Earth and Life Class: Evolution Overview

Earth and Life Class: Introduction

• The class will cover the evolution of life on Earth.
• Topics will include the concept of life, its origins, and the diversification of living things.
• Students will learn about unifying themes in the study of life.
• The objectives include explaining the evolution of life based on evidence, describing unifying themes like structure/function, evolution, and ecosystems, and showcasing interactions among living things and their environment.

Unscrambling Letters

• The content likely involves a word puzzle/game to build engagement and recall important concepts.
• The words are: Cateuri, Sdooanptr, oogcely, Iateraobcnyc, Sooesphsitynth

Evolving Concept of Life Based on Emerging Pieces of Evidence

• Earth took nearly one billion years to cool enough for the first life forms to appear.
• Scientists have been studying living things for hundreds of years.
• This chapter explores how life originated, how species emerged and became extinct, and the present-day environment's development.
• Several theories exist about life’s origin. Some believe in divine intervention, while others suggest extraterrestrial origins.

The Primordial Soup Theory

• Proposed by Alexander Oparin and John Haldane
• Suggests life started in a primordial soup of organic molecules.
• Energy from lightning combined with atmospheric chemicals created the building blocks of proteins (amino acids).

Oparin-Haldane Hypothesis

• Suggests that a reducing atmosphere (lacking oxygen) and energy sources (lightning, UV light) could generate organic molecules.

Early Life Forms

• The oldest discovered fossils are in 3.5 billion-year-old rocks (ocean sediments).
• These ancient fossils are of bacteria.
• Bacteria were the only living things on Earth for 2 billion years.
• Traces of bacteria in rocks show their prehistoric existence.

Bacteria

• Two main types: Eubacteria (true bacteria) and Archaebacteria (ancient bacteria).
• Eubacteria are common, play roles in disease/decay.
• Archaebacteria are rare, thrive in harsh environments (salty lakes, hot springs).

Cyanobacteria

• Evolved from eubacteria around 3 billion years ago.
• Are photosynthetic, generating oxygen released into the oceans.
• These organisms' oxygen production changed Earth's atmosphere significantly.

Ozone Layer Formation

• Oxygen dispersed to the upper atmosphere, forming ozone.
• The ozone layer blocked harmful ultraviolet radiation allowing life to move onto land.
• Ozone is composed of three oxygen atoms (O3).

More Complex Life Forms

• Eukaryotes (more complex organisms) appeared in the fossil record.
• Eukaryotes were larger than prokaryotes (bacteria).
• Eukaryotic cells have a nucleus and more complex internal structures
• Eukaryotic cells evolved into multicellular organisms over 1.5 billion years.

Plants and Fungi

• First living things on land were plants and fungi.
• Mycorrhizae, the mutualistic partnership between plants and fungi, helped plants survive on land.
• Plants provide fungi with food; fungi provide plants with nutrients from organic matter.
• Fungi grow on or in plant roots, extending into rock and soil.

Arthropods

• Fossil records show plants covered Earth surface 80 million years after initial invasion
• The first animals to move to land: arthropods (hard body, jointed legs).
• First arthropods on land were scorpions (carnivorous, relatives of spiders, large pincers and stinger).

Scorpions

• First terrestrial animals .

Major Biological Events

• A timeline of key events in the evolution of life.

Insects

• Today, there are more than 200 million insects per person worldwide.
• More than 70% of discovered animal species are insects.
• Fossil records suggest insects were the first animals w/ wings.

More Complex Animals

• Worm-like animals with notochords (earliest animals) evolved.
• The notochord is present only during embryonic development, replaced by the vertebral column (backbone)
• Chordates, animals with notochords and vertebral columns, are called vertebrates

Early Vertebrates

• Early vertebrates were jawless fishes with bone skeletons.
• For over 100 million years, jawless fishes were the only vertebrate type.
• Today’s jawless fishes include eel-like parasitic lampreys, and scavenging hagfishes.
• 400 MYA, jawed fishes evolved, including sharks and bony fishes.

Amphibians, Reptiles, Dinosaurs

• Amphibians: First vertebrates on land. Evolved from bony fish 350 MYA.
• Reptiles: Evolved from amphibians around 300 MYA.
• Dinosaurs: Massive reptiles, arose around 220 MYA.

Birds, Mammals and Dinosaur Extinction

• Birds are descendants of small insect-eating dinosaurs.
• Birds, mammals and dinosaurs coexisted until the Cretaceous period 65 million years ago when dinosaurs suddenly went extinct.
• The extinction event caused birds and mammals to rapidly diversify to take advantage of the emptied ecological spaces.

Dinosaurs as Dominant Life Forms

• Dinosaurs were dominant life forms on Earth for over 150 million years

Unifying Themes in the Study of Life

• Demonstrates connections between living organisms and their interactions with each other and their environment

Levels of Organization (Biology)

• A hierarchical structure within cells, progressing from molecules to organelles, to cells.

Flow of Energy in Living Organisms

• Organisms use energy to survive, grow, and carry out functions.
• Almost all energy living things need originates from the Sun.
• Plants use photosynthesis to capture sunlight and create complex molecules - acting as a fuel source for animals.
• The flow of energy helps determine how organisms interact within their environment

Evolution

• Evolution describes how organisms change over time.
• Darwin’s theory of natural selection proposes how organisms with favorable characteristics survive and reproduce more effectively.
• Beneficial traits/characteristics are called adaptations.

Interacting Systems

• A significant aspect of biology showing how living things, and their environment depend on one another
• Includes symbiotic relationships (e.g., the way fungi helped plants transition to land).

Structure and Function in Biology

• Biological structures are directly related to their functions.
• For instance, the hummingbird's long tongue is crucial for accessing nectar from deep flowers.

Ecology

• A branch of Biology focusing on the relationships between living organisms and their environment.
• Organisms depend on each other and physical components (water; nutrients; gasses), for survival within their ecosystem.
• The oxygen-carbon cycle, for instance, is vital for all organisms.