Science & Society
A Dallas museum hosts rare hominid fossils from South Africa
Fossils of the South African hominids Australopithecus sediba and Homo naledi are on display at the Perot Museum of Science and History in Dallas.
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Cover Story
For people with HIV, undetectable virus means untransmittable disease
HIV outreach and care in Washington, D.C., reveals the struggles and successes of getting drugs into the hands of those who need them.
Reviews & Previews
Science Visualized
Life
A peek inside a turtle embryo wins the Nikon Small World photography contest
The annual competition highlights the wonders to be found when scientists and photographers zoom in on the world around us.
Notebook
Life
Piranhas and their plant-eating relatives, pacus, replace rows of teeth all at once
Piranhas and pacus both lose and replace all teeth on one side of their mouths in one go, which may help to distribute wear and tear.
Features
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How Julia Robinson helped define the limits of mathematical knowledge
Born 100 years ago, Julia Robinson played a key role in solving Hilbert’s 10th problem.
More Stories from the November 23, 2019 issue
- Climate
50 years ago, scientists puzzled over a slight global cooling
Five decades ago, scientists were puzzled over a slight dip in global temperatures. Today we know it was just a blip, and that Earth’s climate is warming thanks to industrial activity over the last century.
- Plants
Why tumbleweeds may be more science fiction than Old West
A tumbleweed is just a maternal plant corpse giving her living seeds a chance at a good life somewhere new.
- Life
Aye-ayes just got weirder with the discovery of a tiny, sixth ‘finger’
Aye-ayes have a sixth “finger,” or pseudothumb, that may compensate for other, overspecialized fingers by helping the lemurs grip things.
- Space
Voyager 2 reveals the dynamic, complex nature of the solar system’s edge
With two spacecraft outside the sun’s magnetic bubble, researchers get a new look at the boundary between the sun and its galactic environment.
- Animals
White bellbirds have the loudest known mating call of any bird
White bellbirds have the loudest mating call, according to scientists who compared the songs of bellbirds and screaming pihas in the Brazilian Amazon.
- Space
Strontium is the first heavy element detected from a neutron star merger
The discovery of strontium created inside a neutron star smashup gives the clearest picture yet of what goes on inside this chaotic environment.
- Planetary Science
Astronomers have spotted a new type of storm on Saturn
In 2018, telescopes on Earth and in space identified a never-before-seen kind of storm activity on the ringed planet.
- Animals
Spider webs don’t rot easily and scientists may have figured out why
Spider silk doesn’t rot quickly because bacteria can’t access its nitrogen, a nutrient needed for the microbes’ growth, scientists say.
- Life
Bird eggs laid in cold climates are darker, which may keep eggs warm
A global survey of bird egg color reveals a simple trend: the colder the climate, the darker the egg.
- Health & Medicine
These tiny aquatic animals secrete a compound that may help fight snail fever
A newly identified molecule from rotifers paralyzes the larvae of worms that cause schistosomiasis, which affects over 200 million people worldwide.
- Space
Rules guarding other planets from contamination may be too strict
Voluntary international guidelines for visiting the moon, Mars and other places — and for bringing stuff back to Earth — are overly cautious, scientists say.
- Neuroscience
Sleep may trigger rhythmic power washing in the brain
Strong, rhythmic waves of cerebrospinal fluid wash into the human brain during sleep and may help clean out harmful proteins.
- Neuroscience
Alzheimer’s may scramble metabolism’s connection to sleep
Mice designed to have brain changes that mimic Alzheimer’s disease have altered reactions to blood sugar changes.
- Health & Medicine
Prozac proves no better than a placebo in treating kids with autism
In a small clinical trial, drugs called selective serotonin reuptake inhibitors didn’t ease obsessive-compulsive symptoms in children with autism.
- Humans
Humans’ maternal ancestors may have arisen 200,000 years ago in southern Africa
New DNA findings on humankind’s maternal roots don’t offer a complete picture of how and when Homo sapiens emerged.
