Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 122 (8781 total)
Current session began: 
Page Loaded: 08-19-2017 9:12 AM
386 online now:
Faith, JonF, kjsimons, Meddle, PaulK, Percy (Admin), ramoss, RAZD (8 members, 378 visitors)
Chatting now:  Chat room empty
Newest Member: evilsorcerer1
Post Volume:
Total: 816,406 Year: 21,012/21,208 Month: 1,445/2,326 Week: 781/345 Day: 19/124 Hour: 1/9

Announcements: Reporting debate problems OR discussing moderation actions/inactions


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Prev12
3
Author Topic:   {composite\Lucy\Little-Foot\Australopithicus} was bipedal
RAZD
Member
Posts: 18855
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.6


Message 31 of 34 (809462)
05-18-2017 12:52 PM
Reply to: Message 30 by Coyote
05-18-2017 11:04 AM


Re: Pictures
In your second picture, the differences in pelvis morphology is very striking. If you group them into two groups by shape you must group the chimp pelvis by itself and the other two together.

Indeed, and if we throw in Ardipithicus ramidus (Ardi) between them you can see a clear transition in the hips:

with Ardi clearly in transition between chimps and Australopithicus

The bones tell the story -- see The story of Bones and Dogs and Humans in Human Origins and Evolution.

Enjoy

Edited by RAZD, : link promoted version


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆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 30 by Coyote, posted 05-18-2017 11:04 AM Coyote has acknowledged this reply

  
RAZD
Member
Posts: 18855
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.6


Message 32 of 34 (809473)
05-18-2017 1:01 PM
Reply to: Message 29 by Taq
05-18-2017 10:59 AM


Re: Is It Relevant?
Other than knowing when hominids were first bipedal, the question of bipedalism in Australopithecines is rather irrelevant to the question of human evolution. Australopithecines had adaptations for bipedalism seen in modern humans, whether they used them all of the time, some of the time, or only rarely. That's what matters in the larger discussion.

Australopithicines were still able to climb according to some analists (for safety and sleeping possibly), but not as well as chimps. Even more in transition from arboreal to terrestrial habit is Ardipiticus ramidus (Ardi), who seemed about equally adapted to each habitat, but with clear adaptations for bipedal walking and wrists not made for knuckle walking.

Enjoy


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆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 29 by Taq, posted 05-18-2017 10:59 AM Taq has responded

Replies to this message:
 Message 33 by Taq, posted 05-18-2017 1:32 PM RAZD has responded

  
Taq
Member
Posts: 7034
Joined: 03-06-2009
Member Rating: 3.8


(1)
Message 33 of 34 (809485)
05-18-2017 1:32 PM
Reply to: Message 32 by RAZD
05-18-2017 1:01 PM


Re: Is It Relevant?
RAZD writes:

Australopithicines were still able to climb according to some analists (for safety and sleeping possibly), but not as well as chimps. Even more in transition from arboreal to terrestrial habit is Ardipiticus ramidus (Ardi), who seemed about equally adapted to each habitat, but with clear adaptations for bipedal walking and wrists not made for knuckle walking.

I skimmed the thread and didn't see anything on this, so I apologize if I am retreading old info . . .

"Here we present evidence that fossils attributed to Australopithecus anamensis (KNM-ER 20419) and A. afarensis (AL 288-1) retain specialized wrist morphology associated with knuckle-walking. This distal radial morphology differs from that of later hominids and non-knuckle-walking anthropoid primates, suggesting that knuckle-walking is a derived feature of the African ape and human clade.."
http://www.nature.com/...urnal/v404/n6776/full/404382a0.html

It is interesting that some (all?) Australopithecines still had wrist adaptations for knuckle walking that are not seen in modern humans. This is yet another transitional feature that further evidences human evolution.

What we also need to be careful of is viewing any Australopithecine individual or species as being directly ancestral to humans. Transitional does not mean ancestral. It is still possible for side branches of the human lineage to evolve in different directions, even back towards arboreal adaptations.


This message is a reply to:
 Message 32 by RAZD, posted 05-18-2017 1:01 PM RAZD has responded

Replies to this message:
 Message 34 by RAZD, posted 05-18-2017 3:19 PM Taq has not yet responded

  
RAZD
Member
Posts: 18855
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.6


Message 34 of 34 (809496)
05-18-2017 3:19 PM
Reply to: Message 33 by Taq
05-18-2017 1:32 PM


Re: Is It Relevant?
I skimmed the thread and didn't see anything on this, so I apologize if I am retreading old info . . .

"Here we present evidence that fossils attributed to Australopithecus anamensis (KNM-ER 20419) and A. afarensis (AL 288-1) retain specialized wrist morphology associated with knuckle-walking. This distal radial morphology differs from that of later hominids and non-knuckle-walking anthropoid primates, suggesting that knuckle-walking is a derived feature of the African ape and human clade.."
http://www.nature.com/...urnal/v404/n6776/full/404382a0.html

Last I saw there was some some controversy on this. I can't read that article with my limited sign-in.

message me -- can you email a copy?

We don't see knuckle walking with Ardi, and that is after the common ancestor date.

*** update ***

caffeine sent a link to the paper on line: Evidence that humans evolved from a knuckle-walking ancestor
and noted that it was 10 years old, and more recent analysis backs away from the knuckle walking, which jibes with my recollection of the controversy.

I did a search on australopithicine knuckle walking? and found this update:

quote:
Australopithecus

The ancestors of gorillas and chimpanzees are suggested to have become more specialised in climbing vertical tree trunks, using a bent hip and bent knee posture that matches the knuckle-walking posture they use for ground travel. This was due to climate changes around 11 to 12 million years ago that affected forests in East and Central Africa, so periods occurred when openings prevented travel through the tree canopy, and at these times, ancestral hominids could have adapted the erect walking behaviour for ground travel. Humans are closely related to these apes, and share features including wrist bones apparently strengthened for knuckle-walking.[11]

However, the view that human ancestors were knuckle-walkers is now questioned since the anatomy and biomechanics of knuckle-walking in chimpanzees and gorillas are different, suggesting that this ability evolved independently after the last common ancestor with the human lineage.[12] Further comparative analysis with other primates suggests that these wrist-bone adaptations support a palm-based tree walking.[12]


So convergent evolution for chimp and gorilla knuckle walking and palm-based tree walking for Australopithicus.

Palm-based tree walking has also been suggest for Ardi as explanation for development of bipedalism.

quote:
Ardi Is a New Piece for the Evolution Puzzle

... Her wrist, hand and shoulder bones show that she wasn't a knuckle walker and didn't spend much time hanging or swinging ape-style in trees. Rather, she moved along branches using a primitive method of palm-walking typical of extinct apes. "[Ardi is] a lovely Darwinian creature," says Penn State paleoanthropologist Alan Walker, who was not involved in the discovery. "It has features that are intermediate between the last common ancestor and australopithecines."


caveat: that article is 8 years old.

Enjoy

ps -- questions like this are why I love this place.

Edited by RAZD, : update


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆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 33 by Taq, posted 05-18-2017 1:32 PM Taq has not yet responded

  
Prev12
3
Newer Topic | Older Topic
Jump to:


Copyright 2001-2015 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2017