Communication. A transmittal of information by signs, signals, cues, or words from one living thing to another.
Usage: Regarding nonverbal messages, a. all cues are signals, and b. all signals are signs--but c. not all signs are signals, and d. not all signs and signals are cues. Regarding verbal messages, words may be spoken, whistled, written, or manually signed.
See also MESSAGING FEATURE.
Copyright 1998 - 2016 (David B. Givens/Center for Nonverbal Studies)
Photo of U.S. flag flying above Manito Park's Rose Garden (Spokane, Washington, USA). Among its many symbolic, nonverbal messages for Americans is one of territoriality: "This land is our land." That national flags move in the wind makes them "come alive." (Picture credit: David B. Givens, copyright 2005)
I cordially invite you to follow my progress below as I compose this article:
HANDS OR TAILS: Pectoral vs. Caudal Origins of Human Language
By David B. Givens
In an earlier publication (Givens 2015), I proposed that human language developed as a transfer from extant social communication to linguistic (both vocal and gestural) communication about the external environment. The present paper examines this evolution from a novel focus that examines the respective roles played by pectoral (forelimb) and caudal (tail) communication in the advent of speech. If vertebrate forelimbs played a part in the origin of human language, the same cannot be said of tails. While both bodily appendages figure prominently in social communication, a comparative look at the evolution of hands and tails reveals key differences favoring the former's role in linguistic messaging. These differences help explain why human beings, in their linguistic behavior, use both manual speaking gestures and vocal words.
1. Overview of Hands
The 27 bones, 33 muscles and 20 joints of our hand originated ca. 400 m.y.a. from the lobe fins of early fishes known as rhipidistians. Primeval "swim fins" helped our aquatic ancestors paddle through Devonian seas in search of food and mates. In amphibians, forelimbs evolved as weight-bearing platforms for walking on land. In primates, hands were singled out for upgrade as tactile antennae or "feelers." Today (unlike flippers, claws, and hooves), fingers link to intellectual modules and emotion centers of the brain. Not only can we thread a needle, e.g., we can also pantomime the act of threading with our fingertips' mime cues--or reward a child's successful threading with a gentle pat. There is no better organ than a hand for gauging unspoken thoughts, attitudes, and moods.
1.2 Embryology. Hands are visible as fleshy paddles on limb buds of the human fetus until the 6th week of life, when digital rays form separate fingers through a process of programmed cell death. Soon after, hands and arms make coordinated paddling movements in mother's amniotic fluid. Placed in water shortly after birth, babies can swim, as paleocircuits of the aquatic brain & spinal cord prompt newborns to kick with their feet and paddle with their hands.
1.3 Infancy. Babies are born with the primate ability to grasp objects tightly in a climbing-related power grip. Later, they instinctively reach for items placed in front of them. Between 1-1/2 and 3 months, reflexive grasping is replaced by an ability to hold-on by choice. Voluntary reaching appears during the 4th and 5th months of age, and coordinated sequences of reaching, grasping, and handling objects are seen by 3-to-6 months, as fingertips and palms explore the textures, shapes, warmth, wetness, and dryness of Nonverbal World (Chase and Rubin 1979).
1.4 Early signs. By 5 months, as a prelude to more expressive mime cues, babies posture with arms and hands as if anticipating the size and hardness (or softness) of objects in their reach space (Chase and Rubin 1979). Between 6 and 9 months, infants learn to grasp food items between the thumbs and outer sides of their index fingers, in an apelike precursor of the precision grip. At this time, babies also pull, pound, rub, shake, push, twist, and creatively manipulate objects to determine their "look and feel" (Chase and Rubin 1979).
1.5 Later signs. Eventually, a baby's hands experiment not only with objects themselves but with component parts, as if curious to learn more about relationships and about how things fit together (Chase and Rubin 1979). At one year, infants grasp objects between the tactile pads of thumb and index fingers, in a mature, distinctively human precision grip. Pointing with an extended index finger also begins at 12 months, as babies use the cue to refer to novel sights and sounds--and speak their first words.
1.6 Neurology. Our brain devotes an unusually large part of its surface area to hands and fingers (see HOMUNCULUS). In the mind's eye, as a result a. of the generous space they occupy on the sensory and motor strips of our neocortex, and b. of the older paleocircuits linking them to emotional and grooming centers of the mammalian brain, almost anything a hand does holds potential as a sign. Today, our hands are fiber-linked to an array of sensory, motor, and association areas of the forebrain, midbrain, and cerebellum, which lay the groundwork for nonverbal learning, manual sign language, computer keyboard fluency, and the ability to make tools of stone, silicon, and steel.
2. Overview of Tails
The three-to-five (usually four) small, fused triangular bones of the human tail or coccyx originated ca. 400 m.y.a. from the tail fins of rhipidistian fishes. Like pectoral fins the tail fin helped our aquatic ancestors move through Devonian seas in search of food and mates. In amphibians, tail fins evolved as appendages for locomotion and defense in salamanders (order Caudata, "with tail"), but in frogs and toads (order Anura, "without tail") the tail disappeared, leaving a vestigial coccyx known as a urostyle. In primates tails adapted variously as appendages for display and for propagating aroma cues (lemurs), grasping (New World monkeys), and balance (Old World monkeys), or disappeared entirely, becoming rudimentary coccygeal bones in the case of apes and human beings. In Homo sapiens the tail is functionally useless (save for muscle attachment) and expressively mute.
2.1 Embryology. Tails in diverse nonhuman tetrapods are both functionally gifted and socially expressive. In contrast, humans tails peak between 31-to-35 days of age, and shrink to coccygeal size soon after. By comparison in rats, embryonic tail bud and arm buds become recognizable by 11 day of age; both continue to develop before and after birth. In humans, tail folds and limb buds are visible by the 28th day of life; soon after, however, most of the tail begins to disappear through a process of programmed cell death, while hands and arms continue to develop before and after birth.
2.2 Infancy. Babies are born with a wholly invisible tail known as a coccyx. Unlike human hands, this functionally vestigial, unseen appendage plays no role in communication. In certain rare cases babies are born with rather short, fleshy tails supplied with emotionally expressive nerves. The vast majority of human tails, however, do not survive as functional or expressive appendages. In this regard, humans are not alone among the Tetrapod tailless. Apes, frogs, guinea pigs, and seals are among living tetrapods that lack a caudal appendage.
3. Mechanical Function of Hands vs. Tails
Both bodily appendages--forelimbs and tails--are strongly adapted for such mechanical functions as:
Flying and gliding (through air)
Propulsion (through water)
Slapping and striking (e.g., crocodile tails)
Exploring (the environment), fabricating (e.g., tools), and foraging (for food), meanwhile, seem exclusive to forelimbs (e.g., in monkeys and apes).
4. Expressive Function of Hands vs. Tails
Both forelimbs and tails are strongly adapted for social communication, emitting messages about:
Orienting (addressing oneself to another)
Physical presence (I am here)
Beckoning, begging, cajoling, and requesting, meanwhile, seem exclusive to forelimbs (e.g., in monkeys and apes).
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