Mpox Emergency, Stonehenge Altar Stone Provenance, Mars Subsurface Water, and Horse Model-Based Learning | Naked Scientists

Podcast snapshot

The Naked Scientists explore a spectrum of current science stories from a World Health Organization public health emergency to a prehistoric puzzle and a planetary science discovery, plus a surprising finding about equine cognition. The episode also features a community-driven questions segment on wildfires and carbon emissions.

• Mpox declared a public health emergency of international concern with implications for surveillance and vaccine allocation
• Laser grain by grain analysis links Stonehenge's altar stone to a distant Orcadian source, suggesting complex Neolithic connectivity
• Mars Insight seismology implies a subsurface liquid water reservoir at depth with potential habitability considerations
• Horses demonstrate model-based learning by adapting to task rules under penalty conditions
• Wildfires may dramatically amplify global carbon emissions, though vegetation regrowth provides a partial counterbalance

Mpox emergency and public health response

The podcast begins with a major health update from the World Health Organization. A new mpox clade, designated 1B, appears to spread more efficiently and carries a higher mortality risk than the clade responsible for the 2022 to 2023 global outbreak. The WHO Director of Emerging Diseases discusses how this upsurge in Africa, especially in the Democratic Republic of the Congo, is affecting neighboring countries and the potential for returning travelers to seed cases in other regions. The key policy takeaway is that declaring an international public health emergency mobilizes member states to intensify surveillance, epidemiology work, testing, and risk communication, with vaccines and other medical countermeasures deployed in a targeted way to the most at risk groups. The conversation also notes vaccine supply challenges and the need for equitable allocation across nations, while stressing that mpox spreads mainly through direct contact and sexual networks, not the same wide-scale transmission patterns seen with COVID-19.

Stonehenge altar stone origin revealed by laser fingerprinting

The episode then moves to archaeology, explaining how researchers used a grain-by-grain laser ablation technique to profile the altar stone at Stonehenge. Isotopic composition and chemical fingerprints, treated like a rock DNA sequence, were matched against rocks from across Britain and Ireland. The analysis distinctly points to the Orcadian basin in northeast Scotland as the source, roughly 700 kilometres away, rather than local Salisbury Plain or Welsh stones. The researchers emphasize that the altar stone is a sandstone with a complex age profile, making its provenance harder to pin down than the monolithic sarsens or the blue stones which already have established origins. The broader implication is a revision of Neolithic connectivity and transportation capabilities in Britain, suggesting substantial long-distance exchange and maritime activity in the era. The Nature paper by Anthony Clark and colleagues frames Orkney as a hub of trade and sea routes that could have linked disparate parts of the stone circle complex.

Mars water reservoir and its implications for habitability

In the planetary science segment, a discussion with a Mars researcher focuses on Insight's seismometer data and how it supports a model of a crust punctuated by cracks filled with liquid water. The analysis suggests a subsurface liquid water layer with temperatures around 100 to 200 degrees Celsius, existing at depths of about 10 to 20 kilometres under high pressure. While some water has been lost to space, isotopic measurements in rocks and the atmosphere indicate that Mars likely retains a substantial reservoir relative to its size. The presence of subsurface water opens possibilities for chemotrophic life powered by geochemical energy sources such as methane or hydrogen in the rock fractures, given the absence of light. The discussion clarifies that there is no direct evidence of life yet, but the subsurface environment could host microbial communities if energy sources exist and if there is some geochemical disequilibrium to sustain them. The next steps involve deeper seismic analysis and connections to surface environments to trace water movement and history on the planet.

Horses reveal model-based learning abilities

The episode then reports on a Nottingham Trent University study showing that horses can engage in forward planning of actions, a cognitive skill previously thought to be primarily human or more typical of mammals with higher cognitive demands. In the experiment, 20 horses were trained to touch a card for a food reward. A light cue indicated rule changes, and when horses failed to follow the cue, a 10-second penalty was introduced by removing the target. The horses quickly adapted; their performance improved suddenly when the penalty was applied, suggesting they had formed a mental model of the game. This “model-based learning” is described as an advanced cognitive strategy that allows the animal to anticipate outcomes and adjust behavior accordingly, a finding that challenges assumptions about equine cognition and raises questions about potential wild-life decision-making advantages.

Question of the Week: wildfires and carbon emissions

Finally, the program features a listener question about the carbon footprint of wildfires. The segment cites 2023 Canadian wildfires releasing around 2 billion tonnes of CO2 in a single season and estimates of global wildfire emissions at about 8.6 billion tonnes, near doubling the annual emissions from US sources alone. The experts note that regrowth after fires can recapture some carbon, but overall wildfires represent a substantial and potentially increasing source of greenhouse gases that complicates climate mitigation strategies. The discussion invites listeners to contribute to the Naked Scientists forum with further questions and perspectives.

The episode closes with notes about the program’s origins at Cambridge and its sponsorships, and a reminder of the ongoing exploration of science in everyday life.