Are there evolutionary reasons for reproduction?

"Microevolution" doesn't require any loss of genetic material. You can have exactly the same number of chromosomes, which are just shifted around the place; you could have one gene location removed and another doubled to take its place; you can have insertions that result in more genetic information within one subspecies compared to another; you could have two subspecies that both get insertion mutations but in different places.All of those (can) lead to separation into subspecies. All of them exist in addition to and beside deletions (lowering of information content). All of them are microevolution. Macroevolution is merely accumulated microevolution over time. As to the bit after that: microevolution is evidence for microevolution. The fact that it occurs is how we know it occurs.Now that we've dealt with the "information only decreases" and "macroevolution doesn't exist" PRATTs... What is water made of again? Oh, that's right: almost 90% oxygen by mass. And yes, the reactions would have initially occurred entirely submerged in water, just like a majority of all reactions in the body do now. And no, that is absolutely no barrier to the formation of complex molecules* let alone simple ones. Why is phosphate's presence a problem? This from one paper, found in a Google search for "volcanic phosphate":

quote:

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This paper reviews the literature related to total and organic P (Po) levels present in both agricultural and forest soils from southern Chile. Different reports have demonstrated the high contents of total P (Pt) found in agricultural soils (1,000-3,000 mg kg^-1) even in unfertilized soils.

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emphasis added
  —"Borie & Rubio"

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From what else I could find on the subject, this is typical of any region with volcanism; more of 'this' and 'that', a little less of 'these' and 'those'.
So, volcanic soils and assumably other volcanic material contains phosphorous/phosphate in relatively large amounts.
AFAIK the most popular hypothesis for where life started was deep ocean, in areas with high volcanic activity. Meaning lots of heat and lots of stuff that life needs.Which means that your statement viz. 'either way, no life' is based on erroneous information. The opposing statement, that "life could have arisen on its own" AKA abiogenesis remains very much a possibility that fits within the data available.Any support or criticism of the above analysis welcome, provided it's based on facts and not "nuh-uh!".

Because the vast majority of oxygen was stuck in things like water and carbon dioxide. There was very little if any atmospheric oxygen, meaning oxygen in the form of O_2(g). We started with an atmosphere of lots of carbon dioxide, and very little if any oxygen gas - we can see this from the effects of atmospheric oxygen on things like iron and uranium deposits (because oxygen oxidises iron, and it allows water solubility and thereby transfer of uranium; neither occurs until a certain point in the geological record). Once "plants" got reasonably established, they started to convert that carbon dioxide to oxygen.That equivocation on what is meant by "oxygen" is what may have confused you there, I think. As jar pointed out, it doesn't. The water at the deep vents has oxygen, just like water everywhere. Thing is, it's dissolved at somewhat low levels. Hence the mammal inability to breathe water, and why fish use gills. But this amount is sufficient for many reactions to take place over time, and hence there is no problem from the abiogenesis angle.Edited by Nij, : No reason given.