Variations and Adaptations

This video reviews the functions of cell division in both single and multicellular organisms. In addition, it discusses the cell cycle, the phases of the cell cycle and the events in each phase.

One of the basic units of biological classification and a taxonomic rank

Paleolithic period or Old Stone Age, the earliest period of human development and the longest phase of mankind's history. It is approximately coextensive with the Pleistocene geologic epoch, beginning about 2 million years ago and ending in various places between 40,000 and 10,000 years ago, when it was succeeded by the Mesolithic period. By far the most outstanding feature of the Paleolithic period was the evolution of the human species from an apelike creature, or near human, to true Homo sapiens (see human evolution). This development was exceedingly slow and continued through the three successive divisions of the period, the Lower, Middle, and Upper Paleolithic. The most abundant remains of Paleolithic cultures are a variety of stone tools whose distinct characteristics provide the basis for a system of classification containing several toolmaking traditions or industries.

Natural selection is the gradual natural process by which biological traits become either more or less common in a population as a function of the effect of inherited traits on the differential reproductive success of organisms interacting with their environment. It is a key mechanism of evolution. The term "natural selection" was popularized by Charles Darwin who intended it to be compared with artificial selection, which is now called selective breeding.

This lesson will give an in depth explanation of Speciation. This lesson will look at the process of speciation and how species are created.