Do house plants clean your air?

Verdict: yes, though you'd need a lot (but an achievable amount) of plants.

I saw this hopeful video on 9gag, of researchers studying how well house plants filter out petrol vapour.

Interestingly, most the cleaning is done around the roots of the plants – not the leaves!

I wanted to learn more, and found this Guardian article, which (I think) interviews the same researchers, and the actual research paper.

The researchers "tested commercial green walls measuring 725 by 725 mm, each holding four plants, in sealed 216-liter chambers" and found the "planted walls reduced total VOCs by 42.47% over eight hours" (credo tldr).

Pretty impressive! A caveat of course is the researchers used a lot of plant (~72cm^2 square) for the given volume (~60cm^3 cube). So to have the same effect in a room, you'd need a lot of house plants!

In the Guardian article, researchers recommend using wall mounted plants, to help squish more plants in. Intuitively (looking at the math above), if you cover your whole wall with plants, you'd probably get a noticeable (maybe not ~40%) filtering effect!

If you live alone, getting a pet can slow cognitive decline

Interesting UK cohort study: Pet Ownership, Living Alone, and Cognitive Decline Among Adults 50 Years and Older.

It found that pet ownership is linked to slower decline in "composite verbal cognition (a combined score for memory and word production), memory, and word fluency" (credo summary).

There was only a difference for people who lived alone. I.e. if you live with other humans, having a pet wasn't associated with better outcomes. But among those living alone, those with pets were better off.

Another reason to get a pet!

180,000 giant tortoises on Seychelles island!

Saw this very cool Guardian article on Facebook, and had to dig in!

It's based on this University of Exeter research paper: Inferring the Abundance of an Island Megaherbivore From Semi-Structured Distance Sampling

(Got to love that title!)

The research design (summarised in Credo tldr) sounds really interesting. Would be cool to see some kind of video documentary of how the researchers went about it.

The Guardian article says at one point, there were only ~1,000 giant tortoises on the island (due to poaching etc.). So getting to 180,000 sounds fantastic. The research paper does say prior counting methods are probably underestimates, but nonetheless the difference must be huge.

Overall a very uplifting (and true!) story to read on social media.

We should probably parboil rice, to remove harmful heavy metals

Building on a prior post that highlights harmful arsenic levels in rice.

Found this paper that says parboiling rice: "removed 77.9% of toxic metals and 68.4% of essential metals."

The cons are "essential metals" are removed as well, but on balance it's probably safer.

I'm not sure the exact method the paper used to parboil, but here's a recipe!How to parboil rice

"Sugar high" is a myth?

I remember reading that "sugar high" isn't actually real! In other words, children don't actually get overexcited after eating a bunch of sugar.

I find this hard to believe!

But, here's a (pretty old - 1995) meta-analysis which is pretty clear: sugar high is probably a myth.

The meta-analysis covered 23 other studies, and none of them found a significant effect (of sugar intake and child behaviour).

I'm still somewhat skeptical though 😆. Would be interested to delve into more recent analysis and debate.

Do phone bans in schools work?

Most parents have some concerns about phone use. This is an interesting study from the UK, that investigated phone bans in schools.

The study covered 30 schools (20 had phone bans, 10 didn't), with the students aged 12-15.

Their main finding: phone bans don't meaningfully affect/improve mental wellbeing.

Basically the phone bans only reduced phone and social media use slightly, and kids still used their phones at home.

Important point: the phone bans weren't uniform or super strict in all cases -- e.g. some schools just told students keep their phones in their bags.

So we can't say that "phone bans will NEVER work". They just didn't have a huge impact, on average, in the way they were implememted in those 20 schools.

Social media and loneliness

It sounds like the (negative) impacts of social media include loneliness. This think tank report reviews the evidence for Malaysia.

From the executive summary:

For adolescents today, finding acceptance and belonging has become more fraught due to social media, which exponentially raises the stakes of social missteps. Social media’s shift away from encouraging interactions among friends towards feeding users with content from strangers further exacerbates social disconnection. This content-first approach, coupled with addictive design choices, promotes compulsive and passive consumption – precisely the kind of social media use that contributes to loneliness. However, even active use is increasingly linked to loneliness.

The report also looks at ai companions and loneliness. Have a read!

Butterfly effect

Learnt the origin on the term "butterfly effect" – on this Stuff You Should Know rerun, about Chaos Theory.

If I understand it, the term captures how unpredictable (and chaotic) certain systems (like the weather) are.

The term "butterfly effect" made it's first appearance in a 1972 speech by Edward Lorenz titled "Predictability: Does the Flap of a Butterfly's Wings in Brazil Set Off a Tornado in Texas?".

But Lorenz had developed the concept earlier, in a 1963 paper.

The "Marshmellow" test

I remember reading somewhere about the "marshmellow test" – the finding that: if a child could wait longer for a marshmellow (or other snack they liked), the child would be more likely to do well later in life.

Found the original 1990 experiment!

Interestingly, this 2018 study replicated the 1990 experiment.

It basically found the link (between waiting for the marshmellow and later outcomes) to be smaller than the 1990 original – especially after controlling for other factors (like family background, early cognitive ability, etc).

What does this mean?

It doesn't "debunk" the marshmellow test entirely, it just says that other factors matter more.

It seems to me the "marshmellow test" is still an interesting "proxy" test for later outcomes – but unsurprisingly, the full picture matters more.

Plant-based diet - is it fine?

I'm an occasional vegetarian - for health, and environmental and ethical reasons. I think most would already agree that one can have a complete diet, without meat. Nonetheles, I found this paper useful.

It's a narrative review of evidence. A few helpful takeaways (gleaned from the Credo summary):

• A plant-based diet has health benefits, and is better environmentally.

• A plant-based diet can be complete, but there are some potential drawbacks. E.g. it's harder for the body to absorb certain nutrients from plant sources.

• And so, if you're a vegetarian or vegan, you do have to put in some thought, to ensure your diet is complete. (Though the same could be said of any diet!)