One major barrier against the gradual evolution of relatively simple organisms into complex ones rests on the organism’s inability to understand its environment and adapt to it.
For instance, how could a blind organism understand that color is produced by light waves reflected by or absorbed by objects, and correctly deduce that it must create an eye composed of rods and cones to capture these rays and correctly interpret them? How could a blind organism know that light could be too bright or too dark and create a pupil which dilates and contracts to monitor the correct amount of light? It just doesn’t make sense that something blind and primitive could instinctively understand that color is seen according to an object reflecting certain invisible wavelengths of light.
Before the taste buds were formed, it had to have some knowledge that some foods would be sweeter than others and some sour. How did the organism know in advance about the chemical make-up of flavorings to create specific regions on the tongue for detecting the taste of food?
How could an organism deduce that other organisms would emit fragrances and create exactly the olfactory senses needed to interpret those smells? How did it understand their chemical makeup and figure out exactly what’s needed to detect them?
How did it understand the nature of sound waves and deduce exactly the ear formation that would be needed to capture sound and interpret it accurately?
The only idea that makes sense is that the Creator who created the sun and lightwaves also created the matching organs to process them. It makes sense that the God who created all for us to enjoy not only put flavor in edible foods, but gave us the olfactory and taste organs to enjoy them. He who hears our prayers and speaks made us like Himself, and that’s why we can hear and speak.
Science has not given us any indication that we can create new kinds of organs by thinking of or wishing for them. After all, just think of the many times over the centuries that men have loved to be able to soar in the sky like a bird. Yet none of that thinking has produced wings on us. Can thinking and wishing produce new lines of code in our DNA to make this possible? Science answers No.
Admittedly, no one who believes in macro-evolution believes that any creature can think it’s way to new organs. Then by what basis of science do they create new organs? By what basis to they respond to their environment? The people who engineered the first optics did so with a knowledge of how light works. They started with the science of light waves, then designed their optics to work with light waves, and so we have camera and telescope lens well suited to the job. First the designer understood the principles of light, then it created instruments that worked according to those principles. So, how did a creature know to evolve sight when it did not know the principles in advance? What are the current building blocks of macro-evolution that have replaced the old, discredited, foundations?
As usual, the idea of a Creator makes more sense than a gradual mutation of organisms.