Reading Comprehension - Canaries in the Coal Mine

Here is a slightly off-beat topic from Proceedings B (a publication of the Royal Society) I have just discovered this website and at first glance it seems the perfect place to read scientific articles for CAT. 

No. of words:421

Reading time:

Time to beat: 1.35

2.00 minutes – Very Good

2.00-3.30 minutes – Good

3.30-4.30 minutes – Fair

Difficulty Level (5 point scale)

2.5

A dramatic rise in obesity has occurred among humans within the last several decades. Little is known about whether similar increases in obesity have occurred in animals inhabiting human-influenced environments. We examined samples collectively consisting of over 20,000 animals from 24 populations (12 divided separately into males and females) of animals representing eight species living with or around humans in industrialized societies. In all populations, the estimated coefficient for the trend of body weight over time was positive (i.e. increasing). The probability of all trends being in the same direction by chance is 1.2 × 10−7. Surprisingly, we find that over the past several decades, average mid-life body weights have risen among primates and rodents living in research colonies, as well as among feral rodents and domestic dogs and cats. The consistency of these findings among animals living in varying environments, suggests the intriguing possibility that the aetiology of increasing body weight may involve several as-of-yet unidentified and/or poorly understood factors (e.g. viral pathogens, epigenetic factors). This finding may eventually enhance the discovery and fuller elucidation of other factors that have contributed to the recent rise in obesity rates.

Although the increase in obesity rates started over 100 years ago, there has been an acceleration in the last half-century, with reasons incompletely understood. Although there is a focus on a lack of physical activity and a poor diet as the principal contributors to this recent acceleration, there are apparently many causes beyond the conventional wisdom that contribute to body weight increase either by influencing physical activity or dietary intake, or through other means such as influencing nutrient partitioning or energy metabolism.

Model organisms have potential value as ‘canaries in the coalmines’ or ‘sentinels’ informing us about environmental factors potentially impacting humans. In this light, we compiled data to assess time trends in body weight in mammalian species that live with or around humans in industrialized societies. Such observations might help identify environmental influences that might otherwise go undetected.

From 24 distinct populations (12 subdivided into separate male and female populations), representing eight species, over 20,000 animals were studied. Time trends for mean per cent weight change and the odds of obesity were tested for the samples from each population at an age period that corresponded roughly to early-middle adulthood (35 years) in human development because on a per cent basis, in United States adults, 30–39 years is the decade of human life in which obesity has increased at least as much as any age interval during the last several decades.

Tasks:

1. What does this reference to canaries imply? 

2. What is the flow of the article? Is the flow appropriate?