Although the fossil record is not complete, scientists can compare modern species with species believed to exist millions of years ago.
Evolution is the process by which modern organisms have descended from ancient organisms.
Charles Darwin sailed on the H.M.S. Beagle. During his travels, Darwin made numerous observations and collected evidence that led him to prose a revolutionary hypothesis about the way life changes.
James Hutton in 1785 proposed that the Earth is shaped by geologic forces that took place over long periods of time.
Charles Lyell published in 1833, The Principles of Geology that explained that the same geologic principles occurring now are the same as those that shaped the Earth
Jean-Baptiste Lamarck proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in a species.
Lamarck’s theory is flawed because he had no idea how traits were passed and the fact that behavior didn’t “change” an organism. He is important because he realized organisms were adapted for their environment
Thomas Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would insufficient living space and food for everyone.
Darwin realized that this is even more true for plants and animals because they produce far more offspring than humans.
Darwin decided not to publish his work until 25 years later when he received a letter from Alfred Wallace who had reached many of Darwin’s similar conclusions. In 1859, Darin publish, On the Origin of Species
Evidence for Change
Scientists use DNA to compare the amino acid and nucleotide sequences of living species. A lot of similarities indicate that the organisms are closely related.
Evidence for Change
Embryos of many vertebrates look similar. These physical similarities may suggest that the organisms are closely related and thus have a common ancestor.
A homologous structure is a structure that has developed from the same tissues and have similar internal structures, but may look different on the outside and may have different functions. This suggests a common ancestor.
Bird wings and your arms for example
Analogous structures do not arise from the same tissues, but perform similar functions. These structure are not the result of a common ancestor, but evolved separately.
A bug’s wings and a chicken’s wing for example.
A vestigial organ seem to have no useful purpose now although they resemble structures that are useful in other species.
Natural selection is the way in which populations change over time as certain organisms reproduce and pass on their genes to future generations.
The success or failure of an organism depends on its reproductive ability. To be reproductively successful means that the desirable traits might be passed to the offspring.
A species is a group of organisms that can interbreed and have fertile offspring.
A population is a group of members of the same species living in an area.
A niche includes all the living (biotic) and non-living (abiotic) factors in an organisms environment. The niche is the organisms role in the environment.
A group of populations living in an area is called a community.
The process of one species becoming two species is called speciation. This happens when two groups become separated and no longer can interbreed and form offspring.
An adaptation can be any trait, physical or behavioral, that helps the organism to survive.
External fertilization is used by fish and frogs. It involves them producing large amounts of eggs just so some offspring can be successful.
Internal fertilization is used by higher animals. It involves them producing fewer eggs inside the body in which the mother makes sure they can survive.
A behavior involves the way an organism reactions to changes in its internal or external environment.
Hibernation, showy peacock tails, deer fighting, etc are examples of behaviors.