Within the field of developmental psychology, the zygote is recognized as the earliest possible human life stage, initiating the prenatal period which lasts for two weeks. This singular cell with the genetic makeup of a human is created at conception, which occurs when the sperm and ovum unite.
This period is also called the germinal stage of prenatal development. Rapid cell division occurs and the cluster of cells begins the journey to the uterus for implantation. Despite the brief duration, this stage is a development cornerstone. Many pregnancies terminate naturally during this zygote stage, often before the woman discovers about a new pregnancy due to implant failure or abnormal chromosomes. Psychologists focus on this part of development as it is the first point of heredity/environment interaction.
While genetic inheritance determines possible traits, factors such as maternal health, nutrition, or toxin exposure begin shaping the traits. The zygote is important in the field of psychology to understand how primary biological processes build the foundation for cognitive, emotional, and behavioral development throughout the individual’s life.