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Germ Free Animal Lifespan Evidence of Design?

A recent disagreement about the critical importance of gut flora to animal health led me to look for research into germ-free animals. GF animals have been available for research for about 50 years and initially they lived very short lives. The decrease in longevity was eventually traced to lack of critical enzymes in their diet. In order to remain GF their food was sterilized at high temperatures (essentially autoclaved) which caused the needed enzymes to break down. Once their dietary requirements were established an unexpected result emerged – GF animals live twice as long as controls receiving the same complete diet but not housed in sterile conditions.

Germ Free Animals

Germ-free animals were obtained by cesarean section and maintained in special isolators; this allowed the investigator to raise them in an environment free from detectable viruses, bacteria, and other organisms. Two interesting observations were made about animals raised under germ-free conditions. First, the germ-free animals lived almost twice as long as their conventionally maintained counterparts, and second, the major causes of death were different in the two groups. Infection often caused death in conventional animals, but intestinal atonia frequently killed germ-free animals.

This got me thinking about evolution vs. design. The animals raised germ-free could not have evolved in the natural world without exposure to bacteria but they could have been designed for GF life. The fact that they live twice as long in a GF environment when eating a diet that is nutritionally complete except for being sterile seems to be favorable evidence that animals were created in and for a germ-free world.

My experience with rabbits, who often die of intestinal atonia when their diet isn’t perfect, leads me to suspect the frequent early cause of death in GF animals is still related to diet rather than lack of gut flora. Regardless they still live twice as long without bacteria (including gut flora) in them or their environment.

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19 Responses to Germ Free Animal Lifespan Evidence of Design?

  1. Dave –

    What you report here is astounding. I have several points and questions that I am very curious to hear any responses to:

    (1) If life was designed to evolve, and “animals raised germ-free could not have evolved in the natural world without exposure to bacteria,” what you report here would seem to confirm Hoyle’s suspicions about germs and viruses being vectors of evolutionary change. Any thoughts?

    (2) Perhaps this is the biological trade-off for the advantages of evolution? If you want some evolution, you gotta’ sacrifice something critical to the functioning of the organism, perhaps metabolic energy or the like?

    (3) In my understanding of computer technology, there is some sort of analogy for a trade-off like this. If you want a computer program that can change and evolve, you have to have some initial data that is exposed to evolution, and some parts that are not. What is given up to allow a change is in the original data, functionality, etc. Also, my understanding is that the only way around this problem in an evolving program is a regular cycle of information infusion or a direct tweak by the programmer. Is this the case with evolving programs?

    Of course, we’re just speculating here, but this is a very enlightening exercise of logical possibility. How do the GF results play into a front-loading scenario?

  2. Interesting stuff… I have wondered similar things about the diet of humans, not the germ free diet but rather the uniqueness of the diet.

    For an individual to operate optimally we need an incredibly varied diet. I would think that our early ancestors would have a hard time maintaining such a diet, making them “weaker” and as such easier to die off. I would thing it would have been more advantagous to have evolved into a species to require very little nutrients…

    But hey, I am new here and would like to say I like the site, though I am unsure if it’ll persuade me to a theist.

  3. The human requirement for a highly varied diet is a myth. Eskimos eat nothing but animal products, few of those, and almost always raw. Their average lifespan is intermediate between the modern west and undeveloped countries. Given total lack of modern medical care this is especially noteworthy. Cancer, heart disease, and stroke (the top three causes of death in the west) are conspicuously rare in Eskimos as is diabetes which is also a top ten leading cause in the U.S.

  4. The Eskimos get plenty of fish oil, plus they presumably don’t deal with malaria and all sorts of diseases that warmer climates offer. And their allergy season must be quite a bit shorter!

    Maybe the biggest factor is that sugar would be practically non-existent in their traditional diet.

  5. Small correction guys:

    Eskimos are now called by their preferred names, generally – Inuits (Canada, Alaska) or Yupiks (western Alaska and the Russian Far East).

    Take it from a Canadian
    ;-)

  6. Ekstasis

    I think the paucity of tropical diseases is probably made up for in the Inuits’ life by how rough it must be living in igloos, competing with polar bears, and hunting on thin sea ice & arctic water with nothing but spears and homemade kayaks. That can’t be easy and must wear a person down pretty good after 50 or 60 years.

    It just ocurred to me that according to Ernst Mayr I must be a different species from Inuits. We’re reproductively isolated by geography and there isn’t a snowball’s chance in south central Texas I’d be attracted to an Inuit woman anyhow even though we’re probably still physically compatible on a hypothetical basis sort of like brown bears and polar bears. ;-)

  7. Cool post. If the leading cause of death is infection, and you remove germs, then you remove the leading cause of death and you get double the life span. But then the leading cause of death is intestinal atonia.

    The questoin you raise is whether the intestinal atonia is proximately caused by diet or a lack of beneficial intestinal fauna.

    It seems like the proper control would be a germ free animal except for the beneficial intestinal fauna. Or comparison of germ free animals with different diets.

    My question is whether the double life span is due solely to removing the leading cause of death (infection) or are there other benefits to a germ free life?

    If we could eliminate the lack of beneficial fauna as a cause of the intestinal atonia and find benefits to a germ free life beyond removal of the leading cause of death, I think there would certainely be significant design implications.

  8. Jehu

    Sounds like a good ID research program!

    GF animals have to die of something. Maybe living twice as long just runs into the Hayflick limit for rodent intestinal tract cells more often than any other organ system. If I recall correctly the most successful increased longevity protocol in rats that existed before this is an extremely low calorie diet which, probably not uncoincidently, also doubled their lifespans. Once you eliminate all the usual suspects for early death then the Hayflick limit takes you out.

  9. DaveScot,

    I agree, the animal has to die of something … except maybe a turtle.

    Researchers lately have been astonished to discover that in contrast to nearly every other animal studied, a turtle’s organs do not gradually break down or become less efficient over time.

    Dr. Christopher J. Raxworthy, the associate curator of herpetology at the American Museum of Natural History, says the liver, lungs and kidneys of a centenarian turtle are virtually indistinguishable from those of its teenage counterpart, a Ponce de Leonic quality that has inspired investigators to begin examining the turtle genome for novel longevity genes.

    “Turtles don’t really die of old age,” Dr. Raxworthy said. In fact, if turtles didn’t get eaten, crushed by an automobile or fall prey to a disease, he said, they might just live indefinitely

    http://www.nytimes.com/2006/12.....38;ei=5070

  10. The Hayflick limit for individual human cells was overcome through genetic engineering. It is another matter to figure out the aging issue at the organismal level versus the cellular level.

    Rodents with immortalized cells exist, but there has not been established any correlation between mammal cells with no Hayflick limit and mammal longevity. However, I’m not quite ready to throw in the towel in some correlation given the right circumstans. I think the researchers are exploring the right ideas, but there are some missing ingredients to make it work…

    I posted how research in such areas would help win the day for ID in the quest to reverse engineer the original designs. See: How IDers can win the war.

    Regarding long mammalian life, we have at least a claim of it in Jewish tradition when Pharaoh supposedly asked the Jewish Patriarch Jacob how old he was.

    Then Joseph brought his father Jacob and introduced him to the king. Jacob gave the king his blessing, 8and the king asked him, “How old are you?”

    Jacob answered, “I have lived only a hundred thirty years, and I have had to move from place to place. My parents and my grandparents also had to move from place to place. But they lived much longer, and their life was not as hard as mine.”

    Genesis 47

    Whether the account of this conversation is accurate, I will let the readers decide, but I don’t find the prospect of conditions in the past which favored much longer life to be out of the question…

    Sal
    PS
    Interesting find DaveScot.

  11. “The fact that they live twice as long in a GF environment when eating a diet that is nutritionally complete except for being sterile seems to be favorable evidence that animals were created in and for a germ-free world.”
    –DaveScot

    Interesting subject. In addition to the Hayflick limit, cells enter other (presumably pathological) growth-halting modes, such as senescence, where they get bloated, stop dividing, and begin doing things that would appear positively dysfunctional like expressing cytokines that invoke inflammation. This can be instigated by genetic damage and other cellular insults.
    This is one of the major lines of aging research currently.

    As far as the idea that animal life was designed for germ-free living, I don’t think this is a promising line of argument. Animals, particularly mammals, have sophisticated immunological systems. You’d have to argue that these were post-design hacks to the system if the original plans were for a germ-free world. And then there’s the question of why the designer didn’t anticipate germs. And if germs weren’t in the original equation, where’d they come from? I suspect you’d be forced into making eschatological arguments by the end of it.

  12. Wouldn’t a better control start with a completely lab-gestated animal? It seems that a cesarean birth starts the animal out with a helping of inherited germs, which while the animal’s immune system would eventually kill all or most of it off, might leave small amounts unscathed or having done some early undetectable damage.

  13. great_ape

    [blockquote]As far as the idea that animal life was designed for germ-free living, I don’t think this is a promising line of argument. [/blockquote] You’re points are good ones. It’s tough to think of a design scenerio without bacteria.

  14. great_ape

    Animals, particularly mammals, have sophisticated immunological systems. You’d have to argue that these were post-design hacks to the system if the original plans were for a germ-free world.

    Immune systems appeared relatively recently in the history of life. The innate immune system is presumed to date back about a billion years to bilaterians but more interestingly and more to your point the adaptive immune system appeared suddenly in jawed vertebrates about 450 million years ago.

    Given that life has been around for 3.5 billion years and adaptive immune systems to fight invasive pathogens appeared suddenly only half a billion years ago this does have the appearance of a post-design improvement. Sort of like putting a windscreen on a motorcycle to keep the bugs out of your face.

    On your question about where bacteria came from… two answers. Maybe they were here all along but weren’t pathogenic. The second answer is based on the fact that it’s far easier to lose complexity than to gain it. What’s the easier path – for a bacteria to acquire a nucleus out of the blue or for a nucleated cell to lose its nucleus. Devolution is always the easier path. Of course this assumes a complex beginning but complex beginnings are the hallmark of intelligent design and around here we don’t presume intelligent design is out of the question.

  15. great ape

    A designer might design a germ free world with the intention of introducing germs (or knowing that germs might be introduced later) and thus building an immune system. I think the immune system is the evidence that He did anticipate germs.

  16. How’s this for an idea–just a thought.

    Perhaps bacteria were originally ALL beneficial. As a matter of fact, they are necessary for breaking down organic waste and converting it back into substances that can be taken up in plants (this I know from experience with organic gardening and composting). Also, as has been pointed out, intestinal flora is apparently a necessary part of human and animal digestion. What if…. All bacteria were originally for some beneficial purpose and some of them eventually mutated into forms that became increasingly hostile to humans, animals, and plants. Like an errant computer program with a bug that then self-reproduces and gets worse with each generation. Were this the case, one would expect very long lifespans nearer the beginning of time, and much shorter lifespans as time progressed and as bacteria became more and more harmful (which is exactly the sort of thing that is recorded in scripture). This, of course, would leave the question of “how, then, did immune systems come into being?” Which could be answered by saying that immune systems are a check-and-balance mechanism to keep bacterial population levels in check.

    I’m not a biologist, or even very well read in biology, so I might be talking–as expression goes–”out my butt.” But its a thought that occurred to me in this context. What do those of you better versed in biological sciences think?

  17. The immune system may have been front-loaded as well. If front loading is a valid assumption; the Designer may have had the foresight of pathogenic bacteria.

  18. How’s this for an idea–just a thought.

    Perhaps bacteria were originally ALL beneficial.

    This is the view of some in the ID community. Even Stephen Meyer has argued various aboriginal designs may not have been malicious. In his famous debate with Peter Ward, he makes reference to it.

    Gordon Wilson was pretty bold to suggests that duel gene sets exists for benevolent and malevolent modes. If benevolent modes exits and the Designer is will for us to discover them, we can in principle trigger them.

    The Explanatory Filter could be an ideal tool to detect these dormat benevolent modes.

    Salvador

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