If we go back to the development that led to the later emergence of language, the very earliest development was the rise of bipedalism 6 million years ago – when the hominin ancestors to ancestral humans started walking upright.
This left the hands free, eventually enabling the development and use of tools and stone weapons beginning with Australopithecus – an early genus of upright walking apes – and later Homo habilis, (‘handy man’), one of the earliest ancestral human species – from around 2.8 million years ago. As early ancestral humans hunted together, new modes of cooperative living needed to be developed, along with new cognitive strategies and new social arrangements, and it’s likely that language arose within this context.
"A rudimentary gesture-based ‘proto-language’ most likely emerged in order to ensure that the game being hunted was shared out equally. Some form of communicative system would also have been required in order to maintain monogamous mating arrangements and rights."
The next development would have been precursors of language, most likely a gesture-based means of communicating, so some form of sign language. And this probably emerged by around 1.8 million years ago, with the emergence of a more advanced species of ancestral human: Homo erectus (‘upright man’). This species, we now know, was the first species of ancestral human to have a brain capacity that approaches the current standard.
https://www.youtube.com/embed/AD47C8jP6Hw?wmode=opaque
A rudimentary gesture-based ‘proto-language’ most likely emerged in order to ensure that the game being hunted was shared out equally. Some form of communicative system would also have been required in order to maintain monogamous mating arrangements and rights, especially as hunting parties would have entailed a large proportion of the female population, and some males, being left behind while the male hunters were away.
So bipedalism can, I think, be seen as the kickstarter for the later emergence of language, causing a butterfly effect in the evolutionary development of our genus. And the later emergence of a spoken ability to produce language – speech – has taken on its most advanced form yet, in our species, Homo sapiens, which only emerged around 200,000 years ago, in Africa.
An important development, certainly in a European context, would have been the emergence of Proto-Indo-European, an ancestral language, following the diaspora of Stone Age humans from Africa. Proto-Indo-European, or PIE for short, has provided the basis for many of the modern European languages, as well as many of the languages of the Indian subcontinent.
"The world’s first writing system was invented by the Sumerians – narrowly before the slightly later emergence of Egyptian hieroglyphs."
PIE was spoken sometime between 5,000 and 9,000 years ago. There are two theories as to its provenance – one that it originated on the Russian Steppes, before spreading through Europe and branching off into different languages. The other theory is that it originated in Anatolia, what is today mainland Turkey. Whichever theory is correct, around 445 languages spoken today derive from PIE, ranging from English to Russian, and Hindi to Portuguese.
On my list, the next major development would be writing, which separates prehistory from the period we have written records of: history. The world’s earliest writing system, which emerged about 3,400 BCE [also known as BC] – was invented in Mesopotamia. This is the region where the world’s earliest civilisations developed, between the Tigris and Euphrates rivers in modern day Iraq. The Babylonian civilisation was a later development in this region. The world’s first writing system was invented by the Sumerians, who founded Sumer, the world’s first city state. And Sumerian was probably the very first writing system, emerging narrowly before the slightly later emergence of Egyptian hieroglyphs.
https://www.youtube.com/embed/HyjLt_RGEww?wmode=opaque
In the context of the emergence of English, a key important development was the colonisation of modern-day England, from 450 CE [or AD] onwards, by Germanic tribes from the continental North Sea coast. From this point, Old Frisian, a Germanic language, was brought to England by invading tribes of Angles, Saxons and Jutes. The invasions began following the vacuum created by the Roman withdrawal from Britain around 410 CE. These tribes, that inhabited areas in modern-day Netherlands, Germany, and Jutland region of Denmark, spoke dialects of a common tongue that morphed into Old English, and steadily diverged from the continental variety that morphed into Dutch.
Another key development, in the emergence of language, for my money, would be the emergence of printing. The first book printed in English was in Bruges in Belgium in 1473. Then, in 1476, William Caxton brought the process to England, establishing a printing press in Westminster.
In the modern era, 1971 saw the first recorded use of email, while the emergence of emoticons can be dated to 1982, when they were used on electronic bulletin boards in the USA. Also in the 80s, at CERN in Switzerland, Tim Berners-Lee developed the precursor of the World Wide Web, which then became publicly available in the mid-90s, eventually allowing for widespread use of instant messaging and emailing. Those technological advances have been very important for the development of language.
Vyvyan Evans is the author of The Crucible of Language: How Language and Mind Create Meaning.