SPECIES ORIGIN AND DEVELOPMENT


Scientists may trace the origin and development of a species through evidence found in the:

1) fossil record
2) current diversity of life forms
3) observations of similarities across different life forms in physical characteristics, cell information, and DNA samples



The fossil record provides a hands on model for scientists as they make predictions about the origin and development of a species. Fossils need to be properly understood in order to be interpreted successfully. Scientists use technology tools to predict the age of fossils. They also note the soil, surrounding artifacts, layer of earth from which the fossils are taken. All of these may provide clues about the origin and development of a species.

Sometimes the present is the key to the past. Scientists observations of current life forms provide clues to make predictions about the origin and development of a species. Similarities and differences among seemingly different groups of organisms may show evidence---that DNA is similar, cell structures are similar, bone formation is similar---for supporting a prediction that two seemingly separate species had a similar ancestor.



The vertebrate forelimb bones are very similar in structure, although in many cases dissimilar in function. Consider the function of the wing of a bat, the flipper of a whale, the leg of a horse, and your arm! All similar in cell structure and DNA make-up but different in function. This may provide evidence that these organs arose through evolutionary changes from a common ancestor population.