Welcome back to the Abstract!
Here’s some of the most intriguing studies I came across this week: We’ll lead with a nostalgic trip down memory lane—so far down the lane, in fact, that we’ll end up in the Sun’s infancy 4.6 billion years ago. Most of us didn’t have to deal with supernovas exploding in our faces as babies, but that’s the kind of environment that might have greeted our newborn star. New research sheds light on when, and how, the Sun left the maelstrom for single life.
Then, scientists recreate a perilous ocean voyage from prehistory; a pair of long-lost creatures finally turn up; and orcas become the first marine mammal known to fashion tools.
When the Sun declared independence
The Sun was not always a loner. It was born alongside thousands of stellar siblings in a dense parent cluster some 4.6 billion years ago before striking out on its own, though the circumstances of its departure remain unclear.
Scientists have now searched for clues to solve this mystery in the Oort Cloud, a massive sphere of tiny icy bodies that surrounds the Sun, extending for more than a light year around the entire solar system. The cloud is thought to have been formed by the four giant planets—Jupiter, Saturn, Uranus, and Neptune—as they migrated through space, scattering debris to the outer reaches of the solar system where it remains adrift to this day.
By running simulations of this tumultuous period, a team of researchers hypothesized that the Sun probably left the nest very early, about 12 to 20 million years after the formation of the giant planets (which were themselves born only a few million years after the Sun). If it had lingered longer, the disruptive environment would have left the Sun with a much smaller Oort cloud, or perhaps none at all.
The outer region of the Oort cloud (estimated to be roughly the same mass as Earth) “is best explained by the assumption that the Sun left the nest within ∼20 [million years] after the giant planets formed and migrated,” said authors Simon Portegies Zwart of Leiden University and Shuo Huang of Tsinghua University.
“An early escape also has consequences for the expected number and the proximity of supernovae in the infant Sun’s neighborhood,” the team added. “The first supernova typically happens between 8 and 10 [million years] after the cluster’s birth.”
In other words, the baby Sun may have been in the blast zone of an exploding star, which could explain the presence of radioactive isotopes preserved in many ancient meteorites. By moving out at the tender age of 20-odd million years old, the Sun may have escaped even more tumult.
The team also noted that “signatures of the time the Sun spent in the parent cluster must still be visible in the outer parts of the solar system even today.” Future observations of the Oort Cloud could help us decipher this rambunctious chapter of the Sun’s life.
A voyage 30,000 years in the making
About 30,000 years ago, humans living in prehistoric Taiwan managed to cross about 100 miles of treacherous ocean to colonize the Ryukyu Islands of Japan, including Okinawa. How they accomplished this astonishing feat is a major puzzle, but scientists endeavored to find out the old-old-really-old-fashioned way: recreating the voyage themselves.
Using only stone tools that would have been available to Paleolithic humans, they fashioned several watercraft to brave the Kuroshio, “one of the world’s strongest ocean currents,” said researchers led by Yu-Lin Chang of the Japan Agency for Marine-Earth Science and Technology in one of two studies about the project out this week.
“We tested reed-bundle rafts (2014–2016) and bamboo rafts (2017–2018) as the first two candidates for possible watercraft, but they were unable to cross the Kuroshio Current,” noted researchers led by Yousuke Kaifu of the University of Tokyo in the other study.
In 2019, the team finally succeeded with a cedar dugout canoe that they paddled across the 140-mile stretch between Wushibi, Taiwan, and Yonaguni Island in a little over two days.
“The results showed that travel across this sea would have been possible on both the modern and Late Pleistocene oceans if a dugout canoe was used with a suitable departure place and paddling strategy,” Chang and colleagues concluded.
Museums: the world’s biggest lost-and-found boxes
Paleontologists don’t always have to schlep out into the field to find fossils; discoveries can also be made in the air-conditioned comfort of museum collections.
Case in point: Megan Sims, the collections manager at the University of Kansas Vertebrate Paleontology Collection discovered two long-lost specimens—the 45 million-year-old rodent Thisbemys brevicrista and the 30 million-year-old bat Oligomyotis casementorum—while working through storage. Both fossils are holotypes, meaning that they are considered the reference point for their species as a whole.
“The rediscovery of the two holotypes that were presumed lost, T. brevicrista and O. casementorum, are reported below,” said researchers led by Sims. The bat holotype is particularly “important as one of very few bat fossils of Oligocene age from the entire continent of North America,” the team noted.
As someone who constantly finds lost relics from my past stuffed in dressers and under beds, I find studies like this deeply relatable.
A peek inside the orca spa
Orcas fashion tools out of kelp that they then use to groom each other, according to scientists who observed this behavior in a population of resident killer whales (Orcinus orca ater). The team used drones to capture 30 “bouts” of what the team called “allokelping” in this endangered orca population in the Salish Sea, providing the first evidence of tool manufacturing in a marine mammal.
“We observed whales fashioning short lengths of bull kelp (Nereocystis luetkeana) stipe from complete stalks, positioning the stipe between themselves and a partner, and then rolling the kelp along their bodies,” said researchers led by Michael Weiss of the Center for Whale Research.
“We hypothesize that allokelping is a cultural behavior unique to southern resident killer whales. Future work should investigate if and how allokelping is learned, and whether it occurs in other killer whale societies.”
Thanks for reading! We’ll be off next weekend for the Fourth of July holiday. May your next two weeks be as restorative as an orca massage.