Human development is the process of growing to maturity. In biological terms, this entails growth from a one-celled zygote A zygote , or zygocyte, is the initial cell formed when a new organism is produced by means of sexual reproduction. A zygote is synthesized from the union of two gametes, and constitutes the first stage in a unique organism's development. Zygotes are usually produced by a fertilization event between two haploid cells — an ovum from a female and to an adult human being Humans are bipedal primates belonging to the species Homo sapiens in Hominidae, the great ape family. They are the only surviving members of the genus Homo. Humans have a highly developed brain, capable of abstract reasoning, language, introspection, and problem solving. This mental capability, combined with an erect body carriage that frees the.

Contents 1 Biological development 1.1 Physical stages of human life 1.2 Physical development milestones 2 See also 3 Footnotes

Biological development

Sperm fertilizing an egg

Development begins with fertilization Fertilization , is the fusion of gametes to produce a new organism. In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilisation, or outside in the case of external fertilisation, the process by which the male gamete A gamete is a cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete—called an ovum (or egg)—and a, the sperm cell, and the female gamete, the egg In most birds, reptiles, insects, and fish, an egg is the zygote, resulting