Commentary: Regarding the Wood Ape and Vocalization

By Martin L. Lenhardt, Ph.D.


[A couple of months after the publication of Testing of Game Cameras for Sound Emissions at the NAWAC web site, Dr. Martin Lenhardt, who supervised the game camera tests, contacted us again. After he noted, “Jane Goodall thinks there may be something to this story,” Dr. Lenhardt asked if we had “access to any sounds this guy makes?” The following reflections were offered in response to receiving recordings of possible North American wood ape vocalizations.]


Who crossed the Bering Strait Land Bridge? This seems like a simple enough question to pose. One obvious answer is humans (Homo sapiens sapiens). In the case of North American apes, the answer is either one or more species of Asian apes or the mythology of their interactions with humans. While North American apes are certainly real in our culture, it has yet to be established that they are a real part of the environment. Scientists have established that ape migrations definitely took place, much along the lines of one or more human migrations out of Africa, so taking the same route as humans into North America is certainly possible.

Unfortunately, the deficiency of details concerning this ape migration hypothesis is compounded by a dearth of physical evidence. However, we do know that the little hominids of Indonesia, Homo floresiensis, not identified by science until recently, were well known to the island’s native people through their oral traditions. Whether or not these “hobbits” still exist, as some researchers hold out as a possibility, has yet to be determined. According to local legends, apelike creatures may still be hiding in the thick tropical forests of Indonesian islands. An aversion to humans (possibly because they are natural predators) seems to be one trait shared by all apes, including, with little doubt, the North American wood ape. However, elusive behaviors are likely to become less and less successful in this day of high technology.

Despite the absence of anatomical evidence that an undocumented species of ape shares our North American environment, a plethora of sightings exist from across the wilderness areas of the continent. Questions regarding the accuracy of such reports are issues for skeptics. Nonetheless, it appears that these creatures can be characterized as being on the size scale above chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla), exhibiting sexual dimorphism (larger males), and likely exhibiting similar apish behaviors. Based on what is known about African apes, what can be hypothesized about North American apes?


The skulls of gorillas hold a brain of about 500,000 milligrams; chimpanzees have smaller skulls and smaller brains (405,000 mg). These values, when contrasted to human values (1,330,000 mg), should produce an awareness of a very different primate than us (Stephen, Frahm, & Baron, 1981). Since brain size varies with body size, a comparative index, the Encephalization Quotient (EQ), was developed as a way of understanding intelligence and the ability to address complex cognitive tasks. Gorillas have an EQ range of 1.53 to 1.76. Chimpanzees have an EQ range of 2.3 to 2.5 and humans vary from 7.39 to 7.79 (Jerison, 1973). Much of our brain function is devoted to language, symbol processing, imagination, and planning. Taking the wood ape as an example, much of its smaller brain (guessing an EQ of about 1.7) might be devoted to sensorimotor processing, the first stage of cognitive development, and not symbolic cognition. Wood apes are primates, they have survived in this world, but doubtlessly not by the same neural strategies employed by humans. We probably share more with the dog, which evolved with us, than with these animals. When you ask your dog to speak, he barks; if you ask that of a wood ape, it will likely throw a rock at you.


The level of communication learned and exhibited by great apes is not comparable to the capabilities of humans. Chimpanzees have a limited vocal repertoire and do not have the ability to generate the range of human speech sounds. Part of this vocal limitation is due to their peripheral anatomy, and part is due to their neurology. When compared to chimpanzees, humans have a larynx positioned much lower in the throat (vocal tract). This placement allows for more articulated movements which results in more sounds. Apes have a tongue located high in the throat along with a low palate, restricting potential speech sounds.

As important as peripheral anatomy is, neurological control of vocal tracts is critical. Primates in the ape line of descent do not have cortical control of vocalizations. That is, they cannot choose when to vocalize or when not to; their vocal tract is under the control of the emotional part of the brain, the limbic system. Even chimpanzees are sometimes incapable of controlling their vocalizations, despite sharing more than 95 percent of our DNA. It is well known that some chimpanzees, even upon discovery of a food treat, cannot inhibit their vocalizations, which often attracts the interest of others. Some go to the extreme of covering their mouth with the hand to muffle their self-generated sounds.

A common sound exhibited by apes, and a sound recorded in the pursuit of wood apes by the North American Wood Ape Conservancy (NAWAC), is the grunt. The ape grunt can be a reflexive sound emitted while producing an effortful behavior, or it can be an alarm call, or it can relate to a social aspect of group behavior. The grunt recordings provided from wood ape encounters seem to be the effort grunts often associated with rock throwing. These grunts appear to be reflexive, but there is no reason to believe they might not be communicative under other circumstances. That is to say, effort grunts might signal the possibility of some form of communication in these animals.

There is evidence that some great apes can whistle, and an orangutan—an Asian ape—has appeared to acquire it spontaneously in the Washington Zoo (Wich et al., 2009). The ability to whistle is part of the lore pertaining to North American apes. Whistling does require some control of the vocal tract, both breath flow and parsing of the lips. Perhaps whistling is how our human species gained control of self-emitted sounds. In humans, the whistled energy exists in a band from about 1,000 to 3,000 Hz (our most sensitive range of airborne hearing) and is intense (130 dB SPL, as measured at the lips). The Silbo, a whistled form of a Spanish dialect, is a language of the Canary Islands that can be heard over a great distance (Rialland, 2006). This kind of ability would provide a clear advantage to North American apes. What a potentially great shared skill!


Meaningful Interactions with wood apes may not be possible. Humans have a tendency to assume that other creatures think like we do (anthropomorphism), or that at least they try, like the movie alien ET. Humans do this with other humans; it is called Theory of Mind (ToM) (Premack & Woodruff, 1978). When a ToM does not develop normally in humans, as with some neurological diseases, glaring social deficits can result (Korkmaz, 2011). We humans do not think exactly the same, but the insight that minds have much in common has fostered a human social culture. There is no reason to believe that wood apes share even a minimal culture comparable to humans, and we should be on guard in the event of interactions. It may be hard to resist the idea that a creature that looks so much like us must share our way of perceiving the world, but it does not. Yes, it may also share much of our DNA, but the wood ape is a very distant cousin, at best. The “Don’t feed the bears” sign in Yellowstone applies.


With the eventual collection of evidence identifying this species, what would be next? These apes will likely fall under federal protection, and rightly so. They are living forms of a shared common ancestor. With federal protection, conservation efforts will follow, just as the NAWAC has already established as a priority. Well done.


What if only the myth of the Asian Apes was brought to our land across the Bering Strait Land Bridge? Myths are not falsehoods; they are beliefs to live by. For the Yokuts in California, for example, the North American ape is part of their creation story. Their ape, called Hairy Man, helped create humans from the soil, making them bipedal, much in keeping with the creation account in Genesis from the Hebrew Bible, but upon seeing him the people were afraid and ran away. Much the same behavior prevails today. The Yokut taught their children about the dangers of their environment by warning them that Hairy Man is out there in the dark and by the rivers. The children were warned not to go out if they heard whistling, a sound made by Hairy Man. Children need to learn roles in their society for their benefit and that of the group, and in this sense, Hairy Man is their teacher (Moskowitz-Strain, 2003, 2012).

This mask is designated as a chief sasquatch mask at the First Peoples Gallery of the Royal B.C. Museum in Victoria, BC. (Generic url is )


Myths provide beliefs and moral stories to live by, and just as the Yokut believe that their Hairy Man was real, so do some of us in the scientific community. If the Yokut are correct, Asian apes migrated here before the first Native Americans. As Jane Goodall might say, it is possible that apes live with us in North America. I want to think they do.


Jerison, H. J. (1973). Evolution of the brain and intelligence. New York, NY: Academic Press. Also see

Korkmaz, B. (2011). Theory of mind and neurodevelopmental disorders of childhood. Pediatr. Res. 69 (5 Pt 2): 101R–8R.

Moskowitz-Strain, K. (2003, 2012). Mayak Datat. Retrieved from

Premack, D. G., & Woodruff, G. (1978). Does the chimpanzee have a theory of mind? Behavioral and Brain Sciences 1(4): 515–526.

Rialland, A. (2005). Phonological and phonetic aspects of whistled languages. Phonology 22(2), pp. 237–271.

Stephen, H; Frahm, H; and Baron, G. (1981). New and revised data on volumes of brain structures in insectivores and primates. Folia Primatol. 35, 1-39.

Wich, S. A., Swartz, K. B., Hardus, M. E., Lameira, A. R., Stromberg, E., & Shumaker, R. W. (2009). A case of spontaneous acquisition of a human sound by an orangutan. Primates, 50(1):56-64.


Martin L. Lenhardt, Au.D., Ph.D.
Professor of Biomedical Engineering
Virginia Commonwealth University
P.O. Box 0168
Richmond VA 23298-0168

Biographic Sketch

Martin Lenhardt holds a B.S. in Biology, an M.A. in Audiology-Speech Pathology from Seton Hall University in N.J., an Au.D. From Kirksville College of Osteopathic Medicine, and a Ph.D. in Psychoacoustics/Speech Science from Florida State University. He was a postdoctoral fellow in Otolaryngology and Biomedical Engineering at John Hopkins University. Dr. Lenhardt is presently Professor of Biomedical Engineering at Medical College of Virginia, at Virginia Commonwealth University in Richmond. He also teaches in the distance learning Au.D. program at A.T. Still University in Mesa, AZ, where he was awarded the President’s Technology Award for 2001 and a Teaching Award for 2003.

Dr. Lenhardt is both a principal and director in two biotech companies at VCU’s Research Park. His companies have been awarded SBIRs from the NIH and Homeland Security. He secured FDA approval for a tinnitus device and supervises FDA “good manufacturing practices” in its production and clinical distribution. He co-authored, with the late Dan Johnson, the OSHA ultrasonic hearing standards, has authored 100+ publications, and he holds ten US and foreign patents.

Dr. Lenhardt is a licensed audiologist and speech language pathologist in the Commonwealth of Virginia and holds ASHA certification in both fields. His research interests are biomedical acoustics, speech perception, language origins, tinnitus, and habilitative science. He was an Executive Fellow in Patient Safety in Hospital Administration at VCU (2004) and he holds a certificate in Health Care Compliance (Pharmaceutical, Biologics, Medical Devices) from Seton Hall University Law School (2006).

Marty and his wife Anita have fourteen children and reside on the York River in Gloucester, Virginia.

This article was originally published 24 August 2013.

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