We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
How's that for a catchy end-of-holiday-season header? (Metazoans is the new name for the Animalia Kingdom - those creatures with differentiated tissues like sponges, earthworms, and people.)
I have been attempting to familiarize myself a little with the rapidly-expanding science of Epigenetics lately. When I took pre-med Genetics, it was a marginal topic. Now that the fundamental workings of DNA are fairly well understood, epigenetics has become a hot field ("epi" because it's the things - heritable things - that effect cell-differentiation, growth and development, etc. on top of the basic DNA template, but are affected by the environment). Shades of Lamarck.
Epigenetics is interesting partly because it's one of the ways that a metazoan species can be affected by environmental influences during growth and development. Molecular tools for shaping the final product. The complexity of metazoans (as contrasted with fungi, bacteria, and protozoans, for example) requires complex epigenetic processes. Heritable things which switch on or switch off gene expression.
Here's the simplest short piece I could find: What Is Epigenetics? Easy to follow if you ever took intro Bio.
The wiki entry is actually a good intro, but tough sledding unless you had a decent college education or are a bio reader.
Porifera (sponges) are certainly metazoa, but they lack differentiated tissues. In terms of modern cladistics, since all other animals are believed to be descended from sponges, the phylum is paraphyletic, and we humans are merely highly derived sponges.