San Diego Museum of Man - Footsteps Through Time

Humans are primates
We share a common ancestor. Primates are the order of mammals to which humans belong. The primate evolution story begins with a small shrew-like mammal that survived the extinction of the dinosaurs about 65 million years ago and was the common ancestor of all primates.

Primates evolved after the dinosaurs
With the dinosaurs gone, mammals began to flourish and diversify. The earliest primates evolved between 65 and 55 million years ago, but we do not know much about them. Because well-preserved fossils of these small mammals are hard to find, there is little evidence about their lives. With each new fossil find, the primate evolution story becomes clearer.

Follow the footsteps and timestones to see what the fossil record tells us about our closest living relatives-the primates.

Environment
What is the environment's role?

The environment selects the trait
A species is composed of many individuals, each with a unique set of genes. These genes may be helpful, harmful, or neutral, depending on the environment. With helpful genes, organisms survive and reproduce, and so have a better chance of passing the advantage to offspring. However, what is helpful in one environment may be harmful or neutral in another setting. Because nature "selects" a gene's helpful effects, the process is called natural selection.

Bacteria show evolution in "fast-forward"

Bacteria reproduce rapidly and can show a changing environment's effect. To study evolution, scientists start with a bacteria colony, then change the environment by adding an antibiotic. Scientists observe the bacteria over thousands of generations (only few months) and identify the mutations that arise randomly. Some bacteria may have a mutation that makes them resistant to the antibiotic. If so, they survive in the new environment. From these survivors, a new strain evolves.