Dr. Oded Rechavi — Professor of Neurobiology at Tel Aviv University whose lab studies genetic inheritance, transgenerational epigenetics, and small-RNA-based heritable memory in C. elegans. Known on social media for science-themed humor.
The gist
Rechavi gives an accessible primer on DNA, RNA, and proteins (using an IKEA-catalog analogy) before tackling the controversial history of Lamarckian inheritance of acquired traits. He walks through fraud-tainted episodes (Kammerer's inked toads, Lysenko, McConnell's planaria) and the two big theoretical barriers to inheriting experience: the soma-germline (Weismann) barrier and epigenetic reprogramming. He then presents clear evidence from C. elegans that small RNAs let worms pass virus resistance, starvation responses, and even brain-derived behavioral changes across multiple generations. The conversation explores whether specific memories could ever transmit, why the brain's synaptic 'language' resists translation into heritable molecules, and ends with unpublished work on cold exposure and lithium extending memory within a single worm's lifetime.
Big reveals
- In the Soviet Union under Stalin, Lysenko's belief that normal Mendelian genetics was 'bourgeois science' got geneticists killed or sent to Siberia and caused massive starvation.
- Paul Kammerer faked inheritance results by injecting ink into toads to mimic nuptial pads, then killed himself after the fraud was exposed.
- McConnell claimed flatworm memories could be transferred by chopping up trained worms and feeding them to others, and that the RNA fraction carried the memory.
- McConnell's research line ended after he was targeted by the Unabomber; his assistant was injured by a mail bomb.
- Rechavi's lab proved worms inherit virus resistance: progeny lacking the gene to make small RNAs still silenced the virus purely from inherited RNAs.
- A 2019 Cell paper showed manipulating small-RNA production in a worm's brain changes feeding behavior in offspring three generations down, with no tampering of their brains.
- Unpublished finding: teaching worms an association then placing them on ice makes them remember 10x longer instead of forgetting after two hours.
- The single neuron pair governing this memory effect is the only C. elegans neuron sensitive to lithium, the bipolar-disorder drug, which switches forgetting on and off.
Things worth remembering
- Four out of five animals on the planet, counted by individuals, are worms.
- Less than 2% of the genome encodes messenger RNA that makes proteins; much of the rest is transcribed into other RNAs.
- About 90% of epigenetic modifications are erased between generations in mammals, but roughly 10% can survive.
- An adult C. elegans always has exactly 959 cells, 302 of which are neurons.
- C. elegans has a three-day generation time, so a single PhD can span hundreds of worm generations.
- These worms have no T or B cells; they defend against viruses using small RNA molecules that destroy the virus.
- Worm inheritance avoids dilution because an RNA-dependent RNA polymerase re-amplifies the small RNAs every generation.
- The lab named heritability-timing genes 'MoTeC' (Modified Transgenerational Epigenetic kinetics), which also means 'sweetheart' in Hebrew.
- Heat-stressed worm hermaphrodites secrete a pheromone that attracts males for three generations because their own sperm production is compromised.
- In medieval times children were thrown into cold water after lessons to lock in memory via adrenaline release.