ABAC Earth History the Cambrian Explosion & Life Events Explanation Discussion

I’m trying to study for my Science course and I need some help to understand this question.

One of the most mysterious times in the history of Earth is that of the so-called “Cambrian Explosion,” when in a short geologic period of time (few millions of years) most of the animal ancestors of all animals alive today (including humans) suddenly appeared. Why did the “Cambrian Explosion” happen at the time it happened when no event like it happened before it for billions of years of Earth’s history? It is too mysterious that all happened right at the Cambrian in a quick geologic time, and, further, if not for this event no animal we are familiar with today would exist (including us). What really caused the Cambrian Explosion? Was this a random event or a well-explained phenomenon? Can a Cambrian Explosion happen twice? Can it happen on other planets? Hasn’t our planet experience many Cambrian-Explosion-life events after the Cambrian Explosion itself? Why is this an “explosion”? How weird was the Cambrian Explosion? What is the evidence behind this “explosion” of animal groups? What if this Cambrian Explosion never happened? Do we really understand the Cambrian Explosion or we are pretty much only speculating about this event?

Watch the video posted in our Week 5 module (youtube video’s URL link: http://www.youtube.com/watch?v=R5_XLVqrTlM) and investigate and write an essay about the Cambrian Explosion. The questions provided above are to motivate you to investigate about this topic; you do not need to answer them one by one. The essay must be at least four paragraphs long, and each paragraph must contain at least five sentences (you can write more than four paragraphs and more than five sentences per paragraph if you wish to do so). The content of your essay must be written entirely in your OWN words. Use in-text citations in parenthesis, APA style, if you paraphrase information from other authors. Paraphrasing is not copy-pasting or copying and changing a few words from other authors’ writings – it is writing it in your OWN words to explain the authors’ writings. Only when necessary, you can quote, but these quotes do not count towards the last tally of the number of paragraphs and sentences required from your OWN writing. You must at least consult three references to investigate about this topic and must list these three references (can include the video as one of them) at the end of your essay (use APA style)