Biological Markers
One of the possible basic requirements for personhood is individuality, which entails differentiation between the person and its parents. Biology offers a number of stages in the life cycle that have been seen as candidates for personhood:
- fertilization, the fusing of the gametes to form a zygote
- implantation, the start of pregnancy, occurring about a week after fertilization
- segmentation, after twinning is no longer possible.
- when the heart begins to beat
- neuromaturation, when the central nervous system of fetus is neurobiologically "mature"
- "brain birth" concepts (compare with brain death):
- at the first appearance of brain waves in lower brain (brain stem) - 6-8 weeks of gestation (paralleling ′′whole brain death′′)
- at the first appearance of brain waves in higher brain (cerebral cortex) - 22-24 weeks of gestation (paralleling ′′higher brain death′′)
- "brain birth" concepts (compare with brain death):
- the time of fetal movement, or "quickening"
- when the fetus is first capable of feeling pain
- when it can be established that the fetus is capable of cognition, or neonatal perception
- fetal viability
- birth
- post-birth development stages
Read more about this topic: Beginning Of Human Personhood
Famous quotes containing the word biological:
“Although there is no universal agreement as to a definition of life, its biological manifestations are generally considered to be organization, metabolism, growth, irritability, adaptation, and reproduction.”
—The Columbia Encyclopedia, Fifth Edition, the first sentence of the article on “life” (based on wording in the First Edition, 1935)