Apr

‘Macro’ Evolution

In a recent post, I mentioned the term ‘macro evolution’ and said that I’d get back to that in a later discussion. Creationists like to use the terms micro and macro when discussing evolution and often refer to the former as possible/likely/proven (strike out that which doesn’t apply depending on how ‘fundamentalist your views are), while denouncing the latter as being impossible - read this as ‘I don’t understand it so it’s impossible’.

In reality, scientists hardly ever use the terms as they describe the same process that happens in the same way and for the same reasons. The basic evolutionary mechanisms—mutation, migration, genetic drift, and natural selection—can produce major evolutionary change - or ‘macro’ evolution if given enough time.

Of course if you believe the planet is around 6000 years old, then discussing evolution with you is a wasted effort.

Various arguments are postulated by creationists to ‘prove’ that major - ie: species changing - evolution cannot occur. Among those is the Crockoduck - a half duck half crocodile that Kirk Cameron (just Google him, I can’t be bothered putting up a link to this fruitloop) insists must exist for evolution to be true. Unfortunately for him and the other creationists, crocodiles did not evolve from ducks, ducks did not evolve from crocodiles, and nobody is proposing that they did. Crocodiles and ducks both have known evolutionary lineages. In fact, to find a “crocoduck” would contradict both theories of lineage and it would actually be a huge problem for the theory of evolution. Recently, a fossilized skull of a giant, bony-toothed seabird that lived up to 10 million years ago was found on Peru’s arid southern coast and has been named a Pelagornithid. Not a crockoduck but yet another example of a transitional fossil. Wait a moment! They don’t exist! Sorry Kirk, wrong again.

The argument that most ‘educated’ creationists pin their hopes on currently is the grandly named ‘Irreducible Complexity’.

The claim is made that irreducibly complex systems cannot be produced directly by gradual evolution. The reasoning goes this -
(a) Direct, gradual evolution proceeds only by stepwise addition of parts.
(b) By definition, an irreducibly complex system lacking a part is nonfunctional.
(c) Therefore, all possible direct gradual evolutionary precursors to an irreducibly complex system must be nonfunctional.

Of course the argument is invalid since the first premise is false: gradual evolution can do much more than just add parts. For instance, evolution can also change or remove parts. In contrast, irreducible complexity is restricted to only reversing the addition of parts. This is why irreducible complexity cannot tell us anything useful about how a structure did or did not evolve. Gradual Darwinian evolution can easily produce irreducible complexity. All that is required is that parts that were once just favourable become, because of later changes, essential.

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