This Week in Evolution · Vincent Racaniello

The mutations of our lives

·1 hr 19 min·5 clips

Host Nels Elde's internet drops as they welcome guest Alex Kagan for a live stream, setting up a candid and unpredictable conversation.

This episode of This Week in Evolution explores how mutations shape human health and evolution, featuring host Vincent Racaniello and guests Nels Elde and Alex Kagan. The conversation centers on the work of geneticist Alex Kagan, who joins from Cambridge, UK. Kagan's research investigates the origins and impacts of genetic mutations across generations. The discussion details Kagan's study analyzing genome sequences from over 300,000 individuals in the UK Biobank. A key finding is that children inherit approximately 70 new mutations from their parents, a number that increases with the father's age. The episode references the work of J.B.S. Haldane, who first proposed the concept of a "genetic load" from harmful mutations. Specific examples include mutations in the BRCA genes linked to breast cancer and variants in the APOE gene associated with Alzheimer's risk. Kagan explains how natural selection works to remove deleterious mutations from the population over time. The hosts examine why harmful mutations persist despite this selective pressure. They also explore the role of random genetic drift in allowing mutations to spread, especially in small populations. A surprising insight is that most new mutations are neutral, having no immediate effect on fitness. Kagan notes that the mutation rate in humans is not constant and can be influenced by environmental factors. The conversation reveals that even beneficial mutations can carry hidden costs or trade-offs. An interesting moment considers whether modern medicine and technology are altering the selective removal of harmful mutations. The hosts ponder if humans are accumulating a larger genetic burden than in past centuries. Kagan describes using large datasets to distinguish between truly harmful mutations and benign genetic variation. The tone is conversational and educational, with hosts and guest engaging in a relaxed, question-and-answer style. The style is explanatory, breaking down complex genetic concepts for a general audience using clear analogies. Listeners interested in personal genomics, human ancestry, and the future of human evolution would find this episode compelling. Those seeking a highly produced narrative or debate on ethical issues might prefer other content.

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