how life began
why is there life in the first place you ask? i'd say it really has a lot to do with evolution. in evolution, mutations happen that are either beneficial or detrimental to the mutated organism's ability to survive and breed. if it survives and breeds better than the other members of its species than its mutation lives on. and obviously if its mutation is detrimental it does not survive into the next generation.
on earth long ago some chemistry started to happen in the soupy mixture that covered the planet. a little bit of this and a little of that mixed together and formed a simple little thinga-ma-do-dad. in fact, this mixture probably made a lot of thinga-ma-do-dads of all different sorts. but as easy as this, only the thinga-ma-do-dads that could replicate themselves went on to make more of themselves. all the other lumps stayed lumps and eventually disintegrated back into soup. but for the thinga-ma-do-dads that could replicate themselves they too eventually disintegrated back into the soup but before they did they tried to leave a copy of themselves.
why did they want to leave a copy of themselves? it was just the way their mixture worked. some mixtures make glowing light sources, some make tastey sweet breads, and others just happened to make copies of themselves. it is just a random thing.
but these copies were not always perfect. the imperfect parts of the copy were mutations. these mutations either helped or hindered the thinga-ma-do-dad. these mutations eventually led to more complex thinga-ma-do-dads. different thinga-ma-do-dads even had different mutations that worked out to its advantage. thus came different species of thinga-ma-do-dads. some were good at one thing while another was good at another thing. so on and on this went with imperfect copies either being successful or not.
and so here we are today just mutations of some thinga-ma-do-dad that was created when something floating around in the primordial stew bumped into and mixed with some other glop floating around. or more simply stated... "you put your chocolate in my peanut butter!! you put your peanut butter on my chocolate!! two great tastes that taste great together."