Is Darwinist P.Z. Myers right to say that the appendix is vestigial?

Apologetics and the progress of science
Apologetics and the progress of science

First, let’s hear prominent atheist P. Z. Myers, who believes in Darwinism, explain why he thinks that the appendix is a useless vestigial organ leftover from an unguided, random process of evolution:

The appendix in humans, for instance, is a vestigial organ, despite all the insistence by creationists and less-informed scientists that finding expanded local elements of the immune system means it isn’t. An organ is vestigial if it is reduced in size or utility compared to homologous organs in other animals, and another piece of evidence is if it exhibits a wide range of variation that suggests that those differences have no selective component. That you can artificially reduce the size of an appendix by literally cutting it out, with no effect on the individual (other than that they survive a potentially acute and dangerous inflammation) tells us that these are vestigial.

Got that? You can cut out the appendix and it has “no effect on the individual”.

Now let’s look at the peer-reviewed science, so we can get the truth of the matter.

My good friend Joe Coder told me about this article from the Melbourne Herald Sun.


MELBOURNE scientists have discovered new proof that the appendix — the often-removed organ once thought to be redundant — can be crucial to digestive health.

Researchers from the Walter and Eliza Hall Institute have shown how a group of immune cells team up with the appendix to protect the gut during infection.

They work together during bouts of food poisoning and other bacterial illnesses, and also help boost the immune systems of cancer patients.

Lead researcher Professor Gabrielle Belz, a laboratory head from WEHI’s molecular immunology division, said about 70,000 Australians have their appendix removed every year — making it one of the most common surgical procedures.

“Popular belief tells us the appendix is a liability,” Prof Belz said.

“However, we may wish to rethink whether the appendix is irrelevant for our health.”

Prof Belz said surgeons no longer removed the appendix “at the first drop of a hat”, reserving surgery for more serious cases of appendicitis.

The new research, led by Prof Belz and leading French immunologist Prof Eric Vivier, has shown that innate lymphoid cells (ILCs) shield the appendix from harmful bacteria.

This allows the small organ to act as a safe haven for “good” bacteria, which could then “reseed” the intestines and restore the health of the digestive system.

Prof Belz, whose research was published today in Nature Immunology journal, said ILCs offered an added layer of immune protection for healthy people.

But they were vital in fighting bacterial infections in people with compromised immune systems, such as cancer patients, Prof Belz said.

“This is particularly important because ILCs are able to survive in the gut even during (cancer) treatments, which typically wipe out other immune cells,” she said.

Prof Belz said that ability of ILCs to withstand chemotherapy also opened up “new avenues of investigation” for cancer treatment.

This expands on a previous study reported by the Washington Post.


The appendix “acts as a good safe house for bacteria,” said Duke surgery professor Bill Parker, a study co-author. Its location — just below the normal one-way flow of food and germs in the large intestine in a sort of gut cul-de-sac — helps support the theory, he said. Also, the worm-shaped organ outgrowth acts like a bacteria factory, cultivating the good germs, Parker said. That use is not needed in a modern industrialized society, Parker said. If a person’s gut flora dies, it can usually be repopulated easily with germs they pick up from other people, he said. But before dense populations in modern times and during epidemics of cholera that affected a whole region, it wasn’t as easy to grow back that bacteria and the appendix came in handy.

Evolution News comments:

[…][A] few months back David Klinghoffer reported that researchers in the journal Clinical Gastroenterology and Hepatology found:

Individuals without an appendix were four times more likely to have a recurrence of Clostridium difficile, [a pathogen common in hospitals,] exactly as Parker’s hypothesis predicted. Recurrence in individuals with their appendix intact occurred in 11% of cases. Recurrence in individuals without their appendix occurred in 48% of cases.

In other words, the appendix performs important immune-related functions. Thus, the appendix is not there to occasionally explode. With the appendix increasingly considered to be an important organ that you wouldn’t want to lose, researchers have also found that antibiotics can cure many cases of appendicitis (see Eriksson et al., 2006  ).

Look, everyone has to decide whether they want to believe in religion or whether they want to believe in science. I understand that some people want to assume a religion of naturalism, and then try to fit reality into that pre-supposed dogma. But I don’t think that’s the right way to develop an accurate view of reality. We should follow the scientific evidence wherever it leads, and we should seek the truth – no holds barred.

Positive arguments for Christian theism


2 thoughts on “Is Darwinist P.Z. Myers right to say that the appendix is vestigial?”

  1. Vestigial doesn’t mean useless. Vestigial means very reduced from its former self. Crumbs left on the table after eating cake are “vestiges” of the original cake.

    Every trait of an organism has some degree of metabolic or survival cost. If its benefits for survival outweigh the cost, it is a net benefit to the organism. However, if something changes in the environment that reduces the benefit of a trait, it will be a net liability.

    If an trait becomes a net liability, it will be slowly removed by evolution over many generations to the point where only a vestige of it will remain. It will be “tuned down” until its cost is no longer greater than its benefit.

    However, evolution doesn’t care about the history fo the organism. It produces varations in each generation and selects the more favorable ones. That leaves the vestiges of a trait as open to being exploited by evolution as any other aspect of the organisms. As such the former trait will take on new roles just as readily as any other part of the organism.

    And so while a trait is being tuned down in regard to its former function, it can also be repurposed for another function.

    If there were no such thing as vestigial traits, all organisms would have a short existence in regard to extinction. You cannot adapt to a new environment if you cannot tune down some things and tune up something else.


    1. Your entire comment ASSUMES evolution. But if you’re discussing the evidence for or against evolution, you can’t assume evolution in the process. If you’re looking at whether the appendix is a vestigial organ, you have to weigh the evidence that it could be a reduced organ left over from ancestors against the evidence that it is a feature designed as-is to do what it does. You’re assuming the first without even addressing the second.

      “If an trait becomes a net liability, it will be slowly removed by evolution over many generations to the point where only a vestige of it will remain. It will be “tuned down” until its cost is no longer greater than its benefit.”

      That’s a lovely narrative – a just-so story. But where’s the evidence for it? You can’t point to the appendix as evidence that unneeded organs shrink in size and function and then simultaneously “prove” that the appendix is a vestigial organ because unneeded organs shrink in size and function. That’s circular reasoning.

      The evidence presented here fits much better with the hypothesis that the appendix is a designed feature of the immune system rather than a small leftover from long ago ancestors. If you’re going to have an honest and profitable discussion on the topic, you have to stop telling cute stories and start discussing the evidence and how well it supports the competing viewpoints.


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