And you have to assume that half of the mutations are beneficial while the others aren't. And then that beneficial mutations actually win out and reproduce successfully.

k2aggie07 said:

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And you have to assume that half of the mutations are beneficial while the others aren't. And then that beneficial mutations actually win out and reproduce successfully.

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Where are you getting that percentage?

I made it up of course.

I know it's not binary, because mutations could easily be neither beneficial or harmful. But still, if you flip a switch at random it would seem that help or hurt would be 50/50 at best.

Just for reference - the number of nucleotide variations in any two "normal" humans is in the several of million

"Scientists using data from the 1000 Genomes Project, which sequenced one thousand individuals from 26 human populations, found that "a typical [individual] genome differs from the reference human genome at 4.1 million to 5.0 million sites affecting 20 million bases of sequence." Nearly all (>99.9%) of these sites are small differences, either single nucleotide polymorphisms or brief insertion-deletions in the genetic sequence, but structural variations account for a greater number of base-pairs than the SNPs and indels.

The 1000 Genomes Project Consortium (2015-10-01). [url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478][/url]

k2aggie07 said:

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I made it up of course.

I know it's not binary, because mutations could easily be neither beneficial or harmful. But still, if you flip a switch at random it would seem that help or hurt would be 50/50 at best.

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Would it be expected that the animals that were more likely to breed would be those with more than 50% 'good' mutations?

Yeah that's kind of what I meant. In super simple terms - lets say there are 100 mutations at random, 50 more useful and 50 less useful. Less useful includes anything that prevents reproduction, inviability, whatever.

Then of the 50 good ones, nature is a rough place. Even the best most suitable once in a million mutations may just die from dumb luck - a predator, a fall, a disease, who knows.

I'm not sure any mutation could be said to be neutral. Like you said, long term even an apparently neutral mutation matters. With the aid of hindsight you could probably classify all of them in a binary fashion.

Most mutations are much closer to neutral than anything. As you said, nature is rough, having a defection won't tend to propagate long or at all if it's significant.

Martin Q. Blank said:

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Chimps are our nearest living relative, correct? If I'm reading this correctly, 35 million single nucleotide differences and 90 million base pair insertions and deletions.
http://genome.cshlp.org/content/15/12/1746.full

The supposed "split" occurred 5-7 million years ago. So that is a rate of 5-7 single nucleotide differences and 13-18 base pair insertions/deletions per year. Do we observe this rate of change today in mutations?

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I think that your math is off. Divide by two.

The human/chimp divergence is the last common ancestor. Both branches continued to evolve/mutate thereafter, so it is reasonable to assume that half of the mutations occurred on each branch.

Which human?

I'm more interested in know why some things became plants and other things became animals.

I was being a bit more theoretical than that.

I get that there are basically inconsequential changes on the macro scale. What I meant was, with perfect knowledge (let's say we can look back at the branching of every mutation and the result) nothing will truly be neutral. A bit too philosophical, probably.

Even so, if that mutation has no effect in isolation, it may ultimately result in an accumulated change. That's what I'm getting at.

Yeah, it was an arbitrary assumption for simplicity's sake. I think it's probably bounded at the positive end at 50/50.

Even if it's not an amino acid change, it may effect regulation on the DNA or RNA level. Of course there is also a lot of DNA that never gets transcribed so mutations there may truly do nothing.

AstroAg17 said:

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What you said earlier about mutations being equally likely to help or harm isn't correct though. Mutations are much more likely to be harmful and decrease fitness. Orders of magnitude more likely, I think.

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You are incorrect. Most mutations are neutral

I sincerely doubt chimpanzees/apes evolved over a period of time to acquire the ability to reason or have self-awareness or creativity or develop a concept of law as homo sapiens have.

There are a lot of correct statements that can be made on this subject, that are none the less confusing.

There are 3 billion DNA base pairs in the human genome (give or take)

Most of that DNA doesn't get translated into protein.

Because of the degeneracy in the genetic code, a lot of mutations even in protein coding sequences won't result in changes in the amino acid sequence being changed.

Having said all of that, a mutation that does result in an amino acid change is much more likely to be detrimental than positive.

(Caveat inside a caveat, sometimes a detrimental mutation still provides a fitness advantage in certain circumstances. See: sickle-cell anaemia)

Of course, the DNA in your genome doesn't just make proteins. Lots of DNA is regulatory and lots gets turned into all sorts of RNA. So mutations there can have a big effect too.

But none of the above matters at all unless the piece of DNA that gets mutated is under selection pressure. Since any two healthy people on earth will differ by millions of base pairs, clearly not all DNA is under selection pressure at all times.