The History of Life and Human Evolution

These flashcards cover key concepts related to the history of life and human evolution, highlighting major evolutionary events and mechanisms.

Great Oxidation Event

A significant increase in atmospheric oxygen caused by photosynthetic organisms like cyanobacteria around 2.5 billion years ago.

Eukaryotes

Complex cells with a nucleus, arising from more primitive forms of life following the rise of oxygen.

Cambrian Explosion

A period between 540 and 500 million years ago marked by the rapid appearance of most major animal phyla.

Mass Extinction

Events that significantly reduce Earth's biodiversity by wiping out a large percentage of species, with at least five such events in the last 500 million years.

Anaerobic

Organisms that do not require oxygen to survive; early life forms were mainly anaerobic.

Aerobic Respiration

A metabolic process that uses oxygen to convert stored food energy into a usable form, leading to greater energy production.

Common Ancestor

The most recent species from which two or more species have evolved; humans share a common ancestor with modern apes dating back about 7 million years.

Lactose Tolerance

The ability to digest lactose into adulthood, an adaptation that has developed in some human populations due to cultural practices.

Genetic Drift

The random fluctuation of allele frequencies in a population, which can impact genetic diversity, especially in small populations.

Epigenetic Modification

Changes in gene expression that do not involve alterations to the genetic code, potentially leading to rapid adaptations.

Prokaryotes

Single-celled organisms lacking a nucleus and other membrane-bound organelles, representing Earth's earliest life forms.

Natural Selection

A primary mechanism of evolution where individuals with advantageous traits in a specific environment are more likely to survive and reproduce, passing those traits to offspring.

Endosymbiotic Theory

The theory explaining the origin of eukaryotic cells from prokaryotic organisms, particularly the formation of mitochondria and chloroplasts through symbiotic engulfment.

Photosynthesis

The process used by plants, algae, and cyanobacteria to convert light energy into chemical energy, leading to the production of oxygen and a key factor in the Great Oxidation Event.

Great Oxidation Event

A significant increase in atmospheric oxygen caused by photosynthetic organisms like cyanobacteria around 2.5 billion years ago.

Eukaryotes

Complex cells with a nucleus, arising from more primitive forms of life following the rise of oxygen.

Cambrian Explosion

A period between 540 and 500 million years ago marked by the rapid appearance of most major animal phyla.

Mass Extinction

Events that significantly reduce Earth's biodiversity by wiping out a large percentage of species, with at least five such events in the last 500 million years.

Anaerobic

Organisms that do not require oxygen to survive; early life forms were mainly anaerobic.

Aerobic Respiration

A metabolic process that uses oxygen to convert stored food energy into a usable form, leading to greater energy production.

Common Ancestor

The most recent species from which two or more species have evolved; humans share a common ancestor with modern apes dating back about 7 million years.

Lactose Tolerance

The ability to digest lactose into adulthood, an adaptation that has developed in some human populations due to cultural practices.

Genetic Drift

The random fluctuation of allele frequencies in a population, which can impact genetic diversity, especially in small populations.

Epigenetic Modification

Changes in gene expression that do not involve alterations to the genetic code, potentially leading to rapid adaptations.

Prokaryotes

Single-celled organisms lacking a nucleus and other membrane-bound organelles, representing Earth's earliest life forms.

Natural Selection

A primary mechanism of evolution where individuals with advantageous traits in a specific environment are more likely to survive and reproduce, passing those traits to offspring.

Endosymbiotic Theory

The theory explaining the origin of eukaryotic cells from prokaryotic organisms, particularly the formation of mitochondria and chloroplasts through symbiotic engulfment.

Photosynthesis

The process used by plants, algae, and cyanobacteria to convert light energy into chemical energy, leading to the production of oxygen and a key factor in the Great Oxidation Event.

Mutation

A permanent alteration of the nucleotide sequence of an organism's genome, providing the raw material for evolution.

Gene Flow

The transfer of genetic material from one population to another, which can alter allele frequencies and introduce new genetic variation.

Multicellularity

The state of an organism consisting of more than one cell, allowing for cell specialization and the development of complex body plans.

Stromatolites

Layered accretionary structures formed in shallow water by the trapping, binding, and cementation of sedimentary grains by biofilms of microorganisms, notably cyanobacteria, contributing significantly to early atmospheric oxygen.

Adaptive Radiation

A process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.

Convergent Evolution

The independent evolution of similar features in species of different lineages, typically resulting from similar environmental pressures or natural selection.

Horizontal Gene Transfer

The non-sexual movement of genetic material between unicellular and/or multicellular organisms, particularly common among prokaryotes, playing a significant role in their evolution and adaptation.

Speciation

The evolutionary process by which new biological species arise, often due to reproductive isolation.

Homologous Structures

Similar anatomical structures found in different species that share a common ancestor, indicating divergent evolution although they may serve different functions.

Analogous Structures

Structures in different species that have similar functions but evolved independently, not from a common ancestor, illustrating convergent evolution.

Vestigial Structures

Anatomical features or behaviors that no longer serve a purpose in the current form of an organism but were functional in an ancestral organism.

Co-evolution

The process by which two or more species evolve in response to each other, often seen in predator-prey relationships, host-parasite interactions, or mutualistic relationships.