Mind & Matter
Whether food, drugs or ideas, what you consume influences who you become. Learn directly from the best scientists & thinkers alive today about how your mind-body reacts to what you feed it.
The weekly M&M podcast features conversations with the most interesting scientists, thinkers, and technology entrepreneurs alive today.
Not medical advice.
At M&M, we are interested in trying to figure out how things work, not affirming our existing beliefs. We prefer consulting primary rather than secondary sources and independent rather than institutional voices. If we encounter uncomfortable truths or the evidence suggests unfashionable ideas may be valid, so be it.
As the host, my aim is to help you better understand how the body & mind work by curating & synthesizing information in a way that yields science-based insights that you can choose to use or disregard in your own life. Taking ownership of your health starts with taking ownership of your information diet.
I am motivated to connect the dots and distill general principles from what I learn, preferring to ask questions and play devil’s advocate to debating or incessantly pushing my own viewpoint.
My beliefs:
- Taking ownership of your health starts with taking ownership of your information diet.
- All knowledge is provisional and we must work hard to prevent ourselves from becoming attached to our favorite ideas & preferred conclusions.
- Wisdom comes from an iterative, trial-and-error process of learning and unlearning. Letting go of pre-conceived notions can be painful, but pain is information.
Sometimes modern discoveries teach us we must unlearn received wisdom. Other times, modern information overload & historical chauvinism cause us to forget ancient wisdom which stills applies. The framework for learning that I embody is inspired by three Ancient Greek maxims inscribed in the Temple of Apollo at Delphi:
- “Γνῶθι σεαυτόν” (Know thyself)
- “Μηδὲν ἄγαν” (Nothing in excess)
- “Ἐγγύα πάρα δ Ἄτα” (Certainty brings insanity)
Mind & Matter
Human Brain Evolution & Development | Christopher Walsh | Episode 306
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How genomics is used to study what makes a human brain, and how genetically damaged neurons get removed.
TOPICS DISCUSSED:
- Scale & Size: A human brain is about three times a chimpanzee brain by mass, but the larger change is extra association cortex and extra upper-layer circuits that talk mostly to other cortex.
- When Development Ends: Most cortical neurons are born before birth. Myelin and other glia keep forming into the twenties. Synapses keep changing after that.
- Broken Genomes Get Edited: Walsh describes forthcoming work in which ~25–30% of late-fetal cortical neurons carry genetic defects, falling to ~5% by birth, with smaller defects still being removed through adult life.
- Regulation vs. New Genes: Humans and mice both have ~20,000 genes. Most human-specific change is in when and where those genes turn on, not in inventing new proteins.
- Human Accelerated Regions: About half of HARs involve the brain. Rare mutations in them show up more often in kids with intellectual disability and autism.
- ASPM & Microcephaly: Loss of one conserved cell-division gene can shrink a human brain toward chimpanzee volume and shape. The same knockout barely shrinks a mouse.
- Heritability of Genetic Disorders: Autism is highly heritable in twin studies. A whole-genome test today still finds a specific cause in only about a quarter to a third of kids.
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