The smell of cut grass is a distress signal

Love the smell of freshly cut grass? Did you know it’s theorised to be a defence mechanism? Let’s dive into the science!

What is the smell?

When grass is cut, its lipoxygenase enzymes a break down of membranes in the plant’s cells. This ultimately leads to production of Green Leaf Volatiles (GLVs), one of which is cis-3-hexenal, which is what we smell.

What does the distress signal do?

Studies have shown that GLVs attract animals who prey on animals to damage the grass. A 2021 study titled ‘Smell of green leaf volatiles attracts white storks to freshly cut meadows’ by Wikelski M, Quetting M, Cheng Y, Fiedler W, Flack A, Gagliardo A, Salas R, Zannoni N, Williams J. found that White Storks were attracted to fields of freshly mown lawns. This study ensured that smell was the only way the storks found the fields, as they were out of eye sight and auditory distance.

It’s not just grass. In 1990, it was found that corn plant seedlings release a specific odour, terpenoid volatiles, when they’re eaten by catepillars that attract wasps that prey on catepillars. The study, titled ‘Exploitation of Herbivore-Induced Plant Odors by Host-Seeking Parasitic Wasps’ by . C. J. Turlings et al found that the odour only occured when the catepillar saliva mixed with the damaged seedling, simply damaging the seedling itself did not cause this odour to occur.

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`So there you have it!

Why does the sun make me feel happy?

Ever noticed how a sunny day instantly lifts your spirits? Turns out, there's more to that warm, fuzzy feeling than just the beautiful weather. Let's dive into the science behind why the sun makes us feel so happy!

Sunlight helps you create vitamin D

A study by Wacker, M., & Holick, M. F. in 2013 titled “Sunlight and Vitamin D: A global perspective for health” explained that when sunlight hits your skin, your skin absorbs UV B radiation and eventually converts it into vitamin D. Vitamin D plays a crucial role in regulating mood and warding off the blues. Research has shown that low levels of vitamin D are linked to an increased risk of depression and mood disorders.

Sunlight boost serotonin production

Serotonin is the hormone responsible for boosting your mood. In 2002, a study titled “Effect of sunlight and season on serotonin turnover in the brain” was published by
Dr GW Lambert, PhD, C Reid, PhD, DM Kaye, MBBS, GL Jennings, MBBS, MD Esler, MBBS took blood samples from 101 healthy men and measured the serotonin consentration across different seasons and weather conditions. Their study showed that there is a direction relationship between sunlight expose and the production of serotonin - and that the rate of serotonin production in increased brightness.

So, there you have it!

Why don’t we like the sound of our own voice?

Ever listened to a recording of yourself and thought, "Do I really sound like that?" You're not alone! It's a common experience, and there's actually some cool science behind why we feel this way. Let's break it down!

Is it actually different?

No! When you talk, you hear your voice in two ways: through the air and also through vibrations in your skull bones, muscle and tissue (commonly referred to bone-conducted). Békésy did a study in 1949 that confirmed bone-conducted sound was a relevant sound path to how we hear our own voice. But when you listen to a recording, you only hear the air-conducted part, which is different from what you're used to. That mismatch can make your recorded voice sound strange and unfamiliar.

Another study was done in 1995 by G.V and H.Lehnert & F.Giron that found the reflection of your voice from surrounding surfaces also had an impact on our perception of own voice.

Is that why I think my friends always sound the same on recordings? Yes! because you’ve only ever heard their voices through the air and reflected on the surfaces around you.

But why does it make me uncomfortable?

Your voice is part of your identity, right? But when you hear it on a recording, it might not match the mental image you have of yourself. That mismatch can cause some cognitive dissonance, leaving you feeling uneasy. After all, it's like looking in the mirror and seeing someone different staring back at you!