Jaspar Lawrence never claimed, AFAIK, that helminthic therapy works 100% for everyone and he even shared some cautions about some parasitic organisms. I already discussed here -
http://www.rawpaleoforum.com/welcoming-commitee/jasper-lawrence-here/msg63098/#msg63098 - the connection of anemia in the southern US with hookworms is well known (though I think diet likely was a factor in it as well) and was what led to the near eradication of hookworms in the US. We should also bear in mind that a single person's negative story re: hookworms or other parasitic-type organisms does not mean that worm therapies do no good, nor that all raw Paleo dieters should freak out over the risks of eating raw meats.
That they may help people with asthma should be considered an interesting quirk,
If you investigate Jaspar's story, you'll see it was more than an "interesting quirk," for him--it was a lifesaver.
suggesting that these are automatically symbiont is naive.
I haven't seen anyone suggest that for every single individual case. The topic question of this thread is an inquiry re: organisms that "seem like good candidates for symbionts," not a final answer, which I can't provide because I'm not an expert in this field--I'm an interested person asking questions about it and seeking suggestions for candidate symbionts from people in the know like Jaspar. I merely pointed to the accumulating science which indicates that certain "parasites" have co-evolved with humans over millions of years. If you have counter
scientific evidence feel free to share it.
I am not saying be paranoid about parasites, just to keep in mind these things are theoretical until you suffer an infection of one.. then your mind may change a bit. People die from parasite infections. Search google for images of what can happen when worms take over; it's not pretty.
No offense intended, but why do you seem to be of two minds--saying you're not advocating paranoia but then using some of the sensationalistic arguments that the media employs? I'm less interested in sensationalistic images and more interested in broader hard data and scientific research--particularly from evolutionary biology and paleoanthropology. No one has argued that all parasites are benign and this was meant to be an inquiry into which parasitic-type organisms are the best candidates for possible human symbionts and a sharing of research that actually balances out the usual coverage of the subject in this parasite-phobic society, not a "pro-parasite parade" as you characterized it, which I'm hoping was meant in jest.
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Given some of the comments, I can tell that some people didn't read the sources I linked to, so I'll try to make it easier for folks. Here is some of the science on the subject which contradicts the hysteria that lumps all parasitic-like organisms and bacteria together as "lethal":
Meat in the human diet: an anthropological perspective.
http://www.thefreelibrary.com/Meat+in+the+human+diet:+an+anthropological+perspective.-a0169311689
"Cestodes of the family Taeniidae are parasites of carnivores spread by eating meat. Taenia saginata and T. solium use humans exclusively as their host, indicating a substantial period of co-evolution and meat consumption by humans and their ancestors (17 Henneberg M, Sarafis V, Mathers K. Human adaptations to meat eating." (Hum Evol 1998; 13: 229-34. http://resources.metapress.com/pdf-preview.axd?code=e85u8446x8831144&size=largest).
A Worm's View of Human Evolution
Pat Shipman
American Scientist magazine
http://www.americanscientist.org/issues/issue.aspx?id=3294&y=0&no=&content=true&page=2&css=print
[T]he tight adaptational relationship between a particular species of tapeworm and its host means that tapeworms can reveal a great deal about the animals in whose guts they live. Human beings are vulnerable to infestation by any of three species of taeniid tapeworms: Taenia saginata, T. asiatica and T. solium. All three are host-specific, meaning they can't survive as adults outside a human gut. Since tapeworms must be ingested to pass from individual to individual or from species to species, the research team realized that the genetic and host differences among tapeworm species can be used to understand something about the changing dietary habits of a host species.
When did hominids first become definitive hosts for tapeworms?
.... The standard metaphor is that each mutation represents a "tick" of the molecular clock. Because not all molecules tick (mutate) at the same rate, the clock has to be calibrated using data from pairs of species with well-known divergence dates: in this case, chimps and humans, rats and mice, and two species of snapping shrimp. Using this now-standard procedure for estimating divergence dates between T. saginata and T. asiatica, Hoberg got a startling answer: These two sister species of tapeworm diverged from each other not 10,000 years ago, but between 780,000 and 1.71 million years ago. Their ancestor most likely already lived in humans. Clearly, this lineage could not have been acquired because of the domestication of pigs and cattle by modern humans.
The researchers' alternative hypothesis was that the origin of human-specific tapeworms was triggered by a dietary shift from a primarily plant-based diet to one with much more animal flesh, which occurred among early (prehuman) hominids. The estimated divergence dates suggest that the hominid in question was most probably Homo habilis or H. ergaster. (The latter is sometimes considered merely an early African variant of H. erectus.) Where did these early hominids get their tapeworms from? And what role did domestic animals play in this story of worms and hominids? Revealing clues came from the analysis of T. solium, the third human-specific tapeworm, for it is closely related to tapeworms such T. hyaenae, T. crocutae, T. gonyamai and T. madoquae. These last four tapeworms respectively have the following definitive hosts, in order: brown hyenas, spotted hyenas and African hunting dogs; brown and spotted hyenas; lions and cheetahs; and jackals. The fossil record shows that each of these carnivores co-existed with early Homo in Africa for many millennia. These findings suggest that early African hominids got their food and ate in ways roughly similar to these carnivores. But these carnivores were by no stretch of the imagination domestic animals from which hominids "caught" tapeworms; they were instead fierce competitors for the same animal resources.
Personally, I find this a singularly gratifying result, since I was among the first to argue that early Homo hunted and scavenged animal carcasses. My evidence was archaeological—the presence of stone tools, cutmarks and hominid-induced breakage patterns on the fossil bones at hominid sites. Now quite different evidence from taeniid tapeworms provides a strong confirmation of the hypothesis that our hominid ancestors were adept facultative carnivores. The intermediate hosts of these tapeworms tell another important tale. African antelopes are the most common intermediate hosts. Other such hosts include the large buffalo, Syncerus caffer (which is not the domesticated water buffalo), wildebeest, waterbuck, impala, kob and quite small-bodied duikers. Three significant points emerge from these analyses. First, the definitive and the intermediate hosts are all African species. Second, the predators incorporate a wide range of hunting styles. They include classic ambush predators and those that specialize in swift, long-distance pursuit, solitary hunters and group predators, frequent scavengers and habitual hunters. Had all of the carnivores been, for example, swift group predators such as African hunting dogs, this might have suggested that hominids obtained their animal food through a similar strategy, but this idea cannot be sustained. Third, the intermediate hosts exhibit a wide range of habitat preferences, among them wet, marshy areas or dry savannahs; closed forest habitats, open bushland or very open grasslands. Apparently, hominids did not restrict themselves to preying on species of a single habitat. Instead, the pattern is one of diversity, both in the style of obtaining animal food and in the ecological locality in which that food was acquired.
Interestingly, the human-specific T. solium and T. asiatica have intermediate hosts that are not antelopes. The intermediate hosts of T. solium are humans, other primates, hares or rabbits, hyraxes, members of the dog family, and wild or domestic pigs. The intermediate hosts of T. asiatica are the domestic pig and cattle. This observation brings us back to a paradox posed above: If our ancestors weren't initially exposed to tapeworms from their domestic stock, why do human-specific tapeworms have intermediate hosts among domestic animals? Hoberg and colleagues suggest a complex scenario. From their data, they judge that the human lineage acquired taeniid tapeworms in sub-Saharan Africa, quite plausibly coinciding with the onset of regular scavenging and hunting in early Homo between 780,000 and 1.71 million years ago. The eggs of the ancestral taeniids passed from true carnivores to their varied prey, and then from those prey as larvae back to carnivores or on to predatory hominids. In time, the larvae of those carnivore-specific tapeworms evolved into human-specific tapeworms. Hoberg and his colleagues believe there were two independent exposures of hominids to the taeniid tapeworms; one lineage led to T. solium, and the other lineage evolved into T. asiatica and T. saginata. T. asiatica and T. saginata may have diverged when some hominids migrated out of Africa into Eurasia. From currently known fossil evidence, this expansion of hominid territory took place about 1.7 million years ago, when Homo ergaster colonized Eurasia. Moving into a new continent meant Homo encountered new prey species and new carnivore competitors. Many millennia after this great migration out of Africa, archaic Homo evolved into modern Homo sapiens, who still later domesticated animals, perhaps in at least two separate episodes. It now seems that conventional wisdom must be turned on its head. Humans did not "catch" tapeworms from their "dirty" domestic animals, but instead infected the domestic animals with their own tapeworms.
This imaginative and thought-provoking study has given us valuable insights into the human past. The transition from a largely plant-based diet to one incorporating significant amounts of meat was an ancient and profound one. Although the more animal-based diet had advantages—it has been linked to the increasing relative size of the brain in early Homo and to that species' enormous expansion of geographic range—one of the real costs of that change in lifestyle was the acquisition of tapeworms that sapped the energy of hominids. Until now, we have read this history as a hero story in which the clever human lineage triumphantly conquers the world. From the worm's-eye view, this is instead the triumph of the tapeworm, who not only spreads all over the world but persuades another to bear the cost of that expansion.
Human/parasite coevolution
Daniel R. Brooks, "Human/parasite coevolution," in AccessScience, ©McGraw-Hill Companies, 2004, http://accessscience.proxy.mpcc.edu/content.aspx?id=YB040410
"...humans are known to host three species of tapeworms, Taenia solium, T. saginata, and T. asiatica, acquired by eating raw or poorly cooked pork (T. solium) or beef (T. saginata and T. asiatica). Studies comparing phylogenetic relationships among Taenia spp. with those of their hosts indicate that humans acquired Taenia on two separate occasions, correlating with the shift from scavenging to predation (hunting) in humans more than a million years ago in Africa. The closest relative, or sister species, of T. solium is T. hyaenae, occurring in hyaenas and African hunting dogs. Taenia saginata and T. asiatica, themselves sister species, are most closely related to T. simbae, which inhabits lions. This suggests that humans acquired Taenia as a by-product of competition with carnivores, the original hosts for Taenia spp. (Fig. 1). As humans secured their prey farther from competitors through domestication, they isolated strains of Taenia that eventually became distinct species."
HUMAN EVOLUTION
Volume 13, Numbers 3-4, 229-234, DOI: 10.1007/BF02436507
Human adaptations to meat eating
M. Henneberg, V. Sarafis and K. Mathers
http://www.springerlink.com/content/e85u8446x8831144/
It is argued that Homo sapiens is a habitual rather than a facultative meat eater. Quantitative similarity of human gut morphology to guts of carnivorous mammals, preferential absorption of haem rather than iron of plant origin, and the exclusive use of humans as the definitive host by Taenia saginata and the almost complete human specificity of T. solium are used to support the argument.
Hookworm
http://en.wikipedia.org/wiki/Hookworm
the close evolutionary link between the human and canine parasites, which probably have a common ancestor dating back to when humans and dogs first started living closely together. ....
Hygiene hypothesis [An updated version is called the Old Friends hypothesis]
The hygiene hypothesis states that infants and children who lack exposure to infectious agents are more susceptible to allergic diseases via modulation of immune system development. As Mary Ruebush writes in her book Why Dirt is Good, “what a child is doing when he puts things in his mouth is allowing his immune response to explore his environment. Not only does this allow for ‘practice’ of immune responses, which will be necessary for protection, but it also plays a critical role in teaching the immature immune response what is best ignored.[35]” The theory was first proposed by David P. Strachan who noted that hay fever and eczema were less common in children who belonged to large families.[36] Since then, studies have noted the effect of gastrointestinal worms on the development of allergies in the developing world. For example, a study in Gambia found that eradication of worms in some villages led to increased skin reactions to allergies among children.[37]
Although the exact mechanism is unknown, scientists hypothesize that the helper T cells are key players. Allergic diseases, which are immunological responses to normally harmless antigens, are driven by a TH2-mediated immune response. Bacteria, viruses, and parasites, on the other hand, elicit a TH1-mediated immune response which inhibits or down-regulates the TH2 response.[38] TH1 also inhibits the activity of TH17 which is heightened in numerous inflammatory diseases including multiple sclerosis and asthma.[39]
Helminths and the IBD Hygiene Hypothesis
Joel V. Weinstock, MD, and David E. Elliott, MD
http://opensourcehelminththerapy.org/mediawiki2/images/0/05/Helminths_and_the_IBD_Hygiene_Hypothesis.pdf
Most helminths are highly restricted in host selection, attesting to the closeness of this host–parasite association. Also, depending on the worm species, they have preferences for living in various locations of their host like the intestinal lumen, bile ducts, lungs, blood stream, and elsewhere. To accomplish this, they must evade and control the host’s immune system. This has been achieved through millions of years of coevolution allowing time for both the parasite and its host to gradually adjust to this relationship.
....
Humans and helminths and their immune systems evolved closely together over many thousands of years. To promote their own survival, helminths stimulate immune regulatory pathways within their hosts to control immune reactivity. Clean water and food, paved streets and sidewalks, and modern sanitation systems have reduced exposures to helminths and perhaps other microbial organisms. This could be leading to immune dysregulation and increased susceptibility to immunological diseases (Fig 2). Controlled reintroduction of such exposures during childhood and perhaps beyond may help reestablish immune balance and lower the risk for immunological diseases.
So this science indicates that some parasites have co-evolved with humans over
millions of years, not thousands. The domestication of animals, therefore, did not introduce these longtime parasites into the human species, but it probably significantly increased their numbers within human populations, as Jaspar pointed out in the other recent parasite thread.
Tyler has tried since at least as long as I've been a member here to calm down people's fears about parasites and bacteria, apparently with not much success. Yes, there are some dangers, but they tend to be overblown by the public hysteria. Lately that hysteria has been showing its ugly face here and seemingly feeding on itself. It's OK to educate yourself about the risks, but one should also look at the other side of the story--the potential benefits--and not get carried away with paranoia and hysteria. What say we try to maintain a balanced perspective? The dangers of parasites and bacteria are well known and widely published by the sensationalistic media. What we rarely hear about are stories like Jaspar's, and that's where alternative forums like this one can be quite valuable.
If anyone has counter scientific evidence, please do share it, and please bear in mind that your personal story doesn't refute all the scientific evidence, nor does it guarantee that everyone will have the same experience as yours. Personal parasite stories are useful in showing that even RPDers can get parasites and the symptoms can be unpleasant, but from a scientific perspective it is considered anecdotal evidence, rather than universal law.
Topic: Human Symbionts (Read 17596 times)