Olfactory maps overturn our idea of smell

The most detailed map ever of the olfactory receptors in the mouse nose transforms our understanding of the sense of smell. Instead of a handful of broad zones, in which receptors are essentially random, “each receptor adopts a particular position in the nose”, says neurobiologist and study co-author Sandeep Robert Datta. And the arrangement of receptors in the nose is mirrored in the part of the brain responsible for smell. “This means that the maps in the nose and the brain are not two separate problems the system has to solve, but two readouts of the same developmental logic,” says psychologist and experimental neuroscientist Johan Lundström. “This is a landmark paper that overturns one of the foundational textbook models of olfactory organisation.”

Mitochondria can spawn new ‘organelles’ — hinting at how modern cells evolved

When a parasite invades a cell, mitochondria — the cell’s energy producers — respond by shedding their outer layer to form new cellular compartments that digest molecular trash. These new organelles help the parasite to proliferate, possibly because the invader can feed off the degraded material inside the tiny compartments, says immunologist and study co-author Lena Pernas. The findings lend credence to the hypothesis that ancient mitochondria gave rise to the first organelles in complex cells by shedding their outer layer to form new membrane sacs.

Did kraken-like octopuses rule Cretaceous seas? Massive jaw fossils offer clues

In the age of dinosaurs, giant octopuses — sometimes named krakens after the mythological monsters — might have grown to nearly 19 metres in length. The estimate is based on fossilised jaws, which researchers say show patterns of wear that came from devouring animals that had hard shells and skeletons. The team suggest that these giant cephalopods might have sat at the top of the marine food chain in the Cretaceous period alongside huge marine reptiles such as mosasaurs. But other researchers say that estimates about the size of the soft-bodied creatures, and how they hunted, should be taken with a pinch of salt.

Newfound brain network is a ‘secret system’ made of helper cells

Brain cells called astrocytes form extensive networks in the mouse brain that are similar in some ways to those formed by neurons. Researchers have compiled a whole-brain 3D map of astrocyte networks — the first of its kind, they say. The atlas reveals how webs of these cells connect far-flung regions of the brain, allowing them to exchange molecules with each other over long distances.

A Powerful New ‘QR Code’ Untangles Math’s Knottiest Knots

Mathematicians have long tried to untangle exactly what makes a knot a knot. There are several ways to define a knot’s characteristics, referred to as ‘invariants’, but “most invariants are either very strong but impossible to compute, or easy to compute but very weak,” says mathematician Daniel Tubbenhauer. Now researchers Dror Bar-Natan and Roland van der Veen have proposed what they dub “a fast, strong, topologically meaningful, and fun knot invariant” — or Θ for short — that can describe even very complex knots as a rather lovely 2-dimensional pattern.

Sperm whales’ communication closely parallels human language, study finds

The structure of sperm whales’ communications has close parallels with the phonetics of some human languages. The whales (Physeter macro­cephalus) communicate using a series of clicks called codas. The animals can differentiate the sound by changing the click’s length or using rising and falling tones, which researchers found follow patterns that resemble those used in human languages such as Mandarin and Slovenian. “We’re starting to see that these signals are organized in ways we didn’t fully appreciate before,” says behavioural ecologist Mauricio Cantor.

Human evolution sped up after farming

An analysis of DNA evidence from more than 15,000 ancient humans has revealed that human evolution has accelerated over the past 10,000 years. Researchers identified almost 500 gene variants that evolved through natural selection in ancient European and Middle-Eastern people after the dawn of agriculture. Many of those variants are linked to the resistance to diseases, such as tuberculosis. Accelerated evolution could reflect the intensification of lifestyle changes that started in the Neolithic period, such as new foods and pathogens, says population geneticist David Reich.

Sunbirds suck nectar with supple tongues

Sunbirds (Nectariniidae) drink nectar from flowers by generating suction with their tongues — the first example of a vertebrate creating suction without changing the shape of its mouth. As they drink, the birds repeatedly press their tongue against the roof of their beak and then release it. This motion flattens and re-forms a v-shaped groove along the length of the tongue, which researchers believe creates suction that pulls nectar into the birds’ mouths.

Quantum simulations verified by experiments for the first time

For the first time, physicists have matched detailed quantum-computer simulations to experimental data gathered from work with solid materials. Two teams of physicists achieved the feat independently: one simulated the physical properties of a magnetic material, such as its heat capacity, and the other modelled a different material’s response to being excited into a range of energy states. Both agreed with experimental data.