*Intro*

You know that thing, where people give their unborn babies some music to listen to, and hoping to, like, make them smarter or something? Well, it turns out birds do a similar thing, but with actual science to back them up. They sing to their babies while they're still inside their eggs - what's known as 'incubation calling'. And there's a lot that we don't know about how these calls work because they seem to do different things for different species, but we are learning.

And a study published this week in science suggests that some incubation calls can even affect how Australian Zebra Finch embryos grow up. Mother birds seem to pass on chemical signals to their developing offspring before laying eggs, but incubation calls could be a way to tweak the babies' development inside the eggs, before they hatch.

Australian Zebra Finches, for example, make a special incubation call when their eggs are just about to hatch, starting about 5 days before, but only when it's 26° Celsius or warmer. These birds nest year round so, the scientists think it's a way for the parents to give their kids a heads up that it's hot outside.

Here's the weird thing though - the parents' incubation calls made the babies develop differently. As an experiment, the researchers artificially incubated a bunch of eggs that they got from nests in the wild, and during that final 5 day window they played some sounds. Some of the eggs listened to incubation calls while others, other a control, just heard normal Mom and Dad conversation chirps. And the embryos who heard the incubation calls grew up to be smaller.

Now, you'd think that smaller birds would have a harder time surviving, but the scientists think it might be an adaptation for warmer weather. Smaller animals have more skin relative to their mass, and so they can lose more body heat than larger animals - that way they stay cooler in hot weather.

Also, growing up really fast in warmer temperatures has been linked to oxidative stress, which is the build up of oxygen free radicals that can cause damage.

So, if the finches stay small, it could save them from biological problems, which would explain why the birds developed this alternative growth plan, and why it can be triggered by an incubation call. But as far as the mechanism itself, like how exactly a song could affect how an embryo develops, that we do not know.

Enough about bird behaviours though, because a new study published in PNAS talks about people behaviours, specifically about the parts of our brain that activate when we help other people, which psychologists call prosocial behaviours.

The researchers had volunteers play a learning game while getting their brains scanned by an fMRI machine. They wanted to study why different people might be better or worse at learning to help others, and how it might be connected to empathy or your ability to understand someone else's feelings.

Their game was based on a psychological concept called reinforcement learning, which is basically when something like a human or a robot looks at a situation and tries to pick the option that gives it the most reward. As you get predictions right or wrong, you learn how to choose the option that leads to the rewards.

in this study the team tested how 31 people learned to get points for themselves, for someone else - who was an actor pretending to be another participant in the study - and for nobody, as a control.

Here's how the game worked - people had to choose between two symbols, both letters from an abstract symbols font. One symbol had a 75% chance of getting points and one had a 25% chance of getting points. The subjects then had to learn which shape was which through trial and error. Over multiple rounds, they gained points and they were told that more points would earn them more money - though they were all paid the same amount in the end.

The researchers used fMRI to record brain activity while the subjects were making their decisions, and used computer models to find patterns across all the experimental trials.

Unsurprisingly, people learned fastest when they were competing for themselves. But they also had participants take an empathy test, and people who were more empathetic tended to learn almost as quickly when they were playing for someone else - the prosocial behaviour.

So, what was going on inside their brains? Well, in all of the learning tests there was activity in the ventral striatum, which is part of the reward pathways in your brain. A connected region, called the subgenual anterior cingulate cortex was specifically activated when people were playing for someone else.

Other studies have linked this region to prosocial and moral behaviours, social emotions and behaviours trust, so this research seems to reinforce some of what scientists do know.

But the researchers want to learn more about how we learn empathy and prosocial behaviours and how the two are connected. That way, we can better understand the brains of people who struggle with these traits and get a deeper grasp on how our brains work in general.

Thank you for watching this episode of SciShow news, brought to you by our President of Space, Morgan and The Big Try Hard. Morgan completed a bicycle trip across the US, raising by for YouTube channels the he loves - thank you Morgan. You can catch up on his journey at TheBigTryHard.com. If you wanna help support this show, you can go to Patreon.com/SciShow, and don't forget to go to Youtube.com/schishow and subscribe.

*Outro*

Michael: While you might hear bird calls at any time of the year, you're more likely to hear birdsong in the Spring. And these songs are louder and more frequent during the wee hours of the morning. Scientists call this...