This post is in response to Modern Brain Shape Linked to Parietal Lobes and Cerebellum by Christopher Bergland
Wikipedia/Public Domain
Replica of drawing of lions painted in the Chauvet Cave. Art in the cave has been identified as created by early modern humans.
Source: Wikipedia/Public Domain

Neanderthals did not have the globular-brain shape or hand-eye coordination necessary to draw representational images such as the prehistoric cave drawing of lions by paleolithic Homo sapiens pictured above.

What caused the gap in drawing ability between Homo sapiens and Neanderthals? 

A new paper by Richard Coss posits that the same visuomotor coordination (and brain structure/function) that facilitated Homo sapiens ability to accurately throw a hunting spear and their ability to create realistic cave drawings go hand in hand.

Coss speculates that the correlation between spear-throwing accuracy and realistic-drawing ability could help to explain how the modern human brain became more globe-shaped and why humans were more capable hunters than Neanderthals. 

Richard G. Coss is a professor emeritus of psychology at the University of California, Davis and an expert on predator-prey dynamics. He specializes on the impact that hunting behaviors have had on the evolution of human and animal behavior since ancient times. His latest paper, “Drawings of Representational Images by Upper Paleolithic Humans and Their Absence in Neanderthals Might Reflect Historical Differences in Hunting Wary Game,” was recently published in the journal Evolutionary Studies in Imaginative Culture.

For this interdisciplinary paper, Coss incorporated his knowledgebase of animal behavior, predator-prey relations, archaeology, neuroscience, genomics, and prehistoric cave art. By marrying a broad range of seemingly unrelated resources, he developed a groundbreaking hypothesis about hunting, visuomotor coordination, prehistoric art, and human brain evolution. Fascinating stuff!

Dr. Mike Baxter/Wikipedia
Comparison of a modern human skull (left) and a Neanderthal skull (right) from the Cleveland Museum of Natural History.
Source: Dr. Mike Baxter/Wikipedia

In a statement, Coss said, “Homo sapiens developed rounder skulls and grew bigger parietal cortexes—the region of the brain that integrates visual imagery and motor coordination—because of an evolutionary arms race with increasingly wary prey. Early humans hunted with throwing spears in sub-Saharan Africa for more than 500,000 years—leading their increasingly watchful prey to develop better flight or fight survival strategies.”

In the study abstract, Coss elaborates on the parietal lobes' role in hand-eye coordination as linked to Homo sapiens unique hunting and drawing ability:

“For Neanderthals, paleoclimatic fluctuations likely precluded consistent hunting of cold-adapted game, a property making game more approachable for close-range hunting with thrusting spears. As evidence of less historical wariness of humans, many of the species hunted by Neanderthals were eventually domesticated.

Due to strong sources of natural selection on archaic and anatomically modern humans for effective hunting, the parietal cortex that integrates visual imagery and motor coordination expanded progressively, yielding the globular shape of the human cranium that is not evident in Neanderthals.

To characterize how the cognitive properties employed for throwing spears and drawing line work are similar, the Upper Paleolithic drawings of animals in Chauvet cave, France, are discussed in the speculative context of how these artists engaged simultaneously in overt attention to guide their hand movements and covert attention to their mental images during the drawing process.”

Interestingly, Coss’ hypothesis dovetails seamlessly with another January 2018 study, “The Evolution of Modern Human Brain Shape,” by paleoanthropologists from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Max Planck Institute for Evolutionary Anthropology/Simon Neubauer, Jean-Jacques Hublin, Philipp Gunz (CC BY-NC)
Differences in brain shape between a present-day human (left, in blue) and a Neanderthal from La Chapelle-aux-Saints (right, in red).
Source: Max Planck Institute for Evolutionary Anthropology/Simon Neubauer, Jean-Jacques Hublin, Philipp Gunz (CC BY-NC)

This German study corroborates that the globular shape of our modern human brains evolved gradually and is marked by a bulging of the parietal lobes. Notably, the Max Planck team also found that bulging of the cerebellum influenced this globularization. (For more, see “Modern Brain Shape Linked to Parietal Lobes and Cerebellum.”)

According to Coss, early Homo sapiens spent hundreds of thousands of years spear-hunting on the open grasslands of Africa which resulted in the evolution of visuomotor coordination necessary to create cave drawings. On the flip side, Neanderthals relied on close-range thrusting spears because the game they hunted became less fearful of human presence quickly. 

“The visual imagery employed in drawing regulates arm movements in a manner similar to how hunters visualize the arc their spears must make to hit their animal targets,” Coss explained. He believes that prehistoric cave drawings were probably used as a teaching tool to pass on valuable knowledge between generations of early humans.

Coss concludes, "Since the act of drawing enhances observational skills, perhaps these drawings were useful for conceptualizing hunts, evaluating game attentiveness, selecting vulnerable body areas as targets, and fostering group cohesiveness via spiritual ceremonies. As a result, the advent of drawing may have set the stage for cultural changes. There are enormous social implications in this ability to share mental images with group members."

References

Richard G. Coss "Drawings of Representational Images by Upper Paleolithic Humans and Their Absence in Neanderthals Might Reflect Historical Differences in Hunting Wary Game." Evolutionary Studies in Imaginative Culture Vol 1, No 2 (2017) ISSN 2472-9884 (Print) / ISSN 2472-9876 (Online)

Simon Neubauer, Jean-Jacques Hublin, Philipp Gunz. “The Evolution of Modern Human Brain Shape.” Science Advances (First Published: January 24, 2018) DOI: 10.1126/sciadv.aao5961

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