Freethought & Rationalism Archive

caravelair · 05-10-2003, 09:10 AM

sorry to keep bothering everyone, but i need help with yet another creationist claim:

> For instance, the number of
> ribs changes several times in the progression form
> Eohippus to Equus. Eohippus has eighteen pairs of ribs,
> but Orohippus has only fifteen; the rib count jumps to
> nineteen pairs in the Pliohippus but drops back down to
> eighteen in Equus.

i know that it's possible for evolution to "reverse direction", and i also know that equus did not evolve from pliohippus, rather they had a common ancestor. but i would like to make a stronger case against this argument, and i have been unable to find any reliable information on this. i read part of the talkorigins article on horse evolution, but it didn't seem to have anything about ribs at all. does anyone know something about this, or know where i can find an article about it? thanks a bunch.

caravelair · 05-10-2003, 09:14 AM

ooh, hold on. i just found something of interest:

Quote:

The flaw in this argument should be apparent once one understands that the number of ribs can vary within a single species, and modern horses may have 17, 18 or 19 pairs of ribs.

that should help!

Dr.GH · 05-10-2003, 10:01 AM

caravelair,

Good point. It really helps others if you would add the sources for your information, like the web link or citation. Thanks.

caravelair · 05-10-2003, 10:22 AM

you're definately right. i apologize. the quote was taken from the talkorigins feedback for may '01, which can be found here.

Valentine Pontifex · 05-10-2003, 04:53 PM

Quote:

Originally posted by caravelair
sorry to keep bothering everyone, but i need help with yet another creationist claim:

> For instance, the number of
> ribs changes several times in the progression form
> Eohippus to Equus. Eohippus has eighteen pairs of ribs,
> but Orohippus has only fifteen; the rib count jumps to
> nineteen pairs in the Pliohippus but drops back down to
> eighteen in Equus.

i know that it's possible for evolution to "reverse direction", and i also know that equus did not evolve from pliohippus, rather they had a common ancestor. but i would like to make a stronger case against this argument, and i have been unable to find any reliable information on this. i read part of the talkorigins article on horse evolution, but it didn't seem to have anything about ribs at all. does anyone know something about this, or know where i can find an article about it? thanks a bunch.

As you point out and other give even more reason for, this argument is wrong on just many many levels.

The number of ribs is a fairly trivial characteristic and not hard to believe that it could go either up or down even if we did not know that rib number does vary a bit in living organisms.

ps418 · 05-11-2003, 09:06 AM

There is (maybe?) a fallacy here that pops up all the time. But as far as I know, no one has a coined a name for it. Its the fallacy of assuming that there are no morphological 'jumps.' For instance, an 5-ribbed ancestor can only give rise to a 7-ribbed descendent via a 6-ribbed intermediate. Obviously, there are many ways in which a very small genetic change --for instance a SNP occuring in a transcription factor expressed early in development or something-- can result in a morphological "jump."

Patrick

05-10-2003, 09:10 AM	#1
caravelair Regular Member Join Date: Apr 2003 Location: toronto Posts: 420	horse ribs sorry to keep bothering everyone, but i need help with yet another creationist claim: > For instance, the number of > ribs changes several times in the progression form > Eohippus to Equus. Eohippus has eighteen pairs of ribs, > but Orohippus has only fifteen; the rib count jumps to > nineteen pairs in the Pliohippus but drops back down to > eighteen in Equus. i know that it's possible for evolution to "reverse direction", and i also know that equus did not evolve from pliohippus, rather they had a common ancestor. but i would like to make a stronger case against this argument, and i have been unable to find any reliable information on this. i read part of the talkorigins article on horse evolution, but it didn't seem to have anything about ribs at all. does anyone know something about this, or know where i can find an article about it? thanks a bunch.

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search

05-10-2003, 10:01 AM	#3
Dr.GH Veteran Member Join Date: Jul 2001 Location: Dana Point, Ca, USA Posts: 2,115	caravelair, Good point. It really helps others if you would add the sources for your information, like the web link or citation. Thanks.

05-10-2003, 10:22 AM	#4
caravelair Regular Member Join Date: Apr 2003 Location: toronto Posts: 420	you're definately right. i apologize. the quote was taken from the talkorigins feedback for may '01, which can be found here.

05-11-2003, 09:06 AM	#6
ps418 Veteran Member Join Date: Mar 2001 Location: Louisville, KY, USA Posts: 1,840	There is (maybe?) a fallacy here that pops up all the time. But as far as I know, no one has a coined a name for it. Its the fallacy of assuming that there are no morphological 'jumps.' For instance, an 5-ribbed ancestor can only give rise to a 7-ribbed descendent via a 6-ribbed intermediate. Obviously, there are many ways in which a very small genetic change --for instance a SNP occuring in a transcription factor expressed early in development or something-- can result in a morphological "jump." Patrick

Freethought & Rationalism Archive

The archives are read only.