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DD_8630
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It posits that all life on Earth today is ultimately related via one or a few very simple organisms. The evidence confirms that such an organism existed ~3.5 billion years ago.Possumburg said:If the ToE does not say that a single celled organism evolved into all the species we see today exactly what does it say?
If you have reproduction (be they self-replicating molecules or sexually reproducing elephants) with variation (i.e., mutation), then the theory of evolution explains the role of natural selection in guiding this population of reproducers to optimise their environment.Possumburg said:Almost every argument I see on here is basically "You don't understand the Theory of Evolution" So go ahead and tell me what it is all about then?
So you have these reproducers. The next generation will have a genome derived from their parent(s), and with some elements that have spontaneously formed.
Most of the time, these mutations don't do anything.
Some of the time, they are detrimental to the organism (they halt the embryo's gestation, make the organism unable to reproduce, make it susceptible to disease, etc).
On rare occasions, they are beneficial: they make stronger muscles or bones, they increase the speed of action potentials, etc.
These beneficial traits, by virtue of their benefit, quickly become widespread throughout the population after a few generations. This is evolution: the average genome changing over time.
Now, speciation occurs when the population is split into two groups by some barrier that prevents breeding between the two groups: a large river (as in Madagascar and Africa), extraordinary distance, etc.
When this happens, mutations from one group cannot pass to the other. Thus, over time, the two groups accumulate different mutations, and diverge in similarity over the eons. Eventually, if you then remove the barrier and put the two groups back together, you'll find that the gametes of one group no longer recognises the gametes of the other: their respective genomes are too dissimilar.
A single organism, yes, but not necessarily a single-celled organism.Possumburg said:So doesn't common ancestry imply that we all came from a single organism?
A crude way to put it, since it implies some form of goal-orientated progression. But yes, it explains how we get from simple replicators to complex replicators. The evidence tells us that these simple replicators were likely self-replicating molecules that existed ~3.5 billion years ago.Possumburg said:Which is that whole molecules to man thing again?