Ecology, Human Impact, and Evolution: Key Concepts

Posted on Mar 17, 2025 in Geography

Ecology and Human Benefits

Ecology provides crucial information about the benefits of ecosystems and sustainable resource use for future generations.

  • Improves our environment by addressing poor water quality and pollution.
  • Helps manage natural resources, including endangered species protection and forest management.
  • Protects human health through processes like marshes and wetlands filtering toxins, and biomedical applications of plants and animals.

Human Activities and Ecosystem Impact

Human activities significantly impact ecosystem services:

  1. Use of natural resources (fish, timber, grazing land).
  2. Waste accumulation from used resources.
  3. Modification of ecosystems (deforestation, dams).

Ecological Footprint Trends

People in high-income nations have a larger ecological footprint due to higher consumption rates compared to low-income nations.

Threats of Human Population Growth

Overpopulation poses several threats to the Earth:

  • Resource depletion.
  • Emissions of greenhouse gases leading to climate change.
  • Water and atmospheric pollution.
  • Deforestation and loss of ecosystems (coral reefs).
  • Depletion of nonrenewable resources (fossil fuels, minerals, topsoil).
  • Loss of biodiversity.

Causes of Human Population Growth

Factors contributing to human population growth include:

  • Fertility rates.
  • Infant mortality rates.
  • Longevity.
  • Animal domestication and agriculture.
  • Industrial Revolution.
  • Growth of cities and infrastructure (water, energy, transportation).
  • Increased productivity, better nutrition, sanitation, and medicine.

Greenhouse Gas Emissions

Consumption habits are responsible for over 60% of global greenhouse gas emissions.

The Sixth Extinction

Humans are key players in causing the Sixth Extinction through:

  • Habitat loss.
  • Overexploitation (fishing, hunting).
  • Rapid climate change.
  • Altering ocean chemistry.
  • Changing the planet’s surface.
  • Overuse for recreation.

Phylogenetic Tree Factors

Hypothesized phylogenetic trees are based on genetic, physical, and behavioral factors.

Natural Selection Elements

Three elements necessary for natural selection:

  1. Heritable variation among individuals.
  2. Overproduction of offspring.
  3. Differential survival and reproduction.

Charles Darwin’s Predictions

Charles Darwin predicted that all species share a common ancestry and changes occur through natural selection.

DNA’s Role in Understanding the Past

DNA serves as a record of our past. Comparing DNA between humans and other organisms helps identify when species branched. Comparing living humans provides insights into more recent evolutionary history.

Transitional Forms and Fossil DNA

Yes, there are transitional forms of human ancestors. DNA cannot be extracted from all fossils.

Evolution and Allele Changes

Evolution is a result of changes in alleles, not individual organisms.

Sexual Selection

Sexual selection is a special case of natural selection. It does not always result in beneficial features. Example: lemming migrations.

Hominidae Family Characteristics

  • Ardipithecus: Oldest (6-7 mya), closest to primates, evolved in Africa, walked upright, small brains, spinal cord opening underneath skull.
  • Australopithecus: 3.85-2.5 MYA, walked upright, knees curved inwards, small brains, Lucy’s species.
  • Paranthropus: 2.7 MYA, skull adaptation for chewing, large jaw, varied diet.
  • Homo: Large brains, use tools and fire, expanded beyond Africa.