Comparative anatomy also becomes a non-issue today as an argument in favor of Darwinian evolution.
This issue only has relevance if we start with the materialistic program of small-step, continuous biological development, one new and different cell-type at a time.
Once we admit into the discussion the evidence of forward leaps in nature that produce end-point fit and function at the first introduction of new architectural body-plans and lifestyle habits, this requires blocks of new and different cell-types in grouped clusters that in practical terms transcends above materialistic causations.
That Darwin would propose the comparative anatomy of similar features as an argument for gradual continuity reveals a mindset limited to the factors of distance traveled in terms of beneficial features, divided by measurable time within our four-dimensional reality.
This approach will not allow for the possibility of blocks of cell-types in grouped clusters as the explanation for the vast diversity of life, because this entertains the input of information by a timeless Mind/Being who can only be identified through circumstantial evidence, curiously being the same type of evidence introduced by Darwin to make his case for macroevolution.
Adding blocks of cell-types in grouped clusters still maintains true relationships, just not according to the worldview of naturalistic materialism.
As has been said elsewhere in this book, adding new genetic information in blocks of grouped clusters to effectuate fit and function, is entirely consistent with common descent, just not in the universally connected sense required by naturalistic materialism.
The accurately generous thing to say about Darwin’s use of comparative anatomy as an argument in favor of macroevolution is that it was close but still off-target.
The same can be said for many scientific hypotheses at their inception.
Today we can save ourselves a lot of time by side-stepping all of the arguments put forward in the last 160-plus years of Darwinism regarding the importance of comparative anatomy…either confirming or not confirming the small-step, gradual continuity of common descent.
Agatha Christie may type her book Murder on the Orient Express one letter at a time, but her daily writing output of 500-1,000 words or more is created as a block of grouped story-telling information.
In tract housing construction, the first-floor wall framing proceeds one 2×4 stud at a time, but daily progress is evaluated on the number of houses having the first-floor wall framing completed as a grouped output.
When we look at the natural living world, why would we not recognize the same presence of intelligent designing agency in a functioning elephant that we acknowledge to exist within an automobile driving past us down the road?
The comparative anatomy of similar common features has nothing to say whether common descent was achieved one new cell-type at a time, or by blocks of new and different cell-types introduced in grouped clusters.
The similarities in DNA that show commonality between living organisms does not explain the organized complexity of DNA or the origin of this information content.
Similarity does not arbitrate between Darwin or God.
Darwinists still today confuse the evidence of similarity as an explanation that supports macroevolution, when similarity can just as easily be spun into an equally compelling case for intelligent designing agency.
These are competing inferences to the best explanation, and cannot be hijacked by scientific materialists into the camp of Darwinian evolution without facing the push-back of critical cross-examination.
The Principle of Mediocrity
Another old question that can be clarified through the critical analysis of equally competing skeletal explanatory frameworks, is the notion popularized by Carl Sagan in his book The Pale Blue Dot, coined as the Copernican Principle or the Principle of Mediocrity.
The Principle of Mediocrity says that because the earth is smaller in size compared to the vastness of the cosmos, that simply because our earth is inhabited by humans, it nonetheless merits no special significance in the universe.
To paraphrase, Carl Sagan said that our earth was a small speck in the great cosmic dark, enjoying no special or preferred place in the universe, the essence of the concept of the Principle of Mediocrity.
The arguments unwinding this concept begin by saying that the universe has to reach its current size in order to have a large enough sample-size of rapidly receding galaxies to mathematically calculate in reverse-time going backwards, to precisely pinpoint an accurate average of 13.7-billion years ago for the Big Bang beginning of the universe.
The relative ratio between a hypothetically smaller universe and a larger earth would not improve the accuracy of these calculations, and are therefore seen as being irrelevant in determining the importance of the pale-blue dot of earth in terms of its relative size.
The vast size of the universe appears not to be an impediment in calculating a beginning point in time for the universe…the Big Bang being an extremely important scientific discovery.
This line of reasoning would be easily recognized by a cosmologist or astrophysicist.
Having this starting point in time established, we can ask some hypothetical questions relating to this supposed issue of mediocrity.
After the first billion years of the existence of the universe at 12.7 billion years ago, would our Milky Way galaxy exist and how far along would its development be in terms of going from chaos to order?
Could an early universe that had expanded to roughly 7% of its current size (using a linear expansion of 13.7/100 = 7%) be able to produce our Milky Way galaxy to the point where our galaxy would then be able to produce and sustain our solar system and planet earth?
The beginning of the universe at 13.7-billion years ago minus the beginning of the earth at 4.5-billion years ago, equals roughly 9.2-billion years of the expanding universe before our local solar system and earth are formed.
The time-period of another 4.5-billion years of expansion occurs before humans come along and begin to investigate the natural world through science.
If time and space were compressed to make the earth “more significant” in terms of relative size compared to the universe at large, would we still have an earth located within the dark space between two spiral arms within the comparatively safe “goldilocks zone,” a little more than half-way out between the center and the outside edge of the Milky Way galaxy?
Would we have the clear atmosphere of the earth to explore the cosmos through telescopes and outer-space probing satellites?
Would an initial expansion rate of the universe that was less than it was at the Hot Big Bang produce the enormous universe compared to the seemingly insignificant planet earth, having all of the right proportions, sizes, and fine-tuned constants in the laws of physics?
The precisely accurate mathematical calculations fit together like a Swiss watch, including a definitive starting point in time for the beginning of the universe.
Carl Sagan saying that our earth is mediocre within the grand scheme of things, because the worldview of scientific materialism has no place for intelligent agency and thus no purpose or meaning in the universe, is a totally philosophical assumption.
It is an expression of his opinion.
It has no empirical support coming from the fact-based evidence of science itself.
We could ask what alternative size and scope for the universe would provide an equal quantitative and qualitative sample-size to produce the current accuracy of our determinations of the laws of physics, and the characteristics of the fundamental elements of the Periodic Table.
There is a host of reasons why the Principle of Mediocrity is no longer valid, beyond the scope of this book (see the book Why the Universe Is the Way It Is, by Hugh Ross, 2008).
Finally, the recent scientific understanding of how the earth and its moon came into existence, of a Mars sized planet colliding with an originally smaller size earth, creating a larger size earth and its orbiting moon, is anything but mediocre.
 Is Atheism Dead? A Conversation with Eric Metaxas. Premiered Oct. 6, 2021 on You Tube, Dr. Sean McDowell.