The human body is made up of more than 200 different types of specialised cells, most of which are dedicated to performing only one function. Stem cells, however, are unique, in that they have the ability to divide and multiply indefinitely, and can differentiate into almost any cell type. They thus have the potential to cure a great range of debilitating diseases, including Alzheimer's, Parkinson's disease, and most forms of Cancer. While stem cells occur at any age, they are neither as versatile nor abundant in the adult body as embryonic stem cells, which can only be obtained from fertilised human embryos. The embryos, which are usually about a week old, are destroyed in the process, and it is for this reason that stem cell research is considered highly controversial. .
As potentially groundbreaking as this research is, there are many who oppose it. The argument most often put forward is that embryos are people, and it is always morally wrong to kill people. But stem cells, and the embryos they come from, are not people. An "embryo- in this context is a group of about 100 cells, too small to see with the naked eye. It is not conscious. It has no capacity to feel pain. It does not think. It does not reason. It has no conceptual awareness. It does not feel emotion. It does not have a conscience. It has none of the defining qualities of a human being. Granted, it is technically a living thing. But if the very fact that this group of cells is technically alive makes it immoral to facilitate its death, then it should also be unethical to destroy plant life, eat meat, fight viruses and kill household pests. Insects have more awareness than human embryos in this stage of development. How many people do you hear advocating the right-to-life of a mosquito?.
Embryos have no awareness at all. They are not human, and to think of them as such, at the expense of the countless living, breathing, self-aware people dealing with terminal diseases that could potentially be cured, is frankly ridiculous.