Growing up in the tropics where it was always hot during the day and there were very few buildings that were air-conditioned and ceiling fans were the only cooling devices, we used to perspire a lot. But there was never tall of preemptively hydrating by having a regimen of regular water drinking. We drank when we were thirsty and that was it. So I was somewhat surprised to find people in the US obsessing over drinking water. There was a widespread belief that one should drink at least eight glasses of water a day and that coffee and tea did not count towards that total because they were dehydrating. It turns out that both those things are not true, something that researchers have been saying for some time but the message does not seem to be getting through.
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We are the descendants of fish ancestors. Clearly at some point, a transition to land occurred and thus began the process of learning to walk. The question naturally arises of when and why our ancestors made the leap onto land. It is always a tricky to say how any particular feature that is now present evolved in the deep past and there is usually more than one possible explanation.

This caption to the video below explains a possible reason, that moving to land made it possible to see better and farther.

Some 400 million years ago, humanity’s ancient sea-dwelling ancestors made a giant leap to land, sprouting weight-bearing fins that would eventually carry us out of the water forever. So what precipitated this evolutionarily pivotal change of terrain? According to recent research led by Malcolm MacIver, a computational neuroscientist and engineer at Northwestern University in Illinois, the jump to solid ground might have more to do with vertebrates’ eyes than limbs. Testing their theory that exponentially clearer views of bountiful prey above water led our ancestors to select for eyes atop the head, with primitive limbs coming long after, MacIver and colleagues ran extensive fossil-data simulations. They concluded that above-water sight did indeed provide an ‘informational zip line’ out of the water – what they call the buena vista (or ‘good view’) hypothesis. Moreover, they believe that those above-water views would eventually lead our land-dwelling ancestors to select for prospective cognition – the ability to mentally place oneself in the future – while fish were left in the muck of the moment.

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The planets in the solar system rotate at different rates and have different degrees of tilt. Via David Pescovitz, I came across this nice short animation that compares all of them at once.

An interesting short video.