Posted: Jul 25, 2014 9:55 am
by Sendraks
Jayjay4547 wrote:I don’t like to call it a hypothesis,

I don't give two shits what you like to call it, I'm calling it what it is.
Jayjay4547 wrote:IIt’s a staringly obvious inference that was actually drawn decades ago,

If this were true and there were evidence to back it up, we'd not be having this discussion right now.
Jayjay4547 wrote:There is a strange attractor present when the human origin narrative is drawn and I call it atheist ideology.

This is meaningless wibble.
Jayjay4547 wrote:As to your reply it’s unacceptably crude to to claim that variety of predator is irrelevant because “density matters more than variety” Both matter.

Yes, both matter, but density matters more. Which is what I said. If you're going to quote me, at least demonstrate a modicum of understanding in what I have said.
Jayjay4547 wrote:For example to defend against a leopard at a roosting place at night, an australopith would need good night vision and good co-ordination of defenders. To defend against a pack of hunting dogs in the day they would need also endurance against being harried into exhaustion.

In the case of the Leopard, the australopith could simply choose to be where a Leopard was least likely to be and rely on group numbers to ensure that the majority survived the night.
In the case of the african hunting dog, you got any evidence that they hunt chimps or have ever hunted australopiths?
Jayjay4547 wrote:I don’t know really,

In science country, if you don't know, you leave it at that and go look for evidence.
Jayjay4547 wrote:An adult primate of 30kg can be assumed to be a lot more dangerous than a juvenile impala if only because generally speaking, primates have an inclination to fight whereas impala are inclined to flee.

Speculation. Do you have any evidence to support the aggressive tendencies of Australopiths? Are they closer to common chimps in aggression or bonobos?
Jayjay4547 wrote:Leopard density is significant sure.

That’ll do.
Jayjay4547 wrote: But suppose it is low in the savanna,

We know leopard density is lower on the savannah, no supposing about it.
Jayjay4547 wrote: leopards still create a burden on savanna baboons in Botswana.

I imagine they do. I imagine the burden would be a lot higher if the leopard density matched that found in the jungle.
Jayjay4547 wrote: it is also important whether a primate troop is specifically targeted by a particular habitual predator

Such predators are exceptions and when undertaking a study of animal behaviour and survival strategies, you look at the norms not the exceptions.
Jayjay4547 wrote: No Sendraks, I’ll leave you to work that out with Myers, who gave that figure as one limit of the range of predator biomass on the savanna, in his attempt to get some handle on possible predator biomass in the forest. I also used that value as a limiting one.

Basically you don’t know why the crater is a singular environment. That’s hilarious. I would’ve thought anyone, even someone with little or no knowledge of the natural world, would be able to figure that one out.
Jayjay4547 wrote: You claimed that when hominoids left the forest they entered a “low predator environment” That is complete balderdash as you really should have known.

They did enter a low predator environment. The density of leopard’s is lower. If we’re using the leopard/chimp relationship as our nearest comparator, then moving into an environment where your principle predator is of a lower density is a perfectly valid survival strategy.
Jayjay4547 wrote: The predator biomass is at least as great in the savanna (as stands to reason from the mammal-edible savanna grass, that is the primary producer). The variety of savannah predators is higher and finally the visibility of prey on the savanna is higher, where sight, sound and smell carries further. I’ve raised these with you before, so far you have ignored it, instead you obdurately continued with the balderdash.

I’m not ignoring it as I’ve already explained the survival benefits to australopiths of living on the savannah.
1) they were at least partially bipedal, meaning they could stand up to afford themselves a wider view of the landscape which makes it easier to spot predators. This is something that is not an advantage in the jungle.
2) While not adapted to an aboreal lifestyle, their remains show them to be able climbers and therefore have that option for evading predation by larger felids or canines that were less able tree climbers.
3) The biomass of predators =/= density of predators likely to predate on chimps. The high biomass of predators in the crater is due to the high biomass of prey. The other area of savannah you referenced from the paper had a predator biomass of a whole 2kg greater than the forest. However, that additional 2kg does mean an extra 2kg of predator per km to eat chimpanzees or australopiths.
4) Predator diversity is correlated to prey diversity and the biomass data does not take account the size of the predators involved. It would be foolish to assume that all the predators in the savannah biomass figure would be hunting chimps or australopiths for food.
Jayjay4547 wrote: And the whole point of your “low predator environment” balderdash is to take the australopiths out of the trophic pyramid, out of their context embedded in necessities imposed by the African biomes. Well you aren’t alone in that.

No, in fact my proposals squarely place the australopiths in the tropic pyramid. They’re not an apex predator and as you should know from the pyramid, predator density < prey density. Just because an animal is potentially prey, doesn’t necessarily mean it is a favoured prey species for all sorts of reasons that have nothing to do with the ability to defend itself.
Jayjay4547 wrote:So what. Three million years ago the crater was already there and doubtless the australopiths traipsed through it.

Which would mean that three millions years ago the population of the crater was predominantly not australopiths.,
Jayjay4547 wrote:That’s scarcely the issue, which is, could australopiths climb better than leopards?

They could certainly climb better than Lions or hyenas, which would be significant advantage in an environment with a lower density of leopards. It wouldn’t help much in the jungle, for all the reasons you post, but in an environment with less leopards it would be a significant survival benefit.
And we are talking about a creature which moved out into the savannah.