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Author Topic:   Evolutionary History of Apes
Perdition
Member (Idle past 3238 days)
Posts: 1593
From: Wisconsin
Joined: 05-15-2003


Message 1 of 25 (530156)
10-12-2009 2:17 PM


Last night, I watched the Discovery Channel special on "Ardi." It brought up some interesting things I hadn't known until about a week or so ago, namely: "Knuckle-walking" in chimps appears to be an evolved trait from after we split, hominids evolved in forrested areas, and in the just plain cool category, Ardi was bipedal, but still had grasping feet.
One of the threads throughout the special was trying to push human ancestry back to the common ancestor with chimps, but as with Lucy, finding that Ardi was bipedal means it's even farther back.
That got me thinking, what is the fossil record for Chimps and/or the other great apes? We seem to be trying to push our ancestor's back to a common one with chimps, but how far back do they have for chimps? Is it possible we've found our last common ancestor, but until we can link it in time with proto-hominid remains, we just don't know yet?
I'm not sure where this would go, and I've never started a new thread since the "Proposed New Topics" strategy began, so if I need to change it, let me know.

Replies to this message:
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AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 2 of 25 (530166)
10-12-2009 3:05 PM


Thread Copied from Proposed New Topics Forum
Thread copied here from the Evolutionary History of Apes thread in the Proposed New Topics forum.

  
New Cat's Eye
Inactive Member


Message 3 of 25 (530170)
10-12-2009 3:17 PM
Reply to: Message 1 by Perdition
10-12-2009 2:17 PM


Last night, I watched the Discovery Channel special on "Ardi."
How was it? I forgot to set the DVR... is it worth hunting down?
It brought up some interesting things I hadn't known until about a week or so ago, namely: "Knuckle-walking" in chimps appears to be an evolved trait from after we split,
Yup, that was the "neatest" part for me.
That and that chimps are probably just as diverged from the common ancestor as we are. Which simply follows but doesn't seem to "feel" right at first thought.
One of the first things I thought when I saw Ardi was: "Whoa, look at them hands!"
That got me thinking, what is the fossil record for Chimps and/or the other great apes? We seem to be trying to push our ancestor's back to a common one with chimps, but how far back do they have for chimps? Is it possible we've found our last common ancestor, but until we can link it in time with proto-hominid remains, we just don't know yet?
I don't have anything to offer, sorry, but I'm with you in thinking this would be interesting to look at.

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 Message 1 by Perdition, posted 10-12-2009 2:17 PM Perdition has replied

Replies to this message:
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Perdition
Member (Idle past 3238 days)
Posts: 1593
From: Wisconsin
Joined: 05-15-2003


Message 4 of 25 (530172)
10-12-2009 3:27 PM
Reply to: Message 3 by New Cat's Eye
10-12-2009 3:17 PM


How was it? I forgot to set the DVR... is it worth hunting down?
I didn't think it was Earth-shatteringly excellent, but I thought it did very weill, considering it's target. It neatly bookended the show with a description of what we found before Ardi (namely Lucy) and then what we've begun to find since, another Ardipithecus that's a million years farther back than the species in the show, which is, I believe Ardipithecus rapidus? I'm not sure what the name is for the new one, but it seems interesting.
"Whoa, look at them hands!"
Yeah, the thumbs are shorter than I would have thought, and as a whole, the hands seem longer than I would have thought...but then a human hand looks far different without all that skin, muscle and other tissue in the way.
I don't have anything to offer, sorry, but I'm with you in thinking this would be interesting to look at.
I can understand the draw for searching for human ancestors, but it seems to me it would be just as enlightening to follow chimps back and maybe come at it the other way and meet in the middle somewhere.

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 5 of 25 (530188)
10-12-2009 4:54 PM
Reply to: Message 4 by Perdition
10-12-2009 3:27 PM


Hi Perdition,
I can understand the draw for searching for human ancestors, but it seems to me it would be just as enlightening to follow chimps back and maybe come at it the other way and meet in the middle somewhere.
My understanding is that the chimps ancestors generally lived in areas that do not lend themselves to fossil formation.
There was one site that had what appeared to be chimp ancestors with Australopithecus but I've lost the link.
Message 1
It brought up some interesting things I hadn't known until about a week or so ago, namely: "Knuckle-walking" in chimps appears to be an evolved trait from after we split, hominids evolved in forrested areas, and in the just plain cool category, Ardi was bipedal, but still had grasping feet.
I believe this view is relatively recent, and I find it interesting to think that we may already have found a common ancestor, but don't recognize it as such because it is so different (relatively) from chimps. Just my thoughts.
Enjoy.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
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Replies to this message:
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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


(1)
Message 6 of 25 (530194)
10-12-2009 5:04 PM
Reply to: Message 5 by RAZD
10-12-2009 4:54 PM


Clear misinterpretation ...
My understanding is that the chimps ancestors generally lived in areas that do not lend themselves to fossil formation.
This is obviously a serious misinterpretation of the observations. What is clear from the homo and antecedent fossils that we have is that we evolved. What is equally clear from the lack of chimp ancestor fossils is it is they who are the special creation of God.

This message is a reply to:
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New Cat's Eye
Inactive Member


Message 7 of 25 (530208)
10-12-2009 5:19 PM
Reply to: Message 5 by RAZD
10-12-2009 4:54 PM


I find it interesting to think that we may already have found a common ancestor, but don't recognize it as such because it is so different (relatively) from chimps.
I was going to reply this to Perdition, but you already brought it up.
Is it possible that one of these early homos is already the common ancestor between us and chimps? Or do we know that isn't the case (like through genetics or something)?

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 Message 8 by Perdition, posted 10-12-2009 5:26 PM New Cat's Eye has not replied
 Message 9 by Dr Jack, posted 10-12-2009 5:33 PM New Cat's Eye has replied

  
Perdition
Member (Idle past 3238 days)
Posts: 1593
From: Wisconsin
Joined: 05-15-2003


Message 8 of 25 (530212)
10-12-2009 5:26 PM
Reply to: Message 7 by New Cat's Eye
10-12-2009 5:19 PM


Is it possible that one of these early homos is already the common ancestor between us and chimps? Or do we know that isn't the case (like through genetics or something)?
According to the show, the assumption is that bipedality is an evolved trait along the hominid line and is not a trait from before the chimp/hominid split. It seems to make sense, but a lot of things that seem to make sense turn out to be wrong, so I guess it's possible. Could Ardi's descendants split to have on line become better at bipedalism and the other become knuckle walkers with better "foot dexterity"? I'm no where near educated on the topic enough to even hazard a guess.

This message is a reply to:
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Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 9 of 25 (530216)
10-12-2009 5:33 PM
Reply to: Message 7 by New Cat's Eye
10-12-2009 5:19 PM


Is it possible that one of these early homos is already the common ancestor between us and chimps? Or do we know that isn't the case (like through genetics or something)?
Homo itself, no. No way. The earliest known homonids, well, possible but very unlikely for two reasons:
1. The dates are wrong. The consensus dates for when humans and chimps split are about 1-3 million years before these fossils. However, the methods of dating are prone to error so it's possible - if unlikely.
2. All known hominids have derived traits not found in chimps. That is, they have features they share with us and/or later hominids but not with chimps or earlier apes. It is, again, possible that the chimp line evolved these traits but later reverted to the primitive state but it's unlikely.
(Note: primitive here just means in the ancestral state, it's the opposite of derived. For example, in humans, having five fingers and two eyes are primitive traits whilst bipediality and hairlessness are derived traits)

This message is a reply to:
 Message 7 by New Cat's Eye, posted 10-12-2009 5:19 PM New Cat's Eye has replied

Replies to this message:
 Message 10 by New Cat's Eye, posted 10-12-2009 5:40 PM Dr Jack has replied

  
New Cat's Eye
Inactive Member


Message 10 of 25 (530220)
10-12-2009 5:40 PM
Reply to: Message 9 by Dr Jack
10-12-2009 5:33 PM


Homo itself, no. No way. The earliest known homonids, well, possible but...
Holy shit. I was using "homo" as an abbreviation for homonid and not the genus Homo >.< What a stupid abbreviation!
1. The dates are wrong. The consensus dates for when humans and chimps split are about 1-3 million years before these fossils. However, the methods of dating are prone to error so it's possible - if unlikely.
Okay, yeah. I figured someone who knew would chime in before got around to looking into it myself. Thank you.
2. All known hominids have derived traits not found in chimps. That is, they have features they share with us and/or later hominids but not with chimps or earlier apes. It is, again, possible that the chimp line evolved these traits but later reverted to the primitive state but it's unlikely.
That makes sense. The common ancestor is probably farther back then.
Thanks again.

This message is a reply to:
 Message 9 by Dr Jack, posted 10-12-2009 5:33 PM Dr Jack has replied

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Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 11 of 25 (530222)
10-12-2009 5:42 PM
Reply to: Message 10 by New Cat's Eye
10-12-2009 5:40 PM


Homo, shmomo
Holy shit. I was using "homo" as an abbreviation for homonid and not the genus Homo >.< What a stupid abbreviation!
Yeah, I figured you were, but I thought I'd just make sure
And, in general, the naming for the human containing clades is awful Hominidae, Hominid, Hominoidae, Homininae.
Edited by Mr Jack, : Extra, extra!

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ZenMonkey
Member (Idle past 4511 days)
Posts: 428
From: Portland, OR USA
Joined: 09-25-2009


Message 12 of 25 (530255)
10-12-2009 7:03 PM
Reply to: Message 1 by Perdition
10-12-2009 2:17 PM


Before I go shuffling off to do my own research, I too am curious about what the modern chimpanzee lineage looks like. I often think that it's misleading to put modern chimp skulls at the beginning of a series of hominid skulls leading chronologically up to modern humans. After all, aren't they just as evolved as we are? Do we have evidence that chimps have remained more or less stable in a single niche while we've gone off and diverged far more significantly from the common ancestor?

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 13 of 25 (530265)
10-12-2009 8:19 PM
Reply to: Message 12 by ZenMonkey
10-12-2009 7:03 PM


Hi ZenMonkey,
Before I go shuffling off to do my own research, I too am curious about what the modern chimpanzee lineage looks like. I often think that it's misleading to put modern chimp skulls at the beginning of a series of hominid skulls leading chronologically up to modern humans.
I agree, and that is why I feel that the common ancestor is more likely to look like the oldest hominid than a modern chimp.
I'd like to see the intermediate species listed as well.
By the way, this is the one I was thinking may be the "already seen" common ancestor:
Sahelanthropus - Wikipedia
quote:
Sahelanthropus tchadensis is a fossil hominid that lived approximately 7 million years ago. Its position in the Hominid evolution is not widely accepted.
Sahelanthropus may represent a common ancestor of humans and chimpanzees; no consensus has been reached yet by the scientific community. The original placement of this species as a human ancestor but not a chimpanzee ancestor would complicate the picture of human phylogeny. In particular, if Touma is a direct human ancestor, then its facial features bring the status of Australopithecus into doubt because its thickened brow ridges were reported to be similar to those of some later fossil hominids (notably Homo erectus), whereas this morphology differs from that observed in all australopithecines, most fossil hominids and extant humans.
Another possibility is that Touma is related to both humans and chimpanzees, but is the ancestor of neither. Brigitte Senut and Martin Pickford, the discoverers of Orrorin tugenensis, suggested that the features of S. tchadensis are consistent with a female proto-gorilla. Even if this claim is upheld, then the find would lose none of its significance, for at present precious few chimpanzee or gorilla ancestors have been found anywhere in Africa. Thus if S. tchadensis is an ancestral relative of the chimpanzees (or gorillas) then it represents the first known member of their lineage. Furthermore, S. tchadensis does indicate that the last common ancestor of humans and chimpanzees is unlikely to resemble chimpanzees very much, as had been previously supposed by some paleontologists.[7] [8]
While the "split" is estimated to have occurred 5 to 6 million years ago.
Human evolution - Wikipedia
quote:
Species close to the last common ancestor of gorillas, chimpanzees and humans may be represented by Nakalipithecus fossils found in Kenya and Ouranopithecus found in Greece. Molecular evidence suggests that between 8 and 4 million years ago, first the gorillas, and then the chimpanzees (genus Pan) split off from the line leading to the humans; human DNA is approximately 98.4% identical to that of chimpanzees when comparing single nucleotide polymorphisms (see Human evolutionary genetics). The fossil record of gorillas and chimpanzees is quite limited. Both poor preservation (rain forest soils tend to be acidic and dissolve bone) and sampling bias probably contribute to this problem.
Other hominines likely adapted to the drier environments outside the equatorial belt, along with antelopes, hyenas, dogs, pigs, elephants, and horses. The equatorial belt contracted after about 8 million years ago. Fossils of these hominans - the species in the human lineage following divergence from the chimpanzees - are relatively well known. The earliest are Sahelanthropus tchadensis (7 Ma) and Orrorin tugenensis (6 Ma), followed by:
With these fossils being so close to the time of divergence it is likely that the common ancestor was very similar to these species if they are not the common ancestors.
Enjoy.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 12 by ZenMonkey, posted 10-12-2009 7:03 PM ZenMonkey has not replied

Replies to this message:
 Message 14 by Dr Jack, posted 10-13-2009 5:41 AM RAZD has replied

  
Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 14 of 25 (530353)
10-13-2009 5:41 AM
Reply to: Message 13 by RAZD
10-12-2009 8:19 PM


Ah... I see the dating of the split has been revised forward, last I saw it was estimated at 6-8 Ma. So my point 1 above was wrong. Cool

This message is a reply to:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 15 of 25 (530491)
10-13-2009 6:32 PM
Reply to: Message 14 by Dr Jack
10-13-2009 5:41 AM


Hi Mr Jack,
Ah... I see the dating of the split has been revised forward, last I saw it was estimated at 6-8 Ma. So my point 1 above was wrong. Cool
Provided the new estimates are any more accurate than the last it's not much of a move, and I'll be happy to wait for more evidence.
Enjoy.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
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