The first series of India Rakusen’s BBC Sounds podcast, Child, followed the growth of humans from fertilisation to first birthday. Now Rakusen picks up where she left off for series two, which homes in on the developing toddler brain to explore the subject of emotions. Each episode of the eight-part series picks a particular feeling to focus on, starting with happiness. Rakusen explains that this ostensibly sunny and carefree sensation is a lot more complex than it first appears. For starters, there’s the slippery process of defining happiness (which has changed in the two-and-a-half centuries since it was enshrined as a human right in the USA’s Declaration Of Independence). Then there’s its darker side, which comes in the suffocating pressure on parents to ensure their children feel happy at all times.

The episode is a whistle-stop tour, fitting almost half a dozen micro interviews into its 27 minutes. Rakusen visits a neuroscience unit, chats to child psychologist Tovah Klein and hears from human rights lawyer Patience Akumu, who moved her young family from Uganda to Switzerland in search of a happier life, only to discover the dearth of community and extended family support left her exhausted and overstretched.

If you’re an avid consumer of popular psychology, you might find some of the content feels recycled (the neuroscience finds on the toddler brain, for example, have been presented in other documentaries, and Akumu wrote about her Switzerland experiences earlier this year in The Guardian). But Rakusen’s humane and personal engagement with the subject make this a sparky and compelling listen.

Episodes of Child are available on BBC Sounds every Wednesday.