Where Charles Darwin and evolutionists today agree is that humans and modern apes are both naturally descended from a single primate species that long ago went extinct. Darwin and today’s evolutionists also agree that nonhuman primates are incapable of mimicking human speech sounds. Darwin thought that at least part of the reason had to do with brain differences between humans and modern apes. Twentieth and twenty-first century evolutionists, owing to experiments performed in the late 1960s, believed that the reason was the lack in today’s nonhuman primates of the necessary anatomical equipment in their vocal tracts.
Repeated attempts have been made to train nonhuman primates to mimic human speech sounds. Every endeavor has failed.1 Even chimpanzees raised from birth in human homes are unable to mimic even simple human speech sounds.
In a classic study done on a captive rhesus monkey, a chimpanzee, and a gorilla, primatologist Philip Lieberman concluded that “nonhuman primates lack a pharyngeal region like man’s, where the cross‐sectional area continually changes during speech.”2 In a follow-up research study Lieberman and his colleagues asserted that “the vocal apparatus of the rhesus monkey is inherently incapable of producing the range of human speech”3 and “the inability of apes to mimic human speech is thus an inherent limitation of their vocal mechanisms.”4
Lieberman’s team buttressed their conclusions through a computer model of the supralaryngeal vocal tract of a rhesus monkey.5 In this model they systematically manipulated the vocal tract to study the full range of vowel sounds that a rhesus monkey could produce if it exploited the full capability of its supralaryngeal vocal tract. After their subject rhesus monkey died they made a plaster cast of its oral cavity and performed a variety of acoustical tests on the cast.6
Before these experiments on nonhuman primates were conducted, Darwin and many of his evolutionist colleagues believed that the reason nonhuman primates were incapable of mimicking human speech is that they lacked the brain power and brain function to control an otherwise fully functional vocal production system. Since the work of Lieberman and his colleagues, evolutionists have been persuaded that while at least the more advanced nonhuman primates possessed the neural equipment for speech, they lacked the necessary vocal tracts to produce speech.
Lieberman’s conclusions went unchallenged and untested for 46 years. Only months ago did any scientists decide to do follow-up research on the vocal tracts of monkeys.
A research team headed by cognitive biologist Tecumseh Fitch “used x-ray videos to quantify vocal tract dynamics in living macaques during vocalization, facial displays, and feeding.”7 (A rhesus monkey is a macaque.) Fitch’s team showed that “the macaque vocal tract could easily produce an adequate range of speech sounds to support spoken language.”8 They concluded that the previous studies by Lieberman’s team had “drastically underestimated” the vocal capabilities of present-day monkeys and apes. The problem with macaques, they noted, was that while they possess a “speech-ready vocal tract,” they lack a “speech-ready brain” to control it.9
The paper by Fitch et al. does not make any comments on the philosophical implications of their discovery. For me, at least, those implications screamed for attention. For example, why were evolutionists so reluctant to accept that the brains and minds of modern-day primates differ so radically in kind from humans?
In his book The Descent of Man, Darwin explicitly stated that the difference between human and nonhuman minds is merely “one of degree and not of kind” and that “there is no fundamental difference between man and the higher mammals in their mental faculties.”10 A fundamental principle not just for Darwinian evolution but for all naturalistic models for the evolution of life is that “species with shared ancestry will have similar cognitive abilities.”11 Therefore, since evolutionists hold that apes and monkeys are closely related to humans and share a recent common ancestor through natural descent, their brains and minds must be similar in that there is no distinction in the kinds of things they can do, only in the degree to which they can do things. (Lieberman’s conclusions about primate vocal tracts fit evolutionary thinking in that he thought nonhuman primates’ vocal tracts were vocally capable, just not to the same degree as humans’ vocal tracts.)
Fitch and his team demonstrated that the brains and minds of nonhuman primates are almost totally lacking in their capacity to control their fully functional vocal tracts. Thus, humans and present-day monkeys and apes really do fundamentally differ in kind, not just in degree.
In fact, present-day monkeys and apes are far from the closest among all animals to matching the capabilities of human brains and minds. That ranking goes to ravens, crows, and jays.12 As for coming the closest to mimicking human speech, parrots win the prize. Yet no evolutionist would claim that birds and humans are naturally descended from a recent common ancestor.
Even the smartest bird pales in comparison to the intellectual capabilities of a human. Some birds might be able to solve puzzles and mimic our speech, but like all non-human animals they have no understanding of symbols, grammar, word meanings, or mathematics. They have no awareness of God or capacity to engage in philosophy or theology. As the Bible declares, we humans alone among all life on Earth are created in the image of God. We are unique and exceptional. We are not the product of evolution. We are specially created by God who desires to redeem us and spend the rest of eternity in a loving relationship with us.
- Philip Lieberman, “Primate Vocalizations and Human Linguistic Ability,” Journal of the Acoustical Society of America 44 (December 1968): 1574–75.
- Ibid., 1574.
- Philip Lieberman, Dennis Klatt, and William Wilson, “Vocal Tract Limitations on the Vowel Repertoires of Rhesus Monkey and Other Nonhuman Primates,” Science 164 (June 1969): 1187.
- Ibid., 1185–87.
- W. Tecumseh Fitch et al., “Monkey Vocal Tracts Are Speech-Ready,” Science Advances 2 (December 2016): e1600723, doi: 10.1126/sciadv.1600723.
- Charles Darwin, The Descent of Man, in From Simple a Beginning: Darwin’s Four Great Books, ed. Edward Wilson (New York: W. W. Norton, 2006), 798.
- Johan Bolhuis and Clive D. L. Wynne, “Can Evolution Explain How Minds Work?” Nature 458 (April 2009): 832, doi:10.1038/458832a.
- Hugh Ross, Hidden Treasures in the Book of Job (Grand Rapids: Baker, 2011), 119–48.