11.3: Brain, Language, Lithics

Brain, Language, Lithics

Format: In-person or online

Author: Perkl, Bradley

Time needed: 45 minutes

Learning Objectives

• Describe relationships between tool manufacture, increased brain size, and the development of language
• Differentiate between earliest and later stone tool technology.
• Understand changes in planning and teaching behaviors in early hominins

Supplies Needed

• Worksheet (provided)

Readings

• Wolcott Paskey, Amanda; Beasley Cisneros, AnnMarie. "Chapter 11: Archaic Homo”. Explorations.

Chan, Keith. 2019. “Chapter 12: Modern Homo sapiens.” Explorations.

Introduction

This lab explores how an aptitude for forethought allowed for the manufacturing of patterned, chipped stone tools. This is also associated with the ability to teach others to create stone tools. This process accompanied an increase in brain size and spurred the development of language in early hominins.

Steps

1. Students should be aware of increased brain size of hominins through time, of tool use, and how changing technology changed behaviors. If not, a brief tutorial at the beginning of class may help.
2. Provide examples of stone tools and lithic debitage for students to examine if available for in-person classes.
3. Students answer the questions in Exercise 1.
4. Students draw an example of an Oldowan and an Acheulean tool for Exercise 2.

Tips and Suggestions

1. Demonstrate making a chipped stone tool, or produce some flakes, if raw material and safety gear (safety glasses, gloves) are available. The instructor or a visiting expert can do this. Also consider having students create stone tools. Ensure that the lithic debris is properly disposed of in the trash (not thrown out-of-doors, which could confuse future archaeologists). Warning: chipped stone flakes and tools are sharp! Handle with caution.
2. Have students view some flintknapping videos (hundreds of these videos exist on Youtube) ahead of class or show a short video at the start of class. Note how the maker describes what they’re doing: language in action.Teaching through language, gestures, etc. would also be observed/conducted in Tip 1 above).
3. Students can work in pairs or small groups as well. They will teach themselves.
4. Have fun.

Adapting for Online Learning

1 Not adaptable 2 Possible to adapt 3 Easy to adapt

Tips to adapt for an online learning activity: In place of using actual chipped stone tools, have students examine pictures (e.g., print, on-line, posters, etc.) of Oldowan and Acheulean artifacts for reference and make the drawings in Exercise 2 based on these images.

For Further Exploration

Everett, Daniel. 2017. How Language Began: The Story of Humanity’s Greatest Invention. Liveright Publishing Corporation, New York.

Shea, John J. 2017. Stone Tools in Human Evolution: Behavioral Differences Among Technological Primates. Cambridge University Press, Cambridge.

Barnard, Allen. 2016. Language in Prehistory. Cambridge University Press, Cambridge.

Renfrew, Colin, Chris Firth, and Lambros Malafouris. 2009. The Sapient Mind: Archaeology Meets Neuroscience. Oxford University Press, Oxford.

References

Wolcott Paskey, Amanda; Beasley Cisneros, AnnMarie. 2019. Chapter 11: Archaic Homo in Explorations: An Open Invitation to Biological Anthropology, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association. http://explorations.americananthro.org/

Dennell, Robin 2018. The Acheulean Assemblages of Asia: A Review. In R. Gallotti and M. Mussi (eds.), The Emergence of the Acheulean in East Africa and Beyond: Contributions in Honor of Jean Chavaillon, Vertebrate Paleobiology and Paleoanthropology, pp 198-214. https://doi.org/10.1007/978-3-319-75985-2_10

Capasso, Luigi, Elisabeth Michetti, and Ruggero D’Anastasio 2008. A Homo Erectus Hyoid Bone: Possible Implications for the Origin of the Human Capability for Speech. Collegium Antropologicum 32 (2008) 4: 1007-1011.

Image Attributions

Transition of cranial capacity (ordinate) along the evolutionary process of various ancestral prehominids and hominids by Rafael Vieira Bretas et. al. is licensed as CC BY 4.0

Features of a chipped stone flake by Bradley Perkl is licensed as CC BY-NC 4.0.

Percussion Techniques by Bradley Perkl is licensed as CC BY-NC 4.0.

Oldowan stone chopper by Emmy Ne29 is in the public domain.

Handaxe from Isampur, India, about 1.1 million years old. © Copyright Smithsonian Institution.

Handaxe from Meyral, France, about 250,000 years old. © Copyright Smithsonian Institution.

Brain Activation During Stone Tool Production by Bradley Perkl is licensed as CC BY-NC 4.0.

712 Hyoid Bone by OpenStax College is licensed as CC BY 3.0.

Male Homo sapiens and Pan troglodytes hyoid bones by Ruggero D’Anastasio, Stephen Wroe, Claudio Tuniz, Lucia Mancini, Deneb T. Cesana, Diego Dreossi, Mayoorendra Ravichandiran, Marie Attard, William C. H. Parr, Anne Agur, Luigi Capasso is licensed as CC BY.

Chopping tool by José-Manuel Benito Álvarez is used under a CC BY-SA 2.5 License.

Hand axe spanish by Locutus Borg has been designated to the public domain (CC0).

Cut stone Melka Kunture Ethiopia by Ruggero D’Anastasio et. al. is licensed as CC BY 4.0

Acheulean Handaxe A70:11:11. Courtesy of the Science Museum of Minnesota.

Brain, Language, Lithics Worksheet

The manufacture of patterned, chipped stone tools by early hominins appears to have led to the co-evolution of manual praxis, language, and expansion of the brain. Between approximately 2.6 million years ago (mya) and 200,000 years before present (yrs bp), the hominin brain nearly tripled in size, as indicated in the figure below.

Hominin Brain Size Through Time

Some Points on Lithics

Stone (lithic) tool manufacture requires strong, fast, highly controlled (precise) manual praxis (finely attuned awareness and function of the hands). Manipulation of particular types of stone cores (e.g., silicate-based materials with predictable conchoidal fracture) will create a variety of flaked or chipped tools (e.g., chopper, hand axe, scraper, knife, projectile point). The cores, flakes, and tools made by early hominins and modern humans have specific characteristics that distinguish them from features caused by natural processes (e.g., heat, frost, a fall). These features include a striking platform, bulb of percussion, and ripples, as illustrated in the diagram below.

Features of a chipped stone flake. Two views (A: fontal; B: profile) of a flake struck from a core illustrate key characteristics of a purposely made flake.

Worked stone cores are percussed with (typically) harder materials (e.g., other rocks, bone, antler, wood) using a sharp, forceful blow to break off flakes in succession, removing pieces of the core to form the desired tool or finished product. Flakes may also be removed with hard (e.g., harder igneous or metamorphic based rocks) or soft (e.g., antler, bone, hard wood) hammers in carefully controlled strikes. The basic methods are illustrated in the diagram below.

Two basic percussion techniques

The complex motor tasks associated with stone tool production have a strong spatial-cognitive component that activates the neocortex (cerebrum) and cerebellum, which are the areas of greatest brain expansion in hominin evolution. The sometimes tedious and frustrating job of creating stone tools requires motivation, self-control, and future planning: the ability to visualize the final product and its use. Understanding the characteristics of the stone being worked, and the physics of lithic fracture, is necessary. Nuances to successfully create a tool include:, the angle on a lithic edge, the orientation of the percussive blow, and precise aim and timing. Many stone tools are discarded unfinished due to mistakes in knapping. Coincidently, these discarded waste flakes often signal an archaeological site. All of this knowledge is difficult to learn through self-teaching or imitation alone.

Debate continues as to who were the first toolmakers. There is some evidence from East Africa of stone tools associated with Australopithecines ca. 3.3 mya. However, by at least 2.6 mya the Oldowan industry appears in Africa. Oldowan tools may be associated with Australopithecines and/or Homo habilis. The Oldowan industry is composed predominantly of cores, which are lumps of stone that have been slightly modified by removing small pieces around the edges, hammerstones (identified from battering on their surfaces), and flakes struck from the cores offering sharp cutting edges. Flakes are very sharp and useful for butchering animal carcasses. Core choppers were also used to crack open bones to extract nutrient-rich marrow. These crude, simple choppers, and cutting tools are simplistic in design, yet they allowed early hominins to exploit a new niche: animal resources and meat eating. The following figures present some Oldowan tools.

Oldowan choppers from Melka Kunture, Ethiopia. Ca. 1.7 mya.

Drawing of an Oldowan chopper.

By 1.6 mya, bifacially worked cutting tools appear in the fossil record in Africa, known as the Acheulean Industry. The Acheulean toolkit is composed primarily of the hand axe, a teardrop-shaped tool. It also includes assorted cleavers which are characterized by large flakes that were shaped by striking smaller flakes from around two opposing sides-bifaces-to create sharp edges. The Acheulean stone tool industry that Home erectus used displays an advance over the earlier Oldowan tools. These tools are made with a mental template and a preconceived idea in mind; they are not simplistic like the Oldowan tools. The figures below depict Acheulean hand-axes.

Image on left: Handaxe from Isampur, India, about 1.1 million years old. © Copyright Smithsonian Institution.
Image on right: Handaxe from Meyral, France, about 250,000 years old. © Copyright Smithsonian Institution.

Acheulean Handaxe. Dordogne Region, France. Courtesy of the Science Museum of Minnesota.

Some Aspects of the Brain

Stone tool production activates various areas of the brain, such as the cerebrum, cerebellum, and the frontal gyrus. One region in the frontal lobe, Broca’s area, is associated with speech, language, music, math and complex manual actions (manual praxis). Scanning techniques (e.g., Magnetic Resonance Imaging, Positron Emission Tomography) of modern subjects creating stone tools reveal the different areas of the brain are activated when making relatively simple Oldowan tools and more complex Acheulean tools. The figure below reveals one indicator of expanded brain power with more sophisticated toolmaking. In the illustration, numbers 1-4 denote regions active when making both Oldowan and Acheulean tools (i.e., dorsal intraparietal sulcus, anterior intraparietal sulcus, supramarginal gyrus of the inferior parietal lobe, ventral premotor complex). Numbers 1-6 indicate regions utilized when making Acheulean tools (i.e., dorsal intraparietal sulcus, anterior intraparietal sulcus, supramarginal gyrus of the inferior parietal lobe, ventral premotor complex AND dorsal premotor cortex, inferior frontal gyrus).

Some Notes on Language

In the 19th century, Charles Darwin suggested a connection between the intellectual challenges associated with tool manufacture and language as seen in the extreme encephalization of modern humans. However, when toolmaking was observed in nonhuman species (e.g., Jane Goodall’s report of chimpanzee tool use in the mid-20th century), toolmaking as a driver of evolution in humans fell out of favor. Recent research has brought new insights into how we have learned and taught each other to make tools - a process that may have enlarged our brains and spurred language. While imitation and practice are helpful, the nuances of strategy and tactics of stone tool manufacture are best learned from others, particularly via language. Increased manual praxis would allow for increased communication through gestures (associated with Broca’s area), facial sensorimotor systems, and perhaps vocalizations.

It is not yet known what form of language early hominins/Homo had, which may have ranged from gestures, vocalization, and signs, to exosonatic (symbolic) and mimetic (imitative) forms. By approximately 500,000 years ago, the Homo brain had increased synaptic malleability and connectivity. In addition to a big brain, the capacity for spoken language includes morphological changes to the supralaryngeal airway (with a relatively enlarged oral cavity) and the hyoid bone. The hyoid bone is U-shaped and rests under the chin, supporting the tongue, and has a unique shape in the genus Homo. An approximately 400,000 year old Homo erectus hyoid bone from Italy is markedly different from chimpanzee and Australopithecus afarensis hyoid bones, suggesting that Home erectus had the capacity for speech. Genetic research has focused on the FOXP2 gene, the so-called ‘gene for language’. A mutation in the gene occurring between 240,000-270,000 years ago in populations ancestral to living humans is implicated in motor control and cognition. This polymorphism allows for articulate language and enables the use of grammar. The figures below depict the position of the hyoid bone, its characteristics and a comparison with a chimpanzee hyoid bone.

Human hyoid bone

Human hyoid bone (left) and Chimpanzee hyoid bone (right)

The concurrent changes to the brain (increased connections and expansion) is a likely precursor to language (offering a significant learning advantage). Protolinguistic communication would be subject to selective pressure on the early hominin brain, producing adaptations that support language, along with physical adaptations to produce speech (i.e., the supralaryngeal airway, hyoid bone). Tools made by humans share a linguistic structure, as they are assembled in procedural ways (analogous to syntax) that have a nearly infinite capacity for variation (analogous to lexicon).

Exercise 1

Examine the examples of Oldowan and Acheulean stone tools in the figures above and then answer the following questions.

1. How do Oldowan tools build upon former tool technologies?

2. What behavior changes from australopithecines to early Homo may be occuring with the use of chipped stone tools?

3. What improvements in technology and style do you see in the Acheulean tools compared to Oldowan tools?

Exercise 2

In addition to physical changes to the vocal apparatus, genetic influence and other biological processes, different parts of the brain underlie language function and praxis.

Why would language be important in making stone tools?

Provide two examples of how language would benefit Homo.