The news is often flooded with tragic stories of human beings being killed — from shootings to terrorist attacks — and there is an almost universal consensus that to kill innocent people is wrong.
However, is it the victims’ ages that makes the attacks wrong, or is it their humanity?
Clearly, whether a person is 50 years old, 18, or two is not what makes killing wrong. What matters is that the victim is human. Identifying the moment an individual person’s life begins also pinpoints when her human rights begin.
Science teaches us that a new human being begins at the moment of sperm-egg fusion, otherwise known as fertilization. Sperm and egg, by themselves, only contain half the genetic material needed to form a human being. When these cells fuse, however, a new individual who is genetically distinct from both parents comes into existence. There is a wealth of testimony from medical texts which backs this up. 
Consider those who create life: whether a human being is created inside a lab via in vitro fertilization, or whether someone breeds horses on a farm, a female’s egg fertilized by the male’s sperm is required to create offspring. Once fertilization occurs, a new organism of the same species as its parents is formed.
Since life begins at fertilization, an individual grows and develops between the moment of fertilization throughout adulthood. For example, prior to birth, a human being’s reproductive organs develop (in fact, female preborn children have early reproductive cells in their ovaries by 9 weeks post fertilization, or 11 weeks from a pregnant woman’s last menstrual period ). After birth, the person’s reproductive organs continue to develop. Although the individual is less developed at birth compared to adulthood, development does not determine a person’s humanity.
Consider for a moment, if life doesn’t begin at fertilization. The following are the alternatives:
- Implantation — but that’s just a change in location from fallopian tube to uterus.
- Heartbeat or brainwaves — but those are just developmental milestones.
- Pain sensation —but that’s another stage in development (which might never occur, such as for those with congenital insensitivity to pain ).
- Consciousness — but that’s also a stage of development which can even change after birth (while sleeping, being in a coma, or under anesthetic).
- Birth — but that’s just a change in location.
“But what about the hard cases?” some might ask. “What about rape, or if the woman’s life is in danger, or if there’s a poor prenatal diagnosis? Wouldn’t these be good exceptions that justify abortion?”