user5198: How long would a person live without bacteria was recently closed as primarily opinion based. This is puzzling to me.
It can be argued that this (eliminating all microorganisms) has never been tested in humans, but much of out knowledge about human physiology has not been derived from experiments on humans; indeed the vast majority of what we know about human physiology and medical conditions has been derived from animal studies.
The dog genome has been mapped out not only for it's importance to veterinarians, but also because dog-models have been so vital (and suitable) to research of human disease. The role of mouse models has been invaluable. As stated in Mouse Models of Developmental Genetic Disease:

It is the recognition that humans and mice share the same organ systems, similar reproductive cycles, skeletons, biochemistry, physiology, and most importantly pathologies that have enabled us to progress in our understanding of the basis of human disease and this shows no sign of abating in the foreseeable future.

The use of gnotobiotic mice has recently been important to the better understanding of microbiomes and obesity, cholesterol metabolism, inflammatory bowel disease and infection-mediated diseases, type 1 diabetes, allergies, Antibiotic-Associted Diarrhea (C. difficile) and cancer, to mention only a few diseases. 
In defending the use of gnotobiotics as a crucial element in studying human diseases, Rolf Freder points out

…[I]f one chooses to be rigorous in the definition of what constitutes the reproduction of a human disease, one may well state that no such model has ever been discovered.

Why, then, is a question that absolutely can be answered by studies in the murine model judged to be POB?
I would appreciate any insights, as well as what would need to be done to make this question on topic, as I believe an interest in the human (and therefore animal model) microbiomes and disease (or lack thereof) will prove an illuminating subject of study in the coming decades.
Leading the way: canine models of genomics and disease (Disease Models & Mechanisms)
Animal models of human disease: zebrafish swim into view
Mouse models of human disease
Mouse Models of Developmental Genetic Disease
From Structure to Function: the Ecology of Host-Associated Microbial Communities
Gnotobiotics
Methods and Special Applications in Bacterial Ecology

user3340: The post if not opinion based, is broad. And it is just closed and there is a good deal of chance to reopen it. 
Whether a model is sufficient or not depends on the question that is being asked. For basic questions like DNA repair, even yeast model would suffice whereas questions related to reproductive biology of humans would require primate models (especially for questions related to female reproductive biology).
For dependence on microbiome, I think data from mice would not accurately represent human situation because the metabolism and microbiome constitution are quite different. Even primate models may not be appropriate. If I am not wrong, then microbiome constitution also depends on geographical location and dietary practices. 
To conclude, the answer to the question - "Do animal experiments really mean anything when it comes to extrapolating findings to humans?" is:
Depends on what is being extrapolated.

user6: It doesn't matter, at least not here on meta. We don't close questions just because we suspect that the answer isn't known. Even if the actual answer isn't known, a post explaining the current understanding and the limits of out knowledge is a valid answer.
The "primarily opinion based" close reason was created to deal with questions like "What is your favorite text editor?" or "Are tabs better than spaces?". This kind of question is problematic in cases where every answer is equally valid. It doesn't mean that any question that doesn't have a single objective answer is automatically off-topic. 
The question shouldn't be closed in my opinion, it could benefit from a bit of rewriting, but it is a valid question. 

5198: <p><a href="https://biology.stackexchange.com/questions/29980/how-long-would-a-person-live-without-bacteria">How long would a person live without bacteria</a> was recently closed as primarily opinion based. This is puzzling to me.</p>

<p>It can be argued that this (eliminating all microorganisms) has never been tested in humans, but much of out knowledge about human physiology has not been derived from experiments on humans; indeed the vast majority of what we know about human physiology and medical conditions has been derived from animal studies.</p>

<p>The dog genome has been mapped out not only for it's importance to veterinarians, but also because dog-models have been so vital (and <em>suitable</em>) to research of human disease. The role of mouse models has been invaluable. As stated in <em>Mouse Models of Developmental Genetic Disease</em>:</p>

<blockquote>
  <p>It is the recognition that humans and mice share the same organ systems, similar reproductive cycles, skeletons, biochemistry, physiology, and most importantly pathologies that have enabled us to progress in our understanding of the basis of human disease and this shows no sign of abating in the foreseeable future.</p>
</blockquote>

<p>The use of gnotobiotic mice has recently been important to the better understanding of microbiomes and obesity, cholesterol metabolism, inflammatory bowel disease and infection-mediated diseases, type 1 diabetes, allergies, Antibiotic-Associted Diarrhea (C. difficile) and cancer, to mention only a few diseases. </p>

<p>In defending the use of gnotobiotics as a crucial element in studying human diseases, <a href="http://www.ncbi.nlm.nih.gov/pubmed/?term=FRETER%20R[Author]&amp;cauthor=true&amp;cauthor_uid=13242854" rel="nofollow noreferrer">Rolf Freder</a> points out</p>

<blockquote>
  <p>…[I]f one chooses to be rigorous in the definition of what constitutes the reproduction of a human disease, one may well state that no such model has ever been discovered.</p>
</blockquote>

<p>Why, then, is a question that absolutely can be answered by studies in the murine model judged to be POB?</p>

<p>I would appreciate any insights, as well as what would need to be done to make this question on topic, as I believe an interest in the human (<em>and therefore animal model</em>) microbiomes and disease (or lack thereof) will prove an illuminating subject of study in the coming decades.</p>

<p><sub><a href="http://dmm.biologists.org/content/3/1-2/27.full" rel="nofollow noreferrer">Leading the way: canine models of genomics and disease (Disease Models &amp; Mechanisms)</a></sub><br>
<sub><a href="http://www.nature.com/nrg/journal/v8/n5/full/nrg2091.html" rel="nofollow noreferrer">Animal models of human disease: zebrafish swim into view</a></sub><br>
<sub><a href="http://genesdev.cshlp.org/content/11/1/11.full.pdf" rel="nofollow noreferrer">Mouse models of human disease</a></sub><br>
<sub><a href="https://books.google.com/books?id=4TnyszXnYYcC&amp;pg=PA290&amp;lpg=PA290&amp;dq=which+human+diseases+owe+their+understanding+to+mouse+models&amp;source=bl&amp;ots=mS5eLxOBlw&amp;sig=UY-H6Jl0chsQ_yHKQ1Mvalg_JXk&amp;hl=en&amp;sa=X&amp;ei=v_fwVLmTMIijNtyghKAE&amp;ved=0CFEQ6AEwBw#v=onepage&amp;q=which%20human%20diseases%20owe%20their%20understanding%20to%20mouse%20models&amp;f=false" rel="nofollow noreferrer">Mouse Models of Developmental Genetic Disease</a></sub><br>
<sub><a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2937523/" rel="nofollow noreferrer">From Structure to Function: the Ecology of Host-Associated Microbial Communities</a></sub><br>
<sub><a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3918800/" rel="nofollow noreferrer">Gnotobiotics</a><br>
<a href="https://books.google.com/books?id=BYGRgeBChYYC&amp;pg=PA213&amp;lpg=PA213&amp;dq=have+there+ever+been+gnotobiotic+humans&amp;source=bl&amp;ots=CPM3MAYeUc&amp;sig=wiXxlgNFazLI9btshhbAzLaIpC4&amp;hl=en&amp;sa=X&amp;ei=qPzwVP7MDordggTFsoOoCw&amp;ved=0CC0Q6AEwAg#v=onepage&amp;q=have%20there%20ever%20been%20gnotobiotic%20humans&amp;f=false" rel="nofollow noreferrer">Methods and Special Applications in Bacterial Ecology</a></sub></p>
 3340: <p>The post if not opinion based, is broad. And it is just closed and there is a good deal of chance to reopen it. </p>

<p>Whether a model is sufficient or not depends on the question that is being asked. For basic questions like DNA repair, even yeast model would suffice whereas questions related to reproductive biology of humans would require primate models (especially for questions related to female reproductive biology).</p>

<p>For dependence on microbiome, I think data from mice would not accurately represent human situation because the metabolism and microbiome constitution are quite different. Even primate models may not be appropriate. If I am not wrong, then microbiome constitution also depends on geographical location and dietary practices. </p>

<p>To conclude, the answer to the question - <strong>"Do animal experiments really mean anything when it comes to extrapolating findings to humans?"</strong> is:</p>

<p><strong>Depends on what is being extrapolated.</strong></p>
 6: <p>It doesn't matter, at least not here on meta. We don't close questions just because we suspect that the answer isn't known. Even if the actual answer isn't known, a post explaining the current understanding and the limits of out knowledge is a valid answer.</p>

<p>The "primarily opinion based" close reason was created to deal with questions like "What is your favorite text editor?" or "Are tabs better than spaces?". This kind of question is problematic in cases where every answer is equally valid. It doesn't mean that any question that doesn't have a single objective answer is automatically off-topic. </p>

<p>The question shouldn't be closed in my opinion, it could benefit from a bit of rewriting, but it is a valid question. </p>
