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Drought drove early humans from Africa

Genetics studies have dated the largest migrations of early Homo sapiens out of Africa to between 70,000 and 55,000 years ago, although smaller groups may have left earlier. The most widely accepted exodus theory, known as the “green carpet” or “green Sahara” hypothesis, holds that people likely left during wetter periods in the Sahara and Arabia, which would have allowed easier passage into Eurasia via the Middle East. But new research supports the opposite idea: that drier conditions may have triggered at least some of the exodus.

28 Feb 2018

Isotopes reveal sources of centuries-old alabaster artifacts

When geologists think of alabaster, they likely envision blocks of gypsum, its main mineral constituent; when art historians hear the word, statues crafted from the soft rock may come to mind. A new study focused on the sources of centuries-old alabaster artworks has geologists thinking about art history, and art historians pondering geochemistry. In the study, published in Proceedings of the National Academy of Sciences, researchers used isotope fingerprinting along with historical records to tie medieval and Renaissance alabaster sculptures to the quarries from which their materials were excavated.

26 Feb 2018

Spawning salmon engineer landscapes

All animals depend on their ecosystems for habitat. And, in turn, many animals impact their ecosystems by engineering the landscape to suit their needs. Beavers provide an iconic example of ecosystem engineering when they build dams, which influence streams and wetlands. The engineering efforts of salmon, meanwhile, can even shape the bedrock of the watersheds in which they live, according to a recent study that modeled the evolution of those watersheds over several million years.

23 Feb 2018

Meteorite impacts may have kick-started ancient subduction

Earth in the Hadean Eon, between 4.56 billion and 4 billion years ago, was much too hot to support active plate tectonics as we know it today, where cold, established plates slowly march around Earth. Yet some evidence, including from tiny zircon crystals dating to the Hadean, has suggested that a form of plate tectonics was active by about 4.1 billion years ago — about a billion years before many researchers think modern plate tectonics started. The mechanisms that could have initiated and sustained early tectonics are unclear, but according to a new study, constant bombardment of early Earth by meteorites could have triggered temporary bursts of early tectonism.

22 Feb 2018

Coal formation nearly froze Earth

Burning coal releases carbon dioxide, which warms the planet when the gas escapes into the air. On the flip side, coal formation sequesters carbon dioxide removed from the atmosphere by plants, which contributes to global cooling as the planet’s greenhouse gas blanket thins. According to new research, so much carbon was removed from the atmosphere in the Carboniferous Period, when most of Earth’s coal reserves formed, that the planet became almost completely covered in ice.

21 Feb 2018

Growing up saber-toothed: Strong from the start

During the Pleistocene, saber-toothed cats were formidable predators, with their massive canines and powerful front legs sporting razor-sharp claws. The bones of saber-toothed cats are thicker and more robust compared to those of other large cats, both modern and extinct. And previous studies of Smilodon have shown that their forelimbs in particular featured several adaptations, including thickened cortical bone, which would have increased strength, presumably useful in subduing ambushed prey.

19 Feb 2018

Did mud volcanoes set the stage for Burgess Shale fossils?

Canada’s Burgess Shale is famous for a wide array of exquisitely preserved 500-million-year-old fossils, which are found in a dozen localities in the Canadian Rockies. Linking all these localities today is a geologic feature called the Cathedral Escarpment, which formed in the Cambrian as a steep line of underwater cliffs where regular mudslides are thought to have gently buried a diversity of organisms, setting the stage for the prolific fossil beds. However, new mineralogical clues found at several of the fossil-rich sites suggest that mud volcanism may have also played a starring role in creating the Burgess Shale.

16 Feb 2018

Red Planet Roundup: February 2018

With two rovers patrolling the surface of Mars, six spacecraft orbiting above it, and scientists here on Earth studying the Red Planet from afar, new findings are announced often. Here are a few of the latest updates.

09 Feb 2018

Fossil sea turtle hatchling reveals its Eocene proteins

study of a 54-million-year-old sea turtle hatchling found in Denmark is adding to a growing body of evidence that certain proteins can remain intact in the fossil record for tens of millions of years.

08 Feb 2018

Double-dip La Nina blamed for Colorado's dry winter

In January 2017, skiers at Wolf Creek Ski Area in southern Colorado were enjoying a base snow depth of more than 350 centimeters — enough snow to cover most rocks and other obstacles. But this year, as of mid-January, the runs were much sparser, with the base barely clearing 100 centimeters. Powderhorn Resort in western Colorado was so bereft of snow that it had yet to open in mid-January — a month behind their usual December opening. Statewide the snowpack is slim enough to worry not only skiers, but also the state’s climatologists and water resource managers, who held a Water Availability Task Force (WATF) meeting on Jan. 18 to discuss the state’s snowpack and water outlook.

06 Feb 2018

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