A black and white headshot of Andrew Carstens

Andy Carstens

Andy Carstens is a freelance science journalist who is a current contributor and past intern at The Scientist. He has a bachelor’s degree in chemical engineering from the Georgia Institute of Technology and a master’s in science writing from Johns Hopkins University. Andy’s work has previously appeared in AudubonSlateThem, and Aidsmap. View his full portfolio at

Articles by Andy Carstens
A male and female Chiriqui harlequin frog (<em>Atelopus chiriquiensis</em>) photographed in 2010. The species was declared extinct in 2019.
How Do Scientists Decide a Species Has Gone Extinct?
Andy Carstens | Mar 1, 2023 | 10 min read
Getting it wrong can harm the very creatures that scientists are trying to protect.
A Cape ground squirrel sits upright on its hind legs, holding its forelimbs up to its face.
Animals Are Shape-Shifting in Response to a Warming World
Andy Carstens | Jan 3, 2023 | 10 min read
Forced to respond to a climate that’s changing faster than it ever has, it remains unclear whether species’ adaptations can keep pace.
Artist&rsquo;s rendition of neural connections, with inactive neurons in the background
Ketamine Flips a “Switch” in Mice’s Brain Circuitry: Study
Andy Carstens | Dec 9, 2022 | 6 min read
After injecting moderate doses of the dissociative anesthetic into the animals, previously “awake” brain cells go dark, and those that had been dormant suddenly light up.
Diagram of the causes of mortality in the army in the east.
Diagrammatic War, 1858
Andy Carstens | Dec 1, 2022 | 3 min read
Pioneering nurse Florence Nightingale had an eye for creating memorable graphics that helped convince the general population that including sanitation reforms as part of public health policy would save British soldiers’ lives.
Illustration of myelinated neuron axons in light blue, with spindly blue and purple cells interspersed among them.
A Gene Variant Linked to Alzheimer’s May Disrupt Myelin Production
Andy Carstens | Nov 22, 2022 | 5 min read
The APOE4 variant causes cholesterol buildup in the cells that make protective fatty sheaths for neurons, possibly helping explain its role in neurodegeneration.
fluorescently labeled microscopy cross-section of bone
Cancer Cells in Mice May Hitch a Ride with Bone-Healing Stem Cells
Andy Carstens | Nov 7, 2022 | 4 min read
Researchers have long observed a connection between bone metastasis and remodeling, which might be due to a close connection between the two cell types. 
Fernanda, a Fernandina giant tortoise (<em>Chelonoidis phantasticus</em>), was identified in 2019, decades after her species supposedly went extinct.
When an Extinct Species Is Found Alive, What Happens Next?
Andy Carstens | Nov 1, 2022 | 6 min read
Finding a creature in the wild that had been considered long gone brings hope—and quite a bit of uncertainty.
A mesquite tree in an arid environment
Climate Change May Favor Nitrogen-Fixing Plants
Andy Carstens | Oct 17, 2022 | 2 min read
Aridity appears to configure landscapes with a greater diversity of plant species that rely on symbiotic bacteria for nitrogen.
an immune cell in blood
Why Viral Infections Are More Severe in People with Down Syndrome
Andy Carstens | Oct 14, 2022 | 6 min read
In people with the genetic condition, inflammation can cause a mild infection to snowball out of control, a study finds.
Kentish plover standing by nest with eggs
Avian Deception More Widespread Than Previously Thought
Andy Carstens | Oct 3, 2022 | 5 min read
The broken-wing display, in which birds fake being wounded to protect their nests from predators, is found across the avian phylogenetic tree, a study finds.