It's a good article, M.Ted, and I for one don't rely on a single criterion as indicating "human"ness. Over the years archaeologists and others have argued over whether skeletal metrics were "the go" and then the debates turned on "tool use", "language" and symbolic representation; the latter is what I was referring to when I put the "50kya" as a current debating issue.

I remember the disregard I received when I argued that the Laetoli footprints (3.8Mya, from memory, and certainly from a separate genus) showed behaviour one could consider "human". There were three sets, with different separations and regarded as a family group. The two "adult" ones were attributed to the male and female parents while the one with a much smaller sized foot was regarded as a "child", and most of its footprints were within those of the "Dad"; the child was deliberately placing its feet into its father's footprints and it was that feature I regarded as indicating a very human behaviour.

And, back to the GPSs; when plotting firelines in a chopper doing aerobatics over the flame front of a wildfire, you can bet I used the best GPS I could lay my hands on and even I, a serious map user, found coping with five or six 1:25K topo maps in the chopper's cabin more than I wanted to cope with while my mate, with one arm shrivelled from a disability, on the other hand coped with even more maps superbly.

Like I said, I have nothing against the technology, but I'm very selective about which bits I rely on.

Cheers, Rowan