Prehistory, continued

I guess I always thought of technology as strictly cumulative, but reading a little about the Stone Age dispelled that notion. Archaeologists have had to reverse-engineer, from the artifacts they left behind, the toolmaking skills and technology of extinct cultures. How did Cro-Magnon mammoth hunters store meat? Wouldn't it spoil? Well, we really don't know that sort of thing anymore, but there's a way to find out:

…[U. Michigan researcher Dan] Fisher butchered a draft horse using stone tools he'd knapped himself, then cached the meat in a stock pond. Naturally preserved by microbes called lactobacilli in the water, the flesh emitted a faintly sour, pickled odor that put off scavengers even when it floated to the surface. To test its palatability, Fisher cut and ate steaks from the meat every two weeks from February until high summer, demonstrating that mammoth hunters might have stored their kills in the same way.

–Tom Mueller, “Ice Baby”. National Geographic, May 2009.

People showed up on Australia forty thousand years ago. Even though the sea level was lower then, they would have had to cross a channel 55 miles wide to get there. It's a little mysterious to me, as the oldest boats ever excavated anywhere are dugout canoes at most nine thousand years old.

So the first real agriculture (planted fields) happened about ten thousand years ago, dogs were domesticated about fourteen thousand years ago, but apparently people were exploring the South Pacific in logboats, miles from shore, forty thousand years ago. (The oldest stone tools predate H. sapiens and appeared 2.5 million years ago.)

This week I learned...

It's prehistory week at the jorendorff household. This week I learned:

• The fossilized skeletons of a 14-foot Xiphactinus (a mean-looking Late Cretaceous fish) and its last meal, a merely 6-foot bony fish which it swallowed whole, are on display at the Sternberg Museum of Natural History in Hays, Kansas.

• Woolly mammoths had a three-inch-thick layer of fat underneath thick skin, fur, and long shaggy hair. (Yet their environment was such that occasionally one would be flash-frozen, without spoiling the meat, to be eaten by modern dogs ten thousand years later.)

Last week:

• The original Nintendo GameBoy had an 8-bit processor with a HALT instruction which games were supposed to use to wait for interrupts. At least one game would sometimes busy-wait instead (yuck!).

• There's a tool, dwarfdump, that dumps DWARF debug info from an executable or object file.

• On Mac there's a lazy debug-info-linking scheme that causes dwarfdump not to see any DWARF in compiled executables. The Mac tools that come with Xcode are aware of this magic, but dwarfdump isn't.

Earlier still:

• The Spiral of Theodorus shows that the square roots of integers can be constructed with straight edge and compass.

• According to Tim Sweeney, quoted in this DDJ article:

  Any loop written in a traditional programming language can be vectorized, to execute 16 iterations of the loop in parallel on Larrabee vector units, provided the loop body meets the following criteria:

  • Its call graph is statically known.
  • There are no data dependencies between iterations.

  So compilers will be able to do a lot more vectorization.