The author has served us well by first presenting the teachings of the Magisterium, then commenting. I will present data to advance the dialogue where Muller left a challenging question mark: "Homo Sapiens?" on page 509.
Was it Homo Sapiens? Yes indeed. It could be no other.
Why not Homo Habilis who made stone artifacts in Ethiopia 2.5 million years ago? Or Homo Erectus, like Peking Man of 500,000 years ago? Or Neanderthal who was for a time a contemporary with Homo Sapiens some 200,000 years ago? The simple reason is that Homo Sapiens alone could have possessed our advanced type of speech organs, whereas the others had linguistic deficits that disqualified them from taking part in the events of Eden. Lacking adequate linguistic abilities they lacked also the thinking abilities that are necessarily associated with the commission of original sin. Even though speech itself is not identified with thought, in effect, thought requires speaking ability on which to express and elaborate itself. Such is the thrust of this writing.
Theological inquiry into the fact of original sin must take into account pertinent findings in the fossil record. That record indicates that stone tool artifacts were made in Ethiopia 2.5 million years ago. It must have been reasoning humans who made them. Conventionally we call them Habilis. The tools suggest that their makers led social lives and spoke with each other. These are our fellow humans, then, with spiritual souls, who live forever. The record indicates likewise that reasoning Homo Erectus existed from some 2 million years ago. Homo Sapiens records begin more like 200,000 years ago. (More recently, anthropologist Ian Tattersall would date the innovative skull structure of Homo Sapiens at 100,000-150,000 years ago "give or take". See his book The Monkey in the Mirror, A Harvest Book, Harcourt, Inc., 2002, p. 152).
Careful evaluation of successive layers of fossils indicates, surprisingly, that for long periods of time Homo Sapiens lived contemporaneously with Erectus in some areas (in Java), and with Neanderthals (in Europe), though always in social isolation from each other. The artifacts characteristic to each are not found together. Tattersall points to 40,000 years ago as the time when Cro-Magnon, our Homo Sapiens, confronted the Neanderthals in Europe. He dates the appearance of the Neanderthals in Europe and Asia as somewhat over 200,000 years ago and their final demise at 27,000 years ago (p. 111). For other documentation see my book Evolution and the Sin in Eden, A New Christian Synthesis, University Press of America, 1998. The book is now posted on the site: CatholicMind.com. I will therefore omit references in this writing.
The contention of this writing is that Homo Habilis, Homo Erectus, and the Neanderthals had speech deficits or underdevelopment that would necessarily disqualify them from the events of Eden. Speech deficits prevented development of an adult sense of responsibility that is inherent in the commission of original sin. God would not hold people responsible for original sin if they had not yet developed matching powers of reason; and reason develops in parallel with its supporting mechanism of adequate speech ability. Therefore Homo Sapiens, who first possessed modern speech organs, is our immediate ancestor who committed original sin.
Habilis, Erectus, and Neanderthal fossils do not have the shape of the basicranium and upper vertebrae that can accommodate our very sophisticated type of speech organs and the neural substrate to support their functioning. This is verified in the anthropological sections of museum displays, and is acknowledged by scientists. The type of comparatively primitive speech organs that Habilis, Erectus and Neanderthal could have possessed were inadequate to produce our modern type of sophisticated rapid and well articulated speech that can carry advanced spiritual thought. Tattersall, pp. 154-168, would attribute to them even less speech ability than some other anthropologists have been suggesting.
The Catechism tells us that God "manifested himself to our first parents from the very beginning" (CCC 54). They were therefore capable of understanding this revelation, of cultivating it, and of teaching it to their children. The revelation included belief in God, in the afterlife, and in a code of commandments that we might term the "Ten Commandments of Eden." All this is implied in the dogma of original sin.
Homo Sapiens was capable, according to the fossil record, of advanced speech, and therefore of appropriating the Primeval Revelation and being responsible for its reception and transmission to the offspring. We have what is called the two-tubed speech airway. This includes the vertically positioned larynx and a prolonged pharynx extending vertically from the trachea, followed by the sharp turn into the horizontal oral cavity. A constriction at the turn creates the two tubes. In them we format the "AAAH" vowels mainly in the pharynx, the "EEEH" mainly in the oral cavity, and the "UUUH" (sounds like you) in both simultaneously. It also allows the formatting of the "GGGH" and "KKKH" stops, and of the articulation of consonants. For the meaningful calibration and articulation of rapid speech, these are absolutely essential. The endowments of Habilis, Erectus, and Neanderthal lack this turn to the horizontal and the constriction into two tubes. Theirs is a larynx high in the trachea that allows for simultaneous breathing and swallowing, and a long palate with a shallow tongue that allows for unrestricted breathing, but not for a sophisticated calibration of phonemes. If speech is slow and not properly articulated, only very short sentences can be understood. The meaning of long sentences would be lost because the beginning of a sentence would fall out of the short term memory by the time end of the sentence is finally spoken. Scientists tell us to test this, by speaking a long sentence at one tenth the speed at which we ordinarily speak. Inevitably, the beginning of the sentence falls out of the short term memory before the end is reached. The meaning is then incoherent.
By genetic inheritance of speech automatisms, and additional automatisms created by effort during childhood, we express thoughts by producing audible signals - formatted puffs of air is what they are - which are deciphered meaningfully by the hearer. When we engage in conversation our brains, speech organs, eyes, ears, faces, and our entire bodies get into the act. The billions of neurons of the brain - 100 billion by recent estimate - become engaged and swing into action, or stand by for service if needed. Both the speaker and the listener keep track of the nuanced words and sentences in their short-term memories and anchor their thoughts on them, or deduce meaning from them. The meaning of a sentence is usually not known until we hear the end of it. With the short-term memory to hold the entire sentence momentarily in view, we typically scramble the sequential verbiage into an emulsified whole, swirling together the subject, the predicate, the object, together with modifiers. Only then, with the entire sentence held intelligibly as in a bird's eye view, when the concept is in full comprehension of the thought horizon, only then do we grasp its meaning (see the authorÕs Evolution and the Sin in Eden, p. 12).
To amplify the meaning of the audible signals of calibrated air currents we can embellish what we say with added elegance of sparkling eyes, smiling face, and lilting voice when we deliver pleasant thoughts. Or, we can express displeasure by making the voice grate and rasp, by curling the lips, tweaking the nose, arching the eyebrows, clenching the fists, bulging the neck, erecting the hair, flushing the face, and flashing bolts of lightning from the eyes (see ibid, 23).
The spiritual soul does the thinking, of course, but it plays on the neurons to fashion the non-material spiritual thought into electro-chemical nerve transmissions from the motor strip of the brain to the more than 100 muscles involved in speech. These twitch in proper timing and amplitude as commanded by the brain to format the sound that eventually emerges from our lips. The brain, in response to the thinking soul, transmits the stimuli to format the phonemes precisely, their onset, their tonus, their transit to the next phoneme.
The sending terminal at the motor strip of the brain transmits some of the signals in reverse timing order of their execution at the receiving muscle, because signals on thicker nerves may travel at the speed of 300 miles per hour, whereas signals over finer strands may move at the leisurely pace of 1.5 miles per hour. Phonemes are produced properly only when the right set of muscles twitch in proper sequence and amplitude. The ear monitors the process and sometimes interrupts to correct mistakes. The speed at which all this is done is almost incredible. If 100 muscles are engaged, and a speaker pronounces up to six syllables per second, and each syllable has 2.4 separate phonemes, the brain sends 1400 stimuli in proper sequence and amplitude per second, and if so continued, 84,000 per minute, and 5,040,000 per hour to produce the speakerÕs thoughts. Shall we wonder that God bided His time until the human brain had developed adequately before He introduced Adam and Eve into the Garden, which is a symbol of the initial endowment of sanctifying grace.
The non-Homo Sapiens people, on the contrary, had a skull shape set upon the vertebrae with a configuration and angle that could not accommodate our type of speech organs. Were one to place our type of tongues which are thick and are housed partially in the horizontal oral cavity, and partially in the vertical air passage, into a Neanderthal or Homo Erectus type body, the result would be a monster, with the "AdamÕs apple" or larynx in the chest. The long palates of Erectus and Neanderthal fossils indicate that they supported vocal tracts in which the tongue is long and thin and is positioned almost entirely within the oral cavity.
Scientists do not claim that the earlier hominids were totally unable to speak, but that they lacked the ability to speak rapidly and to calibrate the phonemes audibly and sharply as we do routinely, so that both listener and speaker can connect subject and predicate and modifiers in one conscious intellectual overview. The speech production by Habilis, Erectus, and Neanderthal could only have been limited, labored, and slow in comparison with that of Homo Sapiens. So handicapped, they could not have compressed complex meanings into the short term memory. Their sentences were presumably short and simple. At the snail pace of production of speech elements, if the sentence is long, its beginning falls out of the short term memory before the end is reached. Speech limitations thus defined thought limitations and responsibilities of other than Homo Sapiens people. Shall we compare them to juveniles of today?
My concept of our origins is that when our Adam and Eve had achieved adulthood in speech ability, God called them and set them apart to be His favored people. The first, and I think the only two whom God thus called, are our immediate ancestors. As Genesis states: "Then the Lord God planted a garden in Eden, in the east, and he placed there the man whom he had formed" (2:8). I think that the first human pair separated from other Homo Sapiens people, if such there were, and are the apex of our family tree. Either our "Adam and Eve" were the first carriers of the speech novelty, or they were members of a group and subsequently became reproductively isolated from others. But speculation about this assumption can be highly interesting.
Incest is not a problem at this initial stage. In fact, the smaller the reproductive group, the greater is the expectation that a genetic novelty will persist among the offspring. Incestuous congress of the offspring of our first parents would serve to make the genetic novelty reproductively stable among the offspring. Incest for some generations is not a major biological problem because the human genome is amply enriched with genetic materials located in the DNA of sperm and ovum, from which offspring draw their sets of individuating genomes. The random selections done at meiosis of the sperm and ovum draw ever new mixtures of individuating genes from an immense bank of diversified genetic materials contained in the total genome.
God called our Homo Sapiens parents aside, revealed Himself to them, and endowed them with the gift of Sanctifying Grace. They lost it through original sin, but God forgave them after their confession, restored their gift, and helped our socially isolated Homo Sapiens race with selective love from the time of our origins until today. The Catechism supplies us with this beautiful statement of our origins:
54 "God, who creates and conserves all things by his Word, provides men with constant evidence of himself in created realities. And furthermore, wishing to open up the way to heavenly salvation, he manifested himself to our first parents from the very beginning." He invited them to intimate communion with himself and clothed them with resplendent grace and justice.
55 This revelation was not broken off by our first parents' sin. "After the fall, [God] buoyed them up with the hope of salvation, by promising redemption; and he has never ceased to show his solicitude for the human race. For he wishes to give eternal life to all those who seek salvation by patience in well-doing."
Science and theology together, if we allow each to speak, provide us with fascinating insights wherewith to piece together a credible history of our human origins.