When discussing evolution, nearly all people are in agreement that species have evolved. Certainly the evolutionist does, but even the most conservative Young Earth Creationist accepts that the millions of species we see today could not have been all on an ark and so some evolution must have occurred. Thus, microevolution is probably no longer a point of contention. However, it is still often claimed by some that macroevolution did not occur, or could not have occurred.

 

Perhaps one of the best examples of macroevolution we have now includes the evolution of whales. Three broad categories of evidences will be presented: modern whale features, the fossil record, and DNA analysis. It is the independent multiple lines of evidence that tell us whale evolution must have happpened.

 

A. Modern whales - Vestigial structures (may have a function, but the earlier function has been lost)

 

1. Many whales have a vestigial pelvis and paleontologists can often name specific bones such as the ishium, ileum, pubis, and femur still attached. Nearly all of these are found embedded in the sides of modern whales.

2. Whales have vestigial olfactory nerves

3. The auditory meatus (ear canal) is just a closed streak that leads back to ear bones that can no longer function as air hearing bones.

4. They use their thoracic cavity and ribs to breathe yet retain a vestigial diaphragm muscle.

5. As a fetus, they are covered with hair, only to lose nearly all of it before they are born.

6. They have a four chambered stomach, only found in terrestrial ruminant mammals that need to digest grass and chew their cud.

7. They still retain small, useless ear muscles that run out to the skin area where they used to attach to pinnae (outside ear)

8. In Belugas, they still have a pair of vestigial pinnae, not designed well for a hydrodynamic life. 

9. Embryos of whales form ear pinnae (outside ear cartilage) and hind limbs before losing them during their development. 

10. Some Baleen whale embryos first develop teeth, only to absorb them during their development. 

11. Whales and dolphins have huge numbers of olfactory receptor genes that match those that are used by land animals. A large majority of these genes are broken, mutated, and have been transformed into land olfactory receptor pseudogenes

12. Hippos give birth in the water and suckle their young in water. Hippo babies swim before they walk. Hippos only go onto land at night to feed. What if whale ancestors were originally on land, went into the water to feed along shore lines  and eventually gave up going back to land to live? 

13. In some species of whales with vestigial pelvis/leg bones, two of the bones fit together like a hip and femur. At the end of the vestigial femur was a capsule of fluid, a vestige of a vanished knee. Even the muscles around these abandoned bones permitted and restrained different movements in the same way that the muscles around a horse's hind legs do. (Flower made note of these findings in the 1800s).

14. Developing embryonic whales begin their breathing blowhole as a nose and then it migrates to it's adult location on top near birth.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B. Fossil Evidence

 

1. We now have over 30 genera (not just species) of whale fossils, many of them very complete. Whale fossils have specific characteristics that make it easy for paleontologists to classify them as whales: for example, every whale, alive or extinct, has a bony area that keeps their ear bones sequestered so that they can hear underwater. This signature "S" shaped bone is only found in whales. They also have unique teeth and other bones.

2. The legs of earlier whales are seen to slowly shrink through the fossil record

3. The nasal openings in the fossil record migrates to the middle of the skull and then onto the top, forming the blow hole

4. The middle ear bone (the Incus), changes orientation so that looking at Pakicetus it is about 45 degrees. In whales it is rotated a full 90 degrees from land mammals. Thus, the incus bone in Pakicetus is intermediate between present whales and present land animals.

5. Paleobiogeography. The oldest whale fossils are found located in only one area of the globe (mostly Pakistan where 50 million years ago India had yet to slam into Asia to produce the Himalayan mountains. The narrow sea that existed at that time is called the Tethyan Sea.) More recent whale fossils are found more widely distributed around the globe.

6. Paleoenvironment. The early whale fossils are found with surrounding fresh water or brackish animal fossils and plants. Later fossils are found in conjunction with marine fossils of animals and plants

7. The oxygen ratios in the fossil whale teeth enamel tell a story of whale species evolving from more freshwater to more of a marine environment. Sea water tends to have more Oxygen-18 isotope compared to the the lighter Oxygen-16 isotope. In examining the fossil teeth of whale species, the concentration of Oxygen-18/16 changes as one moves from older whale fossils (more fresh water environment) to more recent whale fossils (marine environment), paralleling the paleobiogeography and paleoenvironmental fossil evidence.

8. The pelvis shrinks and become smaller when looking at older whale fossils compared to more recent whale fossils.