Cladistics: The Bare Basics

If like me you are fascinated by the links between all animals, plants and fungi, the wondrous miracles of evolution and the seemingly manufactured perfection of life itself, then you may be wondering how we can record and test these links, graphically recognise the subtle differences between them or identify similarities of traits shared between animals completely different.

Cladistics can

Through the advent of genetics resemblances between species has been taken to a new level, associations between all living things had relied solely on its appearance, not truly understanding its relationship at a genetic level. The tree of life for all its magnificence had to be revised, to incorporate this revision a new method for taxonomic classification was devised, it was called Cladistics. The theory depends on a number of state's being available for certain traits or conditions present in the subjects being tested, for instance humans can talk, this is a trait which Homo sapien has over its cousin Pan troglodytes (chimpanzee), the character states for this trait would be, cannot talk 0 can talk 1.

Traits within cladistic models are borne from a common ancestor having evolved to that point through genetic mutation and then retained if successful. As humans are the only speaking species then that trait is not shared. (except by some birds which as these do not share a recent ancestor must have gained the ability separately). The characteristics are tabled and added to a Cladogram fig 1, which shows graphically how the species are grouped according to their common characteristics.

fig 1 Cladograms

fig 1a.  General Cladogram
fig 1a. General Cladogram
fig1b. Cladogram with 4 species added
fig1b. Cladogram with 4 species added

Cladograms

These are the graphic models which are designed to show time from a common ancestor to new species by changes in their morphology or genes represented by a line. Each time a change occurs a line beaks off representing a new species. fig1 shows a cladogram in which a line representing time has four lines breaking off which are species of organisms sharing the same traits as the common ancestor, the first break is to an outgroup ancestor which represents the control aspect of the cladogram, the three species after form a group or clade which are separated by a smaller number of characteristics. All four species are related from a very ancient common ancestor however we can reduce the time involved and look at which of the four species are more closely related than others using specific characters and the traits that each species has for those characters. We do this by creating a table listing the species the characters and the states Table 1.

Table 1: To show Species character states

Species
Character 1 (Has hair on the body )
Character 2 (Can Talk)
Character 3 (has claws)
Character 4 (lives in the sea)
 
No hair (0), has hair (1)
Cannot (0), Can (1)
No claws (0) has claws (1).
Sea (0), land (1)
Chimpanzee
1
0
0
1
Human
1
1
0
1
fish
0
0
0
0
Bear
1
0
1
1

The first thing that we notice from this table is that the fish has the zero state by all of the characters and share none with any other species, however having hair as a character is shared by three of the species, the fish as a result becomes our outgroup control species with the break away time line 'lives in the sea', and the new clade with three species who all have hair, (in red) fig 2.

A bar crosses the time lines to indicate a character, at the side of the bar is the character and the state, here its character 4 and either state 1 or 0. (4,1) lives on land, (4, 0) lives in the sea and character 1 character states 1 or 0, (1,1) has hair on body, (1,0) no hair on body.

fig 2

We are left with two characters depending on which we consider first will decide how the remaining three species will be organised, at this point we must take a leap of faith, in normal circumstances at least ten characters should be used for three species to ensure that the closest relatives arrive within the correct clade. As we know that a chimpanzee is a closer relative to humans than bears we will use character number three next with character states has claws (1) and no claws (0).Isolating the bear to its own evolutionary time line fig 3. We can then add our final character which discerns an evolutionary split between human and chimpanzee and we have our basic Cladogram.

What we can discern from this is that humans and chimpanzees share more evolutionary characteristics than humans and bears and humans and fish. We have a common ancestor who although related to birds and fish from an even earlier ancestor is recent enough to have evolved separately from other species.

A true cladistic investigation would involve mind numbing equations and tables, there are software programmes which can calculate the similarities for you providing you know the species, the characters and the genetic mutation traits borne out of evolutionary requirement which divide them. Cladistics is most helpful where new species identification is required and where fossil evidence is used to associate Genus resemblances in newly discovered species, or to record and understand families of organisms and there evolutionary appearance in the chronological time scale in comparison to one another. 

An example of how time scale was used with Cladistics is how spiders either form webs or hunt by roaming and attacking prey. It transpired that through a complete cladistic investigation, and fossil evidence, building a web was the most archaic of the characteristics, roaming hunting spiders in evolutionary terms were the younger and most recent mutation.  

Comments 9 comments

menvall 5 years ago

What is a species?


mats envall 5 years ago

I agree, cladistics does, indeed, seem fantastic. Its only problem is that its concept "clade" (i.e., the class "clade") in practice terms a paradox (called Russell's paradox). This fact means that this class (i.e., clades) is contradictory per definition, and thus that all possible such classifications are contradictory per definition. Cladistics' only problem is thus that it is a practical impossibility. A non-conradictory set of clades is simply impossible to find.

Instead, cladistics is actually the typologist dream, and, like all dreams, it would have been fantastic if it would have been possible, but, unfortunately, dream can never become reality. Instead, the hard fact is that cladists have turned the fact that objects have properties into that properties have objects, and thereby created the illusion that their dream is possible (and sensible). However, the truth is that their dream rests on the erroneous axiom that classes are real, and thus that it is contradictory per definition. It simply can't be realized, because a contradiction can't be unambiguous (and thus can't be real).

But, I agree that it would have been fantastic if dream had been practically possible. The problem with this hypothetical situation is that it would have falsified facts, like the fact that the class "clade" is a paradox and the fact that time is relative to space. It would thus have created the conceptual mess that cladistics presently creates. On a closer examination, it is thus probably better to realize that cladistics is just a too simple simplification.


Mats Envall 5 years ago

The only problem is that the concept "clade" (i.e., the class "clade") is doubly ambiguous, that is, contradictory, which we call a "paradox". It is actually the back side (i.e., the subjective side) of Russell's paradox. It means that this class (i.e., "clade") can't be distinguished consistently, that is, that all possible single such classifications (i.e., clades) are inconsistent. The approach (i.e., cladistics) is thus founded on a contradiction, that is, in practice, an illusion, and as such has ONLY subjective solutions.

It is, unfortunately, simply a too simple simplification.


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AngusNz 5 years ago from Auckland Author

I hope that I have understood correctly please advise if I have missed the point.

I may have used some incorrect wording in my Hub and will look into that.

I do not believe that it is affected by the Russells Paradox and if it is questioned as such I would say that it is by people who pertain to an alternative model. The paradox represents definitive lists which incorporate a set of true values, these values are set by observable facts and can only be within that list hence the paradox can be applied to an item which contradicts the list or itself as part of that list. A clade within a cladogram is not a permanent set it is expandable and changeable due to the designs of Evolution. The clade system allows for change by adapting a new clade within a clade represented by time. The Russells paradox does not represent time and change. A cladogram is still in essence a tree which grows from a “root” specified only by the question asked and thereby defining the contents of the group which the group ancestor has to be a part of and does not contradict. If contradiction appears then it is through the process of Evolution and therefore beneficial to the theory of mutation which by now will have expanded the cladogram and considered a new group or clade taking into account the contradiction. For example one clade maybe “has claws”, containing dogs and cats, the common ancestor has claws and can be incorporated within the clade without contradiction. Contradictions appear when the claws are removed by some evolutionary requirement and now the original clade member becomes a contradiction. Here a new clade is derived but not removed from the original as it represents a length of time.

Russels paradox ‘R’ which can be in a list which contains itself but contradicts a list which contains instances not inclusive of ‘R’ does not apply to a clade which would never include a character which describes a none event, “does not have claws" is an actual characteristic and would be shared by the clade common ancestor and does not contradict itself, this clade can follow in time from does have claws without contradiction again.

I think!!!!!


Mats Envall 5 years ago

"It", that is, cladistics, is not "affected" by Russell's paradox, but rests on Russell's paradox. Its class "clade" terms the same phenomenon as "Russell's paradox" does, that is, what is also called "infinite set" in axiomatic set theory.

This phenomenon is actually the opposite to a single object, and is actually just a conceptual interface between different approaches. It does not, and cannot have any reality what-so-ever, because it is contradictory in and between all approaches.

Cladistics thus rests on a paradox, that is, on a practical hallucination. It means that a non-contradictory classification into clades (i.e., cladification), of anything, simply can't be found. The class "clade" simply terms a paradox, also called Russell's paradox.

Everyone that don't understand this fact can prove me wrong by FORMULATING (i.e., in words) a consistent definition of the concept "clade" (you can do it on Wikipedia). I promise that if anyone can, then I will crawl and swim from Sweden to Australia, and apologize to Gareth Nelson, Malte Ebach and John Wilkins. If I'm wrong, then I'm terribly wrong, but if cladists are wrong, then they're terribly wrong. I simply explain that they're terribly wrong. I actually claim that they're totally wrong, that more wrong is simply impossible to be. I claim that they have got matters up-side-down.


Mats Envall 5 years ago

The cladograms of cladistics thus look nice (i.e., free from contradictions), but the "bare basics" of them is thus that all of them contain inconsistencies for the classes in question to be found for people that do not believe, but are skeptical. The problem for biological systematics is not to find a dream (i.e., applied typology), but to describe reality. The problem with clades in this respect is that they do not and cannot break even, per definition, because the class "clade" is contradictory (i.e., a paradox). The "bare basics" of cladistics is thus that it is a dream.


Mats Envall 5 years ago

I just wonder if this post is not embarrasing to you? We have together concluded that cladistics is a conceptual confusion; wouldn't it then be appropriate that you deleted this post from the net. Why hang on a post that is a conceptual confusion? Does it not just confuse people's minds?


Ron 4 years ago

Really fantastic hub. "We must learn our limits. We are all something, but none of us are everything." by Blaise Pascal.

Ron from the http://www.intervalstraining.net


Mats Envall 4 years ago

I agree.

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