Glossary
Analogous Structures
Structures in different species that have similar functions but evolved independently from different ancestral origins.
Example:
The wings of a bird and the wings of an insect both allow for flight but developed from entirely different evolutionary paths, making them analogous structures.
Biochemistry & Molecular Biology
The study of similarities in genetic code, DNA, and protein sequences among different organisms, supporting common ancestry.
Example:
The fact that humans and chimpanzees share over 98% of their DNA sequences is powerful evidence from biochemistry & molecular biology for their close evolutionary relationship.
Biogeography
The study of the geographical distribution of species, which reveals patterns that reflect their evolutionary history and dispersal.
Example:
The unique marsupial diversity found primarily in Australia is a classic case of biogeography supporting the idea that continents separated, isolating these lineages.
Common Ancestry
The principle that all living organisms are descended from a single, shared ancestral form over vast periods of time.
Example:
The universal genetic code shared by all life forms, from bacteria to humans, is strong evidence for common ancestry.
Comparative Anatomy & Physiology
The study of similarities and differences in the structures and functions of different species, indicating evolutionary relationships.
Example:
Comparing the bone structure of a bat's wing to a human arm, despite their different functions, is part of comparative anatomy & physiology that points to a shared ancestor.
Convergent Evolution
The process by which unrelated species independently evolve similar traits or adaptations due to similar environmental pressures.
Example:
The streamlined body shapes of sharks (fish) and dolphins (mammals) are a result of convergent evolution, as both adapted to efficient movement in water.
Evolution
The unifying concept in biology that explains the diversity of life and how organisms change over successive generations.
Example:
The gradual development of antibiotic resistance in bacteria over time is a clear example of evolution in action.
Fossil Evidence
Preserved remains or traces of organisms from the past, providing a historical record of life's gradual changes over geological time.
Example:
Discovering a series of horse fossils showing increasing size and fewer toes over millions of years provides strong fossil evidence for their evolutionary lineage.
Genetic Code
The set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins by living cells.
Example:
The fact that the codon 'AUG' codes for methionine in almost all organisms, from bacteria to humans, highlights the universality of the genetic code.
Homologous Structures
Structures in different species that are similar in underlying anatomy due to shared ancestry, even if they have different functions.
Example:
The similar bone arrangement in the forelimbs of a human, a cat, a whale, and a bat, despite their varied uses, exemplifies homologous structures.
Mathematical Modeling
The use of mathematical equations and simulations to understand patterns of genetic and phenotypic diversity within populations and across species.
Example:
Scientists use mathematical modeling to predict how quickly a new advantageous gene might spread through a population, illustrating evolutionary dynamics.
Paleomagnetism
A dating technique that uses the orientation of Earth's magnetic field, recorded in rocks, to establish their age.
Example:
Analyzing the magnetic signature locked into ancient volcanic rocks to align them with known shifts in Earth's magnetic poles is how paleomagnetism helps date geological events.
Radiometric Dating
A precise method for determining the absolute age of rocks and fossils by measuring the decay of radioactive isotopes within them.
Example:
Using carbon-14 to determine that an ancient wooden tool is 5,000 years old is an application of radiometric dating.
Stratigraphy
A method of dating fossils and rocks by analyzing the relative positions of rock layers, where older layers are typically found deeper.
Example:
Finding dinosaur fossils in a rock layer below a layer containing early mammal fossils uses stratigraphy to infer that dinosaurs lived before those mammals.
Tephrochronology
A dating method that involves matching and correlating volcanic ash layers (tephra) across different sites to build chronological sequences.
Example:
If two archaeological sites contain the same distinct layer of volcanic ash, tephrochronology allows scientists to infer they are roughly the same age.
Vestigial Structures
Structures in an organism that have lost most or all of their original function through evolution, serving as remnants of ancestral traits.
Example:
The tiny, non-functional hind leg bones found in whales are classic vestigial structures, indicating their land-dwelling mammalian ancestors.