Rapid Evolution in Scarlet Monkey Flower, Dust Bathing in Birds, and Social Sharks | Short Wave

Short Wave's biweekly science roundup features three stories: first, researchers tracked scarlet monkey flowers through a megadrought and found rapid evolution in stomata that helped conserve water, enabling survival in extreme conditions; second, a Taiwan study on dust bathing explains how dirt and sand help birds maintain feather oil and shed parasites through wing shaking; third, a six-year study of bull sharks in Fiji reveals individual preferences and age-related roles in social networks, with caution urged against overly human interpretations. The episode highlights long-term fieldwork and the clever, species-specific strategies animals use to cope with harsh environments, plus potential engineering insights drawn from natural behaviors.

Overview

In this biweekly Short Wave science roundup from NPR, host Emily Kwong and co-host Nate Rott guide listeners through three distinct stories that span botany, ethology, and marine biology. The conversations illustrate how natural systems navigate stressors like drought, parasites, and social dynamics in animal communities. The episode emphasizes long-term data collection, interdisciplinary approaches, and the sometimes humorous humility scientists bring to their work.

Rapid Evolution in Scarlet Monkey Flowers

The first segment focuses on the scarlet monkey flower, a plant with vibrant red petals that attract hummingbirds for nectar. Plant biologist Daniel Anstett at Cornell University describes how these populations endured an extraordinary megadrought. Without water, many would perish in days, yet certain wild populations in California and Oregon survived through rapid evolution, a process involving quick genetic changes that shift how the plants cope with drought. The study tracked over more than a decade, returning to remote populations to observe survival rates and collect seeds for genetic sequencing, aiming to understand the longer-term decadal consequences of this rapid response. The researchers found that among the best-recovered populations, stomata—tiny pores on the leaf surface—evolved to open fewer, thereby conserving water during dry periods, effectively slowing down water loss and helping the plants endure prolonged stress. This discovery highlights how plants can adapt on human-relevant timescales, and it raises questions about future resilience as environmental conditions continue to shift.

"rapid evolution" - Daniel Anstett, plant biologist at Cornell University

Dust Bathing in Birds

The second story examines dust bathing, a seemingly counterintuitive grooming behavior observed in ostriches, some songbirds, turkeys, and chickens. Patricia Yang, assistant professor at National Tsinghua University in Taiwan, explains that a bird’s bath involves dirt and sand, and the mechanical action of digging and wiggling wings helps apply oil to feathers. The process is not about cleanliness alone; sand acts as a dry shampoo and aids in removing parasites such as feather mites, which can cause itching and other health issues. To probe the mechanics, Yang and her team collected sand and mite-covered chicken feathers, then vibrated the feathers at a frequency similar to those birds use during dust baths. The mites mostly fell away, supporting the idea that shaking or agitation can dislodge contaminants. An aerospace engineer, Andrew Dickerson, notes that such finely tuned activities show how animals manage contaminants and even offer potential guidance for engineered systems.

"a bath for a chicken involves dirt and sand" - Patricia Yang, assistant professor at National Tsinghua University

Social Sharks in Fiji

The final topic turns to the social lives of bull sharks, as studied by Natasha Morosi and colleagues in the Shark Reef Marine Reserve, Fiji, over six years. The researchers tagged and observed 184 bull sharks, noting that individuals show distinct preferences for particular other sharks and form subgroups. Some sharks consistently hung out together, forming a social circle that researchers nicknamed Chunky, Mogul, and Shark Bite. The study analyzed active choices: parallel swimming, direction changes to join others, and network centralities. Age factored into the social structure, with middle-aged sharks occupying more connected positions within the network than younger or older individuals. While these findings illuminate social patterns, another expert cautions against over-anthropomorphizing these interactions, arguing that the meanings of such associations remain uncertain. The study is published in Animal Behavior with a playful, memorable title Rolling in the Deep.

"some sharks consistently hang out with each other over the course of the study" - Natasha Morosi, shark scientist

Closing Thoughts

The episode closes with thanks to the researchers and a nod toward the broader theme of scientific curiosity and long-term inquiry, underscoring how seemingly simple behaviors can reveal complex adaptive strategies across diverse life forms.