The necessity of genetic similarity

This may seem like a silly question, I’m not sure. But I’ve been thinking about the genetic similarity between living things, for example us and chimps, and wondered whether this similarity is in some way necessary? I ask because it’s often argued that similarity at the genetic level could just be explained by common design (a Maker’s mark, if you will) but to me this implies some sort of necessity - “Of course we’re all similar, we share the same Maker!” But is this the case? Do humans and chimps, for instance, have to be nearly identical at the genetic level or is this the case precisely because we do share a common ancestor?

I’m not a scientist, but there are certainly features that less related animals have and appear the same but are genetically different, while closer related animals are genetically the same.

An example off the top of my head would be the broken vitamin C gene. It’s broken in one way in most primates (not broken in lemurs, whose common ancestor is farther back), but it’s broken in a different way in Guinea pigs and fruit bats. So the gene broke in different ways at different times, causing the affected animals to need to consume a vitamin C source for survival.

You could also look at birds and bats. Both have wings for flying. They evolved in different ways and thus have different genetics. Same function though.

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Thanks for the reply :slight_smile: I understand pseudogenes and so on. My question is simply about whether it’s in some way necessary for us and chimps to be genetically similar, or whether this is so because of common ancestry.

Interesting thoughts. Of course, having to be genetically similar in order to have similar morphology and common descent are not mutually exclusive, so it would not really support ID or progressive creation to argue that it is in fact the case. A book that explores that a bit is “Life’s Solution” by Morris. He essentially argues there is only a limited number of ways to get there from here, so we have to follow the same path most of the way.
Of course, another question to ask, is why are there monkeys? If common descent is wrong, why are there animals that appear to have come from the same linage? There is no good reason the world needs chimpanzees, and the vast majority of earth gets along just fine without them, so why would God create them? Just to make it look like we were related?

I don’t see any reason for it to be required that we’re genetically similar, since there are often multiple ways for a feature to occur, as I mentioned.

In forensic science we use the grooves on bullets slugs to identify the gun which they were fired from and we use fingerprints to identify the person who last touched the object. Why? Can we not argue that the similarity of bullets or fingerprints is just because these guns or people were made by the same creator? The question is where do such differences come from? Just as in the case of fingerprints and grooves on bullets we have learned that a large portion of DNA serves no function and thus have nothing whatsoever to do with the operation and functionality of the body. Therefore to say that these reflect the similarity of purpose for which the body was made simply doesn’t make any sense. The only reason for them to be the same is because they were inherited from the same ancestors.

Thus the argument really comes down to intentional deception on the part of the creator. It is like a criminal wearing fake fingerprints covering their own or altering the barrel of a gun to match the groves on another. These things are certainly possible but both are only done in order to deceive people into believing something which isn’t true.

I cover this question in-depth in Adam and the Genome, FWIW. :slight_smile:
Short answer: no, we do not need to be as similar as we are.


And an article written by @DennisVenema as a teaser:


I definitely need to read the book at some point!

Thanks Matthew. I had read this but had forgotten it discussed my question, so thanks for pointing it out!

There are only a limited ways of achieving anything So similarity can be as much a symptom of necessity as design. The so called 2% difference between chimps and Homonids is still a very substantial difference in reality. Even if Chimps have the capacity for complex language they do not necessarily have the physical dexterity to form all the phonics. Nor the morality or Sentience that distinguishes humanity from the rest of Nature (apparently)
If you take the automobile as an example. Its origins can be traced back as far as the first carts or even the wheel, but, in the developmental process (its Evolution) there are places where the changes are too great (complex) for the evolutionary model of change to accomplish. The difference between a Steam engine, Petrol engine and Diesel might equate to the differences between Amphibian, Reptilian and Mammalian systems. Yes there are similarities but Evolution could not accomplish the vast differences, without help from God.


I see more similarity between a steam engine and a gasoline engine than differences. Both have crankshafts, rods, pistons, cylinders, valves, etc.

Welcome to the forum, Richard! We look forward to hearing your thoughts! It appears you lean towards the ID side of things, which is fine. I think many here who are in the EC camp lean that way philosophically, though feel the science is just not there. In any case, your statement regarding similarities may be by necessity as much as by design, can be used for to support either evolution or design and of course evolution can be the means by which God designs.

The analogy of biological evolution to automotive evolution if often used, but while superficially attractive, falls apart in many respects when pressed as the process is quite different. Still, there are certain similarities with selection pressure, extinction and so forth.

I think there is enough science and visible reality to rule out Genesis 1 as history or fact. The basic understanding of light and the nature of the sun and moon, plus, of course, the dome over the earth. But, I guess, if you believe in God then you will expect Him to have created the Heavens and the Earth one way or another.
As for the amount of Science… We are still learning, obviously, but Science will not be looking for the God connection. Until, or unless God is proven, science does not have to consider Him. I look at the evidence for Evolution and see things are almost irrefutable but, if you take out chance and insert parameters and Specific creations then the basic Evolutionary model becomes viable.


But we have good reason to believe that this has more to do with inherited information than with necessity. Occasional examples outside the usual box like the mazda rotary engines which do not use pistons show that things can be done very differently.

While there are a limited number of ways of achieving anything, that limited number can be very large indeed. In the case of biological systems, it is. Take the DNA coding for a protein that is 100 amino acids in length. There are on average roughly 3 different functionally identical ways of encoding each amino acid; that means there are ~ 3^100 different DNA strings that encode the identical protein. There is no functional reason why such sequences should be more similar between humans and chimpanzees than between, say, humans and orangutans. But they are.


I am not talking about the mechanics of achieving the results. Obviously there is one system that covers everything. That is just logical. The DNA / Gene system is universal is it not? Just because you re using Lego does not mean that the building and the tank are related.

You need to see past the building bricks. What matters is the resulting organisms. You can build anything from a single cell, but it is more difficult to change from one type to another, which Evolution claims to do. It is much more likely that each basic type has its own hereditary rather than evolving via something else (equals God made each to its kind) Evolution, in the form it is presented, cannot bridge from one developed mechanism to another. In reality an Amphibian is as much specialised and highly developed as a Reptile or a Mammal. The system works. To change from an amphibian to a reptile involves devolution before it can re-evolve. Random chance cannot do that. It would involve planning and development, which is a conscious process. Evolution relies on a change being useful in its own right. Feathers are primarily for flight, but they are useless if you do not have the metabolism, weight ratio and other mechanisms needed to fly. The whole notion that dinosaurs could just sprout feathers for display or recognition show a lack of basic understanding. Feathers alone would not provide enough advantage to become dominant.
TOE ignores the complexity problems and the physiological integrations of each type of creature (or plant). It is almost as if they forget, or never learned basic physiology and / or ecology.
The world has balance and self healing properties that bely a random construction. And when you start looking at interdependences of creatures and / or plants it becomes very clear that it is beyond the scope of the basic evolutionary process. The “jumps” or “changes” are too great and too complex for the “simple” deviations of the evolutionary process.
I look around and see a creation, not a random construction.
That is not to say that the Evolutionary process does not exist, only that it needs a controller, or guiding hand, AKA God.


You don’t have to be genetically similar to have similar morphology. Not all genes control morphology and only small parts of the genome do.

I’m not talking about the mechanics of achieving a result either. I’m talking about the subject of this thread: whether functional similarity or common design between species necessitates genetic similarity. The answer is no.

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A whole of assertions there with no science to back it up.

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