constrained by emotion.

Chapter 2 - Laughing & Crying

Origins of Language: A Slim Guide offers a concise and accessible overview of what is known about the evolution of the human capacity for language. Non-human animals communicate in simple ways: they may be able to form simple concepts, to feel some limited empathy for others, to cooperate to some extent, and to engage in mind-reading. Human language, however, is characterized by its ability to efficiently express a wide range of subtle and complex meanings. After the first simple beginnings, human language underwent an explosion of complexity, leading to the very complicated systems of grammar and pronunciation found in modern languages. Jim Hurford looks at the very varied aspects of this evolution, covering human prehistory; the relation between instinct and learning; biology and culture; trust, altruism, and cooperation; animal thought; human and non-human vocal anatomy; the meanings and forms of the first words; and the growth of complex systems of grammar and pronunciation. Written by an internationally recognized expert in the field, it draws on a number of disciplines besides linguistics, including philosophy, neuroscience, genetics, and animal behaviour, and will appeal to a wide range of readers interested in language origins and evolution.