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Huberman Lab
Dr. Oded Rechavi: Genes & the Inheritance of Memories Across Generations
Feb 27, 2023
02:27:23
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Quick takeaways
- Experiences and environmental factors can modify genes and be passed on to offspring through epigenetics and RNA biology.
- The concept of inheritance of acquired traits has a complex history and has been controversial in the scientific community.
- Epigenetic reprogramming is a crucial process in genetic inheritance, erasing most chemical modifications to ensure a blank slate for the next generation.
- Environmental factors, like starvation and metabolic changes, can influence the traits and health of offspring.
- RNA-based mechanisms play a role in the inheritance of acquired traits, as evidenced by studies on resistance to viruses in worms.
Deep dives
Inheritance of Acquired Traits and Epigenetics
The podcast episode discusses the concept of inheritance of acquired traits and the role of epigenetics in transmitting traits across generations. It explores the idea that experiences and environmental factors can modify genes and be passed on to offspring. The episode highlights examples of studies conducted on starvation, metabolic changes, and stress in various organisms, including humans. It emphasizes the barriers to this type of inheritance, such as the separation of soma from germline and the process of epigenetic reprogramming. The episode also mentions the complex nature of epigenetics and the ongoing research to understand the mechanisms involved.
Lamarckian Evolution and Controversies
The episode delves into the history of Lamarckian evolution and the controversies surrounding the concept of inheritance of acquired traits. It explains the differences between Lamarck's beliefs and Darwin's theory of natural selection, highlighting the negative reputation associated with Lamarck's ideas. The episode also mentions the detrimental impact of Lamarckism on scientific research, such as during the Soviet Union era. Additionally, it discusses fraudulent experiments conducted by Paul Kammerer and McConnell that further tainted the perception of inheritance of acquired traits. It highlights the complexities and misconceptions surrounding this concept, emphasizing the importance of evidence-based research.
Epigenetic Reprogramming and Genetic Inheritance
The episode explores the process of epigenetic reprogramming and its significance in genetic inheritance. It describes how, during the transition between generations, most chemical modifications in the genetic material are erased to ensure a blank slate for the development of the next generation. The episode mentions examples of genomic imprinting, where certain genes are regulated differently based on whether they were inherited from the mother or the father. It also discusses the challenges in understanding the mechanisms of epigenetic inheritance and the ongoing debates in the scientific community. Furthermore, the episode highlights the importance of distinguishing between nature and nurture when studying inherited traits.
Examples of Inherited Traits and Environmental Influences
The episode presents several examples of inherited traits influenced by environmental factors. It mentions studies on starvation during pregnancy and its impact on birth weight, glucose tolerance, and neurological diseases in the next generation. The episode also discusses how metabolic changes and nutritional variations can affect the body weight, glucose tolerance, and reproductive success of offspring. It emphasizes the complexity of distinguishing between genetic and epigenetic mechanisms in these phenomena. Additionally, it highlights the importance of considering direct environmental exposure and the challenges in ascribing these effects solely to epigenetic inheritance.
Transmission of RNA-based resistance to viruses in worms
In a podcast episode, the concept of heritable traits through the transmission of RNA was discussed using the example of resistance to viruses in worms. The experiment involved infecting worms with a fluorescent virus and observing their ability to destroy it. The researchers then neutralized the smaller RNA production machinery in the offspring of these worms to see if the resistance could still be passed on. It was found that the resistance to viruses could indeed be inherited, and this effect lasted for multiple generations. The transfer of smaller RNAs from the parent worms to their offspring played a crucial role in this heritable trait. Additionally, certain genes were identified that regulated the duration of the inheritance. Overall, the study provided evidence for the inheritance of acquired traits through the transmission of RNA-based mechanisms in worms.
Model organisms and their importance in scientific research
The podcast highlighted the significance of model organisms in scientific research. Model organisms are organisms that many researchers study, enabling the accumulation of resources, tools, and knowledge within a scientific community. Examples of model organisms include E. coli bacteria, flies, worms (such as C. elegans), fish, mice, and plants. These organisms have played integral roles in understanding various biological aspects, including human diseases. The transparency and simplicity of C. elegans, for instance, make it an excellent model organism for studying the transmission of RNA, inheritance, and other biological phenomena. Model organisms provide researchers with controlled and manipulable systems to explore complex biological processes.
The challenges of transferring synaptic information to heritable traits
The podcast delved into the challenges of transferring neural or synaptic information to heritable traits. While worms can transmit certain behaviors or sensitivities through the transfer of RNA-based information, the translation of complex synaptic information to heritable molecular forms remains an open question. The brain and the processes involved in memory and neural connections present a different language compared to the language of inheritance. Moreover, the specific wiring and neural circuits of the brain in each generation pose difficulties in translating synaptic information back to the brain in subsequent generations. The intricacies of this translation and the mechanisms involved are areas of ongoing research.
The potential for specific memories to be transferred between generations
The podcast explored the possibility of specific memories being passed down to subsequent generations. While the brain may encode elaborate and specific memories, the challenge lies in translating these memories from synaptic connections to heritable information. The translation of complex synaptic information to the language of inheritance, such as RNA, needs further investigation. However, studies conducted on worms indicate that changes in RNA production within the brain can affect behavior in subsequent generations, even without altering the brain itself. This suggests that some specific memories or behaviors could potentially be transmitted across generations through RNA-based inheritance mechanisms, although further research is needed to understand the exact mechanisms involved.
Impact of Stress on Germ Cells and Body Transformation
Stress can affect not only germ cells but also the somatic cells residing in the same microenvironment, leading to bodily transformations. Experiments with worms have shown that preventing sperm production changes their capacity to smell, indicating an impact on brain function. Castration in dogs has also been found to fundamentally change their behavior and health, which can be reversed by the introduction of small amounts of testosterone. These findings highlight the role of germ cells in influencing the rest of the body and the potential for hormonal interventions to modify the system.
Transmission of Information in Worms and the Role of Mating
Worms, specifically hermaphrodites, have the ability to make both sperm and eggs. They can choose to mate with males or not, with mating being energetically costly and risky. Mating with males dilutes the genome and diversifies the offspring, but it also carries the risk of reduced lifespan due to injury. Stressing hermaphrodites with high temperatures leads to increased secretion of pheromones attracting males. This change in mating behavior is linked to compromised sperm production and the need for external sperm to ensure successful reproduction. These findings shed light on the complex decision-making processes in worms and the factors influencing their mating choices.
In this episode, my guest is Oded Rechavi, Ph.D., professor of neurobiology at Tel Aviv University and expert in how genes are inherited, how experiences shape genes and remarkably, how some memories of experiences can be passed via genes to offspring. We discuss his research challenging long-held tenets of genetic inheritance and the relevance of those findings to understanding key biological and psychological processes including metabolism, stress and trauma. He describes the history of the scientific exploration of the “heritability of acquired traits” and how epigenetics and RNA biology can account for some of the passage of certain experience-based memories. He discusses the importance of model organisms in scientific research and describes his work on how stressors and memories can be passed through small RNA molecules to multiple generations of offspring in ways that meaningfully affect their behavior. Nature vs. nurture is a commonly debated theme; Dr. Rechavi’s work represents a fundamental shift in our understanding of that debate, as well as genetic inheritance, brain function and evolution.
For the full show notes, visit hubermanlab.com.
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Timestamps
(00:00:00) Dr. Oded Rechavi
(00:02:25) Sponsor: LMNT
(00:06:04) DNA, RNA, Protein; Somatic vs. Germ Cells
(00:14:36) Lamarckian Evolution, Inheritance of Acquired Traits
(00:22:54) Paul Kammerer & Toad Morphology
(00:25:16) Sponsor: AG1
(00:30:06) James McConnell & Memory Transfer
(00:37:31) Weismann Barrier; Epigenetics
(00:45:13) Epigenetic Reprogramming; Imprinted Genes
(00:50:43) Nature vs. Nurture; Epigenetics & Offspring
(00:59:06) Generational Epigenetic Inheritance
(01:10:20) Model Organisms, C. elegans
(01:21:50) C. elegans & Inheritance of Acquired Traits, Small RNAs
(01:26:02) RNA Interference, C. elegans & Virus Immunity
(01:34:13) RNA Amplification, Multi-Generational Effects
(01:38:41) Response Duration & Environment
(01:47:50) Generational Memory Transmission, RNA
(01:59:36) Germ Cells & Behavior; Body Cues
(02:04:48) Transmission of Sexual Choice
(02:11:22) Fertility & Human Disease; 3-Parent In Vitro Fertilization (IVF); RNA Testing
(02:17:56) Deliberate Cold Exposure, Learning & Memory
(02:29:26) Zero-Cost Support, Spotify & Apple Reviews, YouTube Feedback, Sponsors, Momentous, Social Media, Neural Network Newsletter
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