[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: More on "packs"

Cost to an individual may not be meaningful. The evolutionary stable strategy
may be determined by the successful breeding of the pack as a whole.
If the "pack hunting" gene survives because at least one member of the
pack breeds with higher probability than similar animals without
the gene in many generations, then the gene is successful.
One also needs to consider evidence that carnivores who hunt together
care for each other in other ways than merely bringing down game. These
include sharing food with injured pack members.
An example of altruism of a different sort is the gangs of sibling
lions who cooperate to take over multiple prides of females. Two
lions working together are more successful than one at keeping
a pride. I think the record is the "Seven Samurai of the Serengeti"
who circulated among various prides for some time. In this case,
there is advantage to the genes in the (much longer) time that the
bearers spend breeding, and hence the greater number of offspring.
-Gus Derkits

Nathan Myhrvold wrote:

> I beg to differ on the cost point.
> It is true that there is one study of African wild dogs that claims that the
> total energy is less in a pack, but that study has been disputed by the
> findings or other workers who also watch wild dogs.   In addition, the
> claimed advantage is so small that one can argue it is within experimental
> measurement limits.
> The vast majority of studies continue to show that there is no hunting
> success increase in "pack" hunting. Packer and many others have come up with
> many different ways of looking at hunting success - per individual, per
> energy expended, per km run, and the conclusion remains the same - hunting
> success in ANY definition that people have come up with INCLUDING energy
> expended does not seem to increase with pack size.
> This isn't a misrepresentation of current research - it basically is a
> summary of current research.
> The explanations that seem to work best for group hunting is that the
> animals in question are social.  They hang out together, and when they hunt,
> they hunt together.  Social living probably has some benefit, but not in
> hunting per se.
> Opportunity cost is an interesting economic concept, and as it happens, I am
> working on a game theoretic analysis of pack hunting using it.  I am not
> done yet, but it is my hope that this can throw some light on the topic.
> However, both opportunity cost, and indeed any measure of cost is a side
> issue to the main point, which is that that deeply cooperative "true pack
> hunting" by large mammilian carnivores is elusive at best.
> Regardless of whether you assign low or high cost or opportunity cost, the
> basic message is that the supposedly high intelligence required to cooperate
> "as well as" lions or wolves either has no benefit, or it requires some very
> exotic definition of cost and benefit in order to show a profit.
> Nathan