RE: PACK HUNTING THEROPODS

[Nathan Myhrvold <nathanm@MICROSOFT.com>]

> -----Original Message-----
> From: Larry Dunn [SMTP:larrydunn@hotmail.com]
> 
> >-  There is nothing that prevents vertebrates from having a similar 
> social
> >arrangement. Group living in a manner highly similar to the eusocial 
> insects
> >has been reported for several vertebrate species, notably the naked 
> mole
> >rat. 
> 
> All naked mole rats aside, do you feel that it's more instructive in 
> reconstructing the lives of dromaeosaurs that we analogize between 
> extant vertebrate predators and dromaeosaurs or between insects and 
> dromaeosaurs?
        [Nathan Myhrvold]  

        You make sweeping generalizations to butress your argument.
Unfortunately, they are flatly untrue.  Then when confronted with this you
try to switch the topic and say"all naked mole rats aside...".

        You're wrong about mole rats, you're wrong about wolves - most of
your examples are wrong. You are mainly arguing from a Discovery channel
level folk knowledge rather than the current state of the art in animal
behavior and genetics.  

        The point of this discussion SHOULD be somethnig along the lines of
the following:

        Is it plausible that dromaeosaurs (and potentially other theropod
dinosaurs) hunted cooperatively in groups?

        The specific instance that sparked this was the proposition that
groups of Deinonychus could cooperate at some level to kill a Tenontosaurus.

        Extant vertebrates offer some analogies - but only analogies.  The
top predators in today's ecosystems are mostly mammals, which makes the
comparison more difficult.  We KNOW that many aspects of their physiology,
and probably therefore their behavior was different.

        My claim is that there is no reason to rule this out some level of
cooperation on the basis of cognitive ability.   I say that it is plausible
that evolution would lead to groups of of closely related Deinonychus
hunting together in a reasonable simulation of what is commmonly called
"pack hunting".  In particular they could cooperate to kill prey larger than
they could reliably kill if solitary.

        Two caveats -  First, it is plausible, but of course we cannot prove
it one way or another from current evidence.

        Second, the degree of cooperation may not be identical to extant
mammals.   If you define "pack hunting" as "just what my favorite mammals
do" then there is no point continuing the argument because it is a
tautology.  

        However, in a more general sense cooperation at some level is very
possible.  

        One strong argument for this is that much of the supposed deep
cooperation and cognition that occurs with mammals is ex post facto
anthropomorphising.   Lions, wolves, hyena, African hunting dogs and other
famous examples do not have anywhere near as much deeply cognitive
cooperation as is commonly supposed.   Hunting statistics bear this out - if
the effects are so small that they are missed by the statistics then they
are not very important to survival, and thus to evolution.

        There are other arguments in favor of the propsition, but I won't
try to recapitulate this whole thread here.

        On the other side you have offered very little argument against
EXCEPT the notion that  cooperative hunting = intellegence = mammals.   I
find this unconvincing, in part because your facts about the mammals in
question are wrong, and in part because you are trying to make a connection
based only on negative evidence - in ecosystems where the top predators are
ALL mammals, we find lots of examples of cooperative hunting in mammals.   

        But hey, we are all entitled to our opinions.  At this stage I am
unlikely to convince you.


> >-   It is true that eusocial insects are highly related to one another.
> >This explains the evolutionary MOTIVATION for extreme degree of 
> cooperation
> >to evolve.   You have to separate two issues - the evolutionary 
> motivation
> >that would lead to cooperative hunting, which is one issue, and the 
> level of
> >intellegence (cognitive ability) required to get "cooperation" in 
> hunting
> >and foraging.  
> 
> And what result obtained in the development of cooperation in two cases:  
> lions and ants?  
> 
> Lions took advantage of their ability to cooperate cognitively by doing 
> just that.  
> 
> Ants, unable to develop cooperation through such means, "cooperate" by 
> specializing by function (soldier ants, worker ants, royalty), a 
> hallmark of hive insects, each pursuing a specific role within the hive.  
> They have no identity, even much less so than non-hive insects, outside 
> of their role in the hive.  Such is the result of real cooperation 
> without intelligence.
        [Nathan Myhrvold]  

        I don't think you understand ants very well.  Read E. O. Wilson's
book The Ants.  

        Even within a caste, there is cooperation between individuals.
Also, there are a wide range of ants, bees and wasps including some that are
solitary, some that are group living but have no

> What sort of true cooperation do we recognize at work in dromaeosaurs, 
> presumed to be relatively unintelligent animals?  Were there worker 
> dromaeosaurs, soldier dromaeosaurs, queens breeding them all?   
        [Nathan Myhrvold]  

        The rhetorical question is pointless.  Specialization of function is
interesting but it is not the same as cooperation. 

        In particular, the mammalian examples you are fond of DO have roles
analogous to these.  In a wolf pack, there is only one breeding pair - the
alpha male and female.  They DO play the role of the reproductive royalty.
In lion prides, the males are primarily soldiers - their role in procuring
food is secondary to the female "workers".   In naked mole rats there is a
queen and several other specialized castes.   

        The degree of specialization in group living mammals is LOWER than
the degree in eusocial insects.   However, by the same token it is lower in
some species of eusocial insects too.   You are trying to make black and
white characterization when in fact there is a broad spectrum.

> >  Their overall social structure IS
> >different, but that is a separable issue.  
> 
> Well, I must say I think that this assertion is completely 
> unsupportable,  for the reasons given above.
> 
> >Therepods that are sufficiently related could indeed have made 
> "altrusitic"
> >sacrafices for one another.   So called "selfish genes" can make for
> >apparently altruistic phenotypes. This effect is independent of the 
> degree
> >of intellegence of the creatures involved.
> 
> I cannot think of a single example of a vertebrate of less than 
> mammalian intelligence showing this sort of altrusim.  Can you provide 
> one please?
        [Nathan Myhrvold]  

        There are MANY examples of non-mammalian "altruism" - many species
of birds for example will put themselves at risk defending a nest, or acting
as a decoy to lure predators toward themselves and away from a nest.   Study
the literature before making more sweeping generalizations.

        Saying things like "less than mammilian intellegence" betrays your
position as a mammal bigot.  

        In point of fact there are plenty of intellegent non-mammals - lots
of smart birds,  even a few smart invertebrates (octopus and cuttlefish).
Mammalian cooperators are not more intellegent than solitary foragers.  In
fact, mammalian cooperation has many of the same features as cooperation in
ANY part of the animal kindom - specialization of function (particular in
reproduction), close genetic relationship between cooperators...
>  
> > Schooling fish, most behaviors
> >of ants and many other animal behaviors are the COLLECTIVE result of
> >INDIVIDUAL algorithms.   What appears to be highly orchestrated - has 
> no
> >score, and no composer.  Instead it is what happens when a bunch of
> >individuals following the same set of rules get together.
> 
> Precisely!  A shark which appears to "herd" schools of fish along with 
> other sharks  would still attack its prey with or without the presence 
> of the other sharks, correct? 
> 
> So: Would a solitary Deinonychus hop up on Tenontosaurus regardless of 
> the presence or absence of other Deinonychus?  This puts the lie to the 
> idea of collective result/individual algorithm in this case.
        [Nathan Myhrvold]  

        This does not make sense.   Every group living creature - from ants
to humans - has specific behavior patterns - some which they do in the
presence of others, some which they do solitary.

        The amount of cognitive ability required to decide to jump on a
Tenotosaurus when in a group, but not alone, is truly modest.   Surely that
can't be your argument.
>  
> >There are differences between the social behavior of lions and oras, 
> but
> >that example does not make the point.  
> 
> Please elaborate.
        [Nathan Myhrvold]  

        I think you should do some reading if you are seriously interested
in understanding animal behavior, and its evolutionary origins, rather than
just posting ptolemics.

        If you want to understand Oras, start by reading Auffenberg's books.
If you want to learn about Lions, start with The Serengeti Lion, and then
read recent books and papers by Packer and others.  There is a good review
paper on cooperative hunting in Nature by MacDonald - 1983.  There is a lot
of recent work on this topic as well.

        This is my last post on this topic.

        Nathan