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Author Topic:   Does O. recapitulate P. or doesn't it?
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 4 of 8 (531471)
10-18-2009 6:37 AM
Reply to: Message 1 by tomato
10-18-2009 12:36 AM


This is a good question. Biologists themselves get confused about this.
The prediction of the theory of evolution is as follows
If an embryo develops, and then loses, some significant feature during its embryological development, then that feature must be ancestral (as confirmed by other considerations, such as the fossil record, morphology, molecular phylogeny, and so forth).
Note that this is not at all what Haeckel said.
Edited by Dr Adequate, : No reason given.

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 Message 1 by tomato, posted 10-18-2009 12:36 AM tomato has replied

Replies to this message:
 Message 5 by tomato, posted 10-18-2009 7:04 AM Dr Adequate has replied
 Message 6 by Blue Jay, posted 10-18-2009 12:56 PM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 7 of 8 (531589)
10-19-2009 12:31 AM
Reply to: Message 6 by Blue Jay
10-18-2009 12:56 PM


I don't think this statement is entirely accurate: it's possible for a new feature to evolve for a short-term benefit during some stage of embryological development (I can't think of any examples in which this is the case ...
The egg tooth.
I should have included the word "useless" somewhere in my statement.

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 8 of 8 (531591)
10-19-2009 12:37 AM
Reply to: Message 5 by tomato
10-18-2009 7:04 AM


I guess I score 7 out of 7, then.
All of my examples meet that requirement.
They do indeed. Though I think it is Darwin and not you who gets 7 out of 7.
But yes, that's what the theory of evolution tells us about embryology.
Note that it divides events into those that can happen and those that can't, not those that must happen and those that mustn't. For example, the theory says that humans can grow a coat of fur and then lose it as an embryo. (Which we do.) It also says that we can't grow and then lose feathers. (We don't.) But it also says that we can grow and lose scales, what with being descended from fish. And we don't. It doesn't mandate that we should recapitulate ancestral forms, it says that we can only recapitulate ancestral forms.

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