Opinion: Claims that biologists can determine and agree on the beginning of human life are false

First, Jacobs conducted a survey, meant to be representative of all Americans, by searching for potential participants on Amazon Mechanical Turk’s crowdsourcing marketplace and accepting the 2,979 respondents who agreed to participate. He found that most of these respondents trust biologists over others — including religious leaders, voters, philosophers and Supreme Court justices — to determine when human life begins.

Then it sent 62,469 biologists who could be identified from lists of professors and institutional researchers a separate survey, offering several options for when, biologically, human life might begin. He got 5,502 responses; 95% of these self-selected respondents said life began during fertilization, when a sperm and egg fuse together to form a single-celled zygote.

This result is not a proper method of investigation and has no statistical or scientific weight. It’s like asking 100 people about their favorite sport, finding out that only 37 football fans bothered to answer, and declaring that 100% of Americans love football.

In the end, only 70 of those more than 60,000 biologists supported Jacobs’ legal argument enough to sign the amicus brief, which is a complementary argument to the main case. This may be because there is neither scientific consensus on when human life actually begins nor agreement that this is a question biologists can answer using their science.

Several possible options

Scott Gilbert, Howard A. Schneiderman Professor Emeritus of Biology at Swarthmore College, is the author of the Standard Textbook of Developmental Biology. He identified up to five developmental stages which, from a biological point of view, are all plausible starting points for human life. Biology, as science now knows it, can distinguish these stages, but cannot determine at which of these stages life begins.

The first of these steps is fertilization in the egg duct, when a zygote is formed with the complete human genetic material. But almost every cell in everyone’s body contains that person’s complete DNA sequence. If genetic material alone makes a potential human being, then when we lose skin cells – as we do all the time – we separate potential human beings.

The plausible second stage is called gastrulation, which occurs about two weeks after fertilization. At this point, the embryo loses the ability to form identical twins – or triplets or more. The embryo thus becomes a biological individual but not necessarily a human individual.

The third possible stage is between 24 and 27 weeks of pregnancy, when the characteristic pattern of male-specific brain waves emerges in the brain of the fetus. The disappearance of this pattern is part of the legal norm of human death; by symmetry, perhaps its appearance could be seen as marking the beginning of human life.

The fourth possible step, which is the one approved in Roe v. Wade legalizing abortion in the United States, is viability, when a fetus generally becomes viable outside the womb with the help of available medical technology. With the technology we have today, this milestone is reached at around 24 weeks.

The last possibility is birth itself.

The general point is that biology does not determine when human life begins. This is a question that can only be answered by appealing to our values, by examining what we consider to be human.

Perhaps future biologists will learn more. Until then, when human life begins during fetal developments is a question for philosophers and theologians. And policies based on an answer to this question will remain with politicians – and judges.

This article is republished from The Conversation under a Creative Commons license. Read the original article here.

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