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Author Topic:   Evolving the Musculoskeletal System
molbiogirl
Member (Idle past 2750 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 99 of 527 (577997)
08-31-2010 11:55 AM
Reply to: Message 97 by Bolder-dash
08-31-2010 9:33 AM


We don't see sporadic examples of people born with excess cartilages in random areas, or lubricant forming between some peoples finger joints, or extra ligaments appearing in some individuals which causes some difference of their physical capabilities.
Excess cartilage: osteochondroma, chondosarcoma, acromegaly
Excess joint fluid: pigmented villonodular synovitis (pvns), arthrocentesis, rheumatoid arthritis
Excess ligaments: Madelung's deformity, scoliosis

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 Message 97 by Bolder-dash, posted 08-31-2010 9:33 AM Bolder-dash has replied

Replies to this message:
 Message 102 by Bolder-dash, posted 08-31-2010 1:43 PM molbiogirl has replied

  
molbiogirl
Member (Idle past 2750 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 112 of 527 (578035)
08-31-2010 3:22 PM
Reply to: Message 102 by Bolder-dash
08-31-2010 1:43 PM


Mutations which could possibly, with even the greatest stretch of imagination, actually BENEFIT an individual in the right circumstances.
Tetrapods occasionally produced small, unpaired bones between the paired nasals which articulated with the premaxilla. The appearance of internasals is an example of random genetic drift of a minor mutation which results in a benefit (an additional tooth bearing bone).
The development of the rib serves as another example. The earliest tetrapod ribs were independent of the vertebral column. A mutation of the Hox gene (an increase in the number of copies of the gene) led to fusion of these ribs to the spine. This fusion disengaged the rib cage from the musculature of the body and allowed for greater ventilation (the animal can breathe more easily).

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