Development of the human body

Sperm fertilizing an egg
Stages in prenatal development
Approximate outline of development periods in child development.

Process of growth to maturity.

- Development of the human body

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Human embryonic development

Development and formation of the human embryo.

The initial stages of human embryonic development (embryogenesis)
8-cell embryo, at 3 days
Blastocyst with an inner cell mass and trophoblast.
Trophoblast differentiation
Histogenesis of the three germ layers
Artificially colored – gestational sac, yolk sac and embryo (measuring 3 mm at 5 weeks)
Embryo attached to placenta in amniotic cavity
Neural plate
Neural tube development
9 weeks old human embryo from an ectopic pregnancy
Development of brain in 8-week-old embryo
Movements of embryo at 9 weeks gestational age.
Representing different stages of embryogenesis
Early stage of the gastrulation process
Phase of the gastrulation process
Top of the form of the embryo
Establishment of embryo medium
Spinal cord at 5 weeks
Head and neck at 32 days

In biological terms, the development of the human body entails growth from a one-celled zygote to an adult human being.


Illustration of the Tanner scale for males.
Illustration of the Tanner scale for females.

Preadolescence is a stage of human development following early childhood and preceding adolescence.


A child playing in Warri, Nigeria
Children playing ball games, Roman artwork, 2nd century AD
Children playing the violin in a group recital, Ithaca, New York, 2011
Children in Madagascar, 2011
Child playing piano, 1984
Playing Children, by Song Dynasty Chinese artist Su Hanchen, c. 1150 AD.
The Age of Innocence c. 1785/8. Reynolds emphasized the natural grace of children in his paintings
Armenian scouts in 1918
Children play in the fountain in a summer evening, Davis, California.
Nepalese children playing with cats.
Harari girls in Ethiopia.
Ralph Hedley, The Tournament, 1898. It depicts poorer boys playing outdoors in a rural part of the Northeast of England
Children in front of a movie theatre, Toronto, 1920s.
Children in an outdoor classroom in Bié, Angola
Children seated in a Finnish classroom at the school of Torvinen in Sodankylä, Finland, in the 1920s
Group of breaker boys in Pittston, Pennsylvania, 1911. Child labor was widespread until the early 20th century. In the 21st century, child labor rates are highest in Africa.
World infant mortality rates in 2012.

A child (plural children) is a human being between the stages of birth and puberty, or between the developmental period of infancy and puberty.


Upper body of a teenage boy. The structure has changed to resemble an adult form.
Approximate outline of development periods in childhood and early adulthood development. Adolescence is marked in red at top right.
G. Stanley Hall
The Sisters, by James Collinson
Adolescent couple kissing
Japanese gyaru girls in Tokyo
Painting of an apprentice cobbler, 1877. Despite his youthful appearance, he has taken on adult roles – working for pay and smoking tobacco.
Portrait of a noble girl c. 1571
A sign outside a sex shop reads "Must Be 18 To Enter" in Chapel Hill, North Carolina.
Irish teenagers over 18 hanging around outside a bar. People under 18 are not allowed to drink outside the home; this is not strictly enforced in Ireland.
A girl looking at her smart phone
A young U.S. Marine in the Vietnam War, 1965

Adolescence is a transitional stage of physical and psychological development that generally occurs during the period from puberty to adulthood (typically corresponding to the age of majority).


Any member of a class of signaling molecules in multicellular organisms, that are transported by intricate biological processes to distant organs to regulate physiology and behavior.

Left: A hormone feedback loop in a female adult. (1) Follicle-Stimulating Hormone, (2) Luteinizing Hormone, (3) Progesterone, (4) Estradiol. Right: Auxin transport from leaves to roots in Arabidopsis thaliana
The left diagram shows a steroid (lipid) hormone (1) entering a cell and (2) binding to a receptor protein in the nucleus, causing (3) mRNA synthesis which is the first step of protein synthesis. The right side shows protein hormones (1) binding with receptors which (2) begins a transduction pathway. The transduction pathway ends (3) with transcription factors being activated in the nucleus, and protein synthesis beginning. In both diagrams, a is the hormone, b is the cell membrane, c is the cytoplasm, and d is the nucleus.
Blood glucose levels are maintained at a constant level in the body by a negative feedback mechanism. When the blood glucose level is too high, the pancreas secretes insulin and when the level is too low, the pancreas then secretes glucagon. The flat line shown represents the homeostatic set point. The sinusoidal line represents the blood glucose level.

In vertebrates, hormones are responsible for the regulation of many physiological processes and behavioral activities such as digestion, metabolism, respiration, sensory perception, sleep, excretion, lactation, stress induction, growth and development, movement, reproduction, and mood manipulation.


Humans (Homo sapiens) are the most abundant and widespread species of primate, characterized by bipedalism and large, complex brains.

Reconstruction of Lucy, the first Australopithecus afarensis skeleton found
Overview map of the peopling of the world by early human migration during the Upper Paleolithic, following to the Southern Dispersal paradigm.
Routes taken by barbarian invaders of the Roman Empire during the Migration Period
Humans and their domesticated animals represent 96% of all mammalian biomass on earth, whereas all wild mammals represent only 4%.
Basic anatomical features of female and male humans. These models have had body hair and male facial hair removed and head hair trimmed. The female model is wearing red nail polish on her toenails and a ring.
A graphical representation of the standard human karyotype, including both the male (XY) and female (XX) sex chromosomes.
A 10 mm human embryo at 5 weeks
Humans living in Bali, Indonesia, preparing a meal.
Changes in the number and order of genes (A-D) create genetic diversity within and between population
A Libyan, a Nubian, a Syrian, and an Egyptian, drawing by an unknown artist after a mural of the tomb of Seti I.
Drawing of the human brain, showing several important structures
Illustration of grief from Charles Darwin's 1872 book The Expression of the Emotions in Man and Animals.
Parents can display familial love for their children
The Deluge tablet of the Gilgamesh epic in Akkadian
The SCMaglev, the fastest train in the world clocking in at 375 mph as of 2015
Shango, the Orisha of fire, lightning, and thunder, in the Yoruba religion, depicted on horseback
The Dunhuang map, a star map showing the North Polar region. China circa 700.
Humans often live in family-based social structures.
The United Nations Headquarters in New York City, which houses one of the world's largest political organizations
The Silk Road (red) and spice trade routes (blue)

Human evolution is characterized by a number of morphological, developmental, physiological, and behavioral changes that have taken place since the split between the last common ancestor of humans and chimpanzees.

Precocious puberty

Puberty occurring at an unusually early age.

Precocious development in a child two years of age

In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development.

Early childhood

Sperm fertilizing an egg

Early childhood is a stage in human development.

Médecins Sans Frontières

International humanitarian medical non-governmental organisation (NGO) of French origin best known for its projects in conflict zones and in countries affected by endemic diseases.

MSF international headquarters in Geneva
A child with kwashiorkor during the Nigerian Civil War
Aerial photograph of a Mihanda, Zaire refugee camp in 1996. Pictured are 500+ tents set up in the Mitumba Mountains.
Countries where MSF had missions in 2015.
An MSF outpost in Darfur (2005)
A Médecins Sans Frontières staff member adjusts Dr. Joel Montgomery, Team Lead for CDC’s Ebola Response Team in Liberia, goggles before Dr. Montgomery enters the Ebola treatment unit (ETU), ELWA 3. MSF operates the ELWA 3 ETU, which opened on August 17.
MSF logistician in Nigeria showing plans
Doctors from MSF and the American CDC put on protective gear before entering an Ebola treatment ward in Liberia, August 2014
An MSF health worker examines a malnourished child in Ethiopia, July 2011
James Orbinski speaking about MSF in 2015.

Kwashiorkor, a form of calorie and protein deficiency, is a more serious type of malnutrition in young children, and can negatively affect physical and mental development.


This article concerns ontogeny in biology.

The initial stages of human embryogenesis
Parts of a human embryo
Process of zygote to gastrula in development
Blastula to gastrula more detailed
Germ layers and what tissues they become in humans
Ernst Haeckel, Anthropogenie.
Primary neurulation detailed
Acraea zetes caterpillar to pupae to butterfly metamorphosis by Nick Hobgood

In humans, adulthood is thought to be around 20 or 21 years old and is the longest stage of life, but in all species it ends with death.