Why We Talk and Chimps Don't
As much as I love science, I love science fiction more. Science tells us what is; science fiction tells us what might be. I recently read a unique and revealing science fiction story, "Immersion," written by U-Cal-Irvine physics professor Gregory Benford. In his story, Benford invents the technophile's brand of ecotourism, in which visitors to Africa can undertake not a photo safari, but a brain-meld adventure. Benford's characters Kelly and Leon move into the minds of two chimps, experiencing the sensory world from the perspective of a primate species not their own.
Predictably, the humans find themselves trapped in their hosts, encountering hostile rivals and voracious predators, coping with crisis in chimp fashion-their human mental faculties intact, but constrained. While sex, food, and grooming are infinitely satisfying in chimp minds and bodies, Leon and Kelly find themselves frustrated with their limited abilities to communicate. They invent some sounds and signs to get them through, but they long for language:
It was infuriating. He [Leon] had so much to say to her [Kelly] and he had to funnel it through a few hundred signs. He chippered in a high-pitched voice, trying vainly to force the chimp lips and palate to do the work of shaping words.
It was no use. He had tried before, idly, but now he wanted to badly and none of the equipment worked. It couldn't. Evolution had shaped brain and vocal chords in parallel. Chimps groomed, people talked.
As Benford's Leon observes through the mind of a chimp, human brains are built for language. They are programmed to speak it and programmed to understand it. Now, a collaboration among researchers at UCLA and Emory University's Yerkes National Primate Research Center has revealed part of the reason why. It's in the genes, of course. The human and chimp versions of a gene called FOXP2 are built differently so they work differently.
If you remember your high school biology, you know that the gene is nothing more (and nothing less!) than a long DNA molecule. The order of bases (abbreviated A, T, G, and C) along that strand determines what the gene is and what it will do. Change even one of those bases and you change how the gene will operate.
In this study, the scientists found that a small change in the molecule makes a big difference in the gene's action. "We showed that the human and chimp versions of FOXP2 not only look different but function differently too," said researcher Daniel Geschwind in a press release. FOXP2 is a gene that regulates other genes. In its different forms, it switches on or switches off other genes in a different pattern in humans and chimps. "Our findings may shed light on why human brains are born with the circuitry for speech and language and chimp brains are not," Geschwind said.
This research is of more than academic interest. When FOXP2 mutates, it can disrupt speech and language in humans. We may be seeing its effects in autism and schizophrenia. If we understand the gene's action better, we may find new ways to prevent or treat speech disorders.
For More Information:
Benford's story is reprinted in Gardner Dozois (Ed.), The Year's Best Science Fiction: Fourteenth Annual Collection, New York: St. Martin's, 1997:1-58.
The Emory/UCLA research was published Nov. 11 in the online edition of the journal Nature.
Read the UCLA press release.
The book Brain Sense reveals on how speech is hardwired into the human brain from birth--perhaps even before.
The diagram shows the genes that are targeted by human and chimp forms of FOXP2: Red lines show target genes that both species express in the same direction, while blue lines indicate target genes that the two species express in opposite directions. Bold text and large green circles denote the most connected genes.
