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Motu researchers on the implications of domestic food waste, using maths to improve espresso, how co-workers respond to employees taking parental leave, why certain scents are important to preserve, and are pop lyrics more repetitive now?

Motu researchers on the implications of domestic food waste, using maths to improve espresso, how co-workers respond to employees taking parental leave, why certain scents are important to preserve, and are pop lyrics more repetitive now?

This week’s Top 5 comes from Sophie Hale, Dom White, Livvy Mitchell and Ben Davies of economic research institute Motu.

As always, we welcome your additions in the comments below or via email to

And if you're interested in contributing the occasional Top 5 yourself, contact

1. Estimating food waste for individual households, and implications for your wallet, your health and the climate.

Researchers at Penn State used data from the National Household Food Acquisition and Purchase Survey and participants’ physical characteristics to calculate the amount of food they wasted, given the metabolic requirements of a household’s members and the amount of food purchased.

They found the average American household wastes 31.9% of food acquired, and that higher waste was associated with households with higher incomes, healthier diets (more fresh fruit and veg) and those who don’t take a shopping list to the supermarket.

Even the least wasteful household wastes 8.7% of food they acquire. Minimising food waste has important implications for climate change too – the estimated 3.3 gigatons of emissions produced from food waste per year, if considered a country, would rank third after the U.S. and China.

2. Using mathematic modelling to improve espresso.

Experiments and modelling conducted by an international team of researchers suggest that grinding less coffee beans more coarsely could be the key to cheaper, more consistent and equally strong coffee.

The mathematical model of espresso brewing wasn’t straightforward – author Jamie Foster said that it would require “more computing power than Google has to accurately solve the physics and transport equations of brewing on a geometry as intricate as a coffee bed.”

Dropping the mass of dry coffee by five grams per drink could save the US coffee industry $1.1 billion annually, whilst producing beverages that are no less brew-tiful.

3. Is Parental Leave Costly for Firms and Co-workers?

Family leave policies are often evaluated by looking at its impact on mothers, fathers, and their children. But how do firms and coworkers respond to an employee taking parental leave?

This Danish study found that there is no measurable effect on firm output, profitability or survival when a female employee takes parental leave.

While co-workers experience a temporary increase in hours and earnings, there is no significant change in their wellbeing at work. Overall, firms and coworkers face negligible costs when an employee takes parental leave.

4. Why preserving certain scents is important.

Conservation of human culture and history tends to focus on the visual. This article by the BBC explores the importance of smell to our past and what it would mean to try and conserve smells which may go ‘extinct’ in the near future. It argues that smells are one of the most important parts of an experience whether it is the odour of central London or the aroma of an old library.

There are now ways to study smells which include absorbing the scent in a polymer fibre or identifying the compound from a gas sample.

With such techniques there could be ways to preserve and catalogue the scents of the past and present for future generations.

5. Are Pop Lyrics Getting More Repetitive?

This article by The Pudding analyses the upward trend in lyric repetitiveness among pop songs on the Billboard Hot 100 since 1958.

 The author captures lyric repetitiveness by the amount that a text file containing the lyrics can be compressed in file size.

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That is a beautiful picture of food waste however most of the stuff there appears to truly be waste. Mostly fruit skins and the remains of filleted fish. Would that be regarded as food that is wasted?

Regarding the effects of parental leave, does the study imply that those that take parental leave are not very productive workers anyway?


... good point ... if I scoop out tomato seeds to make a concasse , is that waste ? ... if I put fruit or vegetable peelings into the compost , does it still count as waste ... 'cos , next spring that compost will be growing my kale and basil ... is it a waste if I biff out the fishy bits , rather than make a seafood stock with them ?