National Academies Press: OpenBook

In the Light of Evolution: Volume VI: Brain and Behavior (2013)

Chapter: Part IV: PHYLOGENY OF HUMAN BRAINS AND HUMAN MINDS

« Previous: 13 Evolution of Brains and Behavior for Optimal Foraging: A Tale of Two Predators--Kenneth C. Catania
Suggested Citation:"Part IV: PHYLOGENY OF HUMAN BRAINS AND HUMAN MINDS." National Academy of Sciences. 2013. In the Light of Evolution: Volume VI: Brain and Behavior. Washington, DC: The National Academies Press. doi: 10.17226/13462.
×

showed them to other monkeys with recording electrodes in their vlPFC. This experiment revealed that the majority of vlPFC neurons integrate auditory and visual information in a nonlinear manner. This finding is important because human speech perception also involves a considerable amount of audiovisual integration, as demonstrated by the McGurk effect (McGurk and MacDonald, 1976). Of course, audiovisual integration of vocalization-related stimuli is not identical to speech perception, which requires the integration of sounds and visual information with meanings. The latter type of integration still eludes the understanding of neurobiologists and is extremely difficult to study in monkeys. Nonetheless, the audiovisual integration that Romanski describes in monkeys is likely to have played a major role in the evolution of human language.

In Chapter 16, Jessica Cantlon compares the mathematical abilities of nonhuman primates and humans, especially human children. Although we often think that mathematics requires symbols (e.g., numbers and operators), simple math can be performed without symbols. For example, one can compare two images and estimate, even without counting, which image contains more items of a particular sort. This kind of analog numerical estimation can also be performed by human infants and nonhuman primates. Cantlon further reports that the analog math task activates homologous brain areas in the parietal cortex of both humans and monkeys. Collectively, the data strongly suggest that analog math abilities evolved long before the origin of Homo sapiens. This finding is fascinating, but how did symbolic math evolve? Was it built on top of the more ancient analog skill, using the ancient circuitry with only minor modifications? Or did symbolic math evolve out of symbolic communication (i.e., language)? At this point, the answer is unknown.

In the final Chapter 17, Clark Barrett dispels the notion—promulgated by some evolutionary psychologists—that adaptive specializations in the brain must be hard-wired modules. To grasp the argument, consider face-selective neurons in primate brains. Given the importance of conspecific faces in the lives of most primates, the distinct patches of face-selective neurons in monkey and human brains were likely shaped by natural selection. Nonetheless, the development of face-selective neurons probably depends on extensive experience with faces. Indeed, Barrett hypothesizes that selection generated not an innate face-processing module but a set of mechanisms that, given experience with faces, will generate a large number of neurons that selectively encode faces. Given other types of experience, the same mechanisms would (and do) generate patches of neurons selective for other kinds of behaviorally important stimuli. Stated succinctly, Barrett argues that natural selection generates developmental norms of reaction rather than experience-independent specialized modules. This idea extends evo-devo neurobiology into the realm of evolutionary psychology.

Suggested Citation:"Part IV: PHYLOGENY OF HUMAN BRAINS AND HUMAN MINDS." National Academy of Sciences. 2013. In the Light of Evolution: Volume VI: Brain and Behavior. Washington, DC: The National Academies Press. doi: 10.17226/13462.
×

14

Human Brain Evolution: From Gene Discovery to Phenotype Discovery

cth

TODD M. PREUSS

The rise of comparative genomics and related technologies has added important new dimensions to the study of human evolution. Our knowledge of the genes that underwent expression changes or were targets of positive selection in human evolution is rapidly increasing, as is our knowledge of gene duplications, translocations, and deletions. It is now clear that the genetic differences between humans and chimpanzees are far more extensive than previously thought; their genomes are not 98% or 99% identical. Despite the rapid growth in our understanding of the evolution of the human genome, our understanding of the relationship between genetic changes and phenotypic changes is tenuous. This is true even for the most intensively studied gene, FOXP2, which underwent positive selection in the human terminal lineage and is thought to have played an important role in the evolution of human speech and language. In part, the difficulty of connecting genes to phenotypes reflects our generally poor knowledge of human phenotypic specializations, as well as the difficulty of interpreting the consequences of genetic changes in species that are not amenable to invasive research. On the positive side, investigations of FOXP2, along with genomewide surveys of gene-expression changes and selection-driven sequence changes, offer the opportunity for “phenotype discovery,” providing clues to human phenotypic specializations that were previously unsuspected. What is more,

____________

Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322. E-mail: tpreuss@emory.edu.

Suggested Citation:"Part IV: PHYLOGENY OF HUMAN BRAINS AND HUMAN MINDS." National Academy of Sciences. 2013. In the Light of Evolution: Volume VI: Brain and Behavior. Washington, DC: The National Academies Press. doi: 10.17226/13462.
×
Page 251
Suggested Citation:"Part IV: PHYLOGENY OF HUMAN BRAINS AND HUMAN MINDS." National Academy of Sciences. 2013. In the Light of Evolution: Volume VI: Brain and Behavior. Washington, DC: The National Academies Press. doi: 10.17226/13462.
×
Page 252
Next: 14 Human Brain Evolution: From Gene Discovery to Phenotype Discovery--Todd M. Preuss »
In the Light of Evolution: Volume VI: Brain and Behavior Get This Book
×
Buy Hardback | $69.00 Buy Ebook | $54.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

The central goal of the In the Light of Evolution (ILE) series is to promote the evolutionary sciences through state-of-the-art colloquia--in the series of Arthur M. Sackler colloquia sponsored by the National Academy of Sciences--and their published proceedings. Each installment explores evolutionary perspectives on a particular biological topic that is scientifically intriguing but also has special relevance to contemporary societal issues or challenges.

This book is the outgrowth of the Arthur M. Sackler Colloquium "Brain and Behavior," which was sponsored by the National Academy of Sciences on January 20-21, 2012, at the Academy's Arnold and Mabel Beckman Center in Irvine, CA. It is the sixth in a series of Colloquia under the general title "In the Light of Evolution." Specifically, In Light of Evolution: Brain and Behavior focuses on the field of evolutionary neuroscience that now includes a vast array of different approaches, data types, and species.

This volume is also available for purchase with the In the Light of Evolution six-volume set.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!