Beginning of Life Flashcards
Organism creation
Entity undergoes biological change, and becomes a new substance(an organism)
Development
Organism undergoes biological change, but stays the same. Start of development = beginning of life.
Carnegie stages
Lists stages of development across organisms. Applicable to human beings. Starts at fertilization.
When does science say life begins?
Fertilization. Developmental biology textbooks are unanimous, Carnegie stages agree.
Why does science say life begins at fertilization?
No explanation, or new chromosome composition.
Why is chromosome constitution insufficient?
DNA mutations alter genetic code w/o creating a new organism. Hydatidiform moles aren’t human organisms, but do have complete chromosomal composition. Twins have the same DNA.
Why is fertilization unspecific?
Fertilization is a 12h process, multiple events could indicate the beginning of a human being.
Standard cases
cases of common and typical development. Normal development, multiple species.
Normal development explanation requirement
when in in the process of fertilization does life begin?
Multiple species explanation requirement
A good definition should be applicable across multiple species. Implantaion-based criteria doesn’t apply to organisms w/o a womb. Birth-based definitions don’t apply to organisms that aren’t born.
Unusual cases
developmental anomalies, identical DNA offspring
