Evolution Evidence
The theory of evolution explains how species change over time, with body structures providing clues about their ancestry. Some structures were modified to perform new functions, while others became less useful over time.
Certain body parts, called homologous structures, look alike because they come from a common ancestor, even if they now serve different functions.
For example, the limbs of mammals like bats, lions, and whales have similar bone structures despite being adapted for flying, running, or swimming.
This suggests they evolved from a common ancestor with a comparable limb structure.
On the other hand, some body parts lose their original purpose over time but remain. These are called vestigial structures and provide further evidence of evolution.
For example, ostriches have wings but do not fly. Similarly, whales have pelvic bones, indicating that their ancestors once had legs and walked on land before adapting to life in the ocean.
Likewise, penguin wings, now used as flippers for swimming, suggest that their ancestors likely used them for flying.
Evolution Evidence
How do we know that species change over time? Scientists use many types of evidence of evolution to show how living things have adapted and evolved. This evidence comes from fossils, anatomy, embryos, molecular data (DNA and proteins), and observing how species adapt today. For example, fossils show how ancient creatures are connected to modern animals, while similarities in bones or DNA reveal common ancestors.
All these clues help scientists piece together the story of life on Earth, showing that evolution is a gradual process that explains the diversity of species we see today.
Science and Engineering Practices (SEP): Analyzing and Interpreting Data
Scientists collect and compare data from fossils, body structures, embryos, and DNA to find patterns that reveal evolutionary relationships. You can explore this by comparing skeletons, looking at fossils, or analyzing similarities between species to explain how evolution might connect them.
Activity Ideas:
- Fossil Record Puzzle – Arrange fossil images chronologically to show how a species evolved, highlighting key structural changes.
- Homologous Structures Match Up – Compare images of bones from different animals (like human arms, whale fins, and bat wings) and identify similarities that suggest a common ancestor.
- Embryo Comparison Chart – Examine pictures of embryos from different species and note how they look alike in early stages, providing evidence of shared ancestry.
- DNA Code Comparison – Use simplified DNA sequences to compare "species" and determine which ones are most closely related based on genetic similarities.
Crosscutting Concept (CCC): Scale, Proportion, and Quantity
Exploring evolution requires thinking across different scales from tiny DNA changes to large fossil discoveries, and over long periods. Small genetic mutations (on a molecular scale) can lead to big changes in a species when viewed over millions of years.
- Scale: Tiny changes in DNA can eventually result in noticeable differences in body structure or function.
- Proportion: Some features, like slight changes in beak size, may seem small but significantly impact survival.
- Quantity: The fossil record contains millions of specimens, showing gradual changes across vast timescales.
By understanding how small changes add up over time and across different scales, you can see how evolution shapes life, from microscopic genes to giant dinosaurs!
The theory of evolution explains how species change over time, with body structures providing clues about their ancestry. Some structures were modified to perform new functions, while others became less useful over time.
Certain body parts, called homologous structures, look alike because they come from a common ancestor, even if they now serve different functions.
For example, the limbs of mammals like bats, lions, and whales have similar bone structures despite being adapted for flying, running, or swimming.
This suggests they evolved from a common ancestor with a comparable limb structure.
On the other hand, some body parts lose their original purpose over time but remain. These are called vestigial structures and provide further evidence of evolution.
For example, ostriches have wings but do not fly. Similarly, whales have pelvic bones, indicating that their ancestors once had legs and walked on land before adapting to life in the ocean.
Likewise, penguin wings, now used as flippers for swimming, suggest that their ancestors likely used them for flying.
The theory of evolution explains how species change over time, with body structures providing clues about their ancestry. Some structures were modified to perform new functions, while others became less useful over time.
Certain body parts, called homologous structures, look alike because they come from a common ancestor, even if they now serve different functions.
For example, the limbs of mammals like bats, lions, and whales have similar bone structures despite being adapted for flying, running, or swimming.
This suggests they evolved from a common ancestor with a comparable limb structure.
On the other hand, some body parts lose their original purpose over time but remain. These are called vestigial structures and provide further evidence of evolution.
For example, ostriches have wings but do not fly. Similarly, whales have pelvic bones, indicating that their ancestors once had legs and walked on land before adapting to life in the ocean.
Likewise, penguin wings, now used as flippers for swimming, suggest that their ancestors likely used them for flying.
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