Theory takes bite at explaining human evolution...

These single source explanations bother me. It is not the size of the brain but its' organization that is significant. Hominid behavior was becoming more complex from the middle Australopitheceans (Africanus, Robustus)onward and I think the answer for the appearance of Homo will be found in a more subtle examination of environmental interaction and behavior. Not in a single eureka mutation moment.

Such an event could be crucial in making it possible for the brain to grow. It might also result in the requirement of additional food processing, thus selecting against groups that lacked the intellectual and (perhaps more importantly) skills required to carry this out.

The problem I see is that if this is just a single event, the window between the reduced jaw and being able to compensate for any ill effects would have to have been very short. Or so I'd conjecture without knowing anything more...

The brain does appear to be capable of directing its own development, though. The genome is way too small for all of the connections in the brain to be hard wired. Given room to grow, it may actually be that much greater complexity could result...










(I am taking no position here....)

I'm an archaeologist so I do not know enough about neural development to make a seriously cogent argument on this subject. Besides I am predisposed to material/environmental explanations in any event. But as complex behavior (tool use) precedes Homo, and as we as a species are dependent on culture not instinct for survival. It would seem to me that brain size is secondary to brain organization. Although size can't hurt.
There has been a lot of interesting research done on language recently at Brown University which suggests that it is the result of the interaction of several parts of the brain. Not has Chomsky would have it a hard wired genetic inheritance. If we want to consider langauge as a model for culture, size would seem to be less significant than the collection of parts.

Hmmm - interesting....

What stops the apes, then, from making the leap?

Will language acquisition by some apes make a difference?

But, of course, you are saying that it is a stroll, not a leap.

sorry, I keep forgetting that in some threads we discuss things with different people. The "bush" of life , describe individual bud aand branch structures that persist through time(clades0 We study their appearance and exits by fossil evidence of defined members of those clades. We can then make 'guesstimates' of how species were developing. The quantitative aspects of cladistics allows us to make good estimates of the sizes of the populations and their descendents. Thats why, when i mentioned that we have realy few key fossils to make the leaps that the article wants us to make. Its a good working hypothesis which needs much more data to become a theory.

dog-I saw an article about the most ancient hominid being a "pongid' that was more humna like in dentition and therefore was an ancestor of humans and apes. Yeh.
This is a popular twist in paleo this year. theyve just postulated that birds were actually the ancestors of dinosaurs and not the other way around. i think that, with all the feqathered dinos theyve found, this is close to being a theory. Cladistics again

I have to refute my own bullshit (well a little anyway) Cladistics in paleo , relies on evidence that we get from what?--fossils.
Fossils are not the evidence of evolution , they are more correctly the evidence of extinction, so I must urge caution because when we use claadistics as a tool in exploration , i use it to more closely locate a key bed that maybe contains an economic deposit of some resource.

They did, we're it. Modern apes are fully successful products of evolution. We and modern apes are descendent from a group of ape like species that lived about 7 million years ago. The last common ancestor between chimpanzees and ourselves lived about 6 million years ago. The earliest fossil species that is on our side of the "split" (we think) is a species called Sahelanthropus Tchadensis

Here a web site with a photo: http://www.talkorigins.org/faqs/homs/toumai.html


Here is a link to the Nature articleNature

Some of modern apes appear in the process of extinction, which I am very sorry about. But are they "naturally" selected, or do they evolve with suitable leaps? The latter possibility seems very unlikely, in the sense of probability.

Oh - I know WE are the "leap".

I just am curious about why the modern apes aren't joining us.

Well, they are, in a sense.

Using tools and all....at least chimps do.

Thanks Farmerman - it is good to mix the groups sometimes, eh?

But then you hafta explain! Which is great.

Chimps used tool. The Australopethiceans Afracanus and Robustus used tools, so the assumption is that the common ancestor to both used tools (or could). As to why Apes are not like us? Well in part because we occupy the culture niche, and occupy it very successfully thereby precluding any further change in that direction by other species.

Yeah, what he said.

Different environments place different demand. If the hypothesis that we evolved many of our distinctive features because we occupied a niche as scavengers at the edge of woodlands, our tool kit -- the stuff we think of as being "human" -- is evolved to that purpose. Other apes live in environments that favored different tool kits. And they didn't move into our niche because we were already there.



(Or something. I dunno. I'm just chatty.)

A yes, Daddy-O Pog, but that suggests specialization, and the Australopithicenes were successful because of traits which made them effective generalists, n'est-ce pas?

(Damned wabbit, alus openin' cans of worms . . .)

I dunno. But generalist is a strategy too, ain't it? (And ain't all mammalian scavengers generalists of a sort? Wolves will scavenge, and hyenas will hunt, depending on circumstances.) Just vaguely remembering reading about the idea we evolved to exploit scavenging opportunities at the edge of the African woodlands, and we turned out really weird as a result -- upright, so we would be exposed as little as possible to the midday sun that renders other animals inactive... and a host of other traits that escape me right now. (I've been up for almost 40 hours and am starting to wind down...)

Here, smoke some a this . . .

May still get a call that the puppy needs anesthesia, though the enema seems to have worked. Need to not be silly in case call is from future employer or colleague...

We've got some early hominid people at the asylum I teach at and they have an interesting take on early Oldawan tools. They were basically used in a slash and grab scavenging strategy. Several hominids would scare off the lions (whatever) momentarily from their kill while others slash of a limb or a rib, and then everybody runs like hell. Some what similar to knocking off a jewelry store by smashing in the front window. Not the mighty hunter, but it's a living.

Not a very sexy substitute for fearsome teeth and claws, though.

But ours is a successful niche - I would have thought movement into it would be good? I mean, evolution isn't to know that we would fight to keep them out!

And - besides - don't a number of animals occupy very similar niches?

And - we made our niche huge with our tool set.

Anyhoo - I suspect that apes - if we allow them to live - will gradually develop greater intelligence and more tools and such. I am fascinated by the notion that apes taught language might, if there are enough of them, do a little mini-leap in their small group.