10 Popular Scientific Discoveries From 2021

Read about the year’s most attention-grabbing findings by scientists at the National Museum of Natural History

A humpback whale breaches the surface of the ocean on a sunny day as three birds fly overhead.
Research in 2021 revealed that humpback whales eat three times more than previously thought. They also poop more, providing food for other ocean organisms. John Durban

In 2021, Smithsonian scientists and international researchers continued to uncover the natural world’s mystery and history. Here are the year’s top ten discoveries at the National Museum of Natural History.

People have sustainably shaped Earth’s ecosystems for over 12,000 years

This year, scientists found that humans have been sustainably shaping the world’s ecosystems for 12,000 years, or 11,500 years longer than previously thought. NASA

Most of Earth’s land was thought to be largely unused before 1500 C.E. But this year, anthropologists, ecologists and conservation scientists plowed over that mistaken theory with a paper published in the Proceedings of the National Academy of Sciences.

The team, including co-author and Smithsonian archaeologist Torben Rick, used global models to reconstruct past changes in landscapes from 10,000 B.C.E. onwards and found that people had actually been shaping almost 75% of global ecosystems for a whopping 12,000 years with dramatic biodiversity loss occurring primarily in recent centuries. Understanding how Indigenous peoples and traditional farmers practiced sustainable agriculture for thousands of years could help fertilize current research on non-invasive farming practices and support efforts to repair the current biodiversity crisis.

Our baleen brethren eat and poop a whale of a lot more than thought

The 2021 study showed that whales not only eat more than expected, but also poop a lot more. Their poop provides valuable nutrients for other ocean organisms to feed on. Matthew Savoca

What goes in, must come out — a fact that is especially true for baleen whales, which have recently been found to eat three times more than thought at around 4.4 billion pounds of prey annually. The whales also deposit millions of pounds of iron-rich poop, which becomes nutritious food for organisms living in the iron-deficient open ocean.

The paper in Nature suggests that baleen whales once produced 24 million pounds of iron-heavy poop annually. But that number dropped to 2.4 million pounds after several million whales were killed in the 20th century from industrial whaling. Working to restore global baleen whale populations could be one way to repair malnourished ocean ecosystems, according to Smithsonian paleontologist and study co-author Nicholas Pyenson.

Dire wolves were ousted from the wolf pack

Dire wolves, shown with red fur above, diverged from their grey wolf counterparts over 5.7 million years ago. Mauricio Antón

Names can be deceiving when it comes to the extinct dire wolf, which roamed North America up until 11,000 years ago and was considered a sister species of the gray wolf under the same taxonomic genus, Canis.

But this year, a group of scientists, including Smithsonian’s Audrey Lin, found that dire wolves diverged from gray wolves over 5.7 million years ago. The results, as published in Nature, revealed that dire wolves were so genetically different from today’s wolves that they had to belong to a separate taxonomic genus Aenocyon. What’s more is that the dire wolf is the only species in that genus.

The asteroid that destroyed dinosaurs created modern rainforests

Modern rainforests and their dense foliage appeared after the infamous dinosaur-killing asteroid struck 66 million years ago. ben britten, CC BY 2.0

It only took 66 million years for the asteroid that wiped out dinosaurs to get a rebranding.

By analyzing over 50,000 pollen records and at least 6,000 leaf fossils from across Colombia, scientists found that the dinosaur-killing asteroid’s explosive impact also created modern rainforests. Their Science paper suggests that when the impact caused 45% of existing plants to go extinct, it created an opportunity for tropical flowering plants to diversify. The team, which includes Smithsonian paleontologists Scott Wing and Conrad Labandeira suspect the fiery impact also caused a global downpour of ash, which likely fertilized soil and spurred fast-growing rainforest trees.

Andean societies kept tropical parrots healthy in extreme aridity

Pre-Columbian people built extensive trade networks to bring Amazonian parrots to their Atacama Desert communities. But once the parrots were there, they had to be cared for to survive the different and harshly dry climate. Calogero M. Santoro and José M. Capriles

Amazonian parrots are tropical animals, but their remains can be found throughout the incredibly dry Atacama Desert of northern Chile. This is because the parrots were status symbols for pre-Columbian Andean societies, who valued vibrant feathers.

To figure out how Andean societies kept humidity-loving parrots healthy in such an arid environment, Smithsonian’s Logan Kistler and his colleagues at Penn State and in Chile examined 27 partially mummified and skeletal Amazonian parrot remains from five archaeological sites in the Atacama. The findings, published in the Proceedings of the National Academy of Sciences, show that from 1100 C.E. to 1450 C.E. the communities efficiently reared parrots in the desert by performing beak and nail trimmings and providing them a diet of specially farmed maize.

Early humans raised the “world’s most dangerous” chicks 18,000 years ago

Cassowaries are flightless, omnivorous birds with a reputation for being cantankerous. The southern cassowary above, named Irwin, lives at the National Zoo. Zoogoers can see Irwin and his brother, Dundee, in the Bird House when it reopens in late summer 2022. Roshan Patel/Smithsonian’s National Zoo

Flightless cassowaries may be considered the “world’s most dangerous birds” today, but according to Smithsonian zoologist Teresa Feo, anthropologist Kristina Douglass and their team, humans may have been raising them thousands of years before chickens were even domesticated.

To study ancient cassowary caretaking practices, the group looked at 18,000- to 6,000-year-old eggshells from archaeological sites in New Guinea. They discovered that most of the cassowary eggs had made it to a late or hatched stage of development and had no burn marks from cooking. Meaning, the eggs may not have been not harvested for eating. Cassowaries are notorious for being cranky and combative, but they also imprint on whoever they see immediately after hatching. The Proceedings of the National Academy of Sciences paper suggests early New Guinea communities could have used this imprinting to raise these large birds.

Blackwater photography had its crossover moment

Blackwater photography can provide strong scientific value to scientists seeking to learn more about larval fishes and marine organisms. Images by Jeff Milisen/Collage by Ai Nonaka

At night, marine organisms, larvae fish and blackwater photographers — or photographers who specialize in taking pictures of open water at night — float around the deep water in the open ocean.

Smithsonian’s Ai Nonaka and David Johnson discussed the scientific value blackwater photography has and how scientists should seek collaboration with these photographer-divers. Their Ichthyology and Herpetology article explained that during the night many marine organisms migrate closer to the ocean’s surface. Blackwater diving captures snapshots of these organisms’ behaviors and their life stages, which wouldn’t normally be observed during field research. Working alongside blackwater photographers can help scientists to better understand marine diversity.

The daddy “shortlegs” strolled into town

The harvestman, or daddy longlegs, has limbs that can delicately wrap around twigs thrice over. Ettore Balocchi, CC BY 2.0

Length is the daddy longlegs’ greatest claim to fame. These arachnids, also called harvestmen, have some of the most flexible and sensitive legs in the animal kingdom. This year, Smithsonian’s Vanessa Gonzalez, Jonathan Coddington, and their colleagues decided to get a leg up on understanding the role that harvestmen genomes play in creating their special legs.

Their Proceedings of the Royal Society B paper reveals how altering the genes in one daddy longlegs species’ DNA can alter the animal’s signature look. They found that knocking down two of the three genes associated with the arachnid’s lanky legs turned most of its legs into a type of short limb called a pedipalp. Arachnids use pedipalps for handling food. Doing the same on the third leg gene made the daddy longlegs’ limbs shorter, but not pedipalp-sized small. Knowing how DNA influences daddy longlegs’ limbs’ creation can help scientists learn more about the entire taxonomic order at large.

Mega-mammals in prehistoric India co-evolved with humans to avoid extinction

Around 20% of the Indian subcontinent’s mammalian megafauna went extinct from the arrival of humans. Advait Jukar

In the fossil record, it’s common to see signs of extinct megafauna, like mammoths, after prehistoric humans entered an ecological landscape.

But this wasn’t the case for all mammalian megafauna in the Indian subcontinent. According to Smithsonian paleobiologists Advait Jukar and Mark Uhen. The team’s paper in Palaeogeography, Palaeoclimatology, Palaeoecology points towards co-evolution as the reason for why megafauna like elephants, rhinos, and tigers managed to survive after the arrival of humans. Only 20% of the region’s large mammals died out after humans arrived — a rate 4 times smaller than similar human-related extinction events in North America, Europe, Madagascar and Australia. The big mammals that remained did so by adapting to humans changing the environment.

Some electric eels are happy collective hunters

In 2021, scientists observed the species Volta’s electric eel hunting together in groups. The eels can grow eight feet long and generate 860-volt electric shocks. Jennifer Clausen

The elusive Volta’s electric eel was thought to be a solitary hunter until Smithsonian ichthyologist C. David de Santana stumbled across a lake in the Brazilian Amazon River basin.

His observations, published in Ecology and Evolution paper, show that Volta’s electric eels hunt together by swarming in circles around prey and stunning the prey with 860 volts shocks. Hunting collectively allows the eels to feast on more fish than they could capture alone. Moving forward, the group hopes to learn more about this hunting behavior and explore other electric eel communities in the Amazon River basin to see what other behaviors these eels, which are threatened by the current biodiversity crisis, may be hiding.

May next year’s scientific discoveries be just as shocking.

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