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k3lt01 08-24-2013 01:45 AM

Discussion of Evolution
 
A few years ago, 10 now, I studied Anthropology at USQ in Queensland and Palaeoanthropology at UNE in New South Wales. I did so because I have an interest in human history and cultural practises. I learned so much from people like Mike Morwood (one of the senior team members who discovered Homo Floriensis), Peter Brown (who was one of the first to study the skeletal remains of Homo Floriensis), and other lecturers at both universities, but I still have so much more to learn so I am starting this thread where the topic of Evolution of the human species can be discussed without interfearance of other topics (such as religion).

I would encourage anyone to post but if you do please do everyone a favour and seperate your belief from what is actually known. In other words if you don't really know just say you think or you believe or in your opinion instead of telling everyone this or that is fact and not be able to back it up with anything what so ever.

First up I'll openly state I have no problem with evolution, what I have difficulty with is making the, what I believe to be, giant leap from one genus to another. Did Ardipithicus evolve into Australopithicene and further to Homo and how? What evidence is there? Where is the evidence? How much evidence is there? I personally cannot see a link (missing link?) and don't pretend to be able to explain any other possibility.

I don't mind if other questions of a similar (evolution) nature are asked, the idea of this thread is to foster open discussion but more importantly relevant discussion.

Randicus Draco Albus 08-24-2013 03:32 AM

Since this field is too broad to attempt presenting anything detailed in a writing shorter than a journal-length article, I shall post something about one item. I have chosen
Quote:

I personally cannot see a link (missing link?) and don't pretend to be able to explain any other possibility.
I do not see a missing link either. But before I can explain why, a bit of background is required.

Splitters and Lumpers
The reason there is so much debate among palaeoanthropolists about which species were and were not in our ancestral line is mainly due to two camps of thinking. On one side are the splitters, who favour the idea of dozens of species running around at the same time. On the other side are the lumpers, who see the archaeological remains representing a few species, each with morphological variation. I am a lumper. Why? Anyone who has studied osteology is aware of the tremendous amount of morphological variation in the human skeleton. (For example, people who proudly recite the number of bones in the human skeleton are only half right. The number of bones in the body varies. One person can have one, three or even five more bones than someone else.) Individuals have different bone thickness, different heights, larger muscles that result in larger protuberances where tendons join muscle to bone, and sexual dimorphism. Among the other apes, sexual dimorphism is greater than among humans. The biggest difference is with orangutans, where males can be twice as large as females. Why is all this important? Because this is a great cause of debate when trying to determine if the remains of individuals are the same or separate species.

This brings us back to lumpers and splitters. Splitters will look at three teeth found in isolation and declare a new species, because the teeth are not exactly like those from any other remains. Lumpers on the other hand, will say, "Wait. Not so quick. These teeth may be from a know species." Since they have studied osteology, I cannot understand how splitters can ignore morphological variation, but they do not hesitate to state that three teeth is "clearly a new species." I am quoting a PhD student in Australia with whom I discussed this topic. If ten human skeletons were placed in a room, splitters could identify ten clearly different species if they applied the same logic to us as they do to austalopithicines. An example are robustus and boiseai (I forget the spelling, so please forgive me if it is wrong.) These "two" species are identical, but are classified as different species. Why? One population lived in eastern Africa and the other lived in southern Africa. Or could the remains be the same species with a large habitat? I say the latter.

New Discovery
Now I am almost ready to explain why I do not see a missing link. For the longest time there was a missing link, because the archaeological record had apes that were semi-bipedal, but no fully bipedal apes until homo erectus. I forget exactly when, but in the '90s, a discovery was made. Until then, the few remains of the earliest hominids did not include any lower leg bones, so it was assumed that ape was not bipedal, because later hominids were not. I forget if the species has been designated africanus or afarensis. At the moment I do have access to my library and am writing from memory. Anyway, the recent discovery I mentioned was a four million year old tibia from one of these individuals. The surprise was it is identical to ours.

Climate Change and Speciation
A tiny bit more background before I can state my conclusion. Before five million years ago the entire planet was tropical and sub-tropical. Then Antarctica moved close enough to the South Pole for the south polar ice cap to form. This caused the world's climate to become cooler and drier. Two-and-a-half million years ago North America moved close enough to the North Pole for the north polar ice cap to form. This caused another change in global climate, making the world cooler and drier again. Since then the world has alternated between glacial (so-called ice ages) and inter-glacial periods. This is very important, because evolution does not happen gradually. The current thinking is called punctuated equalibria. According to this line of thinking, a species remains unchanged for a long period of time and then "speciates". Meaning it suddenly evolves into one or more new species. The trigger is usually a change in environment. A species can move into a new habitat or be exposed to global climate change.

Conclusion
The oldest hominid was around at least four million years ago. But when did it first appear? We do not know. The oldest homo erectus remains are 1.8 million years old. Humans and Neanderthals both appeared during a "cold snap" in the last glacial cycle; Neanderthals about 130,000 years ago and us sometime between then and 100,000. So why do I not see a missing link? I believe in the simplest solution being the most plausible. My theory is the first hominid speciated five million years ago with the onset of climate change. This species remained with little or no change until two-and-a-half million years ago, then speciated into one or more new species. Homo erectus being one of them. Between 130,000 and 120,000 years ago a population of homo erectus in East Africa speciated into humans during the a colder period in the last glacial cycle. (I mentioned this in the aforementioned conversation with the splitter. It almost made him froth at the mouth.

jdkaye 08-24-2013 04:31 AM

You'll want to have a look at Jerry A. Coyne's "Why Evolution is True". It is well written, easy to follow (for non-specialists) and extremely convincing. Here's a blurb:
Quote:

In the current debate about creationism and intelligent design, there is an element of the controversy that is rarely mentioned-the evidence. Yet the proof of evolution by natural selection is vast, varied, and magnificent. In this succinct and accessible summary of the facts supporting the theory of natural selection, Jerry A. Coyne dispels common misunderstandings and fears about evolution and clearly confirms the scientific truth that supports this amazing process of change. Weaving together the many threads of modern work in genetics, palaeontology, geology, molecular biology, and anatomy that demonstrate the "indelible stamp" of the processes first proposed by Darwin, Why Evolution Is True does not aim to prove creationism wrong. Rather, by using irrefutable evidence, it sets out to prove evolution right.

Highly recommended. Well worth the time. Enjoy!
jdk (not java)

Randicus Draco Albus 08-24-2013 04:39 AM

That book would not very useful for me, but if it lives up to the hype in the blurb, it might be worth a layman's effort to read it. Looks interesting.

Actually Darwin was not the only one to put forth the theory. Darwin and a man named Wallis submitted a joint paper on the subject. Unfortunately, outside anthropology and palaeontology he has been forgotten.

jdkaye 08-24-2013 06:13 AM

Quote:

Originally Posted by Randicus Draco Albus (Post 5014954)
That book would not very useful for me, but if it lives up to the hype in the blurb, it might be worth a layman's effort to read it. Looks interesting.

Sorry but I wasn't really addressing you. The OP asked something and I did my best to help him. I'm sure you have an impressive list of academic degrees and my apologies for not giving you the adulation you are doubtless accustomed to. I'm sure Coyne's book would be a waste of your time.
jdk

Randicus Draco Albus 08-24-2013 06:17 AM

No I understood your post. I just wanted to emphasize that it appears to something worthwhile for layman to read. I did not intend to make my post arrogant.:)

jdkaye 08-24-2013 06:21 AM

Quote:

Originally Posted by Randicus Draco Albus (Post 5014988)
No I understood your post. I just wanted to emphasize that it appears to something worthwhile for layman to read. I did not intend to make my post arrogant.:)

I accept your comment. It did indeed sound extremely condescending. Let's file it under "misunderstanding" and forget it.
jdk

k3lt01 08-24-2013 06:40 AM

Quote:

Originally Posted by Randicus Draco Albus (Post 5014920)
Since this field is too broad to attempt presenting anything detailed in a writing shorter than a journal-length article, I shall post something about one item. I have chosenI do not see a missing link either. But before I can explain why, a bit of background is required.

fair enough, it was broad to encourage various positions and discussion but feel free to comment on whatever suits you.

Quote:

Originally Posted by Randicus Draco Albus (Post 5014920)
Splitters and Lumpers

I'm not a splitter but I'm not quite a lumper either. When I was studying under Mike Morwood, Peter Brown, and Stephen Collier they spoke of the tendency for some to declare a new species, even a new genus, when a small sample of either dentition, pelvic bone, or cranium was found. The variation within remains doesn't strike me as a reason to split what is, in any other field of study, to small a sample into another species. However, I do recognise in some cases the difference between robust and gracile even though I do not believe this in itself is not a reason to split a species off into a new species (as has happened with Australopithicine and Paranthropus and discussed at humanorigins.si.edu). Australopiticine Boisei is now Paranthrpus Boisei and Australopithicine Robustus is now Paranthropus Robustus, What gain in evidence has this new classification come from? Australopithicine is gracile and Paranthropus is robust but there have been anatomically modern humans who have also been described this way yet they have not been split into seperate genus or species. In Australia we have both gracile and robust remains that are approximately 25-30K years old. These samples are from a time of environmental change (gradual cooling).

Didn't Tim White and one of the Leakeys have a similar discussion only a few years ago about the claiming of new species from such a small sample?

I can't remember the name of the forensics guide we used at UNE but it indicated, as you suggest there is a degree of variance within a species. We had to measure various bones including the cranium and its internal capacity and no two were alike even though they were known human samples (2 of which were people who had died only a few years before). We wre given a group of outlines which we had to use on the skulls to determine whether they were male and female and of the 10 specimens 3 were, based on the skulls, not able to be clearly defined. So even today there is much variation and I recognise that. If there was no variation we would all be much closer in appearance than we are. I wonder what would happen if someone seriously tried to infer that there are, currently, different species of humans, as you correctly suggest it has happened with archaeological samples.

Quote:

Originally Posted by Randicus Draco Albus (Post 5014920)
These "two" species are identical, but are classified as different species. Why? One population lived in eastern Africa and the other lived in southern Africa. Or could the remains be the same species with a large habitat? I say the latter.

I'm not sure the habitats in the 2 locations were the same but that does not mean these species could not live in more than one habitat.

Quote:

Originally Posted by Randicus Draco Albus (Post 5014920)
New Discovery

From memory the discovery you mention is Afarensis and was named Lucy. Not only did they discover the bone etc. they also discovered footprints indicating bipedal locomotion.

Quote:

Originally Posted by Randicus Draco Albus (Post 5014920)
Climate Change and Speciation

I understand climate change and speciation amd have no problem with the ideas but, and this is partly what has never been fully explained, if we are talking species then were are staying within the realms of Homo, or Australopthicine, or Ardipithicus. These, to me are not sudden changes in species like Australopithinces suddenly becoming Homo Habilis or Homo Rudolfensis (some believe they are not Homo but are still Australopithicine which makes sense to me as they are more Australo like in appearance as well as other aspects such as brain size). If this is the case there is still no actual link between the genus Australo and Homo.

Quote:

Originally Posted by Randicus Draco Albus (Post 5014920)
According to this line of thinking, a species remains unchanged for a long period of time and then "speciates". Meaning it suddenly evolves into one or more new species. The trigger is usually a change in environment. A species can move into a new habitat or be exposed to global climate change.

Which is possibly what happened with Homo Floriensis.

Quote:

Originally Posted by Randicus Draco Albus (Post 5014920)
Conclusion
The oldest hominid was around at least four million years ago. But when did it first appear? We do not know. The oldest homo erectus remains are 1.8 million years old. Humans and Neanderthals both appeared during a "cold snap" in the last glacial cycle; Neanderthals about 130,000 years ago and us sometime between then and 100,000. So why do I not see a missing link? I believe in the simplest solution being the most plausible. My theory is the first hominid speciated five million years ago with the onset of climate change. This species remained with little or no change until two-and-a-half million years ago, then speciated into one or more new species. Homo erectus being one of them. Between 130,000 and 120,000 years ago a population of homo erectus in East Africa speciated into humans during the a colder period in the last glacial cycle. (I mentioned this in the aforementioned conversation with the splitter. It almost made him froth at the mouth.

Just getting my understanding of your thoughts correct before I go any further. You believe that the process was for the most part gradual but at times of environmental change relatively quick speciation occured and a new species (if not genus) evolved and this happened a few times throughout history.

I agree with you until we get to the evolve into a new genus idea. I say this for 3 reasons,
The sample size is extremely small from Ardipithicus to Australopithecine and again from Australopithicine to any Homo.
The division among those who study these things concerning what constitutes Ardipithicus, Australopithicine (even splitting off Paranthropus), and Homo muddies the waters somewhat also.
It appears to me that the rush to declare any new discovery as a new species, or even genus, when the sample size is so small (such as a few teeth or a lower mandible) may be an attempt to find links that do not actually exist.

Now that I have said that. I may be wrong and this is just my interpretation of what actual samples are available, the time frames for the samples, and to me extremely importantly the lack of consensus among those out in the field (those digging the samples up and analysing them), I do see links within the different genus I just don't see them from one genus to another.

k3lt01 08-24-2013 06:51 AM

Quote:

Originally Posted by jdkaye (Post 5014948)
You'll want to have a look at Jerry A. Coyne's "Why Evolution is True". It is well written, easy to follow (for non-specialists) and extremely convincing. Here's a blurb:

Highly recommended. Well worth the time. Enjoy!
jdk (not java)

I wouldn't call myself a specialist but I wouldn't call myself a non-specialist either. As I said in my first post I don't have a problem with Evolution so there is no need to try to convert me that it is a reality. I have a problem with interpretation of the archaeological record. This problem is because I perceive, in other words it is my opinion, an "over zealousness" to prove something, as explained in my 2nd post, from a sample size that in other fields would be considered to small.

Anyway I'll look out for that book.

Randicus Draco Albus 08-24-2013 07:08 AM

Quote:

Originally Posted by k3lt01 (Post 5014996)
From memory the discovery you mention is Afarensis and was named Lucy. Not only did they discover the bone etc. they also discovered footprints indicating bipedal locomotion.

Definitely not Lucy. She was the first. And only so much can be inferred from her remains, because her body was crushed after (or while) dying. The discovery I mentioned was in the '90s in, if I remember correctly, Southern Africa.

Quote:

Just getting my understanding of your thoughts correct before I go any further. You believe that the process was for the most part gradual but at times of environmental change relatively quick speciation occured and a new species (if not genus) evolved and this happened a few times throughout history.
Pretty much, give or take a few details. It fits withing the available evidence. Keeping in mind there is very little. If there was a bipedal hominid at least four million years ago, and at least one species two million years ago, it makes more sense to me to draw a link between them than trying to create a convoluted ancestral web that includes a dozen semi-bipedal species that existed in the interim.

My palaeoanthropoly professor (who does her field research in East Africa) posed an interesting question once that I love the implications of. Chimpanzees are a real problem. There are no remains of ancestral chimpanzees more than one or two million years old (I forget which number). Most people assume there are no remains, because the humid jungle environment destroyed them. This professor's question was, "What if we do have ancestral chimpanzee remains? What if many or most australopithicus remains are chimp ancestors and ancestresses?" I love that question. If she is right, it would cause complete chaos in the field.

H_TeXMeX_H 08-24-2013 10:28 AM

Here are some interesting articles:
http://science.slashdot.org/story/11...an-populations
http://science.slashdot.org/story/11...0-year-history
http://science.slashdot.org/story/10...s-from-a-virus
http://science.slashdot.org/story/09...c-human-groups
http://science.slashdot.org/story/12...genome-charted
http://science.slashdot.org/story/13...es-and-monkeys
https://historyplanet.wordpress.com/...ic-ape-theory/

There is no point in discussing "evolution vs. creationism", that can be done in the other thread.

I will focus on evolution and human evolution instead.

It's quite clear to me that humans evolved in coastal areas, and that they belong to the Catarrhini Parvorder. The rest is a matter of opinion, because there just isn't enough data out in the open.

I'm not convinced that humans evolved in Africa. They try to make this fit, but I'm not convinced. Just because the oldest human-like fossils have been found there, doesn't mean that they evolved there.

I also think that evolution is more complicated than they make it seem. Did they take into account convergent evolution ?

Sure, there are similarities between humans and living apes, but does that mean that we are very closely related ? I think not. But, we likely are related at some level. I think there are also political/religious forces at work, because imagine the consequences of being able to prove beyond reasonable doubt, the human evolutionary lineage. I think they made themselves some room, as they have in other fields (physics).

DavidMcCann 08-24-2013 11:27 AM

Quote:

Originally Posted by k3lt01 (Post 5014888)
A few years ago, 10 now, I studied Anthropology at USQ in Queensland and Palaeoanthropology at UNE in New South Wales. I did so because I have an interest in human history and cultural practises. I learned so much from people like Mike Morwood (one of the senior team members who discovered Homo Floriensis), Peter Brown (who was one of the first to study the skeletal remains of Homo Floriensis), and other lecturers at both universities, but I still have so much more to learn

That's a pretty good start. I did a bit of anthropology with David Pilbeam at Cambridge, more years ago than I care to remember.

Quote:

First up I'll openly state I have no problem with evolution, what I have difficulty with is making the, what I believe to be, giant leap from one genus to another. Did Ardipithicus evolve into Australopithicene and further to Homo and how? What evidence is there? Where is the evidence? How much evidence is there? I personally cannot see a link (missing link?) and don't pretend to be able to explain any other possibility.
Surely the point here is that we have such a tiny sample of past populations to work on. Compare how many Australopithicene fossils survive with, for example, the current baboon population! The odds against getting all the intermediate stages between them and us is on a par with winning the lottery. The basic fact of evolution may be incontrovertable, but the details will always involve a lot of conjecture. It could even be that H. sapiens is not descended from Australopithecus, but from a contemporary that's vanished from the record, but we just have to apply Occam's Razor and fit the material we have into the most plausible pattern.

rokytnji 08-24-2013 11:28 AM

Well this thread determined what I was going to watch today in the motorcycle shop. Thanks

https://www.youtube.com/watch?v=gnSf7pAjw38

Arcane 08-24-2013 12:27 PM

The problem with evolution as defined by atheism is that missing link has not been found..while creationism is supported by pretty much everything with no missing links.

jdkaye 08-24-2013 03:08 PM

Quote:

Originally Posted by Arcane (Post 5015127)
The problem with evolution as defined by atheism is that missing link has not been found..while creationism is supported by pretty much everything with no missing links.

I assume you're joking and I'll play the straight man. Creationism is supported by nothing since it has no empirical content. Creationism is, in fact, just another way of saying, "I don't know". I'd be interested in the Creationist take on Tiktaalik roseae and the fact that it existed around 375 million years ago.

Have fun. :)
jdk


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