Luffy

Raju jumped up, grabbed some clothes and 270 rupees (US$3.30) and fled to the evacuation site, he recalled in an interview with Nature last October. The water filled his home during the 2018 flood, Raju said, pointing to a water stain about 1.5 metres up his wall.

The state of Kerala, where the Meenachil River is located, received 164% more rainfall1 than normal that August, triggering what residents call the Pralayam — a flood to end the Universe in the Hindu religion. It was the biggest in the state since 1924. More than 400 people died, more than one million were displaced and damages amounted to US$4.25 billion, according to an Indian government report2.

Since 2018, “the sound of the rain beginning really disturbs my mood,” says Emmanuel. “It is not like before — we were sleeping peacefully even when it’s raining all season. But not any more.”

Intense monsoonal rains caused catastrophic flooding in Kerala, India, during August 2018. Credit: Raj K Raj/Hindustan Times/Getty

Western Ghats, Kerala

The rains did not let up all summer in 2018. By 14 August, most reservoirs had filled up and the people had grown weary of the monsoon. That day, Eby Emmanuel’s phone started buzzing repeatedly with messages from neighbours warning that the Meenachil River was overflowing. He realized areas downhill could flood in hours, endangering a hamlet of 90 poor families living on the sandy riverbank.

Emmanuel, the secretary of the Meenachil River Protection Council in Kidangoor, a collective of local river conservationists, quickly organized with other community workers and the Kottayam fire department to evacuate the people. But one resident, T. Raju, refused to abandon his belongings. He lay down on his stringed bed frame, figuring he had seen plenty of bad rains. Then, his bed moved and his television floated by. This wasn’t normal.

The analyses supported the presence of a ‘Turing reaction–diffusion system’, which can be created when a molecule that activates a developmental process stimulates both itself and an inhibitory molecule. The result is a self-organizing system that creates periodic patterns, says Marian Ros, a developmental biologist at the Institute of Biomedicine and Biotechnology of Cantabria in Santander, Spain.

The maths of patterns
Such systems were proposed3 by mathematician Alan Turing in 1952 as a chemical explanation for developmental processes such as the arrangement of leaves on a plant or tentacles on the small aquatic organisms called hydras. Since then, Turing reaction–diffusion mechanisms have been described as instrumental in establishing a wide variety of familiar biological sights, including the brightly coloured scales of some tropical fish, and feather patterns in birds.

NEWS
09 February 2023
How fingerprints get their one-of-a-kind swirls
The intricate patterns are created during fetal development when fine ridges on the skin form and crash into each other.
Heidi Ledford
Twitter Facebook Email
Multiple fingerprints in white on a dark surface.
No two alike: the patterns on a fingerprint arise from wave after wave of ridges that begin in various spots, spread towards each other and then collide.Credit: Tek Image/Science Photo Library

The whorls, arches and loops that make fingerprints unique are produced during fetal development by waves of tiny ridges that form on the fingertip, spread and then collide with each other — similar to the process that gives a zebra its stripes, or a cheetah its spots.

In a study1 published on 9 February in Cell, researchers found that the interplay between two proteins — one that stimulates ridge formation, and another that inhibits it — produces periodic waves of ridges that emerge from three distinct regions on the fingertip.

The precise locations of these regions and the collisions between the waves yields the unique pattern of a fingerprint. “To come up with these different patterns of arches, loops, and whorls, the key isn’t just the molecular ingredients,” says study co-author Denis Headon, a developmental biologist at the University of Edinburgh, UK. “It’s how they are deployed on the anatomy of the hand.”

Identifying marks
Fingerprints are thought to provide added grip and sensitivity to fingertips, and their patterns have long been used to identify individuals and diagnose some developmental conditions. Last year, Headon and his colleagues published work2 describing the genes that influence fingerprint patterns, many of which are involved in limb development. These genes seemed to lay the groundwork for fingerprint formation, but many of them were inactive during the process, suggesting that they were not directly involved in forming ridges.

To learn more about fingerprint patterning, Headon and his colleagues tracked how fingerprints emerge over the course of fetal development. Anatomical studies and analyses of gene activity showed that the cells that form fingerprint ridges followed a developmental path that initially mimicked that of a hair follicle. But, unlike a follicle’s gene-activity pattern, the ridge cells failed to incorporate cells from deeper beneath the skin’s surface.

NEWS
09 February 2023
How fingerprints get their one-of-a-kind swirls
The intricate patterns are created during fetal development when fine ridges on the skin form and crash into each other.
Heidi Ledford
Twitter Facebook Email
Multiple fingerprints in white on a dark surface.
No two alike: the patterns on a fingerprint arise from wave after wave of ridges that begin in various spots, spread towards each other and then collide.Credit: Tek Image/Science Photo Library

The whorls, arches and loops that make fingerprints unique are produced during fetal development by waves of tiny ridges that form on the fingertip, spread and then collide with each other — similar to the process that gives a zebra its stripes, or a cheetah its spots.

In a study1 published on 9 February in Cell, researchers found that the interplay between two proteins — one that stimulates ridge formation, and another that inhibits it — produces periodic waves of ridges that emerge from three distinct regions on the fingertip.

The precise locations of these regions and the collisions between the waves yields the unique pattern of a fingerprint. “To come up with these different patterns of arches, loops, and whorls, the key isn’t just the molecular ingredients,” says study co-author Denis Headon, a developmental biologist at the University of Edinburgh, UK. “It’s how they are deployed on the anatomy of the hand.”