Cellular clocks help explain why elephants are bigger than mice

Biologists are uncovering how tiny ‘clocks’ in our cells might help govern body size, lifespan and ageing. (Mouse cells seem to run faster than human cells, which tick faster than whale cells.) A wave of research is starting to yield answers for one such timepiece: the ‘segmentation clock’. It helps developing embryos to form repeating body segments, such as vertebrae. Researchers want to understand how differences in developmental pace give rise to organisms with such different bodies and behaviours.

Muon results throw theories into confusion

The news earlier this month that the magnetic moment of muons seems to be larger than predicted by the standard model has thrown particle physics into a tizzy. If the discrepancy pans out, it would be the first time that the theory has failed to account for observations since its inception five decades ago. The finding might breathe new life into the theory known as supersymmetry, or SUSY. It could also provide evidence of either a leptoquark or a Z’ boson — hypothetical particles that could, in different ways, help mesh the results with other measurements by the Large Hadron's Collider LHCb detector. In any case, physicists are cautiously excited.

Little Foot fossil shows early human ancestor clung closely to trees

An analysis of the shoulder girdle of a human ancestor that lived millions of years ago suggests that Australopithecus afarensis retained features that helped it to climb in trees, even after developing the ability to walk on two legs. The shoulder blades belong to a near-complete fossil of a specimen dubbed Little Foot, discovered in South Africa in the 1990s.

First flight on Mars

Ingenuity has made the first powered flight on another world. Today, the robot rotorcraft — part of NASA’s Perseverance mission — lifted off from the surface of Mars for 40 seconds. Ingenuity’s counter-rotating carbon-fibre blades spun at more than 2,400 revolutions per minute to lift the craft 3 metres into the air. The US$85-million drone hovered there, and then, in a planned manœuvre, turned 90 degrees and descended safely back to the Martian surface. Software issues that kept the helicopter from transitioning into flight mode had delayed the flight from 11 April.

How many T. rex ever existed?

Over the 2 million or so years during which the species existed, 2.5 billion Tyrannosaurus rex roamed Earth. Palaeontologists used a method employed by ecologists studying contemporary creatures to estimate the population density of T. rex during the late Cretaceous period. The figure has allowed researchers to estimate just how exceedingly rare it is for animals to fossilise.

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If this speculation did not take into account ecological factors such as the different potential numbers of carnivores vs herbivores, then it is a gross exaggeration.

Oldest DNA from a Homo sapiens reveals surprisingly recent Neanderthal ancestry

Scientists have sequenced the oldest Homo sapiens DNA on record, which showed that many of Europe’s first humans had Neanderthals in their family trees. All present-day people whose ancestry isn’t solely African carry Neanderthal DNA, but there are questions about when and how the genetic mixing occurred. Three individuals found in Bacho Kiro Cave in Bulgaria, dated to between 45,900 and 42,600 years old, had “huge chunks” of Neanderthal DNA and probably had Neanderthal ancestors as recently as the past six or seven generations. A woman found in the Zlatý kůň cave in the Czech Republic is thought to be well over 45,000 years old and has Neanderthal ancestry going back considerably longer: 70–80 generations. None of the individuals are related to later Europeans, but the Bacho Kiro people shared a connection with contemporary East Asians and Native Americans. The research adds to growing evidence that modern humans mixed regularly with Neanderthals and other extinct relatives.

Muon result shakes up physics

Muons — massive, unstable cousins of the electron — seem to be more magnetic than the standard model of particle physics predicts. If this result holds up, it could ultimately force major changes in theoretical physics and reveal the existence of completely new fundamental particles. The Muon g – 2 experiment upheld sensational findings, first announced in 2001, that showed the muon’s magnetic moment — a measure of the magnetic field it generates — is slightly larger than theory had predicted.

Scientists Get Closer To Redefining The Length Of A Second

A new generation of atomic clocks are helping scientists to measure time more accurately than ever before. Standard atomic clocks use the oscillation of caesium atoms to measure seconds with great precision. Now, physicists have built a network of clocks based on elements with faster oscillations — aluminium, strontium and ytterbium — to get even closer to a true second.

Artificial life made in lab can grow and divide like natural bacteria

Scientists have identified seven genes that are essential for minimal cells to reproduce like bacteria in the wild. Minimal cells are made in the laboratory and carry only the essential genes needed for cells to function. Biologists at the J. Craig Venter Institute announced that they’d created a line of minimal cells in 2016, but later realised that these didn’t divide symmetrically like bacteria do. Reintroducing seven genes into the minimal-cell genome fixed the issue, providing further insight into how life works on a molecular level.

Long-awaited muon experiment nears moment of truth

A result that has been 20 years in the making could reveal the existence of new particles and upend fundamental physics. Physicists have high hopes that the magnetism of muons, measured in the Muon g – 2 experiment and scheduled to be released on 7 April, will uphold sensational findings first announced in 2001. The project’s earlier results hinted that the muon’s magnetic moment — a measure of the magnetic field it generates — is slightly larger than theory had predicted. If that finding is ultimately confirmed, it could help to reveal what kinds of ephemeral, unknown ‘virtual particles’ swirl in the vacuum.