--In this page, we will explain how evolution happen!!! The seagreen words are defenitions to some words! The underlined words are important words you need to know. Those words may be defined later. The blue paragraphs are the introduction to the larger paragraphs! Have fun reading! :)
--In the 1800's, geologists began to realize that Earth was much older than anyone had previously thought. Some scientists saw evidence of evolution in the fossil record! However, no one had been able to explain how evolution happens...until Charles Darwin.
--In 1831, 21 year old Charles Darwin graduated from college. He didn't know what he wanted to do with his life. Although he eventually earned a degree in theology, he was most interest in the study of plants and animals. So, he signed for a 5 year voyage around the world! He served as a naturalist on the HMS Beagle. (A HMS Beagle is a British ship). During the long trip, Darwing made observations that helped him form a theory about how evolution happens.
~A NATURALIST is a scientist who studies nature.
--Darwin observed many plants and animals from places such as the Galapagos Islands. These islands are found 965km (600mi) west of Ecudar, a country in South America.
--Darwin observed that the finches on the Galapagos Islands were slightly different from the finches on the other islands. One difference between the finches were their beaks. The beak of each finch is adapted to the way the bird usually get its food.
--Darwin puzzled over the animals that he had seen on his journey. Darwin hypothesized that the island finches descended form South American finches. He proposed that the first finches on the islands were blown there from South America by a storm. He then suggested that the finches evolved adaptations for the various island enviroments over many generations.
--In Darwin's time, farmers and breeders had produced many kinds of farm animals and plants. These plants and animals had traits that were desired by the farmers and breeders.
~A TRAIT is a genetically determined characteristic.
--For an example, redness is a trait, and fruit color is the corresponding characteristics.
-SELECTIVE BREEDING is the human practice of breeding animals or plants that have certain desired traits.
--Most pets, such as dogs have been bred for various desired traits. Selective breeding shows that the traits of organisms can change and that certain traits can spread through populations.
--During Darwin's time, Thomas Malthus wrote An Essay on the Principle of Populations.
--Malthus noted that human population can grow more rapidly than food supplies can grow. He also pointed out that the size of human populations is limited by problems such as starvation and diseases.
--Darwin then realized that any species can produce many offsprings. He also knew that the populations of all species are limited by starvation, disease, competition, and predation. Only a limited number of individuals live long enough to reproduce. Darwin reasoned that the survivors had traits that helped them survive in their enviroments He also thought that some off these traits would be inherited by the offsprings of the survivors.
--During Darwin's time, most geologists thought that Earth was still very young. But important books such as Principles of Geology by Charles Lyell, were changing ideas about Earth. Lyell's book presented evidence that Earth had formed by natural processes over a long period of time. Darwin reasoned that there would be enough time for organisms to slowly change and evolve if Earth was very old.
--After Charles Darwin's voyage on the HMS Beagle, Darwin privately struggled with his ideas for about 20 years! Then, in 1858, he recieved a letter from a naturalist named Alfred Russel Wallace. Wallace had arrived at the same point of ideas about evolution that Darwin had. Darwin had published a very famous book called On the Origin of Species by Means of Natural Selection in 1859. In his book, Darwin proposed the theory that evolution happens by natural selection.
~NATURAL SELECTION is the process by which organisms that are better adapted to their enviroment survive and reproduce more succesfully than less adapted organisms do. (There are 4 steps to this process).
**Further information about natural selection will be mentioned in PG. 3.**
~~genetics and evolution...~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--Today, scientists know what Darwin didn't know then.
--Today, scientists know that variation happens as genetic information is passed form parent to offspring in sexual reproduction. Some genes make an organism more likely to survive to reproduce.
--Natural selection happens when organisms that carry these genes survive and reproduce mroe than organisms that do not carry these genes.
--New fossil discoveries and new information about genes add to scientists' understanding of natural selection and evolution.
This is a picture of young Charles Darwin!
This is an image of the HMS Beagle! This was the British ship Charles Darwin went on for his 5 year voyage! The HMS Beagle is a pretty big ship!!!
This is an image of the Galapagos Islands! It is 965km (600mi) west of Ecuador, a country in South America. Darwin noticed that the animals and plants on the Galapagos Islands were similar to those in Ecuador. But the animals and plants were not identical.
During Darwin's journey, he found finches on the Galapagos Islands that differed slightly from the finches in Ecuador. As explained before in the big paragraph, the beak of eah finch is adapted to the way the bird usually get its food.
#1...This is a picture of the large ground finch. It has a wide, strong beak that it used to crack open big, hard seeds. This beak works like a nutcracker.
#2...This is a picture of the cactus finch. It has a tough beak that it uses for eating cactus parts and insects. This beak works like a pair of needle-nosed pliers.
#3...This is an adorable picture of the warbler finch. It has a small, narrow beak that it uses to carch small insects. This beak works like a pair of tweezers.