From a record-setting black hole to the oldest animal DNA ever recovered, discoveries in 2021 stretched the limits of scientific study — and our imaginations.
Oldest behemoth black hole
More than 13 billion years ago, when the universe was a mere 670 million years old, a black hole was born. At a mass equal to 1.6 billion suns, the newly discovered supermassive black hole J0313-1806 is twice as heavy and 20 million years older than the previous record holder for oldest known black hole (SN: 2/13/21, p. 4). The ancient behemoth is so big that it challenges notions of how supermassive black holes first formed, astronomers say.
Gravity on the smallest scale
Every object with mass has gravity too, according to both Isaac Newton and Albert Einstein, even if it’s barely noticeable. Scientists have now measured the gravity of a gold ball 2 millimeters wide and weighing about 90 milligrams — the smallest object ever to have its gravitational pull measured (SN: 4/10/21, p. five). The tiny tug revealed that gravity behaves as predicted, even for very small masses. Researchers still want to test how gravity behaves on the even smaller quantum scale, where different rules of physics may apply.
Oldest opposable thumbs
A 160-million-year-old pterosaur nicknamed Monkeydactyl is now the earliest known animal with opposable thumbs (SN: 5/8/21 & 5/22/21, p. 16). The flying reptile, officially named Kunpengopterus antipollicatus, may have used its thumbs and flexible joints to clamber up and through trees in what is now northeastern China. The digits could have helped it capture insects and other prey, scientists say.
For the first time, a black hole has been seen gobbling up a neutron star, the collapsed remains of a dead supergiant star. Astronomers detected the event by measuring gravitational waves that emanated from the collision and eventually reached Earth (SN: 7/31/21, p. 6). All previously identified sources of these ripples in spacetime composed of two like objects colliding, such as two neutron stars or two black holes.
Oldest recovered animal DNA
The tooth of a Siberian mammoth that lived more than a million years ago has offered up the oldest DNA ever recovered from an animal (SN: 3/13/21, p. 6). The previous record holder was 700,000-year-old DNA from a fossilized horse. Scientists say the new find probably approaches the limit of how long DNA can persist. Genes from the mammoth suggest that it may have belonged to a previously unknown species.
Most Denisovan DNA
The mysterious hominid group known as the Denisovans died out long ago, but not without leaving a trace. The Indigenous Ayta Magbukon people of the Philippines get about 5 percent of their DNA from Denisovans, a genetic analysis revealed (SN: 9/11/21, p. 16). That’s the highest level of Denisovan ancestry yet found anywhere in the world. Researchers are using the result, along with genetic clues from other groups that carry Denisovan DNA, to retrace Denisovans’ movements through Southeast Asia, Papua New Guinea and Australia.