Enlarge / These complex creatures seem to be the earliest branch of the animal tree. We're more closely related to sponges than we are to them. (credit: Getty Images )

Ask someone to think of an animal, and chances are they'll come up with one of our relatives among the mammals. A few people might go further afield and mention other vertebrates, like birds and fish. But these barely scratch the surface of animal diversity, with things like cephalopods, insects, and echinoderms all having distinct features.

And that's before you get to the really weird stuff, like the radially symmetric Cnidarians, or the sponges that lack muscle and nerve cells. Or the comb jellies, which move themselves around by spinning lots of thread-like cilia. Or the truly bizarre placozoans , disk-like creatures that have two sides but no interior and digest things on their surface.

For people who tend to think that evolution involves adding ever-greater complexity to organisms, it's tempting to imagine that the animal family tree came about by progressively adding more stuff, like nerve cells and muscles. But there has been a steady flow of genetic studies that hint that there are two separate lineages that ended up with nerve cells. The results of these studies were a bit dependent upon the genes and species chosen for the analysis. But a new study that's not as dependent upon individual genes now firmly places sponges as more closely related to humans than some other animals with a nervous system.

Enlarge / People may accidentally sequence your DNA while trying to study something else entirely. (credit: Andriy Onufriyenko )

It used to be that if you wanted to find a DNA sequence in a particular sample, you had to go searching for that specific sequence—you had to fish it out with a hook designed especially to catch it. But no more. DNA sequencing technology has advanced to the point where you can take a sample from almost any environment—a drop of water, an ice core, a scoop of sand or soil, even air—and just see whatever DNA is in there.

This provides a non-invasive way to study wild populations and invasive or endangered species and has been used to monitor for pathogens (SARS-CoV-2, mpox, polio, tuberculosis) in wastewater. But guess who else’s DNA is in those environmental samples? Yup. Ours.

Something identifiable in the air

Liam Whitmore is a zoologist and conservationist who studies green turtles. He and his colleagues realized that having human DNA slip into research samples might be an issue, so they looked to see if they could find any in old water and sand samples they had taken as part of a wildlife and pathogen monitoring study. They did. Then they went intentionally searching for specific human sequences, and, in water, sand, and air samples, they found plenty of genomic regions that could identify a person’s ancestry and susceptibility to several diseases. They didn’t go so far as to identify individuals but noted that someone probably could compare these sequences to public genetic data without too much difficulty.

Enlarge / After Balto died in 1933, his taxidermy mount was put on display at the Cleveland Museum of Natural History. (credit: Cleveland Museum of Natural History)

In 1925, a sled dog named Balto led his plucky canine team on the last leg of a grueling 127-hour dogsled relay across Alaska to bring lifesaving medicine to the people of Nome—the famous " Serum Run ." Balto was lionized for the feat, even inspiring a 1995 animated film and two sequels. Now scientists have sequenced the dog's genome for the first time and compared it to modern dog breeds, shedding light on why Balto and similar sled dogs from that period proved well-suited to thrive in the harsh winter environment.

It turns out Balto was just part Siberian husky, and, contrary to popular legend, he was not part wolf. The authors even used the sequenced genome to reconstruct Balto's physical appearance. These and other findings appear in a new paper published in the journal Science. It's one of several featured in a special issue reporting on results from the Zoonomia Project , an international collaboration to sequence and compare the genomes of 240 mammals in order to discover the genomic basis of traits essential for all animals, as well as changes that underlie the unique traits of individual species.

“The fact that the DNA from a tiny sample of Balto’s skin can provide new scientific insights is a powerful reminder of how advances in science continually allow us to glean new information from museum collections,” said Gavin Svenson , chief science officer of the Cleveland Museum of Natural History in Ohio, where Balto's taxidermied remains are housed. “Every one of the millions of objects in our museum has the potential to reveal an important clue to a future scientist, who in turn can enhance our understanding of the past, present, and future of the world around us.”

Enlarge / Electron micrograph of herpesviruses. (credit: Callista Images )

Double-stranded DNA viruses come in two main flavors, classified by their shapes. One contains large and giant DNA viruses that attack complex cells but also includes some viruses that are much smaller and infect bacteria. These viruses are shaped like soccer balls. The other flavor has tails and primarily infects bacteria and archaea but also contains the herpesvirus family, which infects animals.

The disparate properties of these viruses have raised some questions that have been plaguing virologists: Where did herpesviruses come from? And how are the large and giant DNA viruses related to the smaller viruses within their realm?

Tara Oceans is “an international, multidisciplinary project to assess the complexity of ocean life across comprehensive taxonomic and spatial scales.” Researchers with the project sail around all five oceans and two seas (the Red and the Mediterranean), sampling plankton to try to understand the ocean ecosystem. In new work reported in Nature, a team pulled plankton from the sunlit oceans (it’s a technical term: only down to 200 meters below the surface, where light penetrates and photosynthesis happens). They surveyed all the planktonic DNA viruses by comparing a single hallmark gene among them.

Enlarge (credit: Beth Zaiken)

An international team of scientists has published the results of their research into 23 woolly mammoth genomes in Current Biology . As of today, we have even more tantalizing insights into their evolution, including indications that, while the woolly mammoth was already predisposed to life in a cold environment, it continued to make further adaptations throughout its existence.

Years of research, as well as multiple woolly mammoth specimens, enabled the team to build a better picture of how this species adapted to the cold tundra it called home. Perhaps most significantly, they included a genome they had previously sequenced from a woolly mammoth that lived 700,000 years ago, around the time its species initially branched off from other types of mammoth. Ultimately, the team compared that to a remarkable 51 genomes—16 of which are new woolly mammoth genomes: the aforementioned genome from Chukochya, 22 woolly mammoth genomes from the Late Quaternary, one genome of an American mastodon (a relative of mammoths), and 28 genomes from extant Asian and African elephants.

From that dataset, they were able to find more than 3,000 genes specific to the woolly mammoth. And from there, they focused on genes where all the woolly mammoths carried sequences that altered the protein compared to the version found in their relatives. In other words, genes where changes appear to have been naturally selected.

Enlarge / Portrait of Beethoven by Joseph Karl Stieler, 1820 (credit: Beethoven-Haus Bonn)

Ludwig van Beethoven is one of the greatest composers of all time, but he was plagued throughout his life by myriad health problems, most notably going mostly deaf by 1818. These issues certainly affected his career and emotional state, so much so that Beethoven requested— via a letter addressed to his brothers—that his favorite physician examine his body after his death to determine the cause of all his suffering.

Nearly two centuries after the composer's demise, scientists say they have sequenced his genome based on preserved locks of hair. While the analysis of that genome failed to pinpoint a definitive cause of Beethoven's hearing loss or chronic digestive problems, he did have numerous risk factors for liver disease and was infected with hepatitis B, according to a new paper published in the journal Current Biology. The researchers also found genetic evidence that somewhere in the Beethoven paternal line, an ancestor had an extramarital affair.

“We cannot say definitely what killed Beethoven, but we can now at least confirm the presence of significant heritable risk and an infection with hepatitis B virus,” said co-author Johannes Krause , an expert in ancient DNA at the Max Planck Institute of Evolutionary Anthropology. “We can also eliminate several other less plausible genetic causes.” The fully sequenced genome will be made publicly available so other researchers can have access to conduct future studies.

Enlarge (credit: National Academies of Science )

With the advent of genomic studies, it's become ever more clear that humanity's genetic history is one of churn. Populations migrated, intermingled, and fragmented wherever they went, leaving us with a tangled genetic legacy that we often struggle to understand. The environment—in the form of disease, diet, and technology—also played a critical role in shaping populations.

But this understanding is frequently at odds with the popular understanding, which often views genetics as a determinative factor and, far too often, interprets genetics in terms of race . Worse still, even though race cannot be defined or quantified scientifically, popular thinking creeps back into scientific thought, shaping the sort of research we do and how we interpret the results.

Those are some of the conclusions of a new report produced by the National Academies of Science. Done at the request of the National Institutes of Health (NIH), the report calls for scientists and the agencies that fund them to stop thinking of genetics in terms of race, and instead to focus on things that can be determined scientifically.

Enlarge / The Nicobar pigeon, the dodo's closest living relative, is quite a bit smaller and capable of flight. (credit: Samuel Hambly / EyeEm )

Colossal is a company that got its start with a splashy announcement about plans to do something that many scientists consider impossible with current technology, all in the service of creating a product with no clear market potential: the woolly mammoth. Since that time, the company has settled into a potentially viable business model and set its sights on a species where the biology is far more favorable: the thylacine, a marsupial predator that went extinct in the early 1900s.

Today, the company is announcing a third de-extinction target and its return to the realm of awkward reproductive biology that will force the project to clear many technical hurdles: It hopes to bring back the dodo.

A shifting symbol

The dodo was a large (up to 1 meter tall), flightless bird that evolved on the island of Mauritius in the Indian Ocean. As European sailors reached the islands, it quickly became a source of food for them and the invasive species that accompanied them. It went extinct within a century of the first descriptions reaching Europe.

Enlarge (credit: Aurich Lawson)

Back in the day, taxonomists had to characterize organisms based basically on how they looked. Molecular phylogeny changed that; once scientists could isolate and amplify DNA, they started classifying organisms based on their genetic sequences. But that still usually required that the organisms be cultured (and thus culturable) in a lab.

High-throughput sequencing technology relieved that constraint. Now researchers can basically throw a drop of pus, pee, or pond water into a DNA sequencer and find a host of previously unidentified microbes.

Yet, rare sequences (and the organisms they come from) are still rare, and thus still hard to find. Microbial eukaryotic predators are single cells with complex internal structures, and they’re among the rarest taxa of all. To find some, researchers enriched seawater samples with bacterial prey to stimulate the growth of protists that ate them. The growth in protists in turn stimulated the growth of predators that fed on them. Only then did the researchers run their metagenomic analysis. They found 10 new predator strains that they say form a new supergroup. They named it Provara (for devouring voracious protists).