Take for example the nature of human language: the differences between human and animal vocal communication and their evolution, and the brain mechanisms involved. In the early 1950s, William Thorpe, Professor of Animal Ethology at the University of Cambridge, and a significant British zoologist, ethologist, and ornithologist. investigated bird song behavior as a model for vocal learning with parallels to human speech.

He studied baby finches from the forests of England that had hatched but not yet heard their fathers sing. (Female finches don’t sing.) Back at his Cambridge research facility, Thorpe raised the baby finches in sound-proof boxes. Using sonograms, equipment perfected by the British Navy in World War II, Thorpe recorded the baby birds and compared the songs to those of adult male finches. The babies’ songs were primitive and different from those of the adults. As the baby finches grew, he played the adult song to them at very distinct time periods to determine whether the babies’ singing would change. Thorpe concluded that a distinct window of opportunity existed for the young birds to learn to sing. Hearing the adult songs before or after this window did not give the baby birds the ability to sing as adults.

A hungry baby finch.

Thorpe concluded that the birds’ neurons involved in learning songs grow to a certain point in time when they then need to be stimulated so that the baby birds can learn to mimic the adults’ songs . Neurons do not develop beyond this window of time. (To learn more about William Thorpe’s research, see The Discovery of Animal Behaviour by John Sparks, produced by the British Broadcasting Corporation and WNET in their NATURE Series, 1982).

Imagine conducting a similar experiment on humans, depriving newborn infants of language, and you can understand why such research experiments are not only immoral but “forbidden.”

Cases of feral children, raised in the wild or isolated, are discussed in the award-winning documentary “Genie: Secret of the Wild Child” (1997), and also in the books Genie: A Scientific Tragedy by Russ Rymer (1994) and Genie: a Psycholinguistic Study of a Modern-Day “Wild Child” by Susan Curtiss. “Genie” is the name given to the girl raised by her parents in isolation and neglect without language who, when discovered at age 13, presented animal-like behaviors. This case echoed one nearly 200 years earlier (1790) in southern France when a creature that seemed animal in nature but human in form, mute and naked, appeared. “Victor” had been in the wild most of his life, estimated to be 12 years. In both cases, medical doctors and researchers documented the progress of the children as they began to form attachments, learn, and develop language skills; however, Victor never learned to speak and Genie regressed to silence after being abused in foster care when the National Institute of Mental Health pulled research grant funding in 1975. These cases teach us the risks of conducting human experiments.

Our understanding into the development of language in humans must be conducted without risking harm to human infants or adults. This can only be done to a limited extent in humans using modern techniques such as PET and MEG scans.

The October 4, 2019, issue of the journal Science focuses on current research into human communication. The first article is a synthesis of “…the surge in nonhuman animal studies that inform us about human spoken language.” In “Evolution of Vocal Learning and Spoken Language,” (p. 50–54) Erich Jarvis explains how “…components of spoken language are continuous between species….” The next three research updates describe non-invasive PET and magnetoencephalography (MEG) conducted on humans. In “Inception of Memories That Guide Vocal Learning in the Songbird” (pages 83–89) that a team of researchers conduct invasive experiments in the zebra finch and make advancements in understanding what nerve circuits are involved, what interrupts song imitation, and how language memories are stored at downstream synapses.

Understanding language and communication at the neuroanatomy level requires invasive and large scale techniques that are forbidden with humans but possible with other animals. These results in turn provide important knowledge that will be applied to the benefit of both humans and other animals.