RE

chapter 5

Chapter 5: The Genus Homo and the Emergence of Us

Introduction

  • Focus on the Genus Homo: The rise of genus Homo has at least 8 different species in our lineage, with only H. sapiens surviving today.

  • Diversity and Complexity: The genus reflects a range of australopithecine and Homo characteristics, making classification challenging.

  • Paleoanthropological Insights: This section explores how paleoanthropologists define Homo and the key characteristics of the genus.

5.1 Defining the Genus Homo

Learning Objectives

  • Describe geological context of genus Homo.

  • Identify key differences between Homo and Australopithecus.

  • Understand reasons for classification challenges.

  • Explain encephalization's role in hominin development.

Key Archaeological Periods

  • Lower Paleolithic (3 million years ago - 300,000 BCE): Includes H. habilis (Oldowan tools) and H. ergaster (Acheulean tools).

  • Middle Paleolithic (300,000 - 40,000 BCE): Involves H. heidelbergensis and H. neanderthalensis using Acheulean and Mousterian tools.

  • Upper Paleolithic (43,000 - 26,000 BCE): Emergence of cave art, increased use of bone tools, and adaptations to environmental changes.

  • Neolithic Age (8,000 - 3,000 BCE): Transition to agriculture and permanent settlements by H. sapiens.

Classification Challenges

  • Bipedalism: Key trait shared with australopithecines, indicating evolutionary changes in anatomy.

  • Criteria for Classification: Specific criteria established by researchers include brain size, skull shape, tool use, and postcranial features. H. habilis as a case study:

    • Fossil Evidence: OH 7 specimen indicating physical and anatomical changes necessary for tool making. 661-700 cc brain size with evidence of Broca's area influencing speech development.

5.2 Tools and Brains: H. habilis, H. ergaster, H. erectus

Learning Objectives

  • Compare H. habilis, H. ergaster, and H. erectus anatomy and culture.

  • Understand the Oldowan and Acheulean industries.

  • Explore correlations between environment, diet, and brain growth.

The Toolmakers

  • Oldowan Tool Industry: Earliest known stone tool industry, unclear ownership between H. habilis and Paranthropus. Basic stone tools with crude design.

  • Handedness and Brain Development: Evidence of right-handedness in H. habilis indicates cognitive development and lateralized brain functions.

Homo ergaster

  • Physical Traits: Less sexual dimorphism compared to prior hominins; cranial capacity of 1,100 cc. Nariokotome Boy specimen illustrates modern characteristics with a height of approximately 5’10”.

  • Acheulean Tools: Emergence of bifacial hand axes representing cognitive complexity.

5.3 The Emergence of Us: The Archaic Homo

Learning Objectives

  • Understand anatomical characteristics of archaic Homo.

  • Discuss environmental conditions and their evolutionary impacts.

  • Compare hypotheses on Neanderthal extinction.

Defining the Archaic Homo

  • Early vs. Late Archaic Hominins: Distinguished by cranial capacity, skull features, and social behaviors.

  • Homo heidelbergensis: Represents a mosaic of traits between H. erectus and H. sapiens, significant for tool-making, possibly including controlled fire use.

Neanderthal Insights

  • Larger cranial capacity (1,520 cc) with unique adaptations, potential for complex social structures, and symbolic thought.

  • Practices may include compassion-based behaviors and systematic burial rites based on archaeological findings.

5.4 Tracking Genomes: Our Human Story Unfolds

Learning Objectives

  • Explain mtDNA relations to early human migrations.

  • Investigate coevolution of lice and human evolution.

  • Understand origins of human variation.

Mitochondrial Eve & Human Migration

  • The Out of Africa Model supports that modern humans began migrating from Africa, indicating genetic lineage tracing back to early humans in southern Africa.

  • Coevolution of Lice: Lice evolution informs on human adaptation regarding clothing use and hair loss, linked to environmental adaptation and disease resistance.

Human Variation and Evolution

  • Modern variability arises from genetic and environmental factors, influenced by agriculture and natural selection, exemplified through skin pigmentation adaptation and altitude acclimatization in diverse indigenous groups.