Evidence of Evolution
There is a lot of evidence supporting the theory of evolution. Some of the evidence came from observations that Charles Darwin made while he was on the HMS Beagle voyage. Other pieces of evidence developed over the years after Charles Darwin first proposed the theory of evolution. Watch the video "Origin of Humans", then navigate through the activities below to learn more about the evidence that supports the theory of evolution.
Who Was Charles Darwin?
Charles Darwin was an English naturalist whose theory of evolution changed the way we understood our place in the world. During Darwin's lifetime, he took a voyage on a ship called the HMS Beagle. It was on this voyage that he made observations which would later lead to the development of his theory of evolution.
The video "Darwin and Wallace" shows how Darwin came to his conclusions about the origin of species. The observations that lead to the development of Darwin's theory of evolution, mainly came from his stop at the Galapagos Islands.
3 Key Observations Darwin Made at the Galapagos Islands.
Fossil Evidence
A fossil is the naturally preserved remains or traces of organisms that lived in the geologic past. In general, fossils provide scientists with information about the shapes, sizes and appearances of organisms that lived in a given time period. Fossils can also be used to determine characteristics of their lifestyles, like where they used to roam.
Types of Fossils
Paleontologists are scientists that study and analyze fossils. They categorize fossils into two major types
Trace Fossils
Remains of organisms' activities, such as imprints.
Body Fossils
Remains of body parts of an organism.
Determining the Age of Fossils
Relative Dating: a method used to determine the general age of rocks and fossils by comparing them with rocks and fossils in other layers of soils.
Index fossils: fossils found in only a single rock layer. These fossils are usually located in multiple places around the world and help scientists determine the relative age of the rock layers they are found in.
Radioactive Dating: a method of dating fossils based on the radioactive material that was absorbed while the organism was alive.
Carbon Dating: a type of radioactive dating where scientists measure and compare ratios of carbon-12 and carbon-14 in a fossil.
Although carbon dating is one of the most famous methods, it has a limited use because it does not last long. In order to estimate the age of fossils that were formed millions of years ago other elements are used, such as lead and uranium.
Structure Evidence
There are three main types of structures in organisms that serve as evidence of evolution.
Type 1: Homologous Structures
Homologous structures are organs or bones with similar structures that appear in multiple organisms. The diagram to the right shows how humans, cats, whales, and bats all have the same 6 bones present in their forelimbs for movement. This provides evidence that all organisms arose from one common ancestor.
Type 2: Vestigial Structures
Vestigial structures are structures that organisms have that no longer serve a purpose. These structures support the theory of evolution by demonstrating that organisms have evolved to no longer use certain structures that were vital in their ancestors. The picture to the right shows the appendix, a vestigial structure found in humans.
Type 3: Comparative Embryology
Comparative embryology studies the embryos of different species and compares them to one another. By studying comparative embryology, it became apparent that the embryos of many different species show similarities in structure, such as gill-slits and tails. This study provides evidence that vertebrates are relatively closely related. The picture to the right shows the similarities between the embryos of five different species.
DNA Evidence
DNA is the genetic information in all living things. The base pairs in DNA determine the sequence of bases in mRNA, which then determines the amino acid sequence in the protein. Through sequencing the genetic code of many different organisms, evidence supporting the theory of evolution was found. Organisms that are more closely related have more DNA sequences in common.
The table to the right shows how many different amino acids each organism has in their cytochrome c protein. The fewer the differences, the more related the organisms are.
The table below shows how many different bases each organism has in their Hoxc8 gene. The fewer the differences, the more related the organisms are.
