user16866: I'm curious about best practices for what I'll call tag "hierarchy." 
Is it appropriate or necessary to add more general tags to a question that has a more nuanced/specific tag already associated with it? If so, when is it appropriate?

This is both in the context of re-tagging questions AND simply when adding new questions.

Examples:

Does a question with a human-anatomy tag need (or should it be assigned) an anatomy tag?
Should a question tagged with human-anatomy also be assigned a human-biology tag? 
Should a question tagged with mammaology (or entomology) also be assigned a zoology tag? 
etc. 


user5144: I would also say that this depends strongly on the tags and the question. But there is no real need to use tags which are closely related. So if this is about humans, I would use human anatomy, if this is more general, I would rather use anatomy. 
The tags are more of a general sorting, they don't have to be too specific. Also: Please avoid inventing new tags which are not or only sparsely used, as they are then relatively useless.

user27148: I think it depends on the breadth of the tag and question and whether it would be helpful for people finding the question.
So, for the first example, I would say yes, both human-anatomy and anatomy tags. 
For the second, I think it depends; if the question was purely about anatomy and nothing else, well it might be a bit of a boring question but I would leave the tags as is (for example, maybe the question is one of the common ones about orientation terms for humans). If it is more broad and asks an anatomy question that is relevant to some other part of human biology, then both tags are appropriate.
zoology I feel could become an incredibly broad tag. I would probably leave zoology off unless the question is comparative in some way. Most likely a page tagged mammalogy or entomology would fit that, but I wouldn't suggest tagging every question about human biology with mammalogy and zoology or those tags would start to lose their meaning. I also wouldn't tag a question with zoology that is about, for example, blood circulation, unless it was comparing circulatory systems in different classes of animals.

16866: <p>I'm curious about best practices for what I'll call tag "hierarchy." </p>

<p><strong>Is it appropriate or necessary to add more general tags to a question that has a more nuanced/specific tag already associated with it?</strong> If so, when is it appropriate?</p>

<ul>
<li>This is both in the context of re-tagging questions AND simply when adding new questions.</li>
</ul>

<p><strong>Examples</strong>:</p>

<ul>
<li><p>Does a question with a <code>human-anatomy</code> tag <em>need</em> (or <em>should it be assigned</em>) an <code>anatomy</code> tag?</p></li>
<li><p>Should a question tagged with <code>human-anatomy</code> also be assigned a <code>human-biology</code> tag? </p></li>
<li><p>Should a question tagged with <code>mammaology</code> (or <code>entomology</code>) also be assigned a <code>zoology</code> tag? </p></li>
<li><p>etc. </p></li>
</ul>
 5144: <p>I would also say that this depends strongly on the tags and the question. But there is no real need to use tags which are closely related. So if this is about humans, I would use human anatomy, if this is more general, I would rather use anatomy. </p>

<p>The tags are more of a general sorting, they don't have to be too specific. Also: Please avoid inventing new tags which are not or only sparsely used, as they are then relatively useless.</p>
 27148: <p>I think it depends on the breadth of the tag and question and whether it would be helpful for people finding the question.</p>

<p>So, for the first example, I would say yes, both <a href="https://biology.stackexchange.com/questions/tagged/human-anatomy" class="post-tag" title="show questions tagged &#39;human-anatomy&#39;" rel="tag">human-anatomy</a> and <a href="https://biology.stackexchange.com/questions/tagged/anatomy" class="post-tag" title="show questions tagged &#39;anatomy&#39;" rel="tag">anatomy</a> tags. </p>

<p>For the second, I think it depends; if the question was purely about anatomy and nothing else, well it might be a bit of a boring question but I would leave the tags as is (for example, maybe the question is one of the common ones about orientation terms for humans). If it is more broad and asks an anatomy question that is relevant to some other part of human biology, then both tags are appropriate.</p>

<p><a href="https://biology.stackexchange.com/questions/tagged/zoology" class="post-tag" title="show questions tagged &#39;zoology&#39;" rel="tag">zoology</a> I feel could become an incredibly broad tag. I would probably leave <a href="https://biology.stackexchange.com/questions/tagged/zoology" class="post-tag" title="show questions tagged &#39;zoology&#39;" rel="tag">zoology</a> off unless the question is comparative in some way. Most likely a page tagged <a href="https://biology.stackexchange.com/questions/tagged/mammalogy" class="post-tag" title="show questions tagged &#39;mammalogy&#39;" rel="tag">mammalogy</a> or <a href="https://biology.stackexchange.com/questions/tagged/entomology" class="post-tag" title="show questions tagged &#39;entomology&#39;" rel="tag">entomology</a> would fit that, but I wouldn't suggest tagging every question about human biology with <a href="https://biology.stackexchange.com/questions/tagged/mammalogy" class="post-tag" title="show questions tagged &#39;mammalogy&#39;" rel="tag">mammalogy</a> and <a href="https://biology.stackexchange.com/questions/tagged/zoology" class="post-tag" title="show questions tagged &#39;zoology&#39;" rel="tag">zoology</a> or those tags would start to lose their meaning. I also wouldn't tag a question with <a href="https://biology.stackexchange.com/questions/tagged/zoology" class="post-tag" title="show questions tagged &#39;zoology&#39;" rel="tag">zoology</a> that is about, for example, blood circulation, unless it was comparing circulatory systems in different classes of animals.</p>
