Those who oppose the concept of biological evolution and Darwin’s Theory of the origin of species thru natural selection often come up with specific objections. These were considered in a National Geographic special called “Was Darwin wrong?” (see below for the URL). The most common arguments against Darwin were:
1. There are many missing links in the fossil record
2. How could complex anatomical structures like the eye evolve?
3. How could a land animal that returned to the sea lose its hind legs as in the case of whales?
4. What are the underlying basic (molecular or genetic) processes involved (of which Darwin was unaware)?
I will consider these points in sequence
1. There were in fact many gaps in the fossil record at the time when Darwin published “The Origin of Species” in 1859. However, during the subsequent 150 years many, many more fossils have been discovered, and many gaps have been filled in. What were known as “the missing links” have been found, most notably the links between reptiles (dinosaurs) and birds and the links between early man (apes) and later man. In the case of birds, perfect examples of the intermediate species of archaeopteryx have been found, particularly in China, and there is now no doubt that birds evolved from earlier small reptiles. In the case of man, the findings of Louis Leakey and his followers in Olduvai Gorge in Kenya during the 1950-70s have established beyond doubt that human evolution has taken place through intermediate species.
2. The evolution of the eye has been studied in detail in recent years. What has been discoverd is that there exist in living animals as well as in the fossil record. intermediate states. The evolution of the eye is now known to have started with a light sensitive area of cells, that then evolved into a pit that developed a narrow entrance that concentrates the light. Following this, a piece of tissue grew across the aperture that became transparent and then formed a lens. Finally the whole eye was detached as a separate entity with small muscles that allow its movement. In these small stages of development, the evolution of the eye can be seen as a successful adaptation to the need for organisms to detect danger and to search for food.
3. Similarly, the skeletons of many kinds of underwater creatures have been found over the years. In the specific case of mammals that returned to the sea there are intermediate species that gradually lost the use of their hind limbs in favor of flippers and a powerful tail. When appendages have no useful function they tend to atrophy in succeeding generations, as is the case with the human tail, even though a vestige proves that it was once there.
4. Unknown to Darwin was the existence of DNA and the ability to use DNA sequencing. DNA was not discovered until 1869, its genetic significance was not shown until 1944 and its structure was not determined until 1953. Of course, DNA sequencing can only be done in fossils where there is sufficient stability of the DNA, such as in bone or teeth (that contain cells). This area of molecular genetics has added a major support for Darwin’s theory that was completely inconceivable to him at the time of his publication of “The Origin of Species.”
Altogether these responses to objections to Darwin’s Theory have over the years strongly added support to his basic concept rather than refuting it.