Science in Action – Episode Summary

Episode: Autism and the epigenetics of early brain development
Date: September 25, 2025
Host: Roland Pease (BBC World Service)

Overview

This episode of Science in Action explores the latest scientific developments and research across multiple disciplines. The main theme delves into the relationship between autism, genetics, and epigenetics during early brain development, featuring insights from Dr. Jonathan Mill of Exeter University. Other topics covered include bacterial evolution and antibiotic resistance, the recent seismic activity near Santorini linked to volcanic processes, and global efforts to preserve insect populations vital to pollination.

Key Discussion Points & Insights

1. Autism and Epigenetics in Early Brain Development

(Main Segment: 03:13 – 13:55)

• Current News Context: The episode addresses unfounded claims made in the news (notably by President Trump) regarding the causes of autism, reassuring listeners that the extensive research base points towards genetics and epigenetic regulation rather than vaccines or painkillers (03:13).

  “Get your advice from health professionals if you're concerned. But his remarks ignore the extensive research into the complexities of the condition, which highlight the important role of genetics and inheritance.” – Roland Pease (03:13)

• Genetics vs. Epigenetics: Jonathan Mill explains how every cell contains the same DNA, but epigenetic mechanisms switch genes on or off, guiding cell differentiation and tissue function (04:14).

  “A different set of genes needs to be switched on or off in each of those cell types. And the processes that kind of mediate that switching on and off of genes are these epigenetic mechanisms.” – Jonathan Mill (04:14)

• Study Design: Mill’s team worked with a unique collection of human brain samples, from as early as six weeks post-conception to 100 years old, identifying changes in gene expression through chemical modifications on DNA (05:21).

  “Our earliest sample was from 6 weeks post conception, and we have samples that go up to around about 100 years of age.” – Jonathan Mill (05:21)

• Key Findings:

  • There is extensive epigenetic reprogramming, especially in the prenatal period, which is critical for the development of the brain’s cortex—associated with cognition and executive function (06:52).
  • Genes linked to neurodevelopmental disorders like autism and schizophrenia exhibit highly dynamic changes during early development (08:47).
  • Postnatal epigenetic changes are less pronounced and relate more to aging than to developmental processes (09:44).

• Implications for Autism Research:

  • The data strongly support the role of genetic and early developmental factors in autism and schizophrenia, rather than environmental exposures post-birth (10:56).

    “The evidence is irrefutable that genetic variation plays a really significant role in autism and schizophrenia and other disorders of the central nervous system.” – Jonathan Mill (10:56)

  • The work provides a better understanding of underlying mechanisms, although direct clinical applications or treatments remain a long-term challenge (11:53).
  • Mill emphasizes that treatment for autism is not a straightforward goal, noting the spectrum of traits and the complexity of targeting neurodevelopmental pathways (13:11).

    “I would refute the claim that we really wanted treatment for something like autism. I mean, autism is a, at the end of a spectrum of a personality trait, whereas something like schizophrenia, where there really are kind of severe consequences…” – Jonathan Mill (13:11)

2. Bacterial Evolution and Antibiotic Resistance

(Segment: 13:55 – 22:12)

• Plasmids as Genetic Toolkits:

  • Bath University’s Zamir Iqbal discusses historic bacterial samples to understand how plasmids (mobile genetic elements) have evolved, especially before and after antibiotics became widespread (14:57, 15:54).

    “Plasmids can do different things... They can either be very passive and they provide useful tools, or they can be sort of controllers of the gene expression of the chromosome.” – Zamir Iqbal (15:54)

• Adaptation Mechanisms:

  • Plasmids employ dramatic genome restructuring—fusing, recombining, or ejecting gene sections—to rapidly adapt to antibiotic pressures (18:11, 19:53).

    “It's a bit like lions and eagles mating to form a griffin. The griffin is fertile… So because plasmids can shuffle their DNA in such dramatic ways, it means they just test out all kinds of different options.” – Zamir Iqbal (18:11)

• Historical and Modern Context:

  • Even before the antibiotic era, some resistance genes existed, as antibiotics are natural microbial products (19:53).
  • Modern plasmids often contain a concentration of antibiotic resistance genes, assembled as a result of selective pressures from human antibiotic use.

    “Now, if we look at what's happening today, 50% of the drug resistance genes that we find in our modern data are lying inside plasmids, which have been obviously fitted together...” – Zamir Iqbal (18:11)

• Implications:

  • Plasmids accelerate bacterial adaptability, highlighting an ongoing challenge for medical science and infection control (21:38).

3. The Santorini Seismic Swarm and Volcanic Threats

(Segment: 24:17 – 30:54)

• Recent Seismic Swarm:

  • A series of earthquakes in early 2025 alarmed residents and scientists on the Greek island of Santorini (25:07).

    “In January, there was an intense earthquake sequence starting in Santorini... this very intense shaking was really concerning for the people because we didn't know what was going on at the time.” – Maris Iskun (25:07)

• Scientific Response:

  • Rapid deployment of instruments and AI-driven algorithms mapped seismicity, revealing that the quake swarm was due to magma movement at depths of 18 km, which rose to around 4–5 km (27:25).

    “The activity really started at 18 kilometer depth. So this is really, really deep.” – Maris Iskun (27:25)

• Volcanic Processes and Hazard Assessment:

  • Magmatic "dikes" crack the surrounding rocks, causing waves of earthquakes as pressure builds and magma ascends (27:32).

    “When magma is injected into the rigid rock, it's cracking open new pathways... This is what you feel as earthquakes.” – Maris Iskun (27:32)

  • While the magma is not currently an immediate threat, staying vigilant with scientific monitoring helps ensure community safety (30:01).

4. Declining Insect Populations and Agricultural Sustainability

(Segment: 30:54 – 39:45)

• Pollinator Crisis:

  • Insect populations, especially pollinators like hoverflies and bees, are falling steeply, with up to a 70% decline reported since the late 20th century (31:56).

• Balancing Agriculture and Conservation:

  • Gabriela Bishop from Wageningen University discusses research on how natural habitat restoration within agricultural landscapes can support pollinator populations (31:56).

    “Agriculture needs pollinators, but agriculture, at least the way we do it now, also harms pollinators.” – Gabriela Bishop (31:56)

• Recommendations:

  • Aim for threshold percentages of non-cultivated land (e.g., 6% for hoverflies, 15% for bees) within farms to maintain pollinator populations (34:04).
  • Quality matters as much as quantity—enhancing plant diversity improves habitat suitability (36:04).
  • The approach must be tailored to local conditions and balance multiple land-use needs (33:12, 36:04).
  • Financial incentives for farmers (e.g., EU’s Common Agricultural Policy) are vital for adoption (37:54).

    “Farmers are not only farming food, they're also stewards of the land themselves, they are the land managers.” – Gabriela Bishop (37:54)

  • Private gardens and small green spaces in urban and rural areas also play an essential role in supporting insect biodiversity (39:17).

Notable Quotes & Memorable Moments

• On Autism and Genetics:

  “The evidence is irrefutable that genetic variation plays a really significant role in autism and schizophrenia and other disorders of the central nervous system.”
  – Jonathan Mill (10:56)

• On Plasmid Evolution:

  “It's a bit like lions and eagles mating to form a griffin. The griffin is fertile... because plasmids can shuffle their DNA in such dramatic ways, it means they just test out all kinds of different options.”
  – Zamir Iqbal (18:11)

• On the Human Cost of Science:

  “They were terrified and slept in the car for, for many nights.”
  – Maris Iskun, on researchers enduring the Santorini swarm (02:40, 26:02)

• On Individual Contribution to Biodiversity:

  “People's gardens actually play a really big role in supporting pollinators, not only in urban areas but also in suburban areas.”
  – Gabriela Bishop (39:17)

Important Timestamps

• 03:13–13:55: Epigenetics, autism, and early brain development with Jonathan Mill
• 13:55–22:12: Bacterial evolution, plasmids, and antibiotic resistance with Zamir Iqbal
• 24:17–30:54: Santorini seismic swarm and volcanic threat with Maris Iskun
• 30:54–39:45: Declining insect populations and sustainable agriculture with Gabriela Bishop

This summary captures the core themes and scientific insight of the episode, providing accessible entry points for listeners new to the subjects discussed.