[Sabertooth]

Furthermore, I would expect rude stone hammers to be employed early on in the toolmaking tradition. It's not out of the question that sophisticated organic-material toolmaking existed long before it occurred to anyone to pick up a rock to crack a nut, but it seems unlikely, in my opinion. It's somewhat surprising to me that chimps don't do this even now, and it's certainly surprising that early hominids didn't do it, but they just didn't.

A meandering reply...

How rude can the hammer be?

(I'm trying to remember the anthropological name for clearly artificially fashioned stone tools... something-liths.)

I might be recalling incorrectly, but when Jane Goodall observed the Chimp Wars in N'Goro N'Goro in the 70s, weren't rocks (and branches) used?

I think I've seen reports of chimps using rocks, but if you happened across one, you wouldn't know it was a "tool" of any kind. Seems to me the artificial fashioning of sticks would certainly predate the artificial fashioning of rocks.

I wonder... have any experiments ever been attempted at teaching chimps to make spears and stone tools? Could this learned info be passed on to other chimps?

I've read of a breakthrough among the Japanese snow monkeys which live on the coast. Within the last several decades, one female was observed tossing sandy seeds into shallow pools of water. The sand sank, the seeds floated, and she had a clean meal. Other monkeys learned the technique, and now the whole clan apes the practice (couldn't resist).

I'm guessing that some of the development of toolmaking is going to be cultural like this, awaiting that "eureka" moment when some ape figrued out how to make a rock or stick a little sharper, and the others learned by example.

Part of the problem with labor intensive tools would be having a practical place to keep them... either in a relatively permanent residence (which I don't think chimps generally have), or in some sort of bag, which would likely have come later.

[Physicist]

How rude can the hammer be?

An unfashioned rock off the ground. When someone picks up a rock in his hand and strikes it repeatedly against an anvil of some kind (another rock, typically), it acquires an identifiable pattern of pits and scratches that remain indefinitely. At some point in the fossil record, you start finding rocks that exhibit this wear pattern, but before that, nothing. Apparently these things are common; after all, the "fossilization" rate is near 100%.