Sentence punctuation 1: with one independent clause

The table below illustrates how one basic independent clause "People (subject) + worry." (verb) can be made increasingly complex by adding phrases and clauses to either the verb or the subject or both. The final sentence contains six dependent clauses, each with its own verb; but there is still only one independent clause.

  (1) People worry.(2)  
  People worry about the future.
  People worry about the future of the planet.
  People worry about the future of the planet on which we live.
  People worry about the future of the planet on which we live because many species are disappearing.
  People worry about the future of the planet on which we live because many species are disappearing at an alarming rate.
  People worry about the future of the planet on which we live because many species, that were thought to be protected, are disappearing at an alarming rate. 
Some  people worry about the future.
Although they are normally quite optimistic, (3) some people worry about the future of the planet.
Although they are normally quite optimistic about other things, some people worry about the future of the planet on which we live.
Although they are normally quite optimistic, (5) and often unconcerned, (5)about other things, some people worry about the future of the planet on which we live (4) because many species are disappearing.
Although they are normally quite optimistic, and often unconcerned, about other things (6) which affect their existence, some  people worry about the future of the planet on which we live because many species are disappearing at an alarming rate.
Although they are normally quite optimistic, and often unconcerned, about other things which affect their existence just as much as the issue of biodiversity, some  people worry about the future of the planet on which we live because many species, (7) that were thought to be protected, (7) are disappearing at an alarming rate.

 

(1) Initial capital letter in first word of sentence

(2) Full stop (period) at end of sentence

(3) Comma at end of dependent clause if it comes before independent clause

(4) Comma optional (depending on sentence meaning) if dependent clause comes after independent clause

(5) Comma between two parallel dependent clauses joined by "and", "but" or "or"

(6) No comma before defining relative clause

(7) Comma before and after non-defining relative clause