Comparative anatomy

Comparative anatomy - organisms The useless organs are...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Comparative anatomy More evidence for evolution is offered by comparative anatomy (Figure  1  ). As Darwin  pointed out, the forelimbs of such animals as humans, whales, bats, and other creatures  are strikingly similar, even though the forelimbs are used for different purposes (that is,  lifting, swimming, and flying). Darwin proposed that similar forelimbs have similar  origins, and he used this evidence to point to a common ancestor for modern forms. He  suggested that various modifications are nothing more than adaptations to the special  needs of modern organisms.  Darwin also observed that animals have structures they do not use. Often these  structures degenerate and become undersized compared with similar organs in other 
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: organisms. The useless organs are called vestigial organs. In humans, they include the appendix, the fused tail vertebrae, the wisdom teeth, and muscles that move the ears and nose. Darwin maintained that vestigial organs may represent structures that have not quite disappeared. Perhaps an environmental change made the organ unnecessary for survival, and the organ gradually became nonfunctional and reduced in size. For example, the appendix in human ancestors may have been an organ for digesting certain foods, and the coccyx at the tip of the vertebral column may be the remnants of a tail possessed by an ancient ancestor....
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online