How Intrasexual Competition Suppresses Female Fertility with Dr Dani Sulikowski | Quillette Cetera Ep. 54

Behavioural scientist Dr Dani Sulikowski unpacks the evolutionary logic behind women advising other women not to reproduce.

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In this episode of the Quillette Podcast, host Zoe Booth speaks with Dr Dani Sulikowski, an evolutionary behavioural scientist and senior lecturer at Charles Sturt University.

They discuss the sociocultural and evolutionary forces driving the collapse in fertility across Western societies. Dr Sulikowski examines how intrasexual competition among women, declining testosterone in men, and shifting norms around gender and motherhood may be suppressing reproduction—often unconsciously.

The conversation also explores contentious topics such as surrogacy, abortion, and assisted dying, viewed through the lens of long-term civilisational sustainability.

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Transcript

Zoe Booth: I’ve been very interested in this topic of fertility decline. It was something I was never that interested in until I turned, I don’t know, 28, 29, and started thinking about having kids myself, and now I’m obsessed with the topic. Australia has a declining fertility rate like most OECD nations. You have some really fascinating theories on why that’s the case. Could you tell our audience a little bit about your theory?

Dani Sulikowski: Okay, so we can start small and then continue to add layers and get more big-picture and more complex. But the very basics of human behaviour—or indeed any animal behaviour—is this idea of competitive reproduction.

The currency of evolution is reproductive success. If you have more offspring in the next generation, your genes become overrepresented in that generation. If that continues, generation after generation, then your lineages effectively dominate and come to be what’s there. Therefore, whatever behaviours and any other traits those genes cause due to behaving well—that becomes how the population behaves. Right? Basic principles of selection.

What that means is that all individuals are under selection pressure to win that competitive race. That means not just maximising your own reproductive success, but actually minimising the reproductive success of rivals around you. That’s what we call intrasexual competition.