Evolution Lesson

[HitchSlap]

I'm not the one making scientific propositions here so why are you asking me? Are you making a scientific proposition or positing evidence of some propositional conclusion concerning "young" and "old"? If so, define your terms. If not, what is the relevance? I am asking how you determine when one "thing that looks similar/i.e. species" has changed into another "thing that looks similar/i.e. species" since both will obviously "look similar" and be of the same "thing that looks similar/i.e. species" to begin with.

How can you determine when one past "thing that looks similar" has transformed into a different "thing that looks similar" without having criteria to define "difference in similarity" and enough criteria to justify something as "evidence" of such a process?

Do you have a problem with biologists attempting to categorize life, or how they categorize life? What am I missing, and what do you see as a problem?

 

[John Hyperspace]

Do you have a problem with biologists attempting to categorize life, or how they categorize life? What am I missing, and what do you see as a problem?

Suppose you come to me and say "I have a hypothesis"; I say, "Okay"; you reply, "species in the past turned into other species" and I say "Okay; and how do you define 'species' in order that we may evaluate and seek evidence to support your hypothesis" and you reply, "I don't know how to define a 'species'" - now, do you see the problem here?

Now please turn your brain on for me and realize I am not advocating this is being done (not yet, anyway); but given the above, do you see the problem that will arise when you don't define 'species' and begin looking for evidence to support your hypothesis?

Now my question to you is, if you are wanting to provide evidence to me in order to support your hypothesis, you are going to have to first define the term 'species': and what is the definition? If you cannot define 'species' in context of your hypothesis, you will never be able to provide evidence to support a hypothesis which proposing a hypothetical process concerning 'species'

 

[John Hyperspace]

We already did. Fossil species are defined by their morphology, as explained numerous times now.

Okay, so fossil 'species' are defined by morphology, and morphology is defined by? I throw down in front of you two fossils. One looks like a small cat, one a large cat. Is that the same 'species'? Or is this an evidence of "one species becoming another species"? Both look similar, but when is similar not similar enough to be 'same species'? And the real question, though two different morphologies does show evidence of two different 'species'; how does this provide evidence that one species has transformed into another?

 

[Speedwell]

Okay, so fossil 'species' are defined by morphology, and morphology is defined by? I throw down in front of you two fossils. One looks like a small cat, one a large cat. Is that the same 'species'? Or is this an evidence of "one species becoming another species"? Both look similar, but when is similar not similar enough to be 'same species'? And the real question, though two different morphologies does show evidence of two different 'species'; how does this provide evidence that one species has transformed into another?

It takes a lot more than that to determine the relationship, e.g. where were the fossils found in relationship to one another? What are the points of difference as well as the points of similarity? What points of similarity and difference are observed with other fossils, etc. All quantified and studied and argued over, more than likely.

 

[John Hyperspace]

It takes a lot more than that to determine the relationship, e.g. where were the fossils found in relationship to one another? What are the points of difference as well as the points of similarity? What points of similarity and difference are observed with other fossils, etc. All quantified and studied and argued over, more than likely.

You do realize your reply is just begging the question? Someone earlier mentioned something like "different than the parent species" without realizing using the phrase "parent species" is just begging the question of the process. Before we can start talking about "parent species" we have to first show evidence that the idea actually is evidenced. We may as well be talking about "elfin magic" as evidenced to be real by Keebler fudge-striped cookies.

 

[Speedwell]

Suppose you come to me and say "I have a hypothesis"; I say, "Okay"; you reply, "species in the past turned into other species" and I say "Okay; and how do you define 'species' in order that we may evaluate and seek evidence to support your hypothesis" and you reply, "I don't know how to define a 'species'" - now, do you see the problem here? '

Yes, I see it. First, it's not just an hypothesis. Speciation has been observed in the field and in the lab. It is not controversial. And just because there is no hard boundary between species doesn't mean there is no definition and that it is impossible to tell one species from another.
The world is full of creatures, a virtual continuum of types which, for our convenience, we group by their similarities. "Species" is not something we discover, it's a category which we assign. When a species has become different enough from its parent species, by the criteria already explained, to make it useful to biologists to classify it separately a new species is formed.

 

[Speedwell]

You do realize your reply is just begging the question? Someone earlier mentioned something like "different than the parent species" without realizing using the phrase "parent species" is just begging the question of the process. Before we can start talking about "parent species" we have to first show evidence that the idea actually is evidenced. We may as well be talking about "elfin magic" as evidenced to be real by Keebler fudge-striped cookies.

Are you saying that just because speciation can be observed in the present doesn't mean it could have happened in the past?

 

[John Hyperspace]

Speciation has been observed in the field and in the lab.

Why do I get the feeling that suddenly you're switching definitions of species? Is the speciation observed 'in the field' evidenced by 'clearly delineated'(you realize if you answer 'yes' I'm going to have to ask, 'by what morphological criteria'?) morphology? If not we're not even talking about the same form of speciation anymore. Two different terms defined by two different criteria. Are we just defining the term 'species' at our arbitrary will at this point? Because, if that's the case, then we may as well say the word can define anything we wish, and anything can be evidenced by simple circular defining of the term to suit our hypothesis.

 

[John Hyperspace]

Are you saying that just because speciation can be observed in the present doesn't mean it could have happened in the past?

No, I'm saying it's not even the same thing, not even defined by the same criteria, and not even related to one another by definition of the term.

 

[HitchSlap]

Suppose you come to me and say "I have a hypothesis";
I say, "Okay"; you reply, "species in the past turned into other species" and I say "Okay; and how do you define 'species' in order that we may evaluate and seek evidence to support your hypothesis" and you reply, "I don't know how to define a 'species'" - now, do you see the problem here?

And this is where you may want to turn your brain on for a moment, as it has been sufficiently explained to you how biologists attempt to define and categorize. This doesn't happen in a vacuum, and hundreds of thousands of biologists over the last one hundred years have contributed to this. And BTW, we're way past "hypothesis" here, and fully into theory mode. There is no better explanation for the diversity and distribution of species we see on earth. No other suggestion even comes close.

Now please turn your brain on for me

I'll try.

and realize I am not advocating this is being done (not yet, anyway);

Whew, biologists the world over will sleep tonight.

but given the above,

The above is demonstrably wrong. It's not my fault you're not aware of this.

do you see the problem that will arise when you don't define 'species' and begin looking for evidence to support your hypothesis?

Nope.

Now my question to you is, if you are wanting to provide evidence to me in order to support your hypothesis,

The evidence is there, that's why it's a theory, skippy.

you are going to have to first define the term 'species': and what is the definition? If you cannot define 'species' in context of your hypothesis, you will never be able to provide evidence to support a hypothesis which proposing a hypothetical process concerning 'species'

Shouldn't you let those who work with this on a daily basis worry about this?

 

[Speedwell]

Why do I get the feeling that suddenly you're switching definitions of species? Is the speciation observed 'in the field' evidenced by 'clearly delineated'(you realize if you answer 'yes' I'm going to have to ask, 'by what morphological criteria'?) morphology? If not we're not even talking about the same form of speciation anymore. Two different terms defined by two different criteria. Are we just defining the term 'species' at our arbitrary will at this point? Because, if that's the case, then we may as well say the word can define anything we wish, and anything can be evidenced by simple circular defining of the term to suit our hypothesis.

What two criteria?

We have discussed several different ones, but they all give about the same result with only occasional controversies, and they all boil down to "is this group of creatures sufficiently different from the rest to be worthwhile classifying separately?"

More important, what's the point? I get the feeling that exact determination of species is a lot more important to you than it is for biologists. Once again, I ask why? Are you in any doubt that speciation can occur?

 

[AV1611VET]

LOL

He looks like he just heard Jesus walked on water.

Wait until he hears about the Resurrection!

 

[PsychoSarah]

Well, it's an issue when you propose "this species became that species" in order to produce evidence of your proposition. I'm now having to ask, by what definition, and, by what criteria, are you making the proposition.

-_- going by the fossil record, people actually shouldn't do that, and I hate when they do.

The fossil record is good for example transitions: for example, showing when apes that walked upright started to come into existence, approximately. The chances of, say, Homo habilis being a direct human ancestor are not particularly high, however, whatever human ancestor lived at the time would have had similar traits to Homo habilis.

They're the proof of concept, not the direct human lineage. We would need DNA for an official determination, and the only non human species in the same genus as ourselves (Neanderthals and Denisovans, if I recall correctly) that we have any DNA of are not ancestral to modern humans, but rather lived alongside us.

 

[Bungle_Bear]

No, I'm saying it's not even the same thing, not even defined by the same criteria, and not even related to one another by definition of the term.

Maybe try reading this post.

 

[Loudmouth]

Suppose you come to me and say "I have a hypothesis"; I say, "Okay"; you reply, "species in the past turned into other species" and I say "Okay; and how do you define 'species' in order that we may evaluate and seek evidence to support your hypothesis" and you reply, "I don't know how to define a 'species'" - now, do you see the problem here?

We do know how to define species, and we have shown you how it is done.

 

[Loudmouth]

Okay, so fossil 'species' are defined by morphology, and morphology is defined by?

Morphology is the observation. Morphology is the shape of organisms body.

I throw down in front of you two fossils. One looks like a small cat, one a large cat. Is that the same 'species'?

Size by itself can't be used to determine if they are two different species. I think even you would agree that there are more differences between humans and chimps than just our overall size. To use a slightly different analogy, the differences between your molar and incisor teeth doesn't have to do with size. Morphology is about the actual shape of the bones.

I have also given you the example of H. erectus and H. sapiens (post 80). I pointed to the morphological differences. Perhaps you could address that post.

And the real question, though two different morphologies does show evidence of two different 'species'; how does this provide evidence that one species has transformed into another?

I think I already covered that in post 60:

You can't, unless you can extract DNA from the fossils. Only DNA can give you direct evidence of ancestry and relatedness.

What we can do is test hypotheses. If humans and apes share a common ancestor, and humans evolved from that shared ape ancestor, what should we see in the fossil record? At some point in the last 5-7 million years there should have been individuals that had a mixture of more basal ape features and more modern human features. We can then look in the fossil record to see if those fossils exist, and they do.​

Darwin put it a bit differently:

In looking for the gradations by which an organ in any species has been perfected, we ought to look exclusively to its lineal ancestors; but this is scarcely ever possible, and we are forced in each case to look to species of the same group, that is to the collateral descendants from the same original parent-form, in order to see what gradations are possible, and for the chance of some gradations having been transmitted from the earlier stages of descent, in an unaltered or little altered condition.
The Origin of Species: Chapter 6
​

 

[AvgJoe]

Okay, so fossil 'species' are defined by morphology, and morphology is defined by?

Morphology is the observation. Morphology is the shape of organisms body.

And the real question, though two different morphologies does show evidence of two different 'species'; how does this provide evidence that one species has transformed into another?

I think I already covered that in post 60:

You can't, unless you can extract DNA from the fossils. Only DNA can give you direct evidence of ancestry and relatedness.​

​

So there's no concrete proof that any species has ever evolved into another species? We only have observations that these fossils look similar so it's deemed that one is evolving into the other? Interesting.

​

 

[Loudmouth]

​

So there's no concrete proof that any species has ever evolved into another species?

The concrete proof is the DNA evidence which demonstrates that separate species share a common ancestor.

Fossils aren't the only data set out there.

 

[Loudmouth]

How did new biochemical pathways, which involve multiple enzymes working together in sequence, originate?

I ran across a great resource that may help you with this question:

Sandwalk: The evolution of the citric acid cycle

The TCA cycle is a perfect example of what you are referring to.

 

[John Hyperspace]

Maybe try reading this post.

Not really because that post looks to be begging the question, as well. Perhaps not begging the question in the thread of origin, but begging the question in relation to my question in this thread. Unless you're meaning something different in intent, in which case I need you to elaborate on the relevance.