Origin Of Bipedalism Closely Tied To Environmental Changes

Space Daily ^ | 05-01-2002 | staff writer at Space Daily

[Physicist]

Does evidence for campfires (as opposed to natural fires) predate tools?

Good question, I don't know. However, I imagine that the earliest campfires were probably indistinguishable from natural fires. In a real sense, according to my hypothesis, the earliest campfires were natural fires.

[Maceman]

But we've got fossil evidence for savannah apes, and none for aquatic ones.

If I may re-direct your attention to some comments from Dr. Odent's article, which I recently posted for your benefit:

It appears that the emergence of the savannah occurred after the origin of the human family. Furthermore, we must bear in mind that the bones of our ancestor, the famous Lucy (Australopithecus Afarensis) were found eroding from the sand, lying among turtle and crocodile eggs and crab claws. And the bones of an older Australopithecus, found near Lake Rudolph in Kenya in 1995 were surrounded by many fossil vertebrates including fish and aquatic reptiles.

We must also keep in mind that even though the human family emerged several million years ago, Homo Sapiens - the modern human being - is a young species. It is worth noticing that the oldest known footprints of a modern human being - dating back 117,000 years ago - have been found on the shore of a South African lagoon.

[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.

[Junior]

Interesting. I've subscribed to the aquatic ape theory for quite some time. However, I am quite aware that there is a dearth of fossil evidence to support this theory, even if the physiological evidence for it is quite strong.

[Junior]

If you read the article posted, you'd know that human babies are quite capable of swimming from birth (indeed, some folks actually give birth in swimming pools to ease the process).

[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%.

[Sabertooth]

If you read the article posted, you'd know that human babies are quite capable of swimming from birth (indeed, some folks actually give birth in swimming pools to ease the process).

I'm a former swim coach and have taught babies to "swim." They've got a breathholding reflex which enables them to float and can pump their limbs a little, but they don't have a natural instinct or capacity for swimming.

[Sabertooth]

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.

The key word being "repeatedly," meaning the same favored rock gets used. That means some practical place to keep it.

But stone tools can be much cruder than that, if the rocks are used once and then discarded. And no consistent wear pattern would result.

[Physicist]

The key word being "repeatedly," meaning the same favored rock gets used.

I could be wrong, but I believe the threshold for "repeatedly" is only a few whacks in one spot, enough to distinguish it from the natural bumping and grinding of stones. A couple of nuts should do it.

[Physicist]

Oops, I forgot the second part:

But stone tools can be much cruder than that, if the rocks are used once and then discarded. And no consistent wear pattern would result.

That's true, but then, there's no need to carry those. If tools are the key to bipedalism, "favored" rocks (as opposed to single-use rocks) would appear around the same time as bipedalism.

[Sabertooth]

I could be wrong, but I believe the threshold for "repeatedly" is only a few whacks in one spot, enough to distinguish it from the natural bumping and grinding of stones. A couple of nuts should do it.

I don't know either, but let's assume this is the case.

First, I still believe the earliest stone tools would be used once and disposed. Once you got to the point where a particular stone was used repetedly, that would suggest some way to keep track of it, probably at least a semi-permanent residence.

Such a clan of apes would by definition be isolated to a degree from others... who knows for how long? Toolmaking could have developed for a while before being learned by others of the species.

So I don't think it's a given that we've discovered the earliest stone tools, or even any that are necessarily close to the earliest.

So, any archaeologists lurking out there, start sifting the pebbles!

[Physicist]

So I don't think it's a given that we've discovered the earliest stone tools

Perhaps not, but we've probably discovered the earliest stone tools worth carrying. And if we're postulating that carried tools prompted us to evolve bipedalism, then we'd expect tools worth carrying to be as widespread as walking hominids throughout the fossil record. Since they manifestly aren't, we'd also have to postulate that the carrying of at least stone tools fell out of fashion, for a few thousand millenia, with the descendants of the apes who were bootstrapped (a singularly appropriate term) to bipedalism by the process of carrying them. But why would it cease to be an advantage?

[StriperSniper]

Beside freeing the hands, the greatest advantage I can see is the increased vision over the plains grasses and brush. I guess we won't know for sure until time machines are as popular as cars.

[Physicist]

Beside freeing the hands, the greatest advantage I can see is the increased vision over the plains grasses and brush.

It seems a pretty complicated adaptation for that use. A very long neck would require much fewer genetic changes.

Here's another advantage: bipedal walking is faster and more efficient for long-distance travel. But again, partial bipedalism doesn't cut it.

[Sabertooth]

And if we're postulating that carried tools prompted us to evolve bipedalism, then we'd expect tools worth carrying to be as widespread as walking hominids throughout the fossil record.

First, if you'll recall, I'm backing the shadow-puppet postulate. I actually don't have a hard opinion on why bipedalism evolved.

Second, I think that bones are much more obvious fossils than stone tools, even to a trained eye.

Since they manifestly aren't, we'd also have to postulate that the carrying of at least stone tools fell out of fashion, for a few thousand millenia, with the descendants of the apes who were bootstrapped (a singularly appropriate term) to bipedalism by the process of carrying them. But why would it cease to be an advantage?

Not to be overglib, but I've lost track... is this a hypothetical?

[PatrickHenry]

Your "fire-carrying" hypothesis is interesting, but consider this one, which has the virtue of extreme simplicity: bipedalism developed because two shoes are cheaper than four.

[medved]

Elaine Morgan assumes an evolutionary model, nonetheless as I see it, you do not need to be an evolutionist to comprehend that she is almost certainly correct in thinking that modern humans arose living mainly in water. As opposed to evolutionism, her aquatic ape thesis strikes me as a rational and logical reading of actual evidence.

[Sabertooth]

Your "fire-carrying" hypothesis is interesting, but consider this one, which has the virtue of extreme simplicity: bipedalism developed because two shoes are cheaper than four.

That would presume asexual reprodution in said apes, as women never stop at two shoes.

[Physicist]

bipedalism developed because two shoes are cheaper than four.

Ah, but our knuckle-walking ancestors had opposable big toes, so they would have worn four gloves, and gloves are cheaper than shoes. (Just ask O.J.)

[PatrickHenry]

Shoes or gloves, two or four, all I know is that when my ancestors came down from the trees and stepped out onto the ground they did it in grand style, with the music from "2001" swelling in the background.