HomeHHMI's BioInteractiveThe Making of the Fittest: Evolving Switches, Evolving Bodies


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Short Film
The Making of the Fittest: Evolving Switches, Evolving Bodies


After the end of the last ice age 10,000 years ago, populations of marine stickleback fish became stranded in freshwater lakes dotted throughout the Northern Hemisphere in places of natural beauty like Alaska and British Columbia. These remarkable little fish have adapted and thrive, living permanently in a freshwater environment drastically different than the ocean.

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(Duration: 15 min 27 sec)

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Stickleback bodies have undergone a dramatic transformation, some populations completely losing long projecting body spines that defend them from large predators. Various scientists, including David Kingsley and Michael Bell, have studied living populations of threespine sticklebacks, identified key genes and genetic switches in the evolution of body transformation, and even documented the evolutionary change over thousands of years by studying a remarkable fossil record from the site of an ancient lake ten million years ago. Watch this film to learn about a species where we can study evolution in action, identify key genes, and peer deep into the evolutionary past.

"The film is a first-class production, with distinct graphics, clear reasoning, and captivating footage. It gives an outstanding picture of what is involved in scientific research, especially as it applies to the evolutionary process."

—Richard Lord, Jr., American Biology Teacher, January 2014


  • 2013 Telly Awards; Silver

Curriculum Connections:

AP (2012–13)

1.A.1.a,b,c,d, e,f; 1.A.2.a,b,c; 1.A.3.a; 1.A.4.a,b; 1.C.3.a,b; 2.D.1.b,c; 3.A.1.a,c,d; 3.B.1.a,b,c,d; 3.C.1.a,b,d; 3.C.2.a; 4.A.1.a,b; 4.C.2.a,b; 4.C.3.a,b 

Supporting Materials (5)

Classroom Resource
A hands-on activity in which students analyze the results of genetic crosses between stickleback fish with different traits.
Classroom Resource
A hands-on activity in which students interpret molecular diagrams and build physical models of eukaryotic gene regulation.
Classroom Resource
A worksheet that guides students through The Stickleback Evolution Virtual Lab. The virtual lab lets students learn firsthand the methods for analyzing body structure in stickleback collected from lakes and fossils recovered from a quarry. Students measure, record, and graph their results to discover evolutionary patterns.
Film Guides
These classroom-ready resources complement the short film Evolving Switches, Evolving Bodies, which tells the story of the dramatic transformation of stickleback fish as they adapted to living in freshwater habitats drastically different from the ocean.
Virtual Lab
This virtual lab teaches skills of data collection and analysis to study evolutionary processes using stickleback fish and fossil specimens.

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This series of five short films features unforgettable examples of the evolutionary process in action.

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