How did the human Y chromosome become so small relative to its X counterpart? This animation depicts the 300-million-year odyssey of the sex chromosomes that began when the proto X and Y were an identical pair.
The Y chromosome has been likened to a hall of mirrors because its sequence contains many sections that appear to be palindromes. These palindromes provide a clue to some interesting events that may have occurred during the course of the chromosome's evolution.
This "morph" animation demonstrates how the expression of a particular toolkit gene in a butterfly larva corresponds to the location of the wing eyespots in an adult butterfly.
A quarry site in Nevada carries the evolutionary history of a population of stickleback fish that resided there when it was a freshwater lake.
This animation shows a rotating 3-D image of a stickleback skeleton. The pelvic region, including the pelvic spines, is highlighted in red. Armored plating covers the flanks of the fish. The three prominent dorsal spines give the fish its name.
The rock pocket mouse is found in two color variants, or morphs: light and dark. In different environments, their visibility to predators such as owls varies. The dark morph is more vulnerable on light sandy desert, and the light morph on dark lava rock.
This simulation shows the spread of a favorable mutation through a population of pocket mice. Even a small selective advantage can lead to a rapid evolution of the population.
In two related Drosophila species, a so-called paintbrush gene is activated to "paint" the pigment on the body. In one species, an extra switch activates the gene, resulting in spotted wings.
Regulatory "switches" are found upstream from a gene. Regulatory molecules bind to the switches and recruit RNA polymerase to bind to the gene's promoter region, increasing the transcription of the gene into messenger RNA.
Environmental and cultural factors can affect whether a new human mutation becomes common in a population.
Corn was originally bred from the teosinte plant by native Mexican farmers. The morphologies of modern-day corn and teosinte plants are compared to illustrate how artificial selection can bring about dramatic changes in plants.
An interview with Dr. Carroll.
What does a stack of fruits and vegetables have to do with the theoretical advantages of sexual reproduction? Find out in this demonstration with student audience members and Dr. David Page.
The many forms of dogs that exist today were all created through selective breeding from the dog's ancestor, the wolf. In a span of less than 10,000 years, breeders have changed traits and body shapes of dogs by artificial selection-for example, emphasizing different aspects of hunting and...
The floor of a rift valley is prone to periodic floods that carry in fine silt--the sedimentary matter responsible for fossil formation.
These are some of the animal species Charles Darwin would have seen when he visited the Galapagos Islands.
Due to the delicate nature of fossils, a hardening chemical is dripped onto every fossil before it is removed from the soil.
Chimpanzees are capable of using rocks as tools to crack nuts for eating. But they don't appear to use sharp-edged tools.
African rift valleys were formed by the separation of tectonic plates. Water flows down to the valley floors, creating rivers and lakes.
At the end of the ice age, the retreating ice sheet created many new lakes, some of which were colonized by sticklebacks.
A brief introduction to how stickleback fossils are collected and used to study evolution. It also shows the students who attended the 2005 Holiday Lectures taking part in a fossil-collecting activity.
Prehistoric stone tools are classified into six broad technological modes by the level of sophistication and method of fabrication.
Where and when did humans arise? What distinguishes us from other species? Did our distant ancestors look and behave like us?
How reasoning and evidence are used to understand human evolution.
Genetic evidence shows that humans evolved in Africa and continue to evolve.