EVOLUTION

HISTORY OF LIFE You can now classify living things into kingdoms, but some organisms aren’t living anymore. They are extinct, meaning there are no more of this organism living. This is part of the evidence that life on Earth is different now than it was before.

The word evolution can be used to describe any change over time (music, fashion). In Biology, it describes how over generations, organisms CHANGE based on how well they survive in their ENVIRONMENT.

EVIDENCE OF CHANGE How do we know that life has changed on Earth? 1) One way is to examine living organisms for similarities, as Charles Darwin did with the finches. 2) A second way is to examine the fossil record for similarities. 3) A third way is to examine the DNA sequences for similarities.

Physical observations (begun by Darwin) 1) EVIDENCE OF EVOLUTION Physical observations (begun by Darwin)

CHARLES DARWIN Charles Darwin was a scientist on the ship HMS Beagle He worked on the Galapagos islands. He noticed animals were similar but some had unique differences. His careful observations led him to theorize the idea that animals/plants will survive best in an environment best suited for them.

DARWIN’S FINCHES One example Darwin observed was many different types of birds called finches. They had some of the appearance in common, but some differences like beak shape. The finches’ beak seemed to help them survive based on what type of food was in each islands’ environment. They were different from the mainland birds. Click on the picture of the finches to watch a video about Darwin’s finches.

In summary, Darwin’s theory was the Galapagos finches came from South America, but over the generations the groups changed to better survive in their new environment. The evidence for this change was seen by examining physical characteristics such as beak shape or feather color. This change in species over time is called EVOLUTION.

2) EVIDENCE OF EVOLUTION FOSSIL RECORD

The fossil record is evidence that organisms have changed The fossil record is evidence that organisms have changed. A fossil is a trace of a dead organism. For example, you can compare the bones of a dinosaur to the bones of other reptiles and birds that are living today.

Examining many layers of rocks can show how groups of organisms can change over time. Keep in mind, not every living thing leaves a fossil, so sometimes there are gaps or unexplained blanks. Click on the picture of the amber fossil and then “Launch interactive” to watch a slideshow about amber and what it can show about extinct organisms.

In summary, fossils are evidence of organisms that are dead and can show change through many years. The evidence for this change was seen by examining physical characteristics seen between the different levels of fossils. This change in species over time is called EVOLUTION.

3) EVIDENCE OF EVOLUTION DNA Comparison

REMEMBER - Every living (or once living) organism has DNA in its cells REMEMBER - Every living (or once living) organism has DNA in its cells. This DNA tells the cells how to make proteins that give the living organism its traits (appearance). So, we can compare DNA or proteins to see how similar they are.

If we examine similar genes (like eye development), we can tell how closely related organisms are. For example, even though the proteins are all 100% similar, the shark’s DNA has more in common with the mouse than the fly. DNA evidence is the most reliable because the DNA is either the same or different. Click on the picture of the DNA and then click “Launch interactive” to watch a video about lice and DNA.

In summary, DNA similarities are evidence that organisms may have changed over time. The evidence for this change was seen by comparing how similar the DNA is and grouping organisms into family trees. This change in species over time is called EVOLUTION.

Evidence of Evolution REVIEW

EVOLUTION Evolution is a change in groups over generations. Evidence that organisms have changed can be found by looking at living organisms like Charles Darwin’s finches. Evidence of change can be found by looking at fossils of ancient organisms and comparing them to organisms today. Evidence of change can be found by comparing DNA sequences to see how similar they are.