Harold J. Morowitz, professor of biology, and James Trefil, who teaches physics, both at George Mason University, have produced what I consider to be one of the seminal books on abortion that I have read. They examine the concepts of "life" and humanness. They point out that at the molecular level we are indistinguishable from plants and bacteria -- on a chemical level our cells function the same as brewer's yeast, a single cell organism; and we share a 98.5% genetic (DNA coding) with chimpanzees -- which are also "alive." Therefore, the important question one must ask is at what point the fetus or zygote acquires those characteristics that make us human, for no one would deny that we are indeed profoundly different from other forms of life. The point at which humanness is acquired (not personhood, which is a legal concept) becomes important to help distinguish between the rights of the mother and those of the fetus.
An enormous amount of change occurs from conception to birth, and the authors have examined the biological and scientific evidence to determine at what point this humanness is acquired. From a biologist's point of view, at conception, "two previously existing living things come together to form another living thing." Traditionally the anti-abortion advocates have argued that because the DNA genetic code exists at conception, that is when "life" begins. Morowitz and Trefil suggest that is like saying a building is complete when the blueprints are done. The combining creates the DNA blueprint, but dead tissue excised in a hospital has the same DNA blueprint, and cancerous tumors contain genetic uniqueness, yet no one would call them "life" worthy of preservation. Not to mention the fact that only about 1/3 of all conceptions lead to a successful birth -- nature performs abortions at a much higher rate than humans. (Research being done on parthenogenesis -- birth without conception -- indicates that unfertilized eggs can be stimulated to divide and begin the development of a complete adult: a Gloria Steinem fantasy come true.)
To make a long, but fascinating, story short, the authors propose that humanness begins at the moment when the cerebral cortex is formed and the synapses begin functioning. This is not a unique nor new position. The Jesuit scholar Teilhard de Chardin and the Catholic theologian Bernard Haring have both written that the cerebral cortex is the "center of all personal manifestations and activities." It is here that speech, conscious movement, visual information and sensory stimuli are all processed. The enlarged cerebral cortex is unique to humans, and it becomes a functioning entity sometime between 25 and 30 weeks of development. Coincidentally, that is also when electroencephalographic readings take place. (The absence of EEG readings is now widely used as a determination of death.) Teilhard de Chardin, who was a paleontologist, as well as a theologian, regarded the "development of an enlarged cerebral cortex as almost a second creation -- as a sign from God that humanity is, indeed, special, regardless of the fact that we share a common ancestry with all other life." Hence the authors recommend that in the conflict of rights, until the fetus achieves synapses in the cerebral cortex, at about 7 months, the woman shall choose and her rights must predominate. After 7 months, a loss of certainty occurs and one can no longer deny with certainty the humanity of the fetus, and its rights must be considered and protected.
This book will probably not solve the abortion dilemma, but it goes a long way toward providing a rational and scientific basis for evidence of what constitutes humanness and at what point we achieve that distinction. It should be required reading.