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Author Topic:   The Definition and Description of a "Transitional"
dpardo
Inactive Member


Message 91 of 110 (168633)
12-15-2004 4:12 PM
Reply to: Message 90 by Jazzns
12-15-2004 3:33 PM


Thank you.

I will check them out.


This message is a reply to:
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dpardo
Inactive Member


Message 92 of 110 (168637)
12-15-2004 4:22 PM
Reply to: Message 90 by Jazzns
12-15-2004 3:33 PM


From the second link...

Australopithecus ramidus (mid-Pliocene, 4.4 Ma) -- A recently discovered very early hominid (or early chimp?), from just after the split with the apes. Not well known. Possibly bipedal (only the skull was found). Teeth both apelike and humanlike; one baby tooth is very chimp-like. (White et al., 1994; Wood 1994)
Australopithecus afarensis (late Pliocene, 3.9 Ma) -- Some excellent fossils ("Lucy", etc.) make clear that this was fully bipedal and definitely a hominid. But it was an extremely ape-like hominid; only four feet tall, still had an ape-sized brain of just 375-500 cc (finally answering the question of which came first, large brain or bipedality) and ape-like teeth. This lineage gradually split into a husky large-toothed lineage and a more slender, smaller- toothed lineage. The husky lineage (A. robustus, A. boisei) eventually went extinct.
Australopithecus africanus (later Pliocene, 3.0 Ma) -- The more slender lineage. Up to five feet tall, with slightly larger brain (430-550 cc) and smaller incisors. Teeth gradually became more and more like Homo teeth. These hominds are almost perfect ape- human intermediates, and it's now pretty clear that the slender australopithecines led to the first Homo species.
Homo habilis (latest Pliocene/earliest Pleistocene, 2.5 Ma) -- Straddles the boundary between australopithecines and humans, such that it's sometimes lumped with the australopithecines. About five feet tall, face still primitive but projects less, molars smaller. Brain 500-800 cc, overlapping australopithecines at the low end and and early Homo erectus at the high end. Capable of rudimentary speech? First clumsy stone tools.
Homo erectus (incl. "Java Man", "Peking Man", "Heidelberg Man"; Pleist., 1.8 Ma) -- Looking much more human now with a brain of 775-1225 cc, but still has thick brow ridges & no chin. Spread out of Africa & across Europe and Asia. Good tools, first fire.
Archaic Homo sapiens (Pleistocene, 500,000 yrs ago) -- These first primitive humans were perfectly intermediate between H. erectus and modern humans, with a brain of 1200 cc and less robust skeleton & teeth. Over the next 300,000 years, brain gradually increased, molars got still smaller, skeleton less muscular. Clearly arose from H erectus, but there are continuing arguments about where this happened.
One famous offshoot group, the Neandertals, developed in Europe 125,000 years ago. They are considered to be the same species as us, but a different subspecies, H. sapiens neandertalensis. They were more muscular, with a slightly larger brain of 1450 cc, a distinctive brow ridge, and differently shaped throat (possibly limiting their language?). They are known to have buried their dead.
H. sapiens sapiens (incl. "Cro-magnons"; late Pleist., 40,000 yrs ago) -- All modern humans. Average brain size 1350 cc. In Europe, gradually supplanted the Neanderthals.

What I see here are distinctions made on the basis of height, brain size, teeth size, build, etc.

Are these distinctions not simply possible between different human beings?


This message is a reply to:
 Message 90 by Jazzns, posted 12-15-2004 3:33 PM Jazzns has responded

Replies to this message:
 Message 94 by Loudmouth, posted 12-15-2004 4:27 PM dpardo has responded
 Message 98 by Jazzns, posted 12-16-2004 10:41 AM dpardo has responded

  
Loudmouth
Inactive Member


Message 93 of 110 (168638)
12-15-2004 4:23 PM
Reply to: Message 89 by dpardo
12-15-2004 2:46 PM


quote:
Can you post a link to this/these "very nice" transitional fossil(s) for ape-like ancestor and man?

Here is a picture of the most important transitional fossil skulls.

Key:
(A) Pan troglodytes, chimpanzee, modern
(B) Australopithecus africanus, STS 5, 2.6 My
(C) Australopithecus africanus, STS 71, 2.5 My
(D) Homo habilis, KNM-ER 1813, 1.9 My
(E) Homo habilis, OH24, 1.8 My
(F) Homo rudolfensis, KNM-ER 1470, 1.8 My
(G) Homo erectus, Dmanisi cranium D2700, 1.75 My
(H) Homo ergaster (early H. erectus), KNM-ER 3733, 1.75 My
(I) Homo heidelbergensis, "Rhodesia man," 300,000 - 125,000 y
(J) Homo sapiens neanderthalensis, La Ferrassie 1, 70,000 y
(K) Homo sapiens neanderthalensis, La Chappelle-aux-Saints, 60,000 y
(L) Homo sapiens neanderthalensis, Le Moustier, 45,000 y
(M) Homo sapiens sapiens, Cro-Magnon I, 30,000 y
(N) Homo sapiens sapiens, modern

Additional info:
http://www.talkorigins.org/faqs/comdesc/section1.html#morphological_intermediates_ex3

http://www.talkorigins.org/faqs/homs/ (this page gives the fossil species, creationist arguments, and rebutals to creationists; a nice rounded view of the whole issue).


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Loudmouth
Inactive Member


Message 94 of 110 (168640)
12-15-2004 4:27 PM
Reply to: Message 92 by dpardo
12-15-2004 4:22 PM


quote:
What I see here are distinctions made on the basis of height, brain size, teeth size, build, etc.

Are these distinctions not simply possible between different human beings?


No human falls within the range given for earlier hominids, especially brain size. I believe that some human characteristics, but not all, fall into the range of H. erectus. Also, look at the photos above and focus on the brain case. You will notice that humans obviously have bigger craniums than the earlier fossils.

This message has been edited by Loudmouth, 12-15-2004 04:28 PM

This message has been edited by Loudmouth, 12-15-2004 04:30 PM


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 Message 92 by dpardo, posted 12-15-2004 4:22 PM dpardo has responded

Replies to this message:
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dpardo
Inactive Member


Message 95 of 110 (168663)
12-15-2004 5:15 PM
Reply to: Message 94 by Loudmouth
12-15-2004 4:27 PM


Loudmouth writes:

Also, look at the photos above and focus on the brain case. You will notice that humans obviously have bigger craniums than the earlier fossils.

But don't human heads vary, sometimes greatly, in size from one to another?


This message is a reply to:
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Replies to this message:
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 Message 97 by NosyNed, posted 12-16-2004 1:28 AM dpardo has responded
 Message 103 by Loudmouth, posted 12-16-2004 12:51 PM dpardo has responded

  
Darwin Redux
Inactive Member


Message 96 of 110 (168783)
12-16-2004 1:22 AM
Reply to: Message 95 by dpardo
12-15-2004 5:15 PM


quote:
But don't human heads vary, sometimes greatly, in size from one to another?

No, actually, they don't - certainly not with respect to the cranio-dental morphological features displayed by earlier hominid remains (such as Australopithecus afarensis or the members of the Paranthropus clade)


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NosyNed
Member
Posts: 8863
From: Canada
Joined: 04-04-2003
Member Rating: 4.6


Message 97 of 110 (168785)
12-16-2004 1:28 AM
Reply to: Message 95 by dpardo
12-15-2004 5:15 PM


For fun, what if....
But don't human heads vary, sometimes greatly, in size from one to another?

As noted the older samples are outside of the range of current measurements (certainly with respect to overall body sizes).

But for fun let's say that you're right. There is and has always been a range of features, cranium volumes and more that overlap with the current human range. So everyone of these specimens can be fitted in that normal range. Just pretending here, right?

Now then, explain a couple of things:

How come only those that are on a very extreme end of this hypothetical range are the ones perserved?

and

How come when they are laid out in time various features are closer to the current norms when they are nearer in time and further from those norms when they are further away in time? (With some variance since I don't see that any feature would constantly and smoothly approach the current state)?

When you are hypothosizing you must include all the facts.


This message is a reply to:
 Message 95 by dpardo, posted 12-15-2004 5:15 PM dpardo has responded

Replies to this message:
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Jazzns
Member (Idle past 2199 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 98 of 110 (168878)
12-16-2004 10:41 AM
Reply to: Message 92 by dpardo
12-15-2004 4:22 PM


Pictures
It is better if you see some pictures. I see that Loudmouth has given some information. When you see them all lined up it there is a nice gradient and it is very hard to draw the line between what is an ape and what is a human.

Ned's reply is also very important. It is not just the physical differences that we see but also the fact that the fossils date going back farther and farther into the past AS the physical differences get more and more ape like. No one is just putting a bunch of skulls into a sequence that they think looks like evolution, the order is really how we found them.


This message is a reply to:
 Message 92 by dpardo, posted 12-15-2004 4:22 PM dpardo has responded

Replies to this message:
 Message 101 by dpardo, posted 12-16-2004 12:19 PM Jazzns has responded

  
dpardo
Inactive Member


Message 99 of 110 (168893)
12-16-2004 11:48 AM
Reply to: Message 97 by NosyNed
12-16-2004 1:28 AM


Re: For fun, what if....
NosyNed writes:

How come when they are laid out in time various features are closer to the current norms when they are nearer in time and further from those norms when they are further away in time? (With some variance since I don't see that any feature would constantly and smoothly approach the current state)?

Laid out in time?

How do we know how old they are?


This message is a reply to:
 Message 97 by NosyNed, posted 12-16-2004 1:28 AM NosyNed has responded

Replies to this message:
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Jazzns
Member (Idle past 2199 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 100 of 110 (168895)
12-16-2004 11:53 AM
Reply to: Message 99 by dpardo
12-16-2004 11:48 AM


Re: For fun, what if....
Forget about time. They are laid out in depth.

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dpardo
Inactive Member


Message 101 of 110 (168899)
12-16-2004 12:19 PM
Reply to: Message 98 by Jazzns
12-16-2004 10:41 AM


Jazzns writes:

When you see them all lined up it there is a nice gradient and it is very hard to draw the line between what is an ape and what is a human.

Have we ever confused a human skull for an ape skull or vice versa?


This message is a reply to:
 Message 98 by Jazzns, posted 12-16-2004 10:41 AM Jazzns has responded

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Jazzns
Member (Idle past 2199 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 102 of 110 (168907)
12-16-2004 12:36 PM
Reply to: Message 101 by dpardo
12-16-2004 12:19 PM


Are you talking about modern apes? If so then I suppose someone who is not a palentologist might mistake an ape an a human skull but I don't know.

The thing about these skulls though is that you can't put them definitivly into either category from a paleoanthropic perspective.

Creationists are very fond of putting samples that are closer to ape and closer to human in distinctive human and ape categories but then have trouble with the ones right near the middle of the gradient.

I would expect that under study the distinction between two ends of the gradient would be clear.


This message is a reply to:
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Loudmouth
Inactive Member


Message 103 of 110 (168912)
12-16-2004 12:51 PM
Reply to: Message 95 by dpardo
12-15-2004 5:15 PM


quote:
But don't human heads vary, sometimes greatly, in size from one to another?

Human skulls do vary in size, but not enough for them to fall in the range of some of these hominid fossils. The graph below illustrates the human range (the two ranges on the left hand side of the graph) and the sizes of skulls from prominent hominid fossils.

The symbols are a difficult to pick out so I had to go back to the original paper in .pdf format (found here). I will try and relate the symbols to the data starting on the right hand side of the graph.

As you can see, A. afarensis and A. africanus fall well outside normal ranges for living humans, as do A. robustus and A. boisei. Moving from right to left, the squares with plus signs represent H. habilis, the first species in the genera Homo. This species falls well outside the human range as well, but is slightly bigger than the Astralopithecus genera. The next grouping to the left is H. erectus. Some of the fossils from this species falls within the human range, but most fall below the human range. Next, we have archaic H. sapien, early modern H. sapien, and neanderthals which all fall within the modern H. sapien range. This graph shows a progression of brain size through time, and as someone else mentions above, through geologic depth as well.

So to answer your other question, "Are human skulls sometimes mistaken for ape skulls" the answer would be an emphatic NO. From the picture I listed above (the transitional fossil picture) would you ever confuse the chimp skull with a human skull? I sure wouldn't, nor would any paleontologist. Also, there are other features besides the skulls that differentiate humans from early hominids and apes, such as the pelvic girdle and dentation.


This message is a reply to:
 Message 95 by dpardo, posted 12-15-2004 5:15 PM dpardo has responded

Replies to this message:
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dpardo
Inactive Member


Message 104 of 110 (168916)
12-16-2004 1:03 PM
Reply to: Message 103 by Loudmouth
12-16-2004 12:51 PM


Loudmouth writes:

As you can see, A. afarensis and A. africanus fall well outside normal ranges for living humans, as do A. robustus and A. boisei.

Loudmouth,

Is it possible for a "transitional" skull to be very simply a deformed human or ape skull? Aren't some humans born with gross deformities, sometimes in many features?


This message is a reply to:
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Replies to this message:
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Jazzns
Member (Idle past 2199 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 105 of 110 (168927)
12-16-2004 1:33 PM
Reply to: Message 104 by dpardo
12-16-2004 1:03 PM


Except for the fact that many samples for some of these in-between species have been found. If there only was 1 you might be able to dismiss it as a deformity but there are many. They all would have to of had the same deformity.

Also, why would this deformity be correlated with depth in the geologic column? Why would this pervasive deformity cause humans to look more and more like apes as you go down in the column?

This message has been edited by Jazzns, 12-16-2004 01:37 PM


This message is a reply to:
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