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Line 53: − − === Creationism === − Creationists argue that the inference of common ancestry cannot reasonably be drawn from the evidence, for two reasons: − * Similarity is not meaningful evidence of common ancestry − * Differences which cannot be explained by evolutionary mechanisms are powerful evidence ''against'' common ancestry. − − To illustrate the first objection, one might argue that all ''cars'' are related because they have four tires, an internal combustion engine, a steering wheel, etc. However, obviously cars are not related; they simply share ''common design characteristics''. In the same way, creationists argue that just because humans and plants both have cell membranes is no more evidence of ''common ancestry'' than it is of ''common design''. − − The second objection relies on incidents of [[irreducible complexity]] and [[specified complexity]] to point to the unlikelihood that all life forms diversified through variation and selection alone. They point to issues such as: − * The transition from non-self-reproducing chemicals to self-replicating cells: the process of self-replication requires an enormous number of components be present in the cell for it to function at all, and none of the components required for self-replication serve any purpose unless all are present simultaneously; therefore it is unreasonable to conclude that [[abiogenesis]] occured without [[design]]. − * The transition from asexual reproduction to sexual reproduction: male reproductive organs are incredibly complex, and serve no purpose unless female reproductive organs (which are equally, if not more, complex) already exist. Therefore the sexes could not have evolved in a step-wise fashion, because neither set of reproductive organs would serve any purpose unless the other set already existed. − − For the above reasons, creationists conclude that there is ''insufficient evidence'' to support the conclusion of common ancestry. They further conclude that [[baraminology]] provides a much more meaningful way of studying the [[origin of life]], because it allows for the possibility that ''some'' forms of life are related, but without the rather extraordinary presumption that ''all'' forms of life are related.
Universal common ancestry (view source)
Revision as of 19:58, September 16, 2007
, 19:58, September 16, 2007no edit summary
From these similarities, an evolutionist infers that all life is related through one original life form.
From these similarities, an evolutionist infers that all life is related through one original life form.
Creationists argue that the inference of common ancestry cannot reasonably be drawn from similarity, for two reasons:
* Similarity is not meaningful evidence of common ancestry
* Differences which cannot be explained by evolutionary mechanisms are powerful evidence ''against'' common ancestry.
To illustrate the first objection, one might argue that all ''cars'' are related because they have four tires, an internal combustion engine, a steering wheel, etc. However, obviously cars are not related; they simply share ''common design characteristics''. In the same way, creationists argue that just because humans and plants both have cell membranes is no more evidence of ''common ancestry'' than it is of ''common design''.
The second objection relies on incidents of [[irreducible complexity]] and [[specified complexity]] to point to the unlikelihood that all life forms diversified through variation and selection alone. They point to issues such as:
* The transition from non-self-reproducing chemicals to self-replicating cells: the process of self-replication requires an enormous number of components be present in the cell for it to function at all, and none of the components required for self-replication serve any purpose unless all are present simultaneously; therefore it is unreasonable to conclude that [[abiogenesis]] occured without [[design]].
* The transition from asexual reproduction to sexual reproduction: male reproductive organs are incredibly complex, and serve no purpose unless female reproductive organs (which are equally, if not more, complex) already exist. Therefore the sexes could not have evolved in a step-wise fashion, because neither set of reproductive organs would serve any purpose unless the other set already existed.
For the above reasons, creationists conclude that similarity does not provide meaningful evidence of common ancestry.
=== Shared endogenous retroviruses ===
=== Shared endogenous retroviruses ===
=== Horizonal gene transfer ===
=== Horizonal gene transfer ===
It is also known that genes sometime migrate somehow from one species to another species, so having a common gene is not proof of common ancestry. Maybe there is no universal common ancestor, and important genes were spread by horizontal gene transfer.
It is also known that genes sometime migrate somehow from one species to another species, so having a common gene is not proof of common ancestry. Maybe there is no universal common ancestor, and important genes were spread by horizontal gene transfer.
[[Category:Evolution]]
[[Category:Evolution]]
[[Category:Creationism]]
[[Category:Creationism]]