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Mooby



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What really amazes me is how these complex cells made both male and female versions of every species.
They didn't.  There are many, many species out there that do not have male and female cells, and there are many out there that have both cells.

It has taken a million years to make a male...we really have no clue , just a example.

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Then this complex cell finds another complex cell that has created a female....but wait, did these complex cells happen at the same time ?

One would certainly die before they could reproduce if ether had to wait a 100 yrs or more, and this has to happen for every species.
Yes, things would certainly be different if every organism had to reinvent the wheel.  Luckily, this doesn't happen.  When one fish species splits into two new fish species, they don't have to reinvent gills, and when one bird species splits into two new bird species, they don't have to reinvent wings.  Similarly, not every species had to invent male and female cells (gametes.)

One of the biggest drivers of evolution is natural selection, which favors organisms that are better suited to their environment.  Because of this, the more options that are available, the better the odds are that one group of options is the best fit for that environment.  Mutation is one way to create new options, but it only does so one option at a time.  By combining our options, we can make a spectrum of options.

For instance, if we start off with blue paint, and then a mutation gives us yellow paint, we only have two colors: blue and yellow.  However, if we're allowed to combine those colors, we can make a spectrum of colors in various shades of blue, green, and yellow.  If our environment likes sea green, we're more likely to approximate that if we can combine.

So then how did organisms start combining?  If we made it mandatory from the start, then how would the first cells combine?  For it to even work at all, it'd have to be optional.

And that's exactly what we find.  There are bacteria that can either reproduce by themselves or combine material with other bacteria, in a process known as conjugation.  This process only requires one cell to be "equipped" for mating, which means our cell doesn't have to "wait" around for other cells to evolve this process!

As for male and female gametes, there are primitive creatures that make both gametes, and have them combine on the same organism.  So they mate with themselves to provide different variations of their own genes.  This is a step up from conjugation, but a step down from true sexual mating.

Going another step up, there are creatures that produce both gametes but mate with each other.  Earthworms are a prime example of this.

And then, another step up, there are creatures that only produce one gamete.  This appears to be the ideal as it shows up in higher order organisms, likely because it prevents self-mating and thus maximizes diversity.

So when we look at the history of mating, it appears that this is a gradual process that became more distinct as organisms evolved, rather than something each species learned overnight.
Changed Change Reason Date
Quesi what mooby said June 25, 2012, 08:56:00 PM
wright for a clear, courteous explanation to a very ignorant question June 25, 2012, 08:56:37 PM
Astreja Excellent, very readable explanation of reproductive biology. June 25, 2012, 11:45:59 PM