Hummingbirds may struggle to go any further uphill

Any animal ascending a mountain experiences a double whammy of impediments: The air gets thinner as it also becomes colder, which is particularly problematic for creatures struggling to keep warm when less oxygen is available. ...

Was life on the early Earth purple?

Early life forms on Earth may have been able to generate metabolic energy from sunlight using a purple-pigmented molecule called retinal that possibly predates the evolution of chlorophyll and photosynthesis. If retinal has ...

How nutrients are removed in oxygen-depleted regions of the ocean

In the course of global climate change, scientists are observing the increase of low-oxygen areas in the ocean, also termed oxygen minimum zones (OMZs). Large-scale OMZs exist, for example, in the Pacific off the coast of ...

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