Life: Episode 2— Introduction (01:56)
This segment orients viewers to Dr. Helen Czerski's exploration of colors that drove the spread of life.
Color Green (03:28)
Czerski climbs to the top of a forest canopy and asks why all the plants and trees are green. Stephanie Henson explains that life began in the oceans approximately 3.5 billion years ago.
These organisms developed the process of photosynthesis, changing the course of life. Chlorophyll allowed life to spread across the ocean and the color green became abundant.
Chlorophyll Makes Plants Green (03:58)
Cyanobacteria produced oxygen which created an ozone layer in Earth's atmosphere. Protection from UV rays allowed life to develop and flourish. Czerski demonstrates how leafs absorb the red and blue wavelengths of light; color is a process of light interactions.
Color Brown (02:38)
See an example of the variety of human skin tones; melanin is responsible for the diversity. Melanin has to ability to absorb and scatter ultraviolet radiation.
Skin Color Adaptation (02:17)
Early humans in Africa needed high levels of melanin. Humans began migrating to areas that had less ultraviolet radiation; see a map of UV variation. Nina Jablonski discusses the evolution of human skin color.
Color Diversity (02:36)
Tanning is a form of adaptation that protects human skin. Humans use sunscreen or vitamin D supplements to help control their relationship with the sun; we have evolved to suit our environment.
Color Red (02:39)
The colors green and brown are part of vital functions in life. With the evolution of the eye, color delivered information. Czerski considers various meanings of the color red.
Color Vision (05:13)
Zoologist Andrew Smith works with a group of marmosets; some can distinguish red while others cannot. Czerski wears glasses that restricts her vision and attempts to locate red berries. Berries turn red to attract animals to disperse their seeds.
Survival in the ocean is a challenge; color is sometimes used to conceal. Czerski observes how cuttlefish change color to match the environment.
Color and Light Reflection (02:31)
Kerry Perkins explains how cuttlefish change color to match their environment. Chromatophores contain sacks of different colored pigments.
Pollia berries are a metallic-like blue. Czerski explains how shape makes a color iridescent. Beverly Glover discusses the discovery of iridescence on flowers.
Iridescent Hibiscus Flowers (04:30)
Glover explains her experiment with bumblebees to discover why the flowers are iridescent; iridescent flowers are easier for the bees to see. Color is the result of an organism manipulating or reflecting light.
Mating Display (05:08)
Crowds gather at Great Smoky Mountains National Park when darkness descends. Male fireflies light up the forest in an attempt to catch the attention of females.
Manipulating Color (01:16)
Color is fundamental part of the evolution process. See a preview of the next episode.
Credits: Life: Episode 2—Color, The Spectrum of Science (00:35)
Credits: Life: Episode 2—Color, The Spectrum of Science
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