Re: Are the "mosaic theories" completely vaccuous?

From: Nick Maclaren (nmm1_at_cus.cam.ac.uk)
Date: 11/14/04 

Date: 14 Nov 2004 18:57:53 GMT

In article <dOIld.15933$Gm6.7013@newsread3.news.atl.earthlink.net>,
Bob Keeter <rkeeter@earthlink.net> wrote:
>
>There are in general very few tasks that can provide a mechanism for
>"selection". One is gathering food, another might be escaping from danger,
>and a third would be the actual act of procreation. ...

I agree with you that the last is a non-starter, but there is actually
another, very important, one. That is travelling between sleeping and
eating areas, between water sources etc. That and escaping from danger
are the two main selective pressures on locomotion in modern Africa
outside the rain forest.

> ...Escaping from danger, either by running
>or fighting, is a possibility as is the gathering of food. In either case,
>Id offer up that the ONLY way either becomes a driver for bipedality over
>quadrupedality is if the hands are needed for other tasks. As widely
>varying species as leopards and sea gulls carry food quite nicely without
>the use of hands, so Id discount the "carry" aspect of food gathering,.

And because pretty well all animals with a primate-like diet eat as
they gather.

>Since bipedality sacrifices at least some speed in the first stage of
>"flight or fight", Id suggest that it was not a move to increase the ability
>to run away from danger. So we are left with the possibility of food
>gathering (but not the actually carrying), and surviving dangerous
>encounters (presumably with predators, but not actually running away). Is
>there any one general class of activity that would aid in the collection of
>food, minimize the impact of being relatively slower afoot when encountering
>predators, AND a "forcing function" for bipedality? All I have to do is put
>a tool in the hand of a "slightly more bipoedal chimpanzee-like chimp" and I
>see a clear advantage for selection. Dont you?

No.

The reason that I don't is the way that the major African predators
hunt. One of the main modes is to ambush an outlying animal - and
weapons are no use at all against an attacker you don't see coming
(and I include guns and iron spears in that). But let's assume a
couple of seconds' warning. Unless you are actually holding the
weapon ready for use, the first requirement is to be able to jump
to where it is, and quadrupedal locomotion is streets better for that.
And I can't really see an ape gathering food permanently holding a
weapon - it is an incredible handicap.

Also remember that a lot of the animals gathering food will be young,
and pretty ineffective with weapons. A far more efficient mode of
escaping an ambush (with a few seconds' warning) is to sprint to the
group and let the adults protect them. Given the very low reproductive
rate of the great apes, a small reduction in the rate of survival to
adulthood is a major issue. Again, quadrupedal locomotion wins.

Equally well, they HAVE to scatter to gather food, as there simply
isn't the density of appropriate food for most of the year. Not even
in the more forested parts.

So EITHER the evolution took place in circumstances where there was
very little predation OR there was some aspect that gave a MAJOR
advantage to even a small shift towards bipedality.

>The "mosaic theory" simply provides an obvious and gradual transition phase
>between the wooded areas where it is easier/quicker/safer to just climb a
>tree for protection and the open areas where "stand and fight" is the only
>real option. Evolution favors gradualism and that sudden step from an
>existence in the full blown, uncompromised forest out onto the full blown,
>unmitigated grassland is a doozie!

Quite.

Regards,
Nick Maclaren.

Relevant Pages

  • Re: Bipedalism in different substrates
    ... >>when danger threatens, or you don't. ... > group multiply its defensive capability no end, but weapons without ... gather food come from? ... Chimps didn't evolve them, since they ...
    (sci.anthropology.paleo)
  • Re: War Celebrations
    ... And why draw a line at weapons? ... reservoirs and food factories as it is to bomb weapons factories. ... must be legitimate to cut off that supply as well, by targetting ... supplies them by killing doctors and nurses in the city hospitals as ...
    (uk.legal)
  • Re: Shopkeeper ran out of money?
    ... Earlier he paid me for dwarf cloaks, weapons, etc. ... -- now if I drop something in the store, ... -- killed by a poisonous corpse, because although I had a unihorn with ... I saw my pet's corpse on there and thought it was a food item to pick ...
    (rec.games.roguelike.nethack)
  • Re: Common Painkillers Can Raise Blood Pressure: Study
    ... without American food, jeeps, clothes and other items sent to Russia, ... without training (and sometimes without weapons) or to clear mine fields ... Yeah, docs aren't real big on barbiturates anymore, me thinks. ... Leader buying aluminum tubes to build cascades for iridium enrichment. ...
    (sci.med.cardiology)
  • Re: coconuts & oysters
    ... >one without food and many predators, when no one gets to choose their ... >survival is possible in an alternative habitat, ... we would scrabble round after rabbits in the savannah and eat them ...
    (sci.anthropology.paleo)