Chapter 5

Paleoanthropology

The word paleoanthropology can be broken into three parts: paleo, anthropo, and logy. Paleo means ancient, anthropo means human, and logy means study. If you put that together, you get paleoanthropology, which is the study of ancient humans.

Methods

There are several methods used by paleoanthropologists when studying ancient humans.

Studying Fossils

Paleoanthropologists often study fossils, which are the remains of ancient plants and animals.  The fossil record refers to the amassed collection of preserved remains and traces of ancient organisms found in geological formations, representing the total body of fossil evidence available for scientific study. There are a few types of fossils:

• Trace fossils: foot tracks, bite marks on bones, nests (with eggs), and coprolite (fossilized poop)

• Mold fossils: animal or plant dies and the mud around it quickly makes a mold of its shape

• Resin fossils: animal or plant is trapped in the resin of a plant. A specific type of resin fossil is an amber inclusion, in which an animal's remains are preserved in amber. This type of fossil was popularized in the film Jurassic Park.

• Body fossils: animal whose body underwent a process of permineralization, in which minerals, such as silica or calcite, gradually replace teeth and bones over time. 

Key figures and pivotal fossil discoveries in paleoanthropology include Raymond Dart's (1925) identification of the Taung Child (Australopithecus africanus) in South Africa, Eugene Dubois's (1894) uncovering of Homo erectus remains in Java, Mary Leakey's discoveries of early hominin footprints and significant findings in Tanzania (refer to Leakey and Hay, 1979), and Louis and Richard Leakey's extensive fossil discoveries in East Africa (Morell, 1995), along with the Neanderthal fossils in Europe. These landmark contributions have collectively deepened our understanding of human evolution.

Dating Methods

Paleoanthropologists use a variety of dating methods when trying to discern the age of a fossil or other remnants from past humans, such as tools. We'll cover this topic in much greater detail during the final course unit, which is on archaeology. For now, we can explore some of the basics of dating, including the distinction between absolute and relative dating. Absolute dating provides a specific numerical age for something, whereas relative dating establishes where something fits within a chronological sequence of events or objects. As an easy example, consider a phone. If you found a first generation iPhone, it's pretty easy to figure out how old it is since we know it was created in 2007. That would be absolute dating. Now, imagine you found a really old flip phone, but you don't know when it was made or how old it is. Through relative dating, you would know it's older than an iPhone, but newer than a landline phone technology. You might not know its exact age, but you can place it within a range of other objects for which you do know their age.

There are various forms of absolute and relative dating. Again, we'll explore these in greater detail later, but here are a few of their types.

Absolute Dating

Radiocarbon Dating (Carbon-14): Measures the decay rate of carbon-14 isotopes in organic materials like bone or charcoal to determine ages; effective for dating materials up to approximately 50,000 years old.

Potassium-Argon Dating (K-Ar): Evaluates the decay of potassium-40 isotopes to argon-40 in volcanic rocks or minerals, providing ages for volcanic eruptions or associated fossil-bearing layers; useful for dating volcanic rocks and associated fossil layers ranging from thousands to millions of years old.

Relative Dating

Stratigraphy: Relies on the principle of superposition, where older layers of sediment or rock are found beneath younger layers, establishing a relative chronology of events or artifacts within a site.

Biostratigraphy (Fossil Succession): Uses the principle of fossil succession, where specific fossils with known evolutionary ages correlate with rock layers or sedimentary deposits, aiding in the relative dating of geological or archaeological materials.

Comparative anatomy and morphology

You may remember from Chapter 2, Edward Tyson (1699) compared the anatomy of what he called a pygmie, monkey, ape, and human. While there is some confusion regarding what he actually compared, he formalized a process of comparative anatomy, which is the study of the physical similarities and differences between species, including humans and our ancestors.

Historical Time Periods

Since we're studying ancient humans, now is a good time to familiarize ourselves with some of the basic language used when describing historical periods.  We will use common abbreviations for millions of years ago (mya) and thousands of years ago (kya).

Geological Time Scale

The geologic time scale is a chronological framework that divides Earth's history into distinct intervals based on significant geological events. Just as scientists have organized all life into a classification, we've done the same thing with time by organizing history into periods. We are currently living in the third "age" (the Meghalayan) of the second "epoch" (Holocene) of the third "period" (the Quaternary) of the third "era" (the Cenozoic) of the fourth "eon" (the Phanerozoic). Don't worry, that won't be on a test. 

Again, we are currently living in the epoch Holocene. Take note of the Holocene below as well as the four epochs that preceded it.

• Oligocene: 33.9 to 23 mya

  • Emergence of early primates

  • *Apes split from Old World monkeys (25-30 mya)

• Miocene: 23 to 5.3 mya

  • Early primates and divergence of hominoids.

  • *Subtribe Hominina split from subtribe Panina containing the chimpanzees and Bonobos (7 mya)

• Pliocene:5.3 to 2.6 mya

  • Emergence of hominins and early hominin diversity

  • *Bipedalism (4-6 mya)

• Pleistocene: 2.6 mya to 11.700 kya

  • Diversification of hominin species, glaciations, and adaptation to various environments.

  • Roughly corresponds with the Paleolithic archaeological time scale, also known as the Old Stone Age.

• Holocene: 11.7 kya to present

  • Rise of Homo sapiens, development of agriculture, and the establishment of complex societies.

Archeological Time Scales

Now let's consider the classic archaeological time scale originally created by  C.J. Thomsen (1836) and since refined by other scientists.

• Stone Age: Approximately 2.6 mya to 4 kya

• Bronze Age: Approximately 3300 to 1200 BCE

• Iron Age: Approximately 1200 BCE to 500 CE

The Stone Age has since been divided into the following categories:

• Paleolithic (Old Stone Age): Approximately 2.6 mya to 10 kya (roughly corresponds with the Pleistocene epoch above). The Paleolithic is also sub-divided.

  • Lower Paleolithic: Approximately 2.6 mya to 300 kya

  • Middle Paleolithic: 300 kya to 30-40 kya

  • Upper Paleolithic: 30-40 kya to 10 kya

• Mesolithic (Middle Stone Age): Approximately 10 kya to 8 kya

• Neolithic (New Stone Age): Approximately 8 kya to 4 kya

We'll explore the archaeological time scales in more detail below when we study tool use and again during the archaeology unit of the course.

History and Prehistory

Another time scale to be aware of is the distinction between historical and prehistoric. Historic refers to all history since the beginning of writing. Prehistoric refers to all history before writing. The historical time period is generally considered to start around 3,200 BCE (with the invention of cuneiform in Mesopotamia) but varies depending on the region.

Biological Evolution

In order to understand how these species are related to each other, we need to know what historical time periods they existed in and what their characteristics distinguish them in our shared evolutionary history.

Evolutionary milestones

Chapter 4 discussed the various genera and species of subtribe Hominina. Some of these may be referred to as transitional forms as they have evolutionary transitions. A transitional form is a fossilized organism that displays characteristics of both ancestral and derived forms, illustrating gradual changes in evolutionary lineages. These species are "in between" since they have characteristics similar to species before and after themselves. An evolutionary transition marks a shift in traits or characteristics over evolutionary time. Review the chart in Chapter 4 and the species below, along with their evolutionary transitions.

• Ardipithecus ramidus (~4.4 mya)

  • Represents a transitional form between late Miocene apes and the Australopithecus genus, offering insights into bipedal locomotion.

• Australopithecus afarensis (e.g., "Lucy") (3.9 - 2.9 mya)

  • Illustrates further adaptations to bipedalism and the transition from arboreal to terrestrial environments.

• Australopithecus africanus (3.3 - 2.1 mya)

  • Marks continued adaptations to bipedalism and provides evidence of an expanding hominin diversity in Africa.

• Homo habilis (2.3 - 1.6 mya)

  • Marks the transition from Australopithecus to the Homo genus, showing increased brain size and tool use.

• Homo erectus (2- 0.1 mya)

  • Represents the first hominin species to migrate out of Africa, displaying advanced tool technology and larger brain size.

• Homo sapiens (0.3 mya)

  • Represents the emergence of anatomically modern humans, characterized by advanced cognitive abilities, complex societies, and widespread migration.

Human ancestry

We explored various proto- and archaic-humans in Chapter 4. How are modern humans related to them? Are we descended from them? The human family tree and the various relationships between the species of subtribe Hominina is the subject of much research and debate among paleoanthropologists.

The exact relationships among the species of subtribe Hominina are still subjects of ongoing research and debate in paleoanthropology. Homo sapiens are believed to have evolved from earlier hominin species. Among the potential direct ancestors are Homo heidelbergensis, a species considered a common ancestor of both Neanderthals and Homo sapiens, with fossils found in Africa and Europe. Homo antecessor, identified through evidence from Atapuerca in Spain, is considered an early precursor to both Neanderthals and Homo sapiens. Neanderthals (Homo neanderthalensis) are also part of the evolutionary story, representing a closely related group with evidence of interbreeding with Homo sapiens. The human evolutionary path is complex, and ongoing research continues to refine our understanding of the specific ancestors leading to Homo sapiens. The other Homo species not listed here can be considered siblings or cousins to modern Homo sapiens. The Australopithecus and other proto-homo genera and species can be thought of as more distant cousins.

Behavioral Evolution

Just as we study hominin biological evolution, we can also study behavioral evolution. We'll explore some of these issues in greater depth as we progress through the course.

Tool use and technology

Cultural advancements

Since there is an entire course unit on cultural anthropology, we won't spend much time here. For now, you should be familiar with the following milestones.

Religious and Philosophical Traditions:

• Development of early belief systems and symbolic expressions.

• Cultural practices related to burial, rituals, and symbolic behavior.

• Time Range: Difficult to pinpoint, but evidence of symbolic behavior from the Paleolithic onwards.

Symbolic Representation

• Evidence of symbolic representation in the form of cave art, body ornamentation, or other non-verbal symbolic communication.

• Time Range: Upper Paleolithic period, approximately 40 kya to 10 kya.

Agricultural Revolution

• Transition from nomadic lifestyles to settled farming.

• Impacts on human diet, settlement patterns, and social structures.

• Time Range: Approximately 10 kya to 8 kya.

Formation of Complex Societies

• Emergence of larger and more organized hominin communities.

• Development of social hierarchies within early human groups.

• Time Range: Varies, but notable developments from 12 kya to 4 kya.

Urbanization

• Growth of early settlements and communities.

• Impact on resource utilization and social dynamics.

• Time Range: Depending on region, significant urbanization from 5 kya.

Trade Networks

• Exchange of tools, raw materials, and cultural artifacts among early human groups.

• Connections and interactions between different hominin populations.

• Time Range: Extends throughout prehistoric periods, with increased trade from 10 kya.

Language development

Since there is an entire course unit on linguistics, we won't spend much time here. For now, you should be familiar with the following milestones.

Emergence of Hominin Communication

• Development of basic communication systems among early hominins.

• Use of non-verbal cues and gestures.

• Time Range: Varies, but early forms of communication likely existed several million years ago.

Early Hominin Vocalizations

• Evolution of early vocalizations for communication.

• Limited but increasing complexity in vocal expression.

• Time Range: Over the course of several million years, with more refined vocalizations in later hominin species.

Homo neanderthalensis and Language Development

• Neanderthals were probably the first to use human language. Neanderthal remains found in Palestine showed a developed hyoid bone, which moves the tongue and is necessary for speech communication (Arensburg & Tiller, 1991; D'Anastasio et al., 2013). Fossilized skulls and endocasts (casts of the brain's interior) of early hominins provide insights into brain size and organization. Neanderthals had developed Broca's and Wrnicke's areas. The Broca area is a part of the brain associated with language production and speech formation, and the Wernicke area is a part of the brain associated with language comprehension).

• Time Range: Homo neanderthalensis existed from approximately 1.9 mya to 143 kya.

Transition to Homo sapiens

• Time Range: Homo sapiens emerged around 300 kya years ago, with the development of complex language likely evolving over tens of thousands of years.

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