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Anthropologist’s Research Leads to New Insights Into the Evolution of the Human Brain and Human Behavior

October 8, 2012 -- by Amy Stix
Waves wash ashore at Elands Bay on the Atlantic coast north of Cape Town. The Dunefield Midden archaeological site is located in the center of the photo, above the small town of Elands Bay.
Photo courtesy of Jack Fisher.
Part of the cranium of a mongoose found at the Dunefield Midden archaeological site. The black lines indicate the location of cut marks made by stone tools when the skin from this animal was removed during the Later Stone Age.
Photo courtesy of Jack Fisher.
The lower jaw of a rock hyrax found at the Dunefield Midden archaeological site. It and other rock hyraxes are food remains left by Later Stone Age people. This juvenile rock hyrax contains some teeth still in the process of erupting at the time this animal died. Comparison of the stage of tooth eruption of this specimen to modern rock hyraxes whose age at death is known provides a basis for estimating the age, and season of year, at which this animal died. Photo courtesy of Jack Fisher.
Jack Fisher at the University of Cape Town,
South Africa, examining animal bones from the Dunefield Midden archaeological site.
Photo courtesy of Jack Fisher.

When searching for answers to some of the biggest questions in the field of anthropology today, it helps to have a big study site. That’s just one aspect that Jack Fisher, associate professor of anthropology, appreciated about his recent nine-month sabbatical in South Africa, where he collaborated with John Parkington of the University of Cape Town to investigate the evolution of nomadic hunter-gatherers, and their encampments, over millions of years. 

The colleagues’ research site, Dunefield Midden (DFM), which is located at Elands Bay north of Cape Town on the Atlantic Coast, is rare among research sites for its sheer size. Excavated over an eleven-year period, DFM is a huge, contiguous, rectangular area, which, Fisher says, provides  “snapshots” of Later Stone Age hunter-gatherer life, from AD 1300 to 1400.

Fisher says, “It is great to have a large contiguous area (like DFM) to get a sense of repetition.”

From those repetitive snapshots, scientists can decipher what Fisher calls “patterns of living,” including where hunter-gatherers slept, cooked, built fires, roasted meat and deposited trash. He and Parkington will compare their new findings from DFM with past discoveries from much older hunter-gatherer camps, which they hope will lead to new insights into the question of how human cognition and behavior have changed since the Early Stone Age began, some 2.8 million years ago.

According to Fisher, his research in South Africa, where he has worked since 1998, is “a very long process, but ultimately we do get new insights.”

Those glimmers into early human behavior and interactions with their environment are being gleaned through meticulous study of every single object unearthed at DFM. Fisher says more than two tons of shellfish remains have been found in the coastal camp, as well as 18,000 stone tools and in excess of 10,000 well-preserved animal bones, ranging from the rock hyrax, which resembles a marmot, to fur seal, several species of African antelope and buffalo. Many carnivore bones have also been discovered, including remnants of the striped polecat, mongoose, honey badger and genet. Fisher uses mapping software to show where and how hunter-gatherers at DFM arranged and used their campsite.

Through the mapping process, Fisher has discovered a fascinating pattern to the animal bones at DFM. Bones from herbivores were scattered everywhere throughout the campsite at various fireplaces, roasting pits and other cooking sites, leading Fisher and Parkington to surmise that both small and large herbivores were a staple in the hunter-gatherer diet. Carnivore bones, however, were buried in just a few, specific locations. The carnivores’ bones also contained exacting cuts to their skulls and legs, which were made with stone tools. From this discovery, Fisher and Parkington hypothesize that Later Stone Age people used carnivores for ritual and ceremonial purposes, rather than for food. Also found at DFM were ostrich egg shell beads, which humans used for necklaces, as well as tortoise shell remains and ceramic shards.

In addition to figuring out how early humans arranged and used their encampments, Fisher is researching the season of year and length of time people remained in their camps. His answers are coming largely from the teeth of the herbivorous rock hyrax, which develop fairly rapidly. By studying the ages of rock hyrax teeth collected from both DFM and inland hunter-gatherer campsites, and comparing those findings with a modern-day collection housed at the University of Cape Town, Fisher has attained an accurate accounting for when hunter-gatherers at DFM killed the animals and his analysis of inland sites is underway. The information gleaned supports his and Parkington’s hypothesis that early humans used their camps intermittently, and moved seasonally between the coast and inland sites in their search for food.

As for the next question Fisher would like to investigate at DFM, he says, “We’d like to know more about the social divisions of the people.” He and Parkington will look for clues as to whether hunter-gatherers arranged their camps according to gender, for example.

Ultimately, Fisher hopes they can also shed light on the pace of human cognitive development, and how the brain’s development enabled Early, Middle and Later Stone Age people to make the most effective use of their surroundings.

The question of abrupt versus gradual human cognitive development has long been debated among anthropologists, says Fisher. Through his and Parkington’s studies of objects found at DFM and the arrangements of those objects in the camp, “We feel we can contribute to answering the question of abrupt versus gradual evolution of cognition,” he says.

“DFM can serve as a very good example of patterning in the Later Stone Age, and with that, fully modern human cognition,” that can be compared to earlier times.

In a sense, you can view DFM as a big jigsaw puzzle. And with each puzzle piece Fisher and Parkington put together at Dunefield Midden, their work, he says, is “giving a new body of evidence” to the field of anthropology, and important clues into the behavioral evolution and lives of human beings over millions of years.