11.1: Archaic Homo and the Environment

BREAKING THE STIGMA OF THE "CAVEMAN"

What do you think of when you hear the word “caveman”? Perhaps you imagine a character from a film such as The Croods, Tarzan, or Encino Man or from the cartoon The Flintstones. Maybe you picture the tennis-playing, therapy-going hairy Neanderthals from Geico Insurance commercials. Or perhaps you imagine comic characters from “The Far Side” or “B.C.” comics. Whichever you picture, the character in your mind is likely stooped over with a heavy brow, tangled long locks and other body hair, and clothed in animal skins, if anything. They might be holding a club with a confused look on their face, standing at the entrance to a cave or dragging an animal carcass to a fire for their next meal (Figure \(\PageIndex{1}\)). You might have even signed up to take this course because of what you knew—or expected to learn—about “cavemen.”

Figure \(\PageIndex{1}\): Popular perceptions of human ancestors at the transition to modern Homo sapiens often take the form of the stereotypical, and inaccurate, “caveman.”

These images have long been the stigma and expectation about our ancestors at the transition to modern Homo sapiens. Tracing back to works as early as Linnaeus, scientists once propagated and advanced this imagery, creating a clear picture in the minds of early scholars that informed the general public, even through today, that archaic Homo sapiens, “cavemen,” were somehow distinctly different and much less intelligent than we are now. Unfortunately, this view is incorrect, overly simplistic, and misleading. Understanding what archaic Homo sapiens were actually like requires a much more complex and nuanced picture, one that continues to be understood with greater clarity as current research uncovers the lives of our not-too-distant (and not-too-different) ancestors.

The first characterizations of archaic Homo sapiens were formed from limited fossil evidence in a time when ethnocentric and species-centric perspectives (anthropocentrism) were more extensively accepted and entrenched in both society and science. Today, scientists are working from a more complete fossil record from three continents (Africa, Asia, and Europe) and even genetic evidence that informs their analyses and conclusions. The existence of archaic Homo sapiens mark an exciting point in our lineage—a point at which many modern traits had emerged and key refinements were on the horizon. Anatomically, we today are not that much different from archaic Homo sapiens.

Definition: ethnocentric

Applying negative judgments to other cultures based on comparison to one’s own.

Definition: anthropocentrism

A way of thinking that assumes humans are the most important species and leads to interpreting the world always through a human lens. Species-centric science and thought.

 

This chapter will examine the environment with which archaic Homo sapiens had to contend, one that shaped their, and our, ultimate development. It will also examine the key anatomical traits that define this group of fossils (including the infamous subgroup known as Neanderthals), cultural innovations that aided their adaptation to the changing environment, and their geographic distribution and regional variations. Additionally, it will consider areas of exciting new research that suggest even greater nuance and complexity during this time period. Our understanding of this species and our evolution is complex and exciting and could become even more so as new data is uncovered.

THE CHANGING ENVIRONMENT

While modern climate change is of critical concern today due to its cause (human activity) and pace (unprecedentedly rapid), the existence of global climate change itself is not a recent phenomenon. The climate across the globe has changed, drastically at times, over the course of Earth’s existence. The Pleistocene epoch—between 1.8 million years ago (mya) and 11,000 years ago (kya); was a time of great climatic upheaval. The Middle Pleistocene, roughly between 780 kya and 125 kya, is the time period in which archaic Homo sapiens appear in the fossil record—a time that witnessed some of the most drastic climatic changes that have been seen in human existence. During this time period, there were 15 major and 50 minor glacial events in Europe alone!

What exactly is a glaciation? When scientists talk about glacial events, they are referring to the climate being in an ice age. This means that the ocean levels were much lower than today, as much of the earth’s water was tied up in large glaciers or ice sheets. Additionally, the average temperature would have been much cooler, which would have better supported an Arctic or tundra-adapted plant-and-animal ecosystem in northern latitudes. The most interesting and relevant features of Middle Pleistocene glacial events are the sheer number of them and their repeated bouts—this era alternated between glacial periods and warmer periods, known as interglacials. In other words, the world wasn’t in an ice age the whole time.

Definition: glaciation

A glacial period, or time when a large portion of the world is covered by glaciers and ice sheets.

How have scientists determined how many glaciations there were during the Middle Pleistocene and how severe they were? Several lines of evidence help inform our understanding of past climates. One important source is the study of oxygen isotopes preserved in the shells of marine invertebrates called foraminifera. Foraminifera incorporate oxygen from seawater during their life. When they die, foraminifera shells fall to the ocean floor and can be preserved as microscopic fossils that are part of the sediment, which can later be sampled and studied in sediment cores. Studying these cores has revealed that the oxygen isotope present varies depending on Earth temperatures at the time the foraminifera were alive. During glacial periods, seawater is cooler and one oxygen isotope—¹⁸O—is in higher concentrations in seawater (and, as a result, in foraminifera shells) because it is heavier. In contrast, water with the oxygen isotope ¹⁶O is lighter and therefore evaporates first, becomes part of precipitate (such as snow), and eventually becomes trapped in glaciers. During interglacials, ¹⁶O returns to the ocean in water runoff, resulting in higher ocean and foraminifera concentrations of this oxygen isotope. Recent research with ice cores further confirms the length and severity of glacial periods using similar techniques.

Definition: ice core

A cylindrical sample of ice that is removed from an ice sheet. The annual buildup of snow and ice can be studied and interpreted to better understand climate change, as well as local environmental shifts.

The Pleistocene is characterized by shifts in Earth’s temperatures and their impact on plant and animal life. The Middle Pleistocene was an even more intense period of fluctuation with frequent and severe glacial and interglacial episodes recorded in marine isotopes, among other data points. You can see the dramatic and increasing fluctuations in temperature, recorded through foraminifera, in the chart (Figure \(\PageIndex{2}\)). The distance between lows and highs demonstrates the severity of temperature shift. Much as the Richter scale represents more intense earthquakes with more dramatic peaks, so too does this chart, which uses dramatic peaks to demonstrate intense temperature swings.

Figure \(\PageIndex{2}\): The Geologic Timescale and corresponding temperature shifts. Note the wide and rapid shifts during the Pleistocene (the second box from the right). More dramatic fluctuations depict greater severity of temperature shift.

Glacial periods are defined by Earth’s average temperature being lower. Worldwide, temperatures are reduced, with cold areas becoming even colder. The water cycle experiences limited runoff as water evaporates from the seas, precipitates (often as snow and ice), and accumulates in glaciers with little precipitation melting as runoff. Over time, continued evaporation with little runoff results in the accumulation of snowpacks and glaciers at the expense of sea level, which is lowered. In simple terms, the water that is normally in the sea is now tied up on land as ice. Huge portions of the landscape may have become inaccessible during glacial events due to the formation of glaciers and massive ice sheets. In Europe, the Scandinavian continental glacier covered what is today Ireland, England, Sweden, Norway, Denmark, and some of continental Europe. Plant and animal communities shifted to lower latitudes along the periphery of ice sheets. Additionally, some new land was opened during glacials. Evaporation with little runoff reduced sea levels by as much as almost 150 meters, shifting coastlines outward by in some instances as much as almost 100 kilometers. Additionally, land became exposed that connected what were previously unconnected continents such as Africa at the Gulf of Aden into Yemen.

Glacial periods also affected equatorial regions and other regions that are today thought of as warmer or at least more temperate parts of the globe, including Africa. While these areas were not covered with glaciers, the impact of increased global glaciation resulted in lower sea levels and expanded coastlines. Cooler temperatures were accompanied by the drying of the climate, which caused significantly reduced rainfall, increased aridity, and the expansion of deserts. It is an interesting question to consider whether the same plants and animals that lived in these regions prior to the ice ages would be able to survive and thrive in this new climate? Plant and animal communities shifted in response to the changing climate, whenever possible.

Rather than a single selective force, the Middle Pleistocene was marked by periods of fluctuation, not just cold periods. Interglacials interrupted glaciations, reversing trends in sea level, coastline, temperature, precipitation, and aridity, as well as glacier size and location. Interglacials are marked by increased rainfall and a higher temperature, which causes built-up ice in glaciers to melt. Interglacials are marked by glacial retreat, which is the shrinking of glaciers and the movement of the glaciers back toward the poles, as we’ve seen in our lifetime. During interglacials, sea levels increase, flooding some previously exposed coastlines and continental connections. In addition, plant and animal communities shift accordingly, often finding more temperate climates to the north and less arid and more humid climates in the tropics.

Scientists have found that at one site, the Olorgesailie region in southern Kenya, a single location was at various times in the Middle Pleistocene a deep lake, a drought-dried lakebed, small streams, and a grassland. While various animal species would have moved in and out of the area as the climate shifted, some animal species went extinct, and new, often related, species took up residence. The trend, scientists noted, was that animals with more specialized features went extinct and animals with more generalized features, such as animals we see today, survived in this changing climatic time period. For example, a zebra with specialized teeth for eating grass was ultimately replaced by a zebra that could eat grass and other types of vegetation. The exclusively terrestrial fossil baboon Therapithecus oswaldi was replaced by Papio anubis, the more flexible locomotor baboon that exists in the region today. If this small, localized example shows such a dramatic change in terms of the environment and the plant and animal biocommunities, what would have been the impact on humans?

There is no way humans could have escaped the effects of Middle Pleistocene climate change, no matter what region of the world they were living in. As noted earlier, and as evidenced by what was seen in the other biotic communities, humans would have faced changing food sources as previous sources of food may have gone extinct or moved to a different latitude. Depending on where they were living, fresh water may have been limited. Durial glacials, lower sea levels would have given humans more land to live on, while the interglacials would have reduced the available land through the increase in rainfall and associated sea level rise. Dry land connections between the continents would have made movement from one continent to another by foot easier at times than today, although these passageways were not consistently available through the Middle Pleistocene due to the glacial/interglacial cycle. Finally, as evidenced by the study at the Olorgesailie region in Kenya, during the Middle Pleistocene animal species that were overly specialized to one particular type of environment were less likely to survive when compared to their more generalized counterparts. Evidence suggests that this same pattern may have held true for archaic Homo sapiens, in terms of their ability to survive this dramatic period of climate change.

DEFINING CHARACTERISTICS OF HOMO SAPIENS

Archaic Homo sapiens share our species name but are distinguished by the term “archaic” as a way of recognizing both the long period of time between their appearance and ours, as well as the way in which human traits have continued to evolve over time—making archaic Homo sapiens look slightly different from us today, despite technically being considered the same species. Living throughout the Old World during the Middle Pleistocene, archaic Homo sapiens are considered, in many ways, transitional between Homo erectus and modern Homo sapiens (see Table \(\PageIndex{1}\)). All archaic Homo sapiens share the defining trait of an increased brain size—specifically a brain of at least 1,100 cc and averaging 1,200 cc—but are also characterized by significant regional and temporal (time) variations. Because of these variations, scientists disagree on whether these fossils represent a single, variable species or multiple, closely related species (sometimes called Homo antecessor, Homo heidelbergensis, Homo georgicus, Homo neanderthalensis, and Homo rhodesiensis). For simplicity we are going to lump them all together under the heading of archaic Homo sapiens and discuss them as a unit, with the exception of a particularly unique and well-known population living in Europe and West Asia known as the Neanderthals, which we will examine separately.

Table \(\PageIndex{1}\): A comparison of Homo erectus, archaic Homo sapiens, and anatomically modern Homo sapiens. This table compares key traits of the crania and postcrania that distinguish these three hominins.

Trait	Homo erectus	Archaic Homo sapiens	Anatomically Modern Homo sapiens
Average Brain Size	900 cc	1,200 cc (1,500 cc when including Neanderthals)	1,400 cc
Skull Shape	Long and low Angular	Intermediate	Short and high Globular
Forehead	Absent	Emerging	Present
Nasal Region	Projecting nasal bones (bridge of the nose), no midfacial prognathism	Wider nasal aperture and midfacial prognathism	Narrower nasal aperture, no midfacial prognathism
Chin	Absent	Absent	Present
Other Facial Features	Large brow ridge and large projecting face	Intermediate	Small brow ridge and retracted face
Other Skull Features	Nuchal torus, sagittal keel, thick cranial bone	Projecting occipital bone, often called occipital bun in Neanderthals; intermediate thickness of cranial bone	Small bump on rear of skull, if anything; thin cranial bone
Dentition	Large teeth, especially front teeth	Slightly smaller teeth; front teeth still large; retromolar gap in Neanderthals	Smaller teeth
Postcranial Features	Robust bones of skeleton	Robust bones of skeleton	More gracile bones of skeleton

When comparing Homo erectus, archaic Homo sapiens, and anatomically modern Homo sapiens across several anatomical features, one can see quite clearly that archaic Homo sapiens are intermediate in their physical form. This follows the trends first seen in Homo erectus for some features and in other features having early, less developed forms of traits more clearly seen in modern Homo sapiens. For example, archaic Homo sapiens trended toward less angular and higher skulls than Homo erectus but had skulls notably not as short and globular in shape and with a less developed forehead than anatomically modern Homo sapiens. archaic Homo sapiens had smaller brow ridges and a less-projecting face than Homo erectus and slightly smaller teeth, although incisors and canines were often about as large as that of Homo erectus. Archaic Homo sapiens also had a wider nasal aperture, or opening for the nose, as well as a forward-projecting midfacial region, known as midfacial prognathism. The occipital bone often projected and the cranial bone was of intermediate thickness, somewhat reduced from Homo erectus but not nearly as thin as that of anatomically modern Homo sapiens. The postcrania remained fairly robust, as well. To identify a set of features that is unique to the group archaic Homo sapiens is a challenging task, due to both individual variation—these developments were not all present to the same degree in all individuals—and the transitional nature of their features. Neanderthals will be the exception, as they have several clearly unique traits that make them notably different from modern Homo sapiens as well as their closely related archaic cousins.

Definition: nasal aperture

The opening for the nose visible on a skull. Often pear- or heart-shaped.

Definition: midfacial prognathism

A forward projection of the nose, or middle facial region. Usually associated with Neanderthals.

 

Figure \(\PageIndex{3}\): “Broken Hill Man” archaic Homo sapiens cranium found at Kabwe in Zambia. One of several individuals found at this site, this cranium reflects common traits associated with archaic Homo sapiens in Africa including a large brain, taller cranium, and many Homo erectus-like features such as massive brow ridges, a large face, and thick cranial bones.

The one thing that is clear about archaic Homo sapiens is that regional variation, first seen in the different Homo erectus specimens across Asia and Africa, is clearly present and even more pronounced. While the general features of archaic Homo sapiens, identified earlier, are present in the fossils of this time period, there are significant regional differences. The majority of this regional variation lies in the degree to which fossils have features more closely aligned with Homo erectus or with anatomically modern Homo sapiens.

Figure \(\PageIndex{4}\): Atapuerca 5 archaic Homo sapiens found in northern Spain. One of many fossils found at this site, this fossil is representative of traits seen in archaic Homo sapiens in Europe including thick a cranial bone, enlarged cranial capacity, intermediate cranial height, and a more rounded cranium, as well as increased midfacial prognathism.

To illustrate this point, we will examine three exemplary specimens, one from each of the three continents on which archaic Homo sapiens lived. In Africa, “Broken Hill Man,” one of several individuals found in the Kabwe lead mine in Zambia, had a large brain (1,300 cc) and taller cranium as well as many Homo erectus-like skull features, including massive brow ridges, a large face, and thick cranial bones (Figure \(\PageIndex{3}\)). Conditions for preservation in Asia during the Middle Pleistocene were not as conducive to the fossilization of complete crania; however, many archaic Homo sapiens skullcaps have been found. One partial crania from Dali, China, is representative of archaic Homo sapiens in Asia, including large and robust features with heavy brow ridges, akin to what is seen in Homo erectus, and a large cranial capacity intermediate between Homo erectus and anatomically modern Homo sapiens. Across Europe, many near-complete archaic Homo sapiens crania have been discovered, including one, part of an almost-complete skeleton, found in northern Spain at Atapuerca. Atapuerca 5 (Figure \(\PageIndex{4}\)) has thick cranial bone, an enlarged cranial capacity, intermediate cranial height, and a more rounded cranium than seen previously. Additionally, Atapuerca 5 demonstrates features that foreshadow Neanderthals, including increased midfacial prognathism. After examining some of the fossils, the transitional nature of archaic Homo sapiens is clear—their features place them squarely between Homo erectus and modern Homo sapiens.

Due to the transitional nature of archaic Homo sapiens, identifying the time period they are associated with is problematic and complex. Generally, it is agreed upon that archaic Homo sapiens lived between 600,000 and 200,000 years ago. But regionally this varies with considerable overlap between Homo erectus on the early end of the spectrum and modern Homo sapiens and Neanderthals on the latter end. The earliest-known archaic Homo sapiens fossils tentatively date to about 600,000 years ago in Africa, whereas archaic Homo sapiens fossils in Asia appear around 300,000 years ago and in Europe around 350,000 years ago (and potentially as early as 600,000 years ago). The end point of archaic Homo sapiens is also problematic since it largely depends upon when the next subspecies of Homo sapiens appears and the classification of highly intermediate specimens. For example, in Africa, the end of archaic Homo sapiens is met with the appearance of modern Homo sapiens, while in Europe it is the appearance of Neanderthals that is traditionally seen as the end of archaic Homo sapiens.

Archaic Homo sapiens mark an important chapter in the human lineage, bridging more ancestral forms, such as Homo erectus, with modern Homo sapiens. During this period of climatic transition and fluctuation, archaic Homo sapiens mirror the challenges of their environments. Showing increasing regional variation due to the need for local adaptation, there is no single archetype for this group but, rather, multiple variations; their transitional nature is one of their key defining characteristics.

FIGURE ATTRIBUTIONS

Figure \(\PageIndex{1}\) Big head primitive caveman nose man bone cave at Max Pixel has been designated to the public domain (CC0).

Figure \(\PageIndex{2}\) All paleotemps by Glen Fergus is used under a CC BY-SA 3.0 License.

Figure \(\PageIndex{3}\) Homo heidelbergensis Cranium Broken Hill 1 (Rhodesian Man) by ©BoneClones is used by permission and available here under a CC BY-NC 4.0 License.

Figure \(\PageIndex{4}\) Homo heidelbergensis Skull Atapuerca 5 by ©BoneClones is used by permission and available here under a CC BY-NC 4.0 License.

TABLE ATTRIBUTION

Table \(\PageIndex{1}\) Homo erectus, archaic Homo sapiens, and anatomically modern Homo sapiens table original to Explorations: An Open Invitation to Biological Anthropology is under a CC BY-NC 4.0 License.