The History of Life on Earth

1) What is the current theory of how life arose?

1. small molecules were synthesized
2. these small molecules joined into macromolecules, such as proteins and nucleic acids
3. all these molecules were packaged into protobionts, membrane containing droplets, whose internal chemistry differed from that of the external environment
4. self-replicating molecules emerged that made inheritance possible

2) When was Earth formed (about)?

Earth was formed about 4.6 billion years ago, and life on Earth emerged 3.8 to 3.9 billion years ago.

3) What are stromatolites?

Layered rocks that form when certain prokaryotes bind think films of sediment together.

Facts:

- Amino acids polymerize when added to hot sand, clay or rock.

- The fossil record is largely based on fossils found in sedimentary rocks.

- The absolute ages of fossils can be estimated by radiometric dating and other methods.

- Continental plates move gradually over time, altering the physical geography and climate on Earth.

- Evolutionary trends result from interactions between organisms and their current environments.

Summary:

Earth formed about 4.6 billion years ago, along with the rest of the solar system. Earth’s early atmosphere likely contained water vapor and chemicals released by volcanic eruptions (nitrogen, nitrogen oxides, carbon dioxide, methane, ammonia, hydrogen, hydrogen sulfide).Protobionts exhibit simple reproduction and metabolism and maintain an internal chemical environment. Thegeologic record is divided into the Archaean, theProterozoic, and the Phanerozoic eons. The oldest known fossils of multicellular eukaryotes are of small algae that lived about 1.2 billion years ago. first plants were terrestrial, so oxygen atmosphere must develop to produce protective ozone layer. Continental Drift.

At three points in time, the land masses of Earth have formed a supercontinent: 1.1 billion, 600 million, and 250 million years ago. Mammals underwent an adaptive radiation after the extinction of terrestrial dinosaurs. The Hawaiian Islands are one of the world’s great showcases of adaptive radiation.

Extra:

mass extinctions video