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The number of visitors to California's Yosemite National Park has swelled to four million a year. Now scientists think the impact of so many human beings is rippling among the web of organisms in the park, from cougars to mule deer all the way down to the park's signature wildflower, the evening primrose.

Although many of the Yosemite's cougars were shot by park officials in the 1920's, some of these predators remain. Yet they seem to avoid Yosemite Valley, the picturesque main entrance to the park that is home to numerous roads and buildings. The deer recognize this safe haven, says Oregon State University forestry scientist William Ripple. "We think the deer are moving closer to where the humans are." The many mule deer browse heavily on young California black oak and primrose in Yosemite Valley, and the plants are often unable to reach reproductive age. Ripple and his colleagues noticed that oak trees away from the visitor center were taller and more abundant.

By pushing predatory cougars out of the valley, humans have indirectly increased mule deer and reduced oak and primrose populations. This is an example of a trophic cascade—one that appears to be reducing biodiversity in one of the nation's most spectacular landscapes.

In the rock layers of a vast open-pit coal mine in Colombia, paleontologists have uncovered a fossil of the largest snake known to have existed. The massive 60,000,000-year-old vertebrae suggest that the creature was about as long as a bus and three feet thick. The discovery team, composed of researchers from Canada, Panama, and the United States, named the snake Titanoboa cerrejonensis ("titanic boa from Cerrejón") after its size, its close relatives, and the name of the mine. Researchers think Titanoboa would likely have been too large to climb trees like modern boa constrictors. Instead, it probably sought its crocodile prey while swimming through the myriad rivers that cut through its forested coastal habitat.

Beyond being a winning entry in the animal record books, the snake is also a measuring stick for ancient tropical climate. Because the maximum body sizes of some snakes, turtles, crocodiles and other cold-blooded creatures are regulated by the temperature of their surroundings, their size can be used as a temperature gauge. The researchers estimate that the region averaged at least 30-34°C (86 -93°F) 60 million years ago, giving a new data point from which to compare tropical temperature change over time.

The landscape of human language is complex. Tracing the origins of the 7,000 known modern languages has been a significant challenge for scientists, but a novel new analysis by a researcher at the University of Auckland in New Zealand points to a familiar place: Africa, the birthplace of our species.

This fall, examine the biology of language in a five-part adult course, the Sackler Brain Bench program "Is Your Brain Wired For Language?" For more information, visit: http://www.amnh.org/calendar/is-your-...