Scientists have long wondered when the kangaroo’s distinctive leap first appeared. But ancient kangaroo skeletons are so rare that the hop’s origin has remained a mystery. Now, newly discovered 20-million-year-old fossils reveal kangaroo ancestors got their hop on some 10 million years earlier than previously thought.
Before ancient kangaroos started to hop, they got by clinging to tree branches and plucking fruit from the canopies of a lusher, wetter Australia. Hopping is thought to have emerged as this possumlike ancestor transitioned to life on the ground some 10 million years ago, after a dramatic climatic shift dried out the land down under. Researchers reasoned that the simultaneous expansion of grasslands and deserts drove the evolution of the hop—an efficient way to quickly cover the long distances from food source to food source.
But when one of the study authors was sifting through a pile of fossil fragments recovered from northwest Queensland in Australia, he discovered one of the world’s oldest kangaroo fossils. To find out how this ancient kangaroo moved, he and colleagues analyzed the shape and size of fossilized toe and ankle bones. They then used that information to estimate the creature’s range of motion. When the scientists compared it to those of living kangaroos, some of which also climb, they found similarities to modern species adapted for both hopping and climbing.
In a nuclear power plant, energy is derived from splitting atomic nuclei. The process is called fission, and it heats water to form steam. The steam powers a turbine, which in turn powers a generator that generates electricity.
Fission takes place in the reactor. During the process, atomic nuclei are split by bombarding them with neutrons. When an atomic nucleus is split, it emits new neutrons that can split new atomic nuclei, creating a chain reaction. A nuclear power plant typically uses uranium-235, a special isotope of the element uranium, as fuel. In order to control the process, various types of control rod stems are used to absorb the discharged neutrons, reducing the fission rate or stopping it entirely.
There are several different types of nuclear reactors, the most common of which are pressurised water reactors and boiling water reactors.
Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted and trees are flowering sooner.
Effects that scientists had predicted in the past would result from global climate change are now occurring: loss of sea ice, accelerated sea level rise and longer, more intense heat waves.
Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gases produced by human activities. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century.
According to the IPCC, the extent of climate change effects on individual regions will vary over time and with the ability of different societal and environmental systems to mitigate or adapt to change.
The IPCC predicts that increases in global mean temperature of less than 1.8 to 5.4 degrees Fahrenheit (1 to 3 degrees Celsius) above 1990 levels will produce beneficial impacts in some regions and harmful ones in others. Net annual costs will increase over time as global temperatures increase.
"Taken as a whole," the IPCC states, "the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time."
Ginger is a popular ingredient in cooking, and especially in Asian and Indian cuisine. It has also been used for thousands of years for medicinal purposes.
Possible health benefits include relieving nausea, loss of appetite, motion sickness, and pain.
The root or underground stem (rhizome) of the ginger plant can be consumed fresh, powdered, dried as a spice, in oil form, or as juice. Ginger is part of the Zingiberaceae family, alongside cardamom and turmeric. It is commonly produced in India, Jamaica, Fiji, Indonesia, and Australia.
It is available fresh and dried, as ginger extract and ginger oil, and in tinctures, capsules, and lozenges. Foods that contain ginger include gingerbread, cookies, ginger snaps, ginger ale, and a wide variety of savory recipes.