theSIGNAL SCIENCE
13 July 2026
"The history of life is a graveyard of the inflexible."
NEWSBUSINESSTECHNOLOGYWORLDSCIENCECULTUREENVIRONMENTSPORT
Science

Why clams won and brachiopods lost

A Stanford-led study finally explains which ocean creatures survived Earth's deadliest extinction — and why the answer should worry us today.

Walk along almost any beach on Earth and you will find clam shells. You will not find brachiopod shells, even though those clam-like creatures dominated the seafloor for roughly 280 million years. Why? That question has nagged palaeontologists for decades.

Now, a study published on 6 July in the *Proceedings of the National Academy of Sciences* by a Stanford-led team has delivered what researchers are calling the strongest answer yet. The culprit is the Permian-Triassic extinction event, known as the Great Dying, which struck about 252 million years ago. Triggered by colossal volcanic eruptions that flooded the atmosphere with carbon dioxide and methane, it killed roughly 96% of all marine species. Yet the destruction was strikingly uneven.

Brachiopods, sea lilies, and other bottom-dwelling animals were nearly wiped out. Molluscs — clams, snails, and their relatives — lost only about half of their species. Fish and echinoderms, such as starfish and sea urchins, fared well too. Those survivors went on to build the ocean ecosystems we recognise today.

Photo: Mandy Henry / Unsplash
Brachiopod shells on a rocky seafloor, relics of a world the Great Dying almost entirely erased.
Discuss
  • Why do you think it took scientists so long to combine data from both surviving and extinct groups?
  • The study describes oceans before the Great Dying as similar to pre-industrial seas. What does that comparison imply about current climate change?
  • Should findings about events 252 million years ago influence environmental policy today? Why or why not?
Science

Our rockets are polluting the moon

Picture a crater near the moon's South Pole that has never once seen sunlight — not in three billion years. Inside, ancient ice may be hiding the chemical ingredients that sparked life on Earth. Scientists want to read those molecules like a diary of the early solar system. Here is the uncomfortable twist. Every rocket landing releases methane, and a new study in the Journal of Geophysical Research: Planets finds those molecules can hop from the South Pole to the North Pole in less than two lunar days. "Our activity can actually hinder scientific exploration," warns Silvio Sinibaldi, planetary protection officer at the European Space Agency.…
  • Should moon landings be restricted to protect ancient scientific evidence?
∞
Our findings show that, across different organism groups, extinctions happened at much higher rates for those more vulnerable to increases in water temperature and decreases in oxygen availability.
José Andrés Márquez, lead study author and former PhD student, Stanford University
Science

The Ocean's Secret Pressure Cooker

Picture a tiny snowflake of dead algae sinking four kilometres into darkness. Researchers at the University of Southern Denmark have discovered something startling: the crushing hydrostatic pressure down there squeezes dissolved carbon and nitrogen right out of those particles — like a slow, invisible juicer — feeding microbes that were supposed to be starving. The twist? Up to 50% of the carbon and nearly 63% of the nitrogen leaks away before reaching the seafloor. Scientists had assumed that carbon was safely buried. Instead, it may drift suspended in deep water for thousands of years — quietly rewriting how much the ocean actually locks away.…
  • If the ocean stores less carbon than we thought, how urgently must we act?
WORLD · Science
‘Spermageddon’: is the world facing a male reproductive crisis?
AMERICAS · Science
Q&A: Unforeseen consequences of the 'great aging' of America
EUROPE · Science
Physicists created a tiny universe where time emerged without a clock
GLOBAL · Science
A hidden immune backup system could supercharge mRNA cancer vaccines
theSIGNAL IN THE LAB
1VOCABULARY
naggedcolossal
strikingly unevenmetabolic flexibilityhydrostatic pressure
carbon budgetplanetary protection
2GRAMMAR FOCUS
Participle clauses — present (-ing) and past (-ed)
Participle clauses replace relative clauses or adverbial clauses to make sentences more concise; present participles (-ing) express active or simultaneous actions, while past participles (-ed) express passive or completed ones.
triggered · combining · suspended · known · burning · wiped out · dominated
  1. The Permian-Triassic extinction event, as the Great Dying, killed roughly 96% of all marine species.
  2. The Stanford team, biological data from both surviving and collapsed groups, identified a clear pattern.
  3. Colossal volcanic eruptions, the atmosphere with carbon dioxide, caused the Great Dying.
  4. Carbon may drift in deep water for thousands of years before it has any impact on the seafloor.
  5. Brachiopods, by the extinction event, never recovered their former dominance of the seafloor.
  6. Fossil fuels, by humans today, echo the volcanic carbon that once rewrote life on Earth.
3PHRASAL VERBS
Match the phrasal verb (1–6) to its definition (a–f). All six appear in today's articles.
  1. 1. wiped out
  2. 2. fared well
  3. 3. went on (to build)
  4. 4. locks away
  5. 5. nagged (at)
4CRITICAL THINKING
Two of the three articles describe how human activity is interfering with natural systems we do not yet fully understand — one geological, one astronomical. What does this pattern suggest about the relationship between scientific curiosity and the risk of causing harm through the very act of investigating?
5CREATIVE · HEADLINES
Write a headline for the clam-versus-brachiopod story in each of the following styles. One line each, no explanation:
  • TABLOID NEWSPAPER
  • LUXURY MAGAZINE
  • ACTIVIST BLOG
6WRITING
The deep ocean, the lunar South Pole, and ancient fossil records are all described as archives of Earth's history. Choose one and argue, in a short paragraph, which poses the greater ethical dilemma: leaving it unexplored, or risking its contamination in the process of study.
7DEGREES OF EXTREMITY
Complete each ladder from mild to strong.
  • affected→→
  • changed→→
  • concerned→→
  • declined→→
  • unusual→→
  • warm→→
8SPEAKING
  1. What surprises you most about rocket pollution reaching the North Pole?
  2. Could deep-sea microbes ever be engineered to store more carbon?
  3. Which extinct species would you most want to bring back, and why?
  4. How should space agencies balance exploration with environmental protection?