Human Embryology: Science Politics versus Science Facts

Abstract

As a scientist, I have written and spoken about the topic of human embryology for many years, and I am continuously reminded of both the mystery surrounding human embryos and of the passionate feelings they evoke. The prenatal origin of human life has fascinated biologists, philosophers, and religious thinkers for a very long time.1 Yet in the modern age, thinking about the earliest stages of human life—and considering the value of life at its very beginning—has become entangled with some of the most emotionally compelling issues society and individuals face, including the bearing of children, the relief of human suffering, and the pursuit of scientific knowledge. For the vast majority of human history, prenatal development has been a profound mystery. A host of folklore, mythology, and religious beliefs have arisen surrounding the origin of human life, but until quite recently, we knew very little for certain beyond the basics that can be readily observed; that after a period of confinement lasting approximately nine months, a baby is brought forth from the mother’s womb with much effort and with considerable risk to both mother and child. Over the last several decades, science has begun to unravel the mysteries of human development. Yet despite these advances in our understanding, in many ways, the true nature of our embryonic origin remains shrouded in darkness, mystery, and controversy. One of the challenges we face in thinking about the human embryo is that embryonic development falls outside every-day human experience. Typically, we formulate our opinions about the world based on what we observe, what we feel about our observations, and what we conclude from these observational and emotional events. We develop an intuitive sense of what things are and how they fit into our lives based on our experiences with them over time. This kind of intuitive understanding allows us to overcome our immediate reactions in favor of what we know to be true overall—even when appearances might beg to differ. For example, many of us, quite understandably, react to human toddlers as members of an alien species. They are louder, messier, and consider-