608. Why Imperfection Is Core to Being Human feat. Laurence D. Hurst

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Dec 22, 2025

Laurence D. Hurst, a Professor of evolutionary genetics at the Milner Centre for Evolution, discusses the fascinating limitations of evolutionary perfection. He reveals why humans are afflicted with genetic disorders and high mutation rates, countering the assumption that evolution leads to optimal adaptations. The conversation dives into how maternal costs and fetal-maternal conflicts impact human health, the role of gene therapy in modern medicine, and the ethical dilemmas surrounding germline editing, emphasizing the importance of embracing our inherent imperfections.

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INSIGHT

Path Dependence Stops Perfect Designs

Evolution often produces near-perfect traits like camouflage but can get stuck on local peaks that prevent reaching true optima.
Laurence D. Hurst explains peak-jumping and the eye example to show why good solutions can block better ones.

INSIGHT

Humans Carry Heavy Genetic Load

Humans carry a high load of deleterious mutations and many rare genetic disorders are present in populations.
Hurst states our high mutation rate means we could be biologically much better than we are.

ANECDOTE

Human Embryo Chromosome Failure Rate

Hurst notes about half of human embryos have wrong chromosome numbers and die very early, higher than in other mammals.
He contrasts humans with cows, pigs, mice and says humans hold an unfortunate record.

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While evolution is often thought to be conducive to perfect adaptation, there are plenty of reasons why we never get there.

Laurence D. Hurst is a professor of evolutionary genetics in the Milner Centre for Evolution at the University of Bath. His book, The Evolution of Imperfection: The Science of Why We Aren’t and Can’t Be Perfect is an expansive look into the imperfections of the human genome and why humans seem to be predisposed to so much bad genetic luck.

Laurence and Greg explore the evolutionary constraints that lead to imperfections, how population size affects mutation rates, the advancements in gene therapy, and why imperfection could be key to a deeper understanding of evolution.

*unSILOed Podcast is produced by University FM.*

Episode Quotes:

Why humans have such bad genetic luck

07:13: We have good reason to think that humans are far from being as fit as they might be. We have a very high mutation rate. We've got one of the highest mutation rates going, for example, and most mutations are deleterious. Most of the time, five to 10% of us will have a rare genetic disorder, for example. And we could be better. We could be a lot, lot, lot better.

Medicine is anti-evolution

47:17: Medicine is anti-evolution. Evolution is why we keep on having these genetic diseases, and medicine goes, well, you might have them, but we are going to stop them having their effects.

Childbirth is more dangerous than the most dangerous job in America

12:13: Childbirth is, for humans, a spectacularly dangerous pursuit. There was a lovely survey done by Forbes Magazine of America's most dangerous jobs, and it turns out nothing comes close to childbirth. Childbirth is an order of magnitude more dangerous than America's most dangerous job.

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Guest Work:

The Evolution of Imperfection: The Science of Why We Aren’t and Can’t Be Perfect

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