Animal Domestication

Animal Domestication - ANBI 110

Learning Objectives

  • Define domestication and differentiate it from taming.

  • Describe the three pathways of domestication.

  • Identify traits that make species suitable for domestication.

  • Explain where, when, and why domestication occurred.

  • Describe biological and genetic changes associated with domestication.

  • Recognize key domesticated livestock and companion animal examples.

What Is Domestication

  • Two definitions:

    1. The process of taming an animal and keeping it as a pet or on a farm.

    2. The cultivation of a plant for food.

  • Focus of this class is on animal domestication, although many plants have also undergone domestication processes.

  • Domestication not only changes behavior but also modifies genetic expression of certain traits, as well as physical appearance.

Distinction between Taming and Domestication

  • Taming: Altering an individual animal’s behavior to reduce fear of humans.

  • Domestication: A long-term relationship between humans and animals resulting in altered genetics, often for human benefit. It is crucial to know the difference between these terms.

Historical Context of Domestication

  • Domestication has changed the course of history.

    • It wasn't entirely intentional; it did not involve foresight & evolution.

    • Resulted in advancements in technology, improved biology, and diversified culture.

Three Pathways of Domestication

  • Three recognized pathways for domestication:

    1. Commensal Pathway

    2. Prey Pathway

    3. Directed Pathway

  • These pathways indicate that not all animals followed the same domestication trajectory and some species transitioned from one pathway to another.

  • It is essential to note that these pathways are not rigid or set in stone; there is variability.

Commensal Pathway

  • In this pathway, wild animals voluntarily habituate to human environments to exploit waste or disturbed habitats, eventually forming a mutualistic relationship.

    • Key Concepts:

    • Habituation: Process where animals adapt to human presence.

    • Commensalism: A symbiotic relationship that benefits one party (the animal) without harming the other (the human).

    • Partnership: A mutual relationship forming where both parties gain benefits.

    • Initial desire for food initiates the process, with humans harnessing the potential of less fearful animals, improving safety for both parties.

Prey Pathway

  • Marks the transition from actively hunting wild animals to managing herds for harvesting resources like meat or milk.

    • Key Concepts:

    • Active Hunting: The practice of pursuing game.

    • Game Management: Managing wild animal populations for resource harvesting.

    • Taming/Corralling: Containing animals for further harvesting and breeding.

    • Active Breeding: Cultivating animals from the population in the wild to constrain them for human benefit.

Directed Pathway

  • Involves active human intervention to tame free-living species for specialized purposes (e.g., transport, riding).

    • This pathway can occur more quickly compared to others but may result in significant genetic diversity loss (bottleneck effect).

Early Domestication Events and Centers

  • Key centers of origin for food production include:

    • Eastern US

    • Mesoamerica

    • West Africa

    • Andes and Amazonia

    • Sahel

    • Fertile Crescent

    • China

    • New Guinea

    • Ethiopia

Domestication Details and Timeline

  • The Fertile Crescent is crucial for understanding domestication.

    • Domestication regions indicate where specific species (pigs, cattle, sheep, goats) were first domesticated around 12,000 years ago.

    • Events here sparked subsequent domestications of other animals, influenced by climate, population density, and water accessibility.

Domestication Syndrome

  • Domestication syndrome: A set of correlated physical and behavioral traits found in domesticated animals compared to their wild ancestors.

    • Examples:

    • Increased tameness

    • Floppy ears

    • Varied coat colors

    • Shorter snouts

    • Smaller brains

    • Extended reproductive cycles

    • These traits stem from selective pressure for reduced aggression and juvenile-like behaviors (neoteny).

Case Study – Dog (Commensal)

  • Dogs are recognized as the first domesticated animals, with domestication occurring between 15,000-36,000 years ago.

  • Multiple recorded sites of dog domestication exist globally.

    • Habituation involved wolves with lower fear thresholds becoming accustomed to human habitats.

    • The relationship evolved from commensalism to partnership, allowing both groups to derive mutual benefits leading to harmonious coexistence but still retaining some fear and aggression traits.

Case Study – Sheep and Goats (Prey)

  • Sheep were domesticated approximately 11,000 years ago and goats around 10,500 years ago, primarily in the Fertile Crescent.

  • Today, many sheep and goat breeds exist, specifically bred for various agricultural products:

    • Meat

    • Milk

    • Wool

Case Study – Horse (Directed)

  • Horses were domesticated roughly 5,500 years ago in Central Asia.

  • Their wild ancestors were captured and selectively bred for specific temperaments and traits, supporting their utilization in transport and work.

Biological and Genetic Consequences of Domestication

  • Morphological changes include:

    • Floppy ears

    • Varied coat colors

    • Shorter faces

  • Behavioral changes encompass:

    • Increased sociability

    • Reduced fear responses

    • Neotenous traits

  • Genetic changes involve:

    • Selective sweeps

    • Reduced diversity in specific species

  • These changes have links to modern livestock breeding and production traits.

Obstacles to Domestication

  • Six primary obstacles to domestication identified by Diamond (2002):

    1. Diets not easily supplied by humans (e.g., anteaters).

    2. Slow growth rates and long birth spacing (e.g., elephants).

    3. Aggressive dispositions (e.g., grizzly bears, rhinoceroses).

    4. Reluctance to breed in captivity (e.g., pandas, cheetahs).

    5. Lack of hierarchical dominance (e.g., bighorn sheep, antelope).

    6. Tendency to panic in enclosures (e.g., gazelles).

  • Many species may pass some tests but fail others, hence not domesticated.

Impacts on Human Societies and Economy

  1. Division of Labour:

    • Animal assistance in farming allowed diversification of jobs beyond hunting/food gathering.

  2. Social Stratification:

    • Domestication influenced wealth and social status, leading to collectable resources and land ownership.

  3. Transportation:

    • With the aid of horse/ox power, farming expanded, travel increased, and warfare capabilities grew.

  4. Technological Advancement:

    • Sedentary lifestyles fostered the development of tools and machinery unnecessary for nomadic life.

Impacts on Biology and Environment

  1. Urbanization:

    • Development of cities and villages, transitioning from nomadic cultures.

  2. Landscape Transformation:

    • Land clearing for agriculture and human habitation.

  3. Emergence of Zoonotic Diseases:

    • Close human-animal contact led to new pathogens and disease transfer opportunities.

  4. Dietary Changes:

    • Settlements focused on specific crops and domesticated animals, establishing stable but less diverse food supplies.

Take Home Points

  • Domestication is an evolutionary process shaped by human intervention.

  • Three pathways explain how different species entered domestication.

  • Domestication has lasting genetic, behavioral, and societal impacts.