Changes

* Differences which cannot be explained by evolutionary mechanisms are powerful evidence ''against'' 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''.

To illustrate the first objection, it stands to reason that if a designer were creating several lifeforms, he would probably use similar designs, because the designs are ''functional''.  Just as all cars have design similarities, including four tires, an internal combustion engine, a steering wheel, but obviously are not related; diverse species may simply share ''common design characteristics''. Thus 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 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: