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The history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species ...
Psychology. In psychology, the term early childhood is usually defined as the time period from birth until the age of five or six years, [1] therefore covering infancy, Pre-K, kindergarten and first grade. There are three simultaneous development stages: [2] It is distinct from early childhood education, and does not necessarily refer to the ...
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from matter that does not. It is defined descriptively by the capacity for homeostasis, organisation, metabolism, growth, adaptation, response to stimuli, and reproduction. All life over time eventually reaches a state of ...
Cryogenian ice age. Ediacaran biota. Cambrian explosion. Andean glaciation. Earliest tetrapods. Karoo ice age. Earliest apes humans. Quaternary ice age. The timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth.
Earliest known life forms. Evidence of possibly the oldest forms of life on Earth has been found in hydrothermal vent precipitates. [1] The earliest known life forms on Earth may be as old as 4.1 billion years old (or Ga) according to biologically fractionated graphite inside a single zircon grain in the Jack Hills range of Australia. [2]
Early childhood development. Early childhood development is the period of rapid physical, psychological and social growth and change that begins before birth and extends into early childhood. [1] While early childhood is not well defined, one source asserts that the early years begin in utero and last until 3 years of age.
In relation to biological organisms. Zygote, at the start of an organism's life. Embryo, early in an organism's life. Foetus, early in an animal's life, occurring before birth. Larva, an early stage in many animal life forms before maturity. Child, early human life.
Early Earth is loosely defined as encompassing Earth in its first one billion years, or gigayear (Ga, 10 9 y), [1] from its initial formation in the young Solar System at about 4.55 Ga to some time in the Archean eon in approximately 3.5 Ga. [2] On the geologic time scale, this comprises all of the Hadean eon, starting with the formation of the ...