Evolution/Regarding evolution (
QUESTION: I read below from an article which refutes evolution.
"One-celled orgnisms such as the amoeba reproduce asexually by dividing them selves into two. This system of reproduction is satisfactory because such organisms are still with us multiplying in the same way. What was the need of converting this asexual system into sexual one ? How could male and female sex organs that perfectly complement each other evolve gradually by chance, by the method of trial and error, paralleling each other, yet useless and decidedly disadvantageous until completed ? It may be noted that half-completed useless organs cannot survive even according to Darwin"
Also there was never a scenario of lack of food in oceans, but evolutionists often claim that aquatic animals moved to earth due to lack of food.
Can you address the above?
ANSWER: Dear Amtry,
The quote above cites the old "irreducible complexity" argument, namely that a complex structure cannot evolve from more simple structures. This is simply false.
There is ample evidence that while asexual reproduction is efficient and will get one's entire genome into the next generation, sex is necessary to keep offspring variable. This means that at least SOME of those variable offspring will be able to cope with changes in the environment to which the original, parental genome might not be well suited. In the words of Matt Ridley, quoting Carroll Lewis, the organisms must keep on running to stay in the same place. He calls this the Red Queen Hypothesis, and you can read about it in more detail here:
and in the book of the same title by Matt Ridley.
Once it's been established that sexual reproduction is evolutionarily advantageous (and there are many studies that have demonstrated exactly that:
To address the idea of "irreducible complexity", one need only look at extant organisms to see that there is a progression of complexity in sexual reproductive apparati, from simple contact between sex pores in opposite sexed organisms to increasingly more complex structures. But they vary along a continuum, suggesting that there is nothing "half completed" about sex organs that are less complex than others. They work just fine. But if a mutant happens along in which that simpler sex organ is modified to become better at passing along the genes, then that will likely be favored by natural selection.
You can see examples of this in many other structures, including another "irreducibly complex" one, the vertebrate eye:
For more examples and explanation, please see my Introduction to Evolution lecture on the topic here:
It's just an outline, but I think it will help.
---------- FOLLOW-UP ----------
You have not answered the later part of the question:
"Also there was never a scenario of lack of food in oceans, but evolutionists often claim that aquatic animals moved to earth due to lack of food."
I have never heard an evolutionary biologist claim that aquatic animals (similar to a lobe-finned fish/amphibian) moved onto land because there was a lack of food in the ocean. That's not a very viable hypothesis, as there was abundant food there, especially in the near-shore areas where the first animals stepped onto land.
Plants moved onto land before animals did, and because they lived there for a long time without predators/herbivores, it was a "good" move for them. They could flourish undisturbed. But a nice buffet table like that would not go untapped forever. An ancestral invertebrate able to exit the ocean and take advantage of the abundant plant food on land would certainly have a reproductive advantage: almost unlimited resources!
Similarly, there would have been an adaptive advantage for an ancestral fishlike/amphibianlike ancestor to move onto land to take advantage of the abundant food there in the form of early plants and LOTS of insects. It's as if there was a buffet table in the other room that no one was using, and you'd have it all to yourself if you could just reach it! :)
So it wasn't a lack of food in the ocean that might have made moving on to land adaptive. Rather, it was an abundant, untapped food source on land that made it an ecological niche waiting to be filled.