This week in stem

By | Bryan Donoghue

Ancient feathered ostrich-like dinosaurs laid clutches of blue-green eggs just like the traits of robins from today. The eggs are thought to have camouflaged themselves in forested environments, and they were in open nests dug into the ground. Using chemical analyses, scientists were able to detect traces of two pigments, biliverdin and protoporphyrin, which are commonly found in modern bird eggs. According to David Varricchio, expert on dinosaur reproduction at Montana State University, “The discovery highlights how much our thinking has changed about dinosaur preservation and how much more we can learn about the original animal.”

Source: National Geographic

Known as the “cradle of humanity”, Africa is from where our earliest human ancestors spread across the rest of the world some 50,000 years ago. Africa is also where people—ancient and modern—are most genetically diverse. Harvard University evolutionary geneticist Pontus Skoglund and his colleagues obtained DNA from 15 ancient Africans from between 500 and 6000 years ago and found ancient genomes and evolutionary adaptations. This has been the first big effort to sequence ancient African DNA and reveal how early humans swept across the continent.

Source: Science Magazine

For a long time, scientists have been left wondering if jellyfish can fall asleep. Three Caltech graduate students found that at least one group of jellyfish, the Cassiopeia xamachana or upside-down jellyfish, does get some shut eye. To prove that jellyfish sleep, the students had to demonstrate that they fulfill three behavioral criteria. First, the animals must undergo a period of diminished activity. Second, the animals must show decreased responsiveness to stimuli while sleeping. Three, the animals must show an increased need for sleep if they are kept from it. The upside-down jellyfish fit all these criteria, and thus can be considered sleepy. In addition, the researchers also demonstrated that jellyfish get sleepy when exposed to melatonin, just as humans do.

Source: New York Times

High energetic particles called cosmic rays were found by scientists to come from outside of our Milky Way Galaxy. The ray’s journey possibly starts from a black hole in the center of a distant galaxy. Trying to identify which galaxies and seeing if there is any pattern linking them are the next steps for researchers. That research could help narrow down the processes that can accelerate cosmic rays.

Source: Science News