Review of THE EXQUISITE MACHINE
The science of our resilient heart
Our heart beats 100,000 times per day, every day, relentlessly for decades. It’s an impressive feat! This organ is truly remarkable. Yet, heart disease is a leading killer in today’s world. We take our heart for granted. We eat poorly. Move too little. And we don’t appreciate what this remarkable organ does for us every second of our lives.
But what do we really know about it? In The Exquisite Machine: The New Science of the Heart, Sian Harding shares new knowledge about the heart, yielding insights about interesting questions like why heart attacks are so catastrophic, and why the heart almost never gets cancer – and both are related.
Although this book presents a myriad of interesting facts about the heart, there was a common thread among nearly all the topics that I found to be like candy for my brain. It all has to do with the nature of heart cells, which are different in many ways from other organ cells. Take the liver for instance. You can take half of an adult’s liver and transplant it to another person. And the missing liver regenerates itself within a few weeks. This is an extreme example, as most our organs do not do this, but it highlights a key point: organ cells generate new “daughter” cells often.
The heart, however, does not. And this is what makes the heart different – and exquisite – compared to other organs. As Harding shares, half of your cardiac muscle cells survive from the time you’re born until you die – pumping away from 80+ years. Cardiac muscle cells do not undergo mitosis (i.e., the splitting of one cell to create two new “daughter” cells) to the same extent as other cells in our body and organs.
This is primarily because cardiac muscle cells are engaged in a highly choreographed electrical dance to keep the heart pumping as one. If some cells stopped to split in two, and then those new cells had to have enough time to develop and learn the ‘dance,’ there could be catastrophic consequences to the performance of the heart. So, evolution has crafted cardiac cells that are built to last.
But this relative lack of mitosis has big consequences. First, it means that damage to the heart, from heart disease or a heart attack, kills massive amounts of cells. And because they don’t regenerate, scar tissue forms, weakening the performance of the heart and blocking electrical paths.
We also see this manifest in the lack of heart cancer. I never really thought of this, but do you know anyone who has had heart cancer? Probably not. Because cancer is a malfunction of cellular division (i.e., mitosis), and cardiac muscle cells don’t divide, there is no malfunction to manifest as cancer. Pretty neat.
I did had one small quibble when the author stated early on that “we evolved in a time when humans did not live long enough to have heart attacks.” This is false. There have always been old humans, we just have more old humans today because fewer kids die, and we have medicine to cure infections. Remember life expectancy is not the same as life span.
But overall, this was a fascinating book and a quick read. I learned a lot of new things about the heart, and now have one more interesting nugget of information in my knowledge bank.
Published: September 2022
Publisher: MIT Press
Format: Hardcover
If you think this sounds interesting, bookmark these other great reads:
Zero to Birth: How the Human Brain Is Built by William Harris (2022). READ MY REVIEW
The Cheating Cell: How Evolution Helps Us Understand and Treat Cancer by Athena Aktipis (2020)
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