Cells may naturally proceed or be forced to transition to a state with a radically lower biological age, that is, be rejuvenated. Examples are the conversion of somatic cells to induced pluripotent stem cells and rejuvenation of the germline with each generation. We posit that these processes converge to the same ‘ground zero’, the mid-embryonic state characterized by the lowest biological age where both organismal life and aging begin. It may also be related to the phylotypic state. The ground zero model clarifies the relationship between aging, development, rejuvenation, and de-differentiation, which are distinct throughout life. By extending the rejuvenation phase during early embryogenesis and editing the genome, it may be possible to achieve the biological age at the ground zero lower than that achieved naturally. Conversion of somatic cells to induced pluripotent stem cells and reset of the germline age with each generation represent two examples of rejuvenation.We propose a model of ‘ground zero,’ the mid‐embryonic state characterized by the lowest biological age at which both organismal life and aging begin.We propose that the zygote–ground zero period is associated with rejuvenation, wherein the biological age is decreased, telomeres are extended, and molecular damage is cleared.Ground zero of aging and organismal life may be related to the phylotypic period in the evolutionary hourglass model.