Evolution is any change across successive generation
Generation , also known as procreation in biological sciences, is the act of producing offspring....

s in the heritable
The Heritability of a population is the proportion of observable differences between individuals that is due to genetic differences. Factors including genetics, environment and random chance can all contribute to the variation between individuals in their observable characteristics...

 characteristics of biological
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...

s. Evolutionary processes give rise to diversity at every level of biological organisation, including species
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

, individual organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...

s and molecules
Molecular evolution
Molecular evolution is in part a process of evolution at the scale of DNA, RNA, and proteins. Molecular evolution emerged as a scientific field in the 1960s as researchers from molecular biology, evolutionary biology and population genetics sought to understand recent discoveries on the structure...

 such as DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 and protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...


Life on Earth originated
Abiogenesis or biopoesis is the study of how biological life arises from inorganic matter through natural processes, and the method by which life on Earth arose...

 and then evolved from a universal common ancestor
Last universal ancestor
The last universal ancestor , also called the last universal common ancestor , or the cenancestor, is the most recent organism from which all organisms now living on Earth descend. Thus it is the most recent common ancestor of all current life on Earth...

 approximately 3.7 billion years ago. Repeated speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...

 and the divergence
Anagenesis, also known as "phyletic change," is the evolution of species involving an entire population rather than a branching event, as in cladogenesis. When enough mutations have occurred and become stable in a population so that it is significantly differentiated from an ancestral population,...

 of life can be traced through shared sets of biochemical and morphological traits, or by shared DNA sequences.

Anthropological, biological, and genetic evidence all put the origin of modern humans at between 200,000 and 100,000 years ago, probably in Africa. There is also much data that show an outburst of cultural behavior occurring around 50,000-40,000 years ago in Europe. That's when archaeologists date the oldest evidence of burial ceremonies, body ornaments, and cave paintings.

William J. Cromie, Facing up to Modern Man; Harvard Gazette

I find it hard to swallow that I have only ten times more genes than those lowly bacteria in my gut. I had always liked the fact that they have ten thousand times less DNA than I did - that felt about right - but a factor of ten was carrying democracy a bit too far.

Gottfried Schatz in "Jeff's view on science and scientists", Amsterdam, Elsevier Butterworth-Heinemann, 2006, ISBN 978-0-444-52133-0, ISBN 0-444-52133-X (pbk.), p. 22, "Me and My Genome"

The most preposterous notion that H. sapiens has ever dreamed up is that the Lord God of Creation, Shaper and Ruler of all the Universes, wants the saccharine adoration of His creatures, can be swayed by their prayers, and becomes petulant if He does not receive this flattery. Yet this absurd fantasy, without a shred of evidence to bolster it, pays all the expenses of the oldest, largest, and least productive industry in all history.

Robert A. Heinlein, Time Enough for Love (1973)

[A] curious aspect of the theory of evolution is that everybody thinks he understands it.

Jacques Monod (1910-1979) On the Molecular Theory of Evolution (1974) (French Biochemist, Nobel Prize Medicine 1965)

Orgel's Second Rule: Evolution is cleverer than you are.

Francis Crick (British molecular biologist, 1916- ) quoted by Daniel C. Dennett in Elbow Room (1984)

"Evolution is a tinkerer.

Francois Jacob (French biochemist 1920- )"Evolution and Tinkering" (1977). See "Bricolage|Bricolage"

A hen is only an egg's way of making another egg.

Samuel Butler Life and Habit (1877)