SciBites: Week of March 17th

SciBites: Week of March 17th

Additional extinctions slowed marine recovery after Permian mass extinction

Eighty-one percent of marine species were lost during the late Permian mass extinction, and recovery took longer than for any other extinction event. Previous studies have suggested that additional smaller extinction events following the mass extinction may have delayed the recovery of marine species. To investigate further, William Foster and his colleagues examined marine invertebrate fossils in the Werfen Formation in the Dolomites, Italy, and found that extinction rates of these marine invertebrates peaked twice during the early Triassic, providing evidence of additional extinction events after the Permian mass extinction. Moreover, these elevated extinction rates were associated with changes in the ratios of different carbon isotopes in the fossils, possibly indicating increased stress in the environment that could have affected species’ ability to survive and diversify.

Climate conditions may have influenced human nose shape and size

A recent PLOS Genetics study found that the size and shape of the nose in different human populations is not simply the result of chance, but evolved, at least in part, in response to local climate conditions. The researchers examined the noses of people with West African, South Asian, East Asian, or Northern European ancestry and found that wider nostrils are correlated with ancestors who evolved in warmer temperatures and with greater humidity, suggesting that climate was one factor driving nasal evolution. The nose has had a complex evolutionary history, however, and researchers suspect that additional factors, such as cultural preferences when picking a mate, have also played a role in shaping it. The study of nasal evolution and adaptation to climate may have health implications for humans. For example, it could help determine the likelihood of contracting a respiratory disease when living a different climate from one’s ancestors.

Encouragement to consult GPs did not lead to earlier dementia diagnosis

Encouraging thousands of U.K. patients with potential memory deficits to seek early advice from a general practitioner (GP) empowered more of them to consult their GPs; however, this did not result in earlier diagnosis of dementia, and overall diagnosis rates were unchanged, according to a recently published study in PLOS Medicine. While it is unclear why additional patients visiting GPs did not lead to earlier diagnosis of dementia, the authors speculate that early memory problems were not recognized by the GPs, and suggest that it may be necessary to better inform both doctors and patients about dementia in order to increase early diagnosis.


Image Credit: Richard Twitchett


Tessa is the Journal Media Manager at PLOS. She graduated from the University of California, Berkeley with degrees in Rhetoric and Music. She can be reached by email at and on Twitter at @tessagregs.

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