Test My Theory: Macro evolution DOES happen?

[RoadRunner79]

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I agree with your extrapolation here, and I can add up the pebbles to get explain the final mountain.  I don't however feel that a skyscraper can be explained by the same extrapolation (especially if you are only adding pebbles).  I can take a number of steps down the road, and add those up, and I will reach the coast.  However adding up those steps doesn't get me to Hawaii or the moon.

The issue is not, that I don't understand the claim, but that I question the evidence and reasoning supporting it(or lack there of).  You need to connect the dots, from the small variations, to the quite different results that are being posited.  Why should I infer that this evolutionary change has taken place?

Since we're using analogies, consider microevolution as a ball rolling down a hill: at the top of the hill you've got the first generation of a given species, and at any point along the ball's path, you have another, descendant generation. Obviously, the ball is growing further away from the point we've designated as the first generation, just as each successive microevolutionary change alters the genetics further away from that first generation too. Inch by inch, we get further from what we originally had. But you, in this analogy, are standing at a point down the hill, in the ball's path, pointing a few yards yet further down the hill, and asserting that there's no way for the ball to roll to that point.

But from everything we understand about gravity and momentum, the ball will roll to that point assuming nothing stops it. From everything we understand about mutation and simple accumulation, successive smaller changes can be perceived as larger changes over time. For the ball not to continue rolling down its path, there would need to be some force acting against it to stop it. Without that, inches accumulate, and the ball continues to grow further from generation one. What is the force that will stop the evolutionary ball?

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Essentially what I'm asking is, why did you compare macroevolution to Hawaii and the moon? What is it that's making you assume that the "macro" destination is impossible to get to via the pebble analogy, instead of just something higher than the mountain is currently?

I'm skeptical, why should I assume that it does.   It is up to you, to show that the changes being posited are a result of the addition and combination of the very different changes that are observed. What are these small changes that you can demonstrate, that you think can make a fish walk out of the water and breath air?

Alternatively; rather than showing a reason through the mechanism to make the inference, you could show evidence that it has occurred (despite the ability to explain it).  I normally find that the evidence given assumes evolution, rather than demonstrating it.  That it is little more than this part looks much like this other part over here and since we assume common descent, they must be related (except when it does not fit the model, then this reasoning does not apply).  The data points for this connection is usually low and not always congruent across species, yet evolution is fact, so it must have happened.  But the question is... why is this a fact?

So, what do you know about laryngeal nerves?

The (recurrent, in humans and a lot of vertebrates) laryngeal nerve supports all the muscles in the larynx, and it's a homologous feature shared by most vertebrates. Everything from fish to humans have them, and the structure and purpose is largely identical, except for one key difference: see, in fish, which are more primitive in an evolutionary sense, the nerve simply travels in a straight line down into the larynx. But during the evolutionary progression that led to the development of necks in higher life forms, that nerve became "trapped" under the aortic arch, so that for us it travels down past the larynx, under the aorta in our chest, and then back up redundantly into the neck. Every vertebrate with both a laryngeal nerve and a neck has this, and every vertebrate with a laryngeal nerve and without a neck does not. This extends even to giraffes, where the nerve dips down fifteen feet to come back up, where a straight shot trip would be a couple of inches at best.

Why does this happen? Well, because the genetic plan for the laryngeal nerve altered slowly over time. As organisms evolved necks, they still had the genetics for the original laryngeal nerve, and with no way for it to magically pop into a better position, the nerve continued to grow around the aorta as it usually does, only lengthening to fit the new dimensions of the neck and thoracic cavity. This is a trait that we all share, because we all have the same genetic lineage, a common ancestor with the same nerve whose offspring developed very different neck plans, with that nerve being bound by the laws of physics to simply stretch to accommodate what it was inheriting, because it is an inherited trait.

Now, this is only one point of data, but the only way it makes sense is in light of macroevolution being true, at least in the sense that it's the most parsimonious explanation. Without that heritability there's simply no way that a giraffe would evolve fifteen feet of redundant nerve tissue where five inches would do, nor would that exact trait be held in common with so many other vertebrate species, but not in common with others in places on the evolutionary tree where that heritage wouldn't be an issue. It's a nice little single example to point to, to show that we actually do have a solid base in real biology to conclude that macroevolution is a thing.

I have read some on the laryngeal nerve.  There are four laryngeal nerves (a superior, and a recurrent for both the left and right side).  The recurrent laryngeal nerves starts near the heart from the vagus nerve, and does travel up opposite of the vagus nerve (hence the name).  The left RLV passes under the aortic arch as you state, while the right RLV loops under the subclavian artery (also near the heart).    Through this path, it innervates parts of the heart, the esophagus, mucous membranes,  the trachea, and a number of other parts of the throat and ends at the larynx.   The superior laryngeal nerves travel much more directly as you wish for the recurrent nerves.  There are also a percentage of people, who are born with a non-recurrent laryngeal nerve.  The do suffer some effects, from the condition (mostly minor, unless you have an inexperienced surgeon), but certainly not a better design and natural selection seems to take little notice.

Your source for the giraffe example, does appear to be confusing or including the vagus nerve which does travel down and which the RLN branches from in with the recurrent nerves to get it's 15ft allegation (if a giraffes neck is about 6 foot, and the nerve doesn't loop around a lot).  The RLN travels mostly up, not down and up.  I was curious, so I tried looking up info about the laryngeal nerves in fish.  Most of the info, was pictures or articles referring to something similar to your story.   They didn't include or mention  the laryngeal nerves other than to show the one of attention.  However I was interested, if they also had pairs, of both the superior and recurrent nerves?  It would seem to be difficult to apply the meaning of "recurrent" in fish.