When Is a Fetus a Human Being?

 Last month, The New York Times published a piece by Elizabeth Dias titled “When Does Life Begin?” My reaction to the essay was that it asked the wrong question. A fertilized egg is undoubtedly alive and it is most certainly human. In no way, however, is it a human or, if you prefer, a person.

Two weeks after “When Does Life Begin?” appeared, the newspaper offered a sampling of reader reactions to it. The most helpful reader comment, I thought, came from Richard Ambron, professor emeritus of cell biology at Vagelos College of Physicians and Surgeons of Columbia University.  He wrote:

When during gestation does an embryo become a human? This question has baffled philosophers and theologians largely because they do not understand the workings of the nervous system and the brain.

Two attributes are widely accepted as criteria to be considered human. First is an awareness through our senses that we exist and that we exist within a world of objects. Second is the ability of the brain to use the information from our senses to create ideas and make predictions about how to best survive in that world.

When during embryonic development do these activities emerge? The heartbeat becomes audible on a Doppler fetal monitor at about the 10th week of gestation, movements begin sometime after the 15th week, but the brain and most of the sensory systems develop later.

Each sensation requires the formation of millions of interconnecting neuronal circuits in the cerebral hemispheres that reach critical points of development between the 24th and the 28th week of gestation. Around that time, rhythmic brain waves resembling those of a newborn can be detected, indicating that neuronal circuits in the brain are highly integrated.

What this tells us is that a fetus cannot perceive most sensations, the first attribute of being human, until at least six months after fertilization. The ability to formulate ideas, the second attribute of humans, probably does not occur until after birth when the newborn’s brain begins to correlate all of the sensations into a coherent experience of its surroundings.

Thus, claiming that we become human at the moment of conception is merely a belief that argues against data from decades of research in embryology, neurology and developmental neuroscience.

Ambron implies that it is not a heart that makes us human—animals less complex than humans have beating hearts, but they are not human because of it. It is not unreasonable to assert that it is our working brains that make us human. Significantly, brain death is generally taken to mark the end of one’s life, with the ability to harvest organs for transplant being the only reason for being kept “alive.” Does it not make sense, therefore, to consider a developing fetus less than a human being prior to substantial brain development?

If one has to pick a point in fetal development beyond which abortion should be prohibited, Ambron offers facts that should be considered.