Oh but isn't a sprout a plant?
(It is.)
I really can't believe you guys are still using this argument.
Comparing the development of plants and animals isn't logical.
Plants grow in a completely different way to animals.
For example, I can't clone an animal just by cutting it's leg off and sticking it in a pot of soil and rooting powder.
But I can with a plant.
Furthermore, plants don't have a complex nervous system at ANY point in their development.
Whereas the majority of animals DO have a complex nervous system at a point in their life. Usually this forms part-way through the development of the animal from an embryo.
In addition, plants don't rely on seperate organs for their ability to survive. Plants don't have lungs, or a heart, or a brain.
They don't have a complex circulatory system, nor do they need systems for blood filtration, or waste excrement.
Animals do have these things, and they don't develop until some time through their embryonic development.
I might be able to argue therefore that a sprout germinating from a seed IS a plant, because it contains all the parts required for independent life, such as photosynthetic cells, roots for drawing up nutrients, and Phloem/Xylem for transport of water, nutrients and glucose.
In that sense it's essentially indistinguishable from a full-grown plant.
But a zygote, embryo or foetus of an animal?
They don't have the organs, the structure, the circulatory systems, the (exo/endo)skeleton, the nervous system required to live until part-way through their own development.
Prior to that point where they have all these pieces that would let them survive, they barely resemble a new-born/adult version of themselves, or other animals. The only similarity is having the DNA of their animal species.
And I can argue that the spit, or dead skin cells or blood of an animal has that same DNA.
But there's no point where I would say a few cheek cells happen to be a Person. Those cells might be human, but that doesn't make them a person.
A person is a complete collection of all the Human biological structures that is capable of living of its own accord.
Aborting a zygote/embryo/foetus before this point isn't killing a person, because it wasn't a person, even if it IS human.
