One popular scenario says that the ability to do grammatical hierarchies arose with the speciation event leading to modern humans, about , years ago. Speech, on the other hand, is about the sounds that are used to get language through the air from one person to the next. That requires sounds that contrast enough to keep words distinct. Spoken languages all use contrasts in both vowels and consonants, organized into syllables with vowels at the core.
In that restricted but concrete sense, the dawn of speech was not , years ago, but some 27 million years ago, before the time of our last common ancestor with Old World monkeys like baboons and macaques. Researchers have a lot of work to do to figure out how speech evolved since then, and how language finally linked in. Thomas R. This article is republished from The Conversation under a Creative Commons license. Read the original article. About Us. Support Us Login.
Become A Supporter. Hindi Marathi Urdu. This species-specific problem is a consequence of the mutations that crafted the human face, pharynx, and tongue so as to make it easier to speak and to correctly interpret the acoustic speech signals that we hear.
At birth, the human tongue is flat in the mouth, as is the case for other mammals. The larynx, which rests atop the trachea, is anchored to the root of the tongue.
As infants suckle, they raise the larynx to form a sealed passage from the nose to the lungs, allowing them to breathe while liquid flows around the larynx.
Most mammalian species retain this morphology throughout life, which explains why cats or dogs can lap up water while breathing. In humans, however, a developmental process that spans the first 8 to 10 years of life forms the adult version of the SVT.
First, the skull is reshaped, shortening the relative length of the oral cavity. The tongue begins to descend down into the pharynx, while the neck increases in length and becomes rounded in the back.
Following these changes, half the tongue is positioned horizontally in the oral cavity and thus called the SVTh , while the other half SVTv is positioned vertically in the pharynx.
The two halves meet at an approximate right angle at the back of the throat. See illustration below. These quantal vowels produce frequency peaks analogous to saturated colors, are more distinct than other vowels, and are resistant to small errors in tongue placement. This may explain why all human languages use these vowels. Three years later, using X-ray videos showing the movement of the vocal tract during newborn baby cries, we refined and replicated this study and found that, although chimpanzees and human newborns which start life with a monkey-like SVT produce a range of vowels, they could not produce [u]s or [i]s.
Those scientists used current computer techniques that readily model every vocal tract shape that a macaque could produce, and the research team confirmed that monkey vocal tracts were incapable of producing these vowels. Recent genomic studies have discovered epigenetic modifications that appear to account for the evolution of the species-specific human vocal tract.
It is now apparent that a massive epigenetic restructuring of the genes that determine the anatomy of the head, neck, tongue, larynx, and mouth enhanced our ability to talk after anatomically modern humans split from Neanderthals and Denisovans more than , years ago. A few years ago, David Gokhman, then at Hebrew University of Jerusalem, and colleagues reconstructed the methylated genomic regions of a 40,year-old Neanderthal fossil, an older Denisovan fossil, four ancient humans who lived 7, to 40, years ago, and six chimpanzees, comparing these with a methylation map of human bone cells assembled from more than 55 present-day humans.
This comparison enabled the team to identify differentially methylated regions DMRs between the human and Neanderthal-Denisovan groups, and between humans and chimps.
Current research suggests a deep evolutionary origin for human language and speech. They also lack the neural networks necessary for producing and processing speech. American psychologist E. Some scholars of the twentieth and twenty-first centuries have advocated, nonetheless, for an unconscious transition from gesture to speech, including an intermediary step where limited vocalizations—perhaps onomatopoeic or related to pain or pleasure—accompanied gesture. The prevalence of both gesture and speech cautions against selecting one to the exclusion of the other.
Studies have shown that significant effort is required to not gesture, even in circumstances where gesture is clearly unnecessary, like talking to a friend on the telephone. It seems possible that, while gestural communication served our progenitors well in most scenarios, there were still times when imitative speech was necessary. One theory, proposed by American linguist Derek Bickerton, imagines an early human hunter coming across an animal far too large for him to kill alone.
Bees and ants are capable of doing something similar by producing pheromones. In Darwinian terms, such a situation models environmental pressure, and it leads to one more question: Why communicate in the first place? At its simplest, theory of mind is our ability to grasp that others have a mental state just as we do. Psychologists have created tests for measuring it in children, who, around the age of four, begin to demonstrate awareness of other minds.
We need something like theory of mind to desire to speak in the first place, hence the problem it causes in origin-of-language debates. So there is a kind of mutual song-and-dance.
Okay, so we now have—depends on the analysis—three or four levels of intention. And here is my worry about this: Look at the structure of the thought that you have to have in order to engage in utterances with speaker meaning.
All this embedding, right? In order to cross the psychological Rubicon, you have to have this language-like thought. Bar-On proposes an alternative way of looking at the problem, one that assumes theory of mind could evolve in parts. This approach draws on research that young children are still developing fuller theory of mind past age four, as well as studies of high-functioning persons with autism, who conventionally fail theory-of-mind tests but nevertheless have highly developed language.
If theory of mind can come in degrees and have various components—a theory that more psychologists espouse today—many of our problems are, if not solved, then certainly easier. Mimicking a laugh to signal your own happiness does not require as deep a level of speaker meaning as signaling to get your beer refilled. Perhaps, as human communication evolved, so too did mindedness; as one grew more complex, more capable of organizational structure, so did the other.
Its authors argue that the anatomical ingredients for speech were present in our ancestors much earlier than , years ago. In fact, they propose that the necessary equipment—specifically, the throat shape and motor control that produce distinguishable vowels—has been around as long as 27 million years, when humans and Old World monkeys baboons, mandrills, and the like last shared a common ancestor. Read: A rare universal pattern in human languages. Those speech abilities could include distinct vowels and consonants, syllables, or even syntax—all of which, according to LDT, should be impossible for any animal without a human vocal tract.
For proponents of LDT, it was the reshaping of the human throat.
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