A biologist explains why ‘heartbeat laws’ are nonsensical

A scientist is working in her lab, quietly culturing heart cells. She puts Petri dishes full of them into an incubator to grow. A few days later, she takes them out and inspects them under a microscope to see if they have multiplied as she wanted. 

As she innocently adjusts her scope, she sees—they are beating. What’s more, when she puts two of them near each other, they beat together! When she moves all of them together, they still beat together, in one great throbbing mass!  “IT’S ALIIIIVE!” she shrieks.

That scientist would be me. I didn’t really shriek, “It’s alive!” But I did see individual heart cells beating, cells that I had cultured, beating with no brain, nerves, organism, or even heart around them. They just contracted rhythmically—that is to say, they beat—all by themselves. 

Because that’s what heart cells do. 

Biologists sometimes have weird jobs. One summer, I worked in a lab that looked at how embryonic heart cells take up various chemicals. One of my jobs was to culture the heart cells— that is to say, grow them. I dissected embryonic chickens, took out the hearts, dissolved the connective tissue between the cells, and spread the cells out in Petri dishes along with the food and fluids they would need to be happy. Then I put them into incubators, hoping they would multiply.

After a few days, I took them out and checked them under a microscope to see if they were multiplying. And sometimes, when I looked at them, they were beating. The individual heart cells kind of looked like they were twinkling, with their little, individual contractions.

As for putting them together to see if they beat together, I didn’t actually do that. But other scientists have done so, and that’s exactly what they found: when cardiac muscle cells are placed together, they will beat together. It’s so well established that it’s common knowledge, written into textbooks. We know that they do it, and we know why they do it. Here’s a paragraph about this from the textbook Anatomy and Physiology:

If embryonic heart cells are separated into a Petri dish and kept alive, each is capable of generating its own electrical impulse followed by contraction.

It goes on to say:

When two independently beating embryonic cardiac muscle cells are placed together, the cell with the higher inherent rate sets the pace, and the impulse spreads from the faster to the slower cell to trigger a contraction.

In short, it is not mysterious, it is not magic. It’s biology doing what biology has evolved to do.

The anti-abortion movement’s cynical “heartbeat laws” are all manipulation, no science

There are many so-called “heartbeat laws” on the books in the United States at this time, laws that outlaw abortion after an embryonic “heartbeat” has been detected. Many others have been proposed. The most egregious current example is the law in Texas that states that a woman may not get an abortion after she has been pregnant for six weeks. Specifically, it bans abortion after cardiac activity is detectable. Other states are following suit as of this writing.

To most people, “cardiac activity” and “heartbeat” sound synonymous, and this mistaken assumption has been exploited by those who wish to deny women their right to an abortion. 

The assumption may be easy to make, but it is glaringly incorrect, as is illustrated by the narrative that began this article. It’s simple: heart cells beat all by themselves, entirely on their own. If an individual heart cell is alive, it contracts in a rhythmic manner—that is to say, it beats. “Cardiac activity” means that a few heart cells are alive and beating, not that a heart actually exists.  A true heartbeat, on the other hand, is, technically speaking, the beating of a heart. An actual complete heart, not a few cardiac muscle cells. A complete heart does not exist at six weeks’ gestation. 

To further illustrate just how independent a heart cell’s beating is from there being an actual living organism, consider the following two facts:

1) Beating heart cells need not come from an embryo. At Vienna University of Technology, descendants of stem cells called progenitor cells were induced to become heart cells in a laboratory, and they too beat on their own, in a Petri dish.

2) It is also possible for a person who is brain dead to still have a beating heart.

Heart and soul

If all of this seems spooky, it is largely because we incorrectly but understandably associate a beating heart with an intrinsic, even mystical life force; it is associated with the presence of a soul itself.

Ancient Egyptians and some ancient Greeks believed that the heart housed the soul, as well as our ability to think. Christianity adopted the idea that the heart is the seat of consciousness, intelligence, free personality, intrinsic knowledge of right and wrong, and a place over which God could have direct influence. These feelings continue in our culture to this day.  

But what we know, through science, is that the heart is a muscle that pumps blood throughout the body. We know that a heart can be transplanted from a dead person to someone else, and that a soul is not transplanted at the same time. We know that cardiac muscle cells will contract in a rhythmic manner, regardless of the state of the body around it, or even the existence of a body around it, or even the existence of a heart around it. 

The religious idea that the heart is the seat of the soul stalks the subject of abortion. In fact, in general, the religious concept of “ensoulment” has been the unspoken underpinning of the anti-abortion movement for decades.

“Ensoulment” is the idea that there is a specific moment when a developing embryo is endowed with a soul. Once a divine soul is placed in an embryo, terminating that embryo is thought to constitute the murder of a divine soul.

The laws of a secular democracy should offer no place for magical thinking of this kind. When anti-abortionists ask “When does life begin?”, they are really asking, “When does life with a soul begin?” It should be noted that no one is arguing about whether or not the organism created through conception is alive.

The egg and sperm were alive. The parents were alive. All the ancestors back to the dawn of life on the planet were alive. Life is involved at every juncture before, during, and after conception. So the question “When does life begin?” regarding pregnancy is a nonsensical one. Once you realize this, you see that the question is a stand-in for ensoulment. 

“Cardiac activity” is likewise a stand-in for ensoulment. When such activity begins, it only means that some individual heart cells are alive. The sound is nothing more than the greatly-amplified rhythmic contracting of a collection of muscle cells that do not form a heart.

It needs to be stated in plain English: All anti-abortion fetal “heartbeat laws” are based on unscientific nonsense and should be abrogated. Cardiac muscle cells will contract on their own, even in a Petri dish, with no brain, no nervous system, no organism, and no heart attached to these cells. A “heartbeat” at six weeks’ gestation does not involve an actual heart. Further, muscle cells contracting are not the sign of a soul.

And regardless of the beliefs in the individual minds of citizens, the concept of a soul has no place in the laws of a secular democracy.