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Corals get much of their energy from symbiotic algae that live inside their cells. When ocean temperatures rise beyond a certain threshold, the algae’s photosynthetic machinery may be damaged and produce harmful reactive oxygen molecules. This animation shows how corals subsequently eject their algae in a process called coral bleaching, which causes the corals to turn white and often eventually die.
The discovery of Archaeopteryx in a quarry in Germany in the early 1860s provided the first clue that birds descended from reptiles. In the last 40 years, scientists have identified many shared features between birds and two-legged carnivorous dinosaurs called theropods.
Charles Darwin once boldly predicted that buried deep in the earth are transitional fossils of creatures with intermediate features between ancestral animal groups and the modern animal groups. Since Darwin’s time, many transitional fossils have been discovered, and they provide crucial insights into the origin of key structures and the creatures that possess them. And University of Chicago paleontologist and award-winning author Neil Shubin provides a first-hand account of the painstaking search for the transitional fossil of Tiktaalik, a creature with a mix of features common to fish and four-legged animals.
Anole lizards are highly territorial and typically stick close to their home tree. So, what happens when a team of researchers carries them far away into the forest? Will they find their way back? Dr. Manuel Leal and colleagues designed an experiment to find out. They displaced the lizards from their home territories and then tracked their movements using radio transmitters. Most of the lizards were able to orient themselves and head in the right direction, with some making a beeline back to their original tree in less than 24 hours.
Paleontologists have studied the fossil record of human evolution just like they have done for other major transitions, including the evolution of tetrapods from fish and the evolution of birds from dinosaurs. Sean Carroll and Tim White discuss the most important human fossils and how they illuminate key phases of human evolution, focusing in particular on three traits: larger brains, tool use, and bipedality.
Identifying the key molecular players in planarian regeneration may offer clues into how the process may work in other species, including humans. HHMI investigator Alejandro Sánchez Alvarado and postdoctoral fellow Alice Accorsi use RNA-mediated genetic interference (RNAi) to silence different genes in planaria and determine how they affect regeneration.
Dr. Ronald Evans describes how fat communicates with muscle and how diet and exercise influence that relationship. Part of the 2004 Howard Hughes Holiday Lecture Series.
Ants play important roles in many ecosystems, and a team of scientists are surveying ant populations in Gorongosa Park. Leading the study is Leeanne Alonso, she is cataloging the different species of ants in Gorongosa National Park and establishing a species census to monitor the ongoing recovery of the park.
This animation zooms into a coral reef to explore the tiny animals that build reefs, the photosynthetic algae inside their cells, and the damaging process of coral bleaching. Corals get much of their energy from symbiotic algae that live inside their cells. When ocean temperatures rise beyond a certain threshold, the algae’s photosynthetic machinery may be damaged and produce harmful reactive oxygen molecules. This animation shows how corals subsequently eject their algae in a process called coral bleaching, which causes the corals to turn white and often eventually die.
Journalist Greg O'Brien reveals his struggle living with Alzheimer's disease, including the effects on his family. Harvard scientist, Rudy Tanzi, explains the mechanism by which this disease robs the identities of those affected. Tanzi also reveals current research into the treatment of the disease. Part of the “Think Like a Scientist” series.
Gorongosa National Park was once famous for its lion population. However, during Mozambique’s struggle for independence and subsequent civil war, the park’s iconic wildlife was slaughtered. In 2008, a massive ecosystem restoration project began. Today, many animals are bouncing back in large numbers, but it is unclear if the lions are also making a strong recovery. Paola Bouley heads the “Gorongosa Lion Project,” an effort to document the lions’ response to the park’s restoration and identify any factors that may be limiting their recovery.
Ten thousand years ago, corn didn’t exist anywhere in the world, and until recently scientists argued vehemently about its origins. Today the crop is consumed voraciously by humans, by livestock, and as a major part of processed foods. So where did it come from? Evolutionary biologist Neil Losin tells the story of the genetic changes involved in the transformation of a wild grass called teosinte into corn. Evidence from genetics supports archeological findings pinpointing corn’s origins to a very particular time and place in Mexico.
James Watson and Francis Crick collected and interpreted key evidence to determine that DNA molecules take the shape of a twisted ladder—a double helix. The film presents the challenges, false starts, and eventual success of their bold chase. Watson relates what those early days in the Cavendish Laboratory were like, including his friendship with Crick and their shared ambition and passion. Rarely seen archival footage is combined with interviews with some of today’s leading scientists to bring this landmark discovery and all of its implications to life.
Fruit bats carry the Nipah virus, which can be transmitted to humans and cause severe disease. In Bangladesh, the virus causes a disease outbreak almost every year. Dr. Jon Epstein of the EcoHealth Alliance explains the evidence that revealed bats are the natural reservoir of the virus. Their research also shows the route of transmission to humans. Dr. Epstein and collaborators in Bangladesh are now monitoring bat populations throughout the country for the presence of the virus to identify human populations that might be at risk of transmission.
The tragic 2013-2015 Ebola outbreak in West Africa shocked the world. Computational geneticist Pardis Sabeti and disease ecologist Lina Moses explain the science behind how this event became the largest Ebola outbreak in history. Part of the “Think Like a Scientist” series.
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 little fish have adapted and thrive, living permanently in a freshwater environment drastically different than the ocean. 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.
The rock pocket mouse is a living example of Darwin's process of natural selection. Not only is evolution happening right now everywhere around us, but adaptive changes can occur in a population with remarkable speed. This speed is essential if you're a desert mouse living in an environment where a volcanic eruption can reverse selective pressure in nearly an instant. Features Dr. Michael Nachman, whose work in the field and in the lab has quantified the selective pressure of predators and identified the genes involved in adaptation. From ecosystem to molecules, pocket mice show the viewers how random changes in the genome can take many paths to the same adaptation-a colored coat that hides them from predators.
Working in the islands of the Caribbean, biologist Jonathan Losos has discovered the traits that enable dozens of anole species to adapt to different vertical niches in the forest. Differences in limb length, body shape, and toepad size allow different species to flourish on the ground. However, lizards living on thin branches or high in the canopy have different characteristics. These varied adaptations have played a key role in reproductive isolation and the formation of new species.
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