A couple of decades a famous book proposed that consciousness only goes back a few thousand years, to the age of the Iliad and the Odyssey, say 3500 years ago. But it is now solidly established that conscious thoughts, images, perceptions, and action plans depend on the huge cortical mantle and its major satellite organ, the thalamus. If only a tiny part of the visual cortex in the back of the brain is damaged, patients may lose consciousness of the visual world (but not of other conscious modalities) — a condition called “blindsight”. Similar tiny holes in cortex can cause very precise impairments.
But those huge chunks of the human brain are shared with all other mammals. Your cat or dog has a cortex and thalamus, with closely similar functions and dysfunctions. In fact, the “cortico-thalamic” roof of the brain goes back at least 200 million years, to the first mammals (and even earlier, but 200 million is good enough). In other words, in a mere couple of decades we’ve gone from the wild guess that consciousness only goes back to Homer, to the much more certain knowledge that it is unimaginably more ancient in evolution. Three thousand years versus 200 million: We were off by a factor of 100,000.
Darwinian eons are scary, which is one of the reasons why it is hard for some to accept biological evolution. The pre-Darwinian world was much more comfortable, more human-sized, and more homey.
Now the same things seems to be happening with language — which includes major changes in the brain and body, involving both hearing and speaking.
Based on archaeological findings, human SYMBOLIC BEHAVIOR goes back about 100,000 years, just a flash in the pan for “deep biology.” New evidence for human body decoration may double or triple that estimate. For example, pierced shells and beads used for necklaces were traded in Africa a few hundred thousand years ago. Colored clay were also used for body decoration, just as they are today, and deposits of colored clay were mined and traded over long distances as well, suggesting that “behaviorally modern humans” go back another few hundred thousand years.
Now a fascinating article by three famous psychobiologists — Sue Savage-Rumbaugh, xxx and xxx — presents evidence for symbolic gesture and vocalizations in three closely related species: A human child, a bonobo, and a chimp. This is important, because all three belong to the same biological “clade” — they are so closely linked genetically that human-type symbolic behavior plausibly goes back to a common ancestor. Humans diverged from chimps and bonobos about four million years ago — which means that suddenly, instead of several thousand years, or even hundreds of thousands of years, we are NOW talking about the evolution of language-like capacities over several MILLION years.
This is not as confusing as it sounds. Our vocabulary is an enormously important part of spoken language. Educated people know hundreds of thousands of words, and we see our mental dictionary growing every day: Words like bits and bytes, spyware and e-fraud, SEO’s and Bing are coming and going right in front of our eyes. Our huge vocabulary is specific to humans. Even the most talented chimps learning sign language seem to hit the limit at a few hundred symbolic gestures.
So words with meanings are relatively recent, maybe somewhere in the hundreds of thousands of years. Syntax — the ability to string words together in ways that signal specific meanings and relationships between subjects, objects and verbs — is also species-specific. It’s hard to train other species to do it, while human babies learn to talk with amazing speed. It is practically impossible to keep human babies from learning a spoken language, starting early on. Twins sometimes make up their own private language spontaneously.
So – words with specific meanings, and syntax (grammar) may have come in over the last few hundreds of thousands of years.
Not so with the intention to communicate, which is easy to see in chimps and bonobos, going back at least four million years in the higher primates, critters like us.
Based on a chimp, a bonobo, and a human child, the authors make an “evo-devo” argument, which is not a new kind of gangsta rap. “Evo-devo” stands for “evolution and development.” It is an attractive scientific method that looks at the evolution of developmental trajectories that each member of a species tends to follow. Babies coo and sing, along with their caretakers, from very early on. Parents spontaneously coo and sing along with their babies. When babies are going to sleep by themselves they can be heard to babble — but human babbling shows all the usual phonemes and syllables of our many languages. Spontaneous babbling is not arbitrary. It is a developmental stage all human beings go through at about the same early age, and in about the same order. Early babbling is phonologically very diverse, and as the baby learns its first language, it begins to babble more in the small set of sounds. After adolescence, English speakers can no longer learn the phonology of Chinese, Italians can never quite speak English like the Beatles. Our phonological range becomes crystallized. All these facts point to a developmental program for natural language learning. This evo-devo program also seems specific for humans (and probably related hominins, like the Neanderthal).
The question “When does language begin?” is therefore very different for our vocabulary, syntax, and phonology. The AUTHORS now present evidence that the language of gestural signaling, of eye contact and head movements, the sing-songs of everyday speech (intonation), may develop in the higher apes much the way it does in young humans. MORE.
This work by Bernard J Baars and the Society for Mind Brain Sciences is licensed under