Controversy of Human Taxonomy

This is an admittedly academic topic with few real world implications, but it is something I've devoted a lot of thought to anyway. Our place in nature is an intriguing scientific and moral question to consider.

The appropriate place to start is a discussion of taxonomy. Taxonomy is how we classify species. The premise of taxonomy is that we group species hierarchically based on how similar they are.

However, this raises the question of what we mean by similar. Do certain characteristics take precedence over others? Why?

The point is that grouping species together simply because they happen to have anatomical similarities carries a bias; it isn't objective, and it may not actually "tell" us anything about the relationship those species share. It is, in a single word, arbitrary.

For example, should a whale be classified as a fish since it swims or a mammal since it has mammary glands? Should bats be classified with the birds because they fly?

There is one sensible (i.e. objective) way to group species, however, and that is based on their evolutionary relationships. Evolutionary relationships reflect genetic similarity, which is an objective measure that actually tells us something meaningful about the species in question.

Applying this kind of taxonomy, we know to classify whales as mammals, and an analysis of their DNA confirms this. It isn't arbitrary at all.

Aside from the fact that whales being mammals is pretty dang cool, this isn't really a big deal. It isn't scientifically or morally controversial.

But that changes when we talk about humans.

Even before the theory of evolution was formulated, taxonomists knew to group humans with the primates. Within this order, it was also intuitive to say we had more in common with the great apes than the monkeys. But it is molecular data that revealed the real shocker . . .


Great Ape Phylogeny. Learn to interpret these
correctly for your own sake!

An analysis of the genes of these species has shown that humans and chimpanzees share more DNA in common than either does to a gorilla.

Intuitively, this makes very little sense--how can it be possible? In so many ways, we are not like them. Culturally, we developed agriculture, sophisticated technology, language, and inhabit the entire globe. Biologically, we've lost our hair, walk on two legs, and have a plethora of a other unique physical characteristics--even with respect to our closest relatives.

How such a small difference in DNA can account for such significant phenotypic differences is a question that boggles the minds of our best scientists. Yet the data itself is well established.

One implication of this is that it makes no sense to call Orangutans, Gorillas, and Chimps "apes" unless we also are willing to adopt that name for ourselves. In fact, we cannot legitimately apply ANY scientifically meaningful label to chimps and gorillas unless we apply it to ourselves as well because humans and chimps share a more inclusive relationship (note in the figure above that the lineage that led to Gorillas diverged before the lineage that led to either chimps or humans).

Some scholars (like Jared Diamond*) go even further. He notes that the genetic difference between humans and chimps is smaller than that between some species that are classified under the same genus (he cites lions and tigers as an example--so, unbelievable as it may seem, the genetic difference between a lion and tiger is greater than between a human and a chimp). Thus, he argues that chimps should really be called "Homo Troglodytes."


*Jared Diamond's book. An excellent and highly
recommended read, although I have a problem with
the cover art since it invites the misconception that
humans evolved from chimps

Of course, there is disagreement with this perspective. My "Primate Behavior" professor, for example, sees no problem with dividing a humans and human ancestors from the rest of the great apes (referring to the former as "hominins and the latter as apes). He believes there are sound scientific and moral reasons for doing so.

I have tons of respect for this professor. He is a great teacher and well known in his field (he is the head of the Harlow Laboratory, the lab that pioneered the famous study that demonstrated a Macaque would choose nurture over nourishment, drastically altering our perspective on parenting.)



And on one level I agree with him. Humans are very clearly different than the other great apes. We are special. And our big brains and bipedal nature are fairly reasonable phenotypic markers of this difference.

Yet, if we believe the molecular data, the distinction remains entirely arbitrary. There is no way around it. I think it is justifiable (and useful) to use the term "ape" informally to refer to Chimps, Gorillas, and Orangutans, but we should never be fooled into thinking it "means' anything. Apes cannot represent a clade unless that clade includes us.

This situation should highlight the inherent bias of taxonomy (even among scientists). For my own part, I try to compromise. I do think we must consider ourselves "apes" (and if we find the connotations of that term offensive, then we should devise a new term). However, unlike Jared Diamond, I do NOT think we need or ought to include Chimps in the genus Homo. Evolutionary relationships are an exact science, but the definition of what constitutes a genus is not. Since we don't have an exact definition of "genus," it is reasonable to "fudge" it a bit to accommodate our anthropocentric view of the world.

What do you guys think about this? For the record, I don't expect many replies, but I hope at least some of you got something out of the above and give it some thought . . .

I'm by no means a biologist or taxonomist, so I really can't comment in too much depth, however, I do think that the natural human perspective of what constitutes an 'ape' and what does not is not completely objective. It is natural for us to see more similarities between chimps and orangutans, for example, then between ourselves and chimps. Where we can see the minute differences between any two humans (usually), it's much more difficult for us to see the differences between animals outside of our species, as this ability hasn't really been evolutionarily relevant.

So yes, if we look at these species completely objectively than humans must be apes.

Chimps are interesting animals. They have complex social structures, and have their own technological developments, much like humans.

Chimps are interesting animals. They have complex social structures, and have their own technological developments, much like humans.

Yes. Chimps are the only species aside from humans that can be said to possess a rudimentary "culture." Tool use in chimps is not innate. Of course, a sophisticated brain is a prerequisite, but "termite fishing" and "nut cracking" is not an innate behavior (like a bird building a nest).

The best definition of "culture" is learned, shared knowledge. Once a chimp "discovers" a behavior, they can transmit it to their social group from generation to generation. Consequently, different chimp groups have different "cultures" (some know the nut cracking technique while others do not).

In fact, the discovery of tool use in chimps has forced us to redefine what it means to be human, since tool use was once thought to be exclusive to us.

I'm going to have to agree with you on not including Chimps the "Homo" genus. From what I understand, the fundamental difference (other than appearance) between us and the Chimpanzee, is the way our two species learn.

As far as Humans being given the classification of ape. I though we already classified ourselves as "great apes"?

Originally Posted by Eternal Paradox

I'm going to have to agree with you on not including Chimps the "Homo" genus. From what I understand, the fundamental difference (other than appearance) between us and the Chimpanzee, is the way our two species learn.

Yes. We are in agreement here, even though it remains challenging to justify (so keep in mind that in what follows, I am simply playing devil's advocate, trying to illustrate the dilemma of taxonomy)

You brought up that chimps and humans learn differently. Surely this is true. But is it reason to divide them into separate genera? Do we divide other species on this basis?

If it is in fact true that we share more DNA in common with chimps than tigers do with lions, and lions and tigers are placed in the same genus, doesn't that mean we should be placed in the same genus with chimps?

Again, keep in mind that I don't actually believe we should. But it is a very hard position to justify without being arbitrary, anthropocentric or inconsistent.

As I pointed out in the original post, the "escape" from this problem is the fact that "genus" does not (at this time) have a precise meaning. If we did give it a precise meaning (as in, if you share X amount of DNA in common, you're in the same genus) then we would be required to place chimps and humans together (or place lions and tigers into separate genera).

As far as Humans being given the classification of ape. I though we already classified ourselves as "great apes"?

There is dispute and confusion. In an informal context, "ape" usually refers to Orangutans, Gorillas, and Chimps (in fact, many people will erroneously refer to this group as monkeys).

But there are varying interpretations even among scholars. My professor, as previously noted, is very respected in his field and fully embraces evolution. But when it comes to taxonomy, he draws a line between "apes" (orangutans, gorillas, chimps) and "hominids/hominins" (humans and human ancestors). He argued that there were scientific as well as moral reasons for this perspective.

However, as I argued, dividing humans from the other apes is not consistent with a taxonomy based on evolutionary relationships. You could divide humans and chimps from gorillas and orangutans, but you cannot divide gorillas and chimps from humans; the molecular data simply does not support that.

Well as far as sentience and cognitive ability goes, I don't think chimpanzees (and other apes) are actually as different from human beings as they might first appear. Recently, one chimpanzee at a Swedish zoo was observed hoarding rocks during the morning, and then waiting until visitors to his exhibit arrived later in the day before hurling them at the guests and driving them away. This demonstrates that they are indeed capable of making connections between events in the present and future, and can plan accordingly.

Furthermore, some apes have been observed using tools in a rather innovative manner. For instance, I remember observing a video of a gorilla wading through deep water - it was using a stick to prod the ground in front of it, thus avoiding any sudden drops in depth. Furthermore, chimpanzees in the Fongoli savannah actually sharpen their sticks and fashion them as weapons against their prey. Sound familiar?

I think genetics are a more reliable way of diving animals into different classifications, rather than behavioural or physical traits. For instance, consider the Caspian tiger. A subspecies of tiger once predominant in central Asia and the Middle East, it was thought to have gone extinct in the 1950s. These tigers were slightly smaller than Bengal tigers on average. However, recent genetic analysis has confirmed that they were not really a subspecies in their own right, but actually just a subpopulation of the Siberian tiger - a subspecies that is on average the largest of the tigers. The separation of the two groups is thought to have occurred as little as 100 years ago due to human intervention - and in that short span of time, the physiology of the "Caspian" tiger had already changed, so that it was rather smaller than its northern cousins, with marked differences in its fur length and stripe pattern. I think that this demonstrates that classifying an animal species or subspecies based on its physical appearance or biological behaviour along can be extremely misleading.

Originally Posted by Asta

This demonstrates that they are indeed capable of making connections between events in the present and future, and can plan accordingly.

Apes (but not monkeys) have also been shown to have a concept of self. Show them a mirror and place a dot on their head, and they are able to point at the dot, which indicates that they understand the image they see is themselves.

Furthermore, chimpanzees in the Fongoli savannah actually sharpen their sticks and fashion them as weapons against their prey. Sound familiar?

That must have been a recent find, because I've never heard anything like that and almost find it hard to believe.

Behavior like that makes me wonder . . .

If humans suddenly went extinct, how likely is it that another species would fill the "cognitive niche?" This is one question that we can never know, but my own personal belief is that given enough time, it is almost inevitable.

A similar (and equally fascinating) thought experiment is to ponder what would happen if life on earth was "rerun" from the beginning. Just how "unlikely" is the biosphere we inhabit?

I think genetics are a more reliable way of diving animals into different classifications, rather than behavioural or physical traits.

That was one of the main arguments of my initial post. Using genetics ensures objectivity, consistency, and power (in the sense that it actually tells us something, whereas taxonomy based on shared characteristics is arbitrary).

Switching between these two styles of taxonomy causes confusion. The traditional taxonomy groups the three apes together and apart from humans. This is a common sense division for anyone to make if they are unaware of the molecular data.

That's what I don't understand about my professor's perspective. As we surveyed the primate order through prosimians, monkeys and apes, he endorsed evolutionary taxonomy. But once we came to humans, he switched over to taxonomy based on characteristics. The only thing I can chalk this up to is anthropocentrism.

The fact of the matter is that many people, even intellectuals, find the notion that we are just another ape offensive. They want to reserve a special place for humans.

I don't think there is anything wrong with that, but it is very, very hard to justify in light of the evidence.

Which brings me back to an earlier question; just how is it that humans are so different? While I am totally fine accepting the conclusion that humans and chimps share more DNA than either does to a gorilla, the phenotypic expressions of these genes still confuse me profoundly.

Chimps and gorillas have thick hair that carries their entire body. Humans don't. Chimps and gorillas are knuckle walkers. Humans walk bipedally. A human brain is three times as big as a chimp brain. And then there is the whole development of advanced culture (which must have genetic underpinnings). Yet we are to believe that the gorilla is the out-group!

The million dollar question is how less than a percent change in DNA can account for the massive difference in phenotype. Something truly profound happened to humans in the six million years since they diverged from the chimp lineage. Scientists still don't know what that "something" is . . . Here's hoping to a good answer in the near future!

That must have been a recent find, because I've never heard anything like that and almost find it hard to believe.

It was fairly recent - 2007. Here's a link: http://www.newscientist.com/article/...ushbabies.html

Apparently, the chimps were observed using their teeth to sharpen the ends of branches, turning them into crude spears, and then jabbing them into holes containing bush babies.

Incidentally, about the apparent physical differences between humans and the rest of the apes, despite being genetically so similar: how big a role do you think neoteny has played?

Originally Posted by Asta

Incidentally, about the apparent physical differences between humans and the rest of the apes, despite being genetically so similar: how big a role do you think neoteny has played?

That is not something I have ever studied in depth. It was briefly mentioned in both my biological anthropology and primate classes, but never explored in detail.

In both classes, it was presented as a possible explanation, but both professors emphasized that it was only conjecture for now. In the anthropology class, we compared a chimpanzee infant skull to an adult human skull, noting how both were flatter than the adult chimpanzee.

Out of curiosity, how would you test the degree to which neoteny played a role?

You questioned how such a small change in DNA can account for the drastic change of phenotype. DNA plays the role in cellular production of proteins. There is a grow consensus that it might not be as essential to life as it was once thought. Genetics is a funny thing, different equestrian and feline species can produce sterile hybrids when they mate.

Horse + Donkey = Mule
Tiger + Lion = Liger

But then there are canines. Dogs, wolves, foxes, coyotes, jackals...Dingos can all cross breed and have viable offspring.

Perhaps where the DNA code differentiates matters as much as how much it differentiates. A glitch in the just the wrong place can result in cancer after all.

On another note, it is a fallacy of creationists and egotistical intellectuals to assume that every scientific discovery must have a moral connotation to it.

I'd like to point out that the human body also shares DNA with bananas. Something like 60% of our DNA, as a matter of fact, is shared with bananas. By contrast, even very visibly different races within humanity have less than a fraction of a percent of a percent of difference. Saying we are apes because we share DNA with them is well and good, but I imagine lions share quite a bit of DNA with wolves. That doesn't mean they had the same ancestor (though if I remember my evolution tables correctly, that's what's believed). It's entirely possible that the entire line of thinking is entirely flawed and that similarities can be attributed to something else.

I'm not a scientist. I don't know. If I were to hazard a really off-the-wall guess, though, I'd say we share the same planet, the same general environment, and the same basic needs. The differences between fish and humans seems really big, but we're all made of the same basic components. It seems to me that if she share similar or identical environments with something, it simply makes sense that our evolutionary patterns would have similarities as well. That doesn't mean, however, that we came from the same place. Maybe chimps were tadpoles and we were shrimp. My point is that we don't know.

We never will know. Knowing will never be applicable to anything. If it's not applicable to anything, it's not useful for anything.

Honestly, is this "serious" discussion at all, or just hot air passed around like a bong?

one must realize that a significant part of our genetic structure goes towards many cellular operations. We humans, share roughly half of our genetic sequence with a tape worm.

a 1% difference is huge.

genetically, humans are apes and there is no reason to try and dispute that. Now, I don't think this justifies renaming the genus of the chimpanzee or anything, but there isn't any reason either in arbitrarily drawing a line in the sand between chimpanzee and human and saying that one is an ape and the other is not simply because you would prefer it that way.

Originally Posted by Ron_Mexico

A similar (and equally fascinating) thought experiment is to ponder what would happen if life on earth was "rerun" from the beginning. Just how "unlikely" is the biosphere we inhabit?

given the exact same conditions, if life on Earth was re-run from the same starting point it would turn out exactly the same as it is now, no matter how many times you reset it. There is, after all, no such thing as true random chance. Everything that happens is the result of something that happened before it. If you re-run something from a certain starting point and gave it the exact same conditions each time, it would do the same thing every time you re-ran it.

To everyone who mentioned that we share a significant portion of our DNA with every species, yes, that's very true and important to keep in mind.

It still doesn't explain, though, how chimpanzees and humans can share more DNA in common than chimps and gorillas when any rational observer (ignorant of the molecular data) would group the latter two closer together.

Although tough to measure objectively or quantitatively, it would be hard to argue against the position that gorillas and chimpanzees are phenotypically more similar than humans and chimps. That's the thing that is difficult to understand for me.

Now, chimps and humans do have a few phenotypic traits in common (distinct from gorillas). Both incorporate meat into their diet, whereas gorillas are strict herbivores. The fission/fusion social structure of chimpanzees is rather similar to our own. Sexual dimorphism is less pronounced in the chimp--also similar to us. The potential for tool use is another commonality.

But to reiterate from a post, chimps and gorillas are knuckle walkers, their brains are fairly similar in size, their body is covered by hair, and their potential for ingenuity/culture is nowhere near our own.

given the exact same conditions, if life on Earth was re-run from the same starting point it would turn out exactly the same as it is now, no matter how many times you reset it. There is, after all, no such thing as true random chance.

Hm. Are you sure about that? Prominent scientists have debated this question. I came across the idea in The Ancestor's Tale by Richard Dawkins, but I'm sure it has been addressed in many other works.

Aren't mutations random? Yes, they can be influenced by the environment (UV and other carcinogens), but the same mutations wouldn't necessarily arise even given identical environmental conditions, would they? Wouldn't events like endosymbiosis, which led to the evolution of the Eukaryotic cell, contain and element of chance to them?

Saying we are apes because we share DNA with them is well and good, but I imagine lions share quite a bit of DNA with wolves. That doesn't mean they had the same ancestor

The consensus is that every species has a common ancestor if you go back far enough in time.

We never will know. Knowing will never be applicable to anything. If it's not applicable to anything, it's not useful for anything.

Honestly, is this "serious" discussion at all, or just hot air passed around like a bong?

^This kind of attitude is very frustrating to me for several reasons. First of all, if you take that kind of viewpoint, almost any endeavor is worthless.

"Knowing" things in general is very applicable and has improved our lives considerably. At the very beginning of the thread, I conceded that this particular topic does not have many "real world" implications, but that doesn't mean it shouldn't be discussed. It's no more worthless than talking about video games or sports or entertainment or literature or even "serious" topics like politics or religion. It's not like anything we do or say on here matters anyway. But it is a place to share our ideas and shape the thinking of others. And yes, I enjoy it too. "The Controversy of Human Taxonomy" is probably not something I am ever going to have a chance to talk about in real life, so here is an opportune place to do it.

So if you don't enjoy it, think it's a worthless or just a platform for pretentious pseudo-intellectuals to spew hot air, fine. Don't waste your time posting.

To be honest, this thread has already done much better (in terms of both quantity and quality of posts) than I expected . . .

Originally Posted by Red Dingo

There is a grow consensus that it might not be as essential to life as it was once thought.

Eh, that's the first time I've hear that before.

Genetics is a funny thing, different equestrian and feline species can produce sterile hybrids when they mate.

Horse + Donkey = Mule
Tiger + Lion = Liger

But then there are canines. Dogs, wolves, foxes, coyotes, jackals...Dingos can all cross breed and have viable offspring.

Perhaps where the DNA code differentiates matters as much as how much it differentiates. A glitch in the just the wrong place can result in cancer after all.

That's because all dogs (including wolves) are part of the same species, while horses and donkeys are not. There is a whole list of possible barriers that can stop viable offspring from forming - different chromosome numbers, for example.

Horses and donkeys are going to have way more genetic changes between them because diverged much earlier than dogs.

Originally Posted by Ron_Mexico

Hm. Are you sure about that? Prominent scientists have debated this question. I came across the idea in The Ancestor's Tale by Richard Dawkins, but I'm sure it has been addressed in many other works.

Aren't mutations random? Yes, they can be influenced by the environment (UV and other carcinogens), but the same mutations wouldn't necessarily arise even given identical environmental conditions, would they? Wouldn't events like endosymbiosis, which led to the evolution of the Eukaryotic cell, contain and element of chance to them?

well I'm no expert, I'm hardly a scientist, and I don't know what endosymbiosis is. But I am pretty sure that true random chance doesn't really exist. Everything that happens is a result of things that happened before it, and two events with identical initial conditions and identical external influences should have the same result every time. After all, this is why scientific experimentation works. If we could run identical experiments and end up with different results then experimentation would be virtually useless.

Imagine that you have two Earths which are, in every possible way shape and form exactly identical. Starting from scratch, if the initial conditions were the same, and it experienced all the same external influences, wouldn't both Earths develop in exactly the same way? For there to be a difference between them, one Earth would have to experience an influence that the other one did not, right?

Of course I could be wrong. Like I said, I'm no expert. Maybe mutations really are based on some random dice roll. But then you have to wonder what's rolling the dice and how it can be rolled without any external influences whatsoever.

^I think we need someone else to come in and answer that question.

I've always been under the impression that, while the mutation rate can be influenced by environmental conditions, the nature of the mutations themselves is truly random.

The only reason I think I am "right" in this example is because prominent scientists have debated this question and I doubt they'd make such an oversight.

Of course, perhaps their premises were different than the way I presented them. Maybe they didn't posit identical conditions . . .

Endosymbiosis is the uptake of one cell by another. It is believed to be the process whereby the eukaryotic cell evolved (specifically, our mitochondria and the chloroplasts of plants are believed to be descended from ancestral bacteria). Personally, I find this pretty neat. And the evidence in favor of it is strong: these organelles divide independently and have circular (rather than linear) chromosomes, and their DNA is distinct from the cell's nuclear DNA.

Out of curiosity, how would you test the degree to which neoteny played a role?

I'm not sure that it can be tested, but, if neoteny has played a significant role in human evolution, we can try to come up with ideas as to why exactly this occurred, and theoretically explore its ramifications. Perhaps our large brain size and lack of hair are just by-products of some other evolutionary process, for instance?

There's a book that explores this idea called "The Eternal Child" by Clive Bromhall. It's not a scientific book (more popular science than anything), but it does at least make an honest attempt to explore the extent to which neoteny may have played in human evolution. I disagree with a lot of the assumptions that Clive makes and the conclusions that he draws (he doesn't always justify his assumptions or provide sources to back himself up, and the last section on personality types, I feel, strays away from the realm of science altogether - not to mention his belief that neoteny can explain homosexuality!), but it's still worth a read at some point, I'd say.

Originally Posted by Asta

I'm not sure that it can be tested, but, if neoteny has played a significant role in human evolution, we can try to come up with ideas as to why exactly this occurred, and theoretically explore its ramifications. Perhaps our large brain size and lack of hair are just by-products of some other evolutionary process, for instance?

I doubt think the threefold increase in brain size can be explained as a byproduct.

Surprisingly, most of that increase probably occurred in the last two millon years (with the advent of the genus homo). The Australopithecines were bipedal, but their skulls were not much larger than modern chimps.

I personally find the hypothesis that stone tool use drove selection for a bigger brain attractive since these two landmarks--the expansion of the skull and the first stone tools--overlap, somewhat attractive. The complexity of social life surely played a role too.

Loss of hair is probably associated with the move on to the African Savanna. Our ability to sweat is quite unique. Interestingly, it is also hypothesized that a loss of facial hair may have been adaptation to facilitate social interaction (a similar explanation is given for the whites of our eyes).

What I don't understand is how we can tell whether the changes you mentioned are a result of neoteny or simply normal selection . . . it seems almost impossible. That's why I'm hesitant to say too much on neoteny (that and I'm not overly knowledgeable on the topic).

I also don't think the role of sexual selection should be underestimated. Infants are meant to look "cute" so we care for them, and women retain many infant like physical characteristics into adulthood--probably for the same reason. Hair can be likened to the peacock's tail. And then of course there are the reproductive organs . . . woman's breast and the male genitalia are both way bigger than they "need" to be.

There's a book that explores this idea called "The Eternal Child" by Clive Bromhall. It's not a scientific book (more popular science than anything), but it does at least make an honest attempt to explore the extent to which neoteny may have played in human evolution. I disagree with a lot of the assumptions that Clive makes and the conclusions that he draws (he doesn't always justify his assumptions or provide sources to back himself up, and the last section on personality types, I feel, strays away from the realm of science altogether - not to mention his belief that neoteny can explain homosexuality!), but it's still worth a read at some point, I'd say.

Yeah, I'd be skeptical of the claim that neoteny explains homosexuality.

Here's another (extremely disturbing) thought . . .

With the understanding that is totally unethical, do you think a human and a chimp could produce viable offspring?

After all, we know a lion and a tiger can, and they share less DNA than we do with chimps . . .

I have to admit, part of me wishes it wasn't so unethical. There's no way to justify such an experiment (what would be done with the potential offspring?) But I'd really be curious . . . could we produce a Manpanzee? What would it look/behave like?

Originally Posted by Black_Mamba

^I think we need someone else to come in and answer that question.

I've always been under the impression that, while the mutation rate can be influenced by environmental conditions, the nature of the mutations themselves is truly random.

The only reason I think I am "right" in this example is because prominent scientists have debated this question and I doubt they'd make such an oversight.

Of course, perhaps their premises were different than the way I presented them. Maybe they didn't posit identical conditions . . .

Endosymbiosis is the uptake of one cell by another. It is believed to be the process whereby the eukaryotic cell evolved (specifically, our mitochondria and the chloroplasts of plants are believed to be descended from ancestral bacteria). Personally, I find this pretty neat. And the evidence in favor of it is strong: these organelles divide independently and have circular (rather than linear) chromosomes, and their DNA is distinct from the cell's nuclear DNA.

I don't know, I have a pretty hard time believing in something like truly random chance. I was always under the impression that everything that happens is both caused by something before it, and causes something after it. This is after all a basic element of the nature of energy and the laws of motion. An object will retain whatever conditions it currently has indefinitely until acted on by some other force.

For a random "die roll" to take place in the genetic mutations in DNA, would not something have to ultimately "decide" upon the result of that roll? I mean, technically, even a die roll or a coin flip is not actually random.

Dice rolls are decided by the way the die is thrown, how much energy is put into it, the direction it spins, the way the air moves around it, and even the surface it lands on (softer surfaces absorb more energy and cause the die to stop faster, harder surfaces cause the die to bounce, etc.) A die roll repeated in exactly the same way with exactly the same conditions ad infinitum will end the same way every single time.

Likewise, I should think the same thing of genetic mutation. Now no doubt it's about as close to random as you can get, and there is certainly no possible way to predict the result, but I cannot simply believe that there are no influences at all in the result of the mutation. If there is no force acting on the mutation then the mutation can not happen. If there is a force acting on the mutation, then that force should do the same thing in the same way every time.

As mentioned before, this is the basis of scientific experimentation. We must be absolutely sure that experiments, when repeated under the exact same conditions, will always have the exact same results. Were this not true then scientific experimentation would be useless and we would never have gotten as far as we have in our scientific understanding and inventions. After all, if random chance were involved in the way energy worked, or in the way anything worked, we would have no way of being sure of anything ever. What if an object in motion could randomly change its direction with no external forces? It doesn't make sense.

Not even human thought is random. Two humans who are identical and experience identical external influences will think identical thoughts and make identical decisions.

I'm no expert, but I should think the same is true of everything. I find it hard to believe in something like "random chance." The only way random chance could exist is if it were possible for something to happen without the influence of an external force, and this is as we know it impossible. In fact, I'm finding it pretty hard to even define random chance.

What is "random"?