By: Dr. Jerry Bergman
Montpelier, Ohio
The thymus begins shrinking almost as soon as a child is born. In babies, it fills a big share of the chest cavity.
By age 70, it is largely replaced by fatty tissue. Doctors assumed a shrunken thymus meant a useless one. By the time most people retire, it barely functions.
At least that was the view once taught by doctors. German anatomist Robert Wiedersheim, relying heavily on Charles Darwin’s work, published an expanded list of 86 “wholly or in part functionless” human organs.
Influenced by Darwin, he wrongly categorized the thymus, along with the pineal and pituitary glands, as useless vestigial structures. Because the thymus naturally shrinks (actually atrophies) after puberty, early anatomists assumed it had lost all its functions in adulthood.
For decades, the thymus was historically considered a vestigial organ with no useful function in adults. For this reason, when surgeons needed to reach the heart or lungs, they often removed the thymus without much worry.
The thymus’s critical role was not understood until the 1960s, when scientists at the National Institutes of Health identified the thymus as a primary lymphoid organ essential for training T-cells, which orchestrate the body’s immune system.
Specifically, immature white blood cells travel from the bone marrow to the thymus, where they develop into specialized T-cells. The thymus teaches T-cells how to recognize foreign invaders, including bacteria and viruses, while ignoring the body’s own healthy cells to prevent autoimmune reactions.
We also now know that it produces several vital hormones, including thymosin, thymulin and thymopoietin, that support our immune function and help to mature T-cells.
New Research Documents More Critical Functions For The Thymus
New analysis has documented that the thymus keeps churning out new immune cells for at least the first 55 years of a person’s life, far longer than once believed.
Furthermore, researchers who compared adults who had the organ removed with those who kept it found a significant outcome gap: adults who had their thymus surgically removed showed sharply higher rates of death, cancer and autoimmune disease.
The evidence for this discovery included a major study published in The New England Journal of Medicine. A 2024 hematology conference presentation found a five-year mortality risk 2.4 times higher in thymectomy patients compared to those who retained the organ.
The difference was dynamic. Five-year survival for people who lost their thymus was measured at 8.1 percent lower compared to those who still had it, resulting in a 2.9-times higher risk of death.
The researchers concluded that keeping the thymus intact protects against cancer and, in turn, death.
A separate summary published in a major neurology research journal reached a similar conclusion: patients who lost their thymus faced a higher risk of death, cancer and autoimmune disease. When multiple independent reviews reach the same conclusion, it strengthens the case.
These findings ran contrary to the old Darwin assumptions, which treated thymus removal as a routine, low-consequence step during other chest operations. An organ that still functions, even at a reduced capacity, is very different from one that has fully died.
Now, according to Professor Edward Chen, the thymus is also the key to aging. Could this mysterious disappearing organ hold the key to longevity?
The Evidence Is More Complicated
One recent analysis looked at adults who had small, localized thymomas removed and did not find an increase in the five-year mortality rate or cancer death. Thus outcomes depend on why the surgery was done and how advanced the underlying disease was.
The strongest support for the adverse results of a thymectomy comes from people who had chest surgery for another medical reason, and not from healthy adults tracked over a lifetime.
This proves thymus removal is linked to worse outcomes in surgical patients. It does not prove that natural thymic shrinkage, which everyone experiences with age, functions the same way in the general population.
What This Means For How We Think About Aging
The research reframes an organ that doctors largely ignored due to evolutionary conclusions about useless organs. It supports the conclusion that the immune system’s staying power, and possibly a person’s cancer risk, is tied more closely to thymus health than previously assumed.
Surgeons weighing whether to remove the thymus during heart or lung procedures now have data to support their decision, not decades-old assumptions about an organ that supposedly stopped working long before old age set in.
Scientists still need long-term studies tracking healthy adults, not just surgical patients, to determine whether protecting thymic function results in a longer, healthier life for the average person.
Sources:
youtube.com; ash.confex.com; news.harvard.edu; pubmed.ncbi.nlm.nih.gov; ascopost.com; pmc.ncbi.nlm.nih.gov. Chen, Edward. 2026. Could this mysterious disappearing organ hold the key to longevity? Nature 655 560-561, https://www.nature.com/articles/d41586-026-02149-5, July 14.
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Dr. Bergman is a multi-award-winning professor and author. He has 9 degrees and has taught at both the graduate and undergraduate level for over 40 years. His over 2,100 publications are in both scholarly and popular journals. Dr. Bergman’s work has been translated into 15 languages. He has spoken over 2,000 times to college, university and church groups in America, Canada, Europe, the South Sea Islands, and Africa. He lives in Montpelier and is available to present in churches and schools. Jerry can be reached at jbergman1946@gmail.com Bergman’s website is: https://crev.info/author/jbergman/
