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Evolution: The change in the genetic makeup of a population over time. This process is supported by scientific evidence from various disciplines.
Types of Evidence Supporting Evolution
Geographical Evidence:
Observation: Similarities in organisms between different latitudes and areas.
Example: Species that are geographically close to each other tend to have more similarities than those that are far apart, even if the environments are similar.
Geological Evidence:
Observation: The study of rock layers (stratigraphy) and volcanic activity provides insights into the history of life on Earth.
Example: Fossils found in lower rock layers are older than those in upper layers, providing a timeline of evolutionary changes.
Physical Evidence:
Observation: Physical traits and characteristics of organisms that indicate evolutionary relationships.
Biochemical Evidence:
Observation: Changes in DNA and amino acid sequences among organisms.
Example: Comparing DNA sequences to identify similarities and differences that indicate evolutionary relationships.
Mathematical Evidence:
Observation: Mathematical models and equations, like the Hardy-Weinberg equilibrium, help explain how allele frequencies in a population change over time.
Fossil Record:
Observation: Fossils are the preserved remains or traces of organisms that lived in the past.
Dating Fossils: Fossils can be dated using relative dating (comparing layers) and absolute dating (radiometric methods).
Significance: Fossils show that organisms from the past are not the same as those today, indicating evolutionary changes over time.
Structural Evidence
Homologous Structures:
Definition: Similar structures found in different species that indicate common ancestry.
Example: The bones in the forelimbs of humans, bats, whales, and birds have similar structures but different functions.
Analogous Structures:
Definition: Structures that have the same function but different underlying structures.
Example: Wings of insects, birds, and bats. These structures evolved independently to serve the same function (flying) but do not indicate a recent common ancestor.
Vestigial Structures:
Definition: Structures that have lost their original function through evolution.
Example: Human wisdom teeth and the appendix. These structures were functional in ancestral species but are no longer necessary.
Embryo Development:
Observation: Early stages of embryonic development are remarkably similar across different species.
Significance: Suggests that diverse species share a common ancestry because the early developmental stages are conserved.
Comparative Biochemistry:
Observation: Comparing DNA and protein sequences among different organisms.
Example: Organisms that share more DNA and protein sequence similarities are more closely related, indicating common ancestry.
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