Origin of Earth and Evolution of Life

This theory states that the universe began from a single point of extreme density and heat, rapidly expanding outwards.

This theory explains how stars and planets form from large, diffuse clouds of dust and gas known as nebulae.

This process involves the clumping of smaller particles into larger masses, gradually forming planets from the dust and debris around a young star.

The early Earth's atmosphere was primarily composed of hydrogen, helium, methane, ammonia, carbon dioxide, and water vapor.

The process of gases trapped within the Earth being released to the surface through volcanic vents.

These are fossilized microbial mats consisting of layers of filamentous prokaryotes and trapped sediments. They provide evidence of ancient microbial life and the evolution of photosynthesis.

This theory proposes that life originated spontaneously from lifeless matter. The process is believed to have occurred under the harsh conditions of early Earth.

This theory states that life on Earth originated from spores or seeds from outer space. These spores or seeds are believed to have been carried to Earth by meteorites or asteroids.

This theory proposes that all living organisms arise from pre-existing life. This principle refutes spontaneous generation and is a cornerstone of modern biology.

The process involving the formation of diverse organic molecules from inorganic constituents. This is crucial to understanding how life arose from non-living matter.

These are lipoprotein vesicles capable of growth by absorption and reproduction by budding. They were a significant step towards the formation of the first living cells.

The stage of evolution where RNA served as both a genetic material and a catalyst. This was a key period in the evolution of life on Earth.

A process by which a primitive eukaryote engulfed a bacterium, leading to the formation of mitochondria. This symbiosis was crucial for the evolution of eukaryotes.

A process by which a primitive eukaryote engulfed a cyanobacterium, resulting in the formation of chloroplasts. This symbiosis gave rise to photosynthetic eukaryotes.

This theory proposed that all living organisms are related and have descended from a common ancestor. The primary mechanism of evolution proposed was the inheritance of acquired characters.

This theory emphasized natural selection as the main driver of evolution. Organisms with favorable traits are more likely to survive and reproduce, passing on their advantageous traits to their offspring.

These are sudden, inheritable changes in an organism's genetic material. Unlike Darwinian gradualism, mutations can lead to large, abrupt changes in traits.

This principle describes a theoretical population that is not undergoing any evolutionary change. It is based on five basic conditions: no mutations, random mating, no gene flow, a large population size, and no natural selection.

Movement of alleles from one population to another due to interbreeding. Gene flow can introduce new alleles into a population and change its genetic makeup.

Random changes in allele frequencies in a population, especially prominent in small populations. It can lead to the loss of some alleles and the fixation of others.

The geological time scale divides the history of the Earth into eras, periods, and epochs. The entire interval of visible life on Earth is known as the Phanerozoic eon.

These are periods of time when exceptionally large numbers of species become extinct, often due to catastrophic events or major environmental changes.

A period when numerous species became extinct, possibly due to a drop in sea levels followed by rising sea levels. This event occurred about 439 million years ago.

A mass extinction event that took place about 251 million years ago. This event was the most devastating in Earth's history, with approximately 95% of all species becoming extinct.

This extinction event occurred about 65 million years ago, resulting in the extinction of the dinosaurs. Scientists believe an asteroid impact may have been the primary cause.

Often described as the sixth mass extinction, this ongoing event is driven by human activities, such as habitat destruction, pollution, and climate change. It is causing the rapid decline of biodiversity.

These are mammals characterized by traits adapted for life in trees, such as limber shoulder joints, dexterous hands, and sensitive fingers with nails.

These are the first to diverge from the primitive primate lineage. They are mostly nocturnal and include lemurs, lorises, and tarsiers.

These include all primates except prosimians. They are characterized by larger brains, a more complex social behavior, and a greater reliance on sight than smell. They also have a more refined opposable thumb.

These are a group of primates that includes humans and their direct ancestors. They are characterized by bipedalism, larger brains, and more complex social structures.

This refers to the ability to walk upright on two legs. It is a key characteristic that distinguishes hominids from other primates.