This chapter examines how environmental variability and language evolution created feedback loops that amplified human behavioural plasticity. First, environmental variability during the Pleistocene reinforced selective pressure favouring human prosociality and intergroup peaceful cooperation, alongside the evolution of cumulative culture and, later, selection against reactive aggression. Rapidly shifting environmental conditions favoured behavioural versatility in the genus Homo as cumulative culture was emerging. This, coupled with the selection against reactive aggression (‘self-domestication’) and the resulting increase in prosociality over the past ~315,000/300,000 years, then enabled Homo sapiens communities to establish increasingly extensive networks of exchange for accessing distant resources, providing a key advantage over other human species in surviving Pleistocene climate fluctuations. Second, Proto-language and later the modern faculty of language interacted closely with cumulative cultural evolution and ‘self-domestication’, amplifying both intergroup peaceful cooperation and lethal conflict and playing a central role in their co-evolution. Language-enabled cumulative cultural evolution further augmented and refined the human capacity for intergroup lethal conflict; it allowed for more effective cultural teaching across generations of the know-how employed for coalitionary killings, underpinned the cumulative evolution of weapon technology, and introduced and then expanded cultural incentives associated with warfare such as status and prestige. At the same time, cultural practices such as inter-tribal marriages, cultural kinship, long-distance exchange networks, and peacemaking and conflict resolution practices between groups fostered larger-scale peaceful cooperation.

How did language emerge? It has been suggested that language developed through mimicry of the sounds of nature and animals. Some propose that speech arose from grunts and groans, gestures, dance, or music. Others believe that language has more divine origins. A number of scientists speculate that language appeared spontaneously in our species, while opposing theories say that language evolved over a very long period of time. And which was the original language anyway? It makes sense that the question of how language emerged has been called “the hardest problem in science.” All of that being said, researchers don’t always agree as to what constitutes language. It’s generally accepted that communication differs from language in that the latter involves the use of symbols and syntax. For this reason, some argue that language is uniquely human. Others think our hominin relatives may have had speech as well. Animals have their own versions of communication too, while there are always quirky news stories about talking birds, signing chimpanzees, and even monkeys that use grammar. What are we to make of these claims? Let’s look at who has language and how it emerged.

The aim of a toponymist is to reconstruct and analyse the most original or ancient possible root of a toponym. This requires the linguist to go back to prehistoric times. Yet, at a certain point, scholars will run out of historical sources that can be analysed. They can then postulate the existence of pre-languages that predate proto-languages (since toponymic roots belong to proto-languages). Both types of prehistoric languages are unattested, but a proto-language can be reconstructed by using historical-linguistic methods, while a pre-language cannot. This chapter focusses on the most well-researched language family in the world, Indo-European, and surveys a number of theories on the origins of the speakers of Proto-Indo-European and their relations to Pre-Indo-European civilisations. Toponyms are often ‘linguistic relics’ and, at times, can provide useful insights into pre- and proto-languages spoken in prehistoric times and the dynamics between ancient groups of speakers. This is discussed through the analyses of two case studies, and shows that a root may be reused and refunctionalised in a new proto-language and acquire new meanings and uses.

The chapter explains the basic principles of linguistic change from a sociolinguistic variationist perspective. It begins with an explanation of the inextricable relationship between linguistic variation and change, and proceeds to demonstrate how language change can be observed, investigated, and explained. Sociolinguists can document and analyse language change using either the real-time method or the apparent-time construct; these methods and their advantages and pitfalls are explained and exemplified.