Biological Anthropology: Archaic Homo sapiens and Neanderthals

Announcements

  • First Test: Scheduled for two weeks from now.

  • Format: 50 questions, covering Weeks 1 through 5

  • Topic: Biological Anthropology.

  • Location & Time: Will be held in this Lecture Hall from 9-10 AM.

  • Study Guide: The PowerPoints provided for the lectures serve as the study guide.

  • Coverage: Lectures, discussion readings, and videos are all testable material.

  • Example Question: "Which of our ancestors was the first to leave Africa?"

    • A. Australopithecus afarensis

    • B. Homo habilis

    • C. Homo erectus

    • D. Homo floresiensis

    • E. None of the above

    • Correct Answer: C. Homo erectus.

  • Review Session: A partial review might be held next week during the lecture if time permits. Discussion sessions next week will also cover some review material.

The Genus Homo: Upright Walking, Brain Expansion, Tool Use, and Migration

  • Key species discussed:

    • H. habilis

    • H. erectus

    • H. neanderthalensis

Homo erectus: The First to Expand from Africa

  • Review: Homo erectus was the first human ancestor to leave Africa, a process facilitated by advanced culture which allowed adaptation to diverse ecological niches.

  • Geographic Spread: Spread across much of the "southern" Old World.

  • Relevant Sites: Atapuerca, Dmanisi, Zhoukoudian, Salé, -Ubeidiya, Lantian, Ternifine, Turkana, -Bouri, Hexian, Yuenmou, Modjokerto, Olduvai, Sangiran, Trinil, Jaya, -Swartkrans, Ngandong.

Homo floresiensis

  • Discovery: Remains were found 15 years ago on the island of Flores, Indonesia.

  • Timeline: Existed as recently as 100,000 – 50,000 years ago, challenging previous assumptions about human evolution.

  • Characteristics:

    • Height: Extremely small, approximately 106 cm (for LB1).

    • Weight: Approximately 28 kg (for LB1).

    • Brain Size: Relatively small, about 426 cm^3 (for LB1), much smaller than Homo erectus (860 cm^3) and Homo habilis (614 cm^3).

    • Tool Use: Despite small brains, they made stone tools.

    • Dwarfism: May represent rapid dwarfism from a larger Homo erectus population due to island isolation.

  • Ongoing Discoveries: New types of early humans continue to be found, highlighting the dynamic nature of paleoanthropology.

Neanderthals and Other Archaic Homo sapiens

  • Transitional Stage: Seen as a transitional stage between Homo erectus and modern humans.

  • Diversity: There were several different kinds of archaic Homo sapiens.

  • Neanderthals (Homo neanderthalensis):

    • Time Period: Approximately 250,000 to 28,000 years ago.

    • Geographic Range: Primarily associated with Western Europe initially, but occupied a very large area including parts of Asia. Their northern presence correlates with glacial coverage during the last ice age.

  • Key Questions for the Lecture:

    1. Who were they, where did they live, what were their characteristics, and what tools did they use?

    2. Why did they disappear after being a successful species for over 200,000 years?

    3. Were there other types of humans living elsewhere concurrently?

    4. What special adaptive features did they possess?

    5. What are Bergman's and Allen's rules and their significance?

    6. What are the differences between the Replacement vs. Multiregional models of modern human origins?

Neanderthal Tools: The Mousterian Tool Industry

  • Complexity: Far more complex than the Acheulian tools of Homo erectus.

  • Characteristics: Greater variety of tools, utilizing smaller flake tools over larger core tools.

Neanderthal Physical Characteristics

  • Cranial Features:

    • Large Noses: Likely an adaptation for warming cold air.

    • Large Brow Ridge.

    • Large Occipital Bun.

    • Cranial Capacity: Averaged about 1,550 cc, slightly larger than modern humans on average.

  • Post-cranial Features:

    • Shorter and stockier build than modern humans.

    • Average male height: 5 feet 6 inches (167.6 cm).

    • Barrel-shaped chest.

    • Shorter limbs.

    • Larger areas for muscle attachments, indicating significant muscularity.

    • Thicker, more robust limb bones.

    • Overall Impression: Shorter, heavier, and more muscular than modern humans, with slightly "heavier" faces.

Neanderthal Culture and Lifestyle

  • Caring for Others:

    • Buried their dead, suggesting profound social organization and possibly a belief in an afterlife.

    • Cared for their elderly and injured, similar to Homo erectus. Evidence includes healed broken bones (e.g., Shanidar 1), implying community support during recovery.

  • Hard Life: Almost all Neanderthal remains show evidence of healed fractures and multiple injuries, a pattern compared to modern-day bull riders, indicating a physically demanding existence.

  • DNA Studies: Recent studies indicate some Neanderthals had red hair and pale skin, providing more detailed insights into their appearance. These studies are rapidly expanding our understanding beyond skeletal and tool evidence.

  • Language: Brain and bone studies indicate they possessed the brain capacity and the throat/mouth morphology necessary for speech.

Cold Adaptations: Bergman's and Allen's Rules

  • Context: Neanderthals flourished during the last ice age when Europe and Asia were covered by glaciers, suggesting they were a cold-adapted people.

  • Bergman's Rule:

    • Definition: Within a broadly distributed taxonomic clade, populations and species of larger size are found in colder regions, and those of smaller size are in warmer regions. Larger bodies have a smaller surface area to volume ratio, which helps conserve heat.

    • Examples: Applied to bears, foxes, and even penguins, showing larger body sizes in colder climates.

  • Allen's Rule:

    • Definition: Populations from colder climates usually have shorter limbs than populations from warmer climates. Shorter limbs (extremities like legs and ears) reduce the surface area exposed to cold, minimizing heat loss.

    • Examples: Illustrated with rabbits (northern arctic hare vs. southerly desert jackrabbit) and the absence of long-limbed animals like giraffes in cold regions.

  • Neanderthal Adaptation: The heavy body, short limbs, and large noses of Neanderthals are all features consistent with successful cold-weather adaptation, suggesting they were exceptionally well-suited to their environment, rather than being "primitive."

The Disappearance of Neanderthals and Other Early Humans

  • The Question: Why did such a successful species disappear by around 28,000 years ago?

  • Other Contemporaneous Humans:

    • Denisovans: Identified solely through DNA from a few teeth and bone fragments. This discovery confirmed the existence of other distinct human populations living simultaneously with Neanderthals and early modern humans.

    • Crowded World: In the last decade, it has become clear that multiple human species (at least Denisovans, Neanderthals, and Homo sapiens/AMH) inhabited different regions globally at the same time.

Models for Modern Human Origins

  • The Central Debate: Did modern humans replace other types of humans, or are we descendants of these early groups through continuous regional evolution and gene flow?

  • Replacement Model (Out of Africa Model):

    • Hypothesis: Proposes that anatomically modern humans (AMH) originated in a single region (Africa) and then migrated out, completely replacing populations of Homo erectus and archaic Homo sapiens in Asia and Europe, leading to their extinction.

  • Multiregional Model:

    • Hypothesis: Suggests that humans developed from Homo erectus in many different regions of the world. It proposes regional continuity and local selection pressures, with gene flow (due to occasional migrations) between populations maintaining a single species across these regions.

  • DNA Evidence:

    • DNA evidence largely supports the Replacement Model as the primary mode of modern human dispersal and replacement of other forms.

    • However, the Multiregional Model is partially true because DNA studies confirm some interbreeding and gene flow occurred between Anatomically Modern Humans (AMH) and other related human groups, such as Neanderthals and Denisovans.

Concluding Thought

  • The question "Am I a Neanderthal?" will be addressed in the next lecture, hinting at the shared genetic heritage with Neanderthals.

Key Terms for Archaic Homo sapiens (Extra Study Slide)

  • Homo sapiens neandertalensis: anatomy, regions, dates, tools, behavior.

  • Denisovans.

  • Cold adaptation.

  • Homo sapiens sapiens (200,000 - present B.P.): Anatomically modern humans (AMH).

  • The spread of AMH.

  • Multi-regional hypothesis.

  • Replacement model (Out of Africa II).

  • Bergman's rule: An ecogeographical principle stating that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder regions, and of smaller size are in warmer regions. (e.g., Lepus arcticus vs. L. alleni in terms of body size).

  • Allen's Rule: States that populations from colder climates usually have shorter extremities (legs & ears) and leaner bodies than populations from warmer climates. (e.g., progressive lengthening of extremities from northern arctic hare to southerly desert jackrabbit).