Well from a personal perspective it's hard for me to distinguish, because evolution seems pretty incontrovertible to me.
But I have many creationist friends, and the parts they don't seem to accept as "fact" are:
- Speciation (how given any amount of time we could get things as distinct as flowers and dogs and humans from a common ancestor)
- Emergent complexity (how given any amount of time, small changes in the genetic code could have led to things as complex as eyes and brains and so forth)
- Sentience and self-awareness (how given any amount of time our brains could have evolved to possess this seemingly magical and qualitatively different trait)
Again, I want to emphasize that I don't personally think any of these are great mysteries solvable only by appeals to spirituality. However, I hope everyone reading this could see how there's a bit of a jump from the 'fact' of (say) evolution of drug resistance in bacteria to the 'fact' of longer-term cumulative evolutionary effects like speciation and the eventual emergence of "eyes from non-eyes", etc.
Most of these points rely on the belief that evolution is always made up of slow, small changes in the genetic code. While this is the case most of the time (and enables the fine tuning that we see in many species), evolution can happen very quickly.
Population bottlenecks cause species that were once very fit to no longer be fit for an environment, enabling vastly different organisms to become dominant very quickly.
Then there are phenomena like Chromothripsis[1] (only discovered last year), whereby the genetic code of a cell is literally smashed into thousands of pieces and seemingly randomly reassembled. No one is saying that Chromothripsis is a major driver of evolution, but it is interesting in that massive rearrangements of this nature can still provide cells capable of reproducing. In the case of cancer, where it was first discovered, these cells are even able to reproduce faster than normal cells.
The other thing is that even advanced life like mammals and humans have more than 10 times as many bacterial cells than human cells[2]. Since bacteria can evolve very quickly, they play a very important role in evolution.
The eyes from no eyes makes no sense to me, since the entire array of light sensing capabilities are seen in nature. From eagles to plants. The same is true for many of the examples of emergent complexity that are thrown out there.
>The eyes from no eyes makes no sense to me, since the entire array of light sensing capabilities are seen in nature. //
A few articles addressing eyes from a creationist perspective, the first addresses your point most directly. I'll give author and credentials as it seems fitting.
These, indeed the first alone, should make sense at least of the argument from Christian creationist scientists against Darwinian evolution providing a convincing argument for the undirected formation of the eye.
Interestingly this, http://www.answersingenesis.org/articles/am/v3/n3/seeing-eye, answers a question that I've seen raised about the development of the retina and cornea+lens and how they can possibly combine if they develop separately; it gives a very brief acknowledgement of the retina and rearward parts forming from a brain "bud" and the cornea and lens forming from the over-covering flesh of the to-be-formed eye socket. Of course Haeckel's fraud makes one rightly nervous about assuming 'ontogeny recapitulates phylogeny' but it at least provides an insight in to a potential evolutionary process.
I'm an atheist and believe in evolution but I find these three things hard to grasp as well. I just find it fantastic that seemingly random mutations which grant marginally better chances to survival can lead to all these things.
Those are partially hard to grasp due to lacking knowledge of biology. For example almost all the possible steps between non-eyes and eyes exist in animals currently living today. Simply having a patch of light sensitive skin is better than no eyes at all.
But I have many creationist friends, and the parts they don't seem to accept as "fact" are:
- Speciation (how given any amount of time we could get things as distinct as flowers and dogs and humans from a common ancestor)
- Emergent complexity (how given any amount of time, small changes in the genetic code could have led to things as complex as eyes and brains and so forth)
- Sentience and self-awareness (how given any amount of time our brains could have evolved to possess this seemingly magical and qualitatively different trait)
Again, I want to emphasize that I don't personally think any of these are great mysteries solvable only by appeals to spirituality. However, I hope everyone reading this could see how there's a bit of a jump from the 'fact' of (say) evolution of drug resistance in bacteria to the 'fact' of longer-term cumulative evolutionary effects like speciation and the eventual emergence of "eyes from non-eyes", etc.