Tag Archives: biology

When did human beings start wearing clothes?

Interesting discussion on Reddit. Two answers:

Bone needles and scraped skins found in archeological digs suggest we started wearing clothes 100,000 to 500,000 years ago.

Body lice suggest a date of 100,000 years ago. Unlike other primates, human beings have different, but related, kinds of lice: One for the head, and one for the body. Head lice live in hair, and body lice live in clothes. The lice diverged about 100,000 years ago.

What do we know about when humans started wearing clothes? When? Where first?

A hundred thousand years of evolution — and now people can’t wait to get home from work so they can take off their pants.

Carl Sagan was wrong: Why astronomers and journalists should pay attention to biologists about ET

The reason we haven’t been contacted by other intelligent life forms is they aren’t out there, according to Praxtime.

  1. Time for intelligent life to fill a galaxy: super short 20 million years
  2. Time for intelligent life to evolve in a galaxy: moderate 20 billion years
  3. Time of universe to keep having stars: super long 20 trillion years

The first perspective shift is to step back in time, and realize the universe is very young. With 20 trillion years of star generation ahead, the universe has only covered 13.7 billion years or roughly .07% of its life span. Compare this to a person who expects to live 70 years, and you’d get .07% * 70 years = roughly 18 days. So in human terms the universe is a three week old baby. No wonder there’s not too much life out there yet.

The Fermi Paradox states that the Earth is a commonplace planet circling a commonplace star. There’s nothing special about us. Therefore intelligent life should be common in the universe. And here’s the paradox: They should be here already. So where are they?

That’s how astronomers think. But biologists know better. Of the 2 million species on Earth, only one has evolved humanlike intelligence: Us. There’s no reason to assume that it’s happened again elsewhere. And if it had, it would fill the galaxy relatively quickly, and would have left no room for us.

They’re not here because we’re the first.

Avoiding “Sagan Syndrome.” Why Astronomers and Journalists should pay heed to Biologists about ET.