Darwin's Theory of Evolution

Darwin's Theory of Evolution

Darwin's Theory of Evolution
Reading Level

	edHelper's suggested reading level:	grades 9 to 12
	Flesch-Kincaid grade level:	9.28

Vocabulary

	challenging words:		selective, dome-shaped, seaweed, tremendous, organism, evolution, better, adaptation, fertile, rocks, prickly, diversity, concept, cactus, gradual, process
	content words:		Charles Darwin, HMS Beagle, South America, In Brazil, In Argentina, Galapagos Islands, Pacific Ocean, As Darwin

Print Darwin's Theory of Evolution
edHelper.com subscriber options:

	Print Darwin's Theory of Evolution (font options, pick words for additional puzzles, and more)
	Quickly print reading comprehension
	Print a proofreading activity

Feedback on Darwin's Theory of Evolution

Leave your feedback on Darwin's Theory of Evolution (use this link if you found an error in the story)

Darwin's Theory of Evolution
By Cindy Grigg

¹     In 1831, Charles Darwin set sail from England on the HMS Beagle for a five-year-long journey. Darwin's job was to learn as much as he could about the living things he saw on the voyage.

²     Darwin saw plants and animals he had never seen before. He wondered why they were so different from those in England. Darwin's observations led him to develop one of the most important scientific theories of all time: the theory of evolution by natural selection.

³     One of the Beagle's first stops was the coast of South America. In Brazil, Darwin saw insects that looked like flowers and ants that marched across the forest floor like huge armies. In Argentina, he saw armadillos, burrowing animals covered with small, bony plates. He also saw sloths, animals that moved very slowly and spent most of their time hanging upside down in trees.

⁴     Darwin was amazed by the tremendous variety of living things that he saw. Today scientists know that living things are even more diverse than Darwin could ever have imagined. Scientists have identified more than two-and-a-half million species of living organisms on Earth. A species is a group of similar organisms that can mate with each other and produce fertile offspring.

⁵     Darwin saw something else in Argentina that puzzled him: the bones of animals that had died long ago. From the bones, or fossils, Darwin inferred that the animals had looked like the sloths he had seen. However, the bones were much larger than those of the living sloths. He wondered why only smaller sloths were alive then. What had happened to the giant creatures from the past?

⁶     In 1835, the Beagle reached the Galapagos Islands, a group of small islands in the Pacific Ocean six hundred miles off the west coast of South America. It was on the Galapagos Islands that Darwin observed some of the greatest diversity of life forms. The giant tortoises, or land turtles, he saw were so tall that they could look him in the eye. There were also seals covered with fur and lizards that ate nothing but tough, prickly cactus plants.

⁷     Darwin was surprised that many of the plants and animals on the Galapagos Islands were similar to organisms on mainland South America. For example, many of the birds on the islands, including hawks, mockingbirds, and finches, resembled those on the mainland. Many of the plants were also similar to plants Darwin had collected on the mainland.

⁸     There were also important differences between the organisms on the islands and those on the mainland. Large sea birds called cormorants lived in both places. The cormorants on the mainland were able to fly, while those on the Galapagos Islands were unable to fly. The iguanas on the Galapagos Islands had large claws that allowed them to keep their grip on slippery rocks where they fed on seaweed. The iguanas on the mainland had smaller claws. Smaller claws allowed the mainland iguanas to climb trees where they ate leaves.

Paragraphs 9 to 16:
For the complete story with questions: click here for printable

Copyright © 2008 edHelper