Subject
Fw: Victoria Alexander: A nice example of non-utilitarian
"mimicry"
"mimicry"
From
Date
Body
EDITOR's NOTE. Jerry Friedman's comments follow the re-run of Dr.
Alexander's posting.
----- Original Message -----
From: "Jerry Friedman" <jerry_friedman@yahoo.com>
To: "Vladimir Nabokov Forum" <NABOKV-L@LISTSERV.UCSB.EDU>
Sent: Monday, September 09, 2002 8:13 AM
Subject: Re: Victoria Alexander: A nice example of non-utilitarian "mimicry"
>
> ----------------- Message requiring your approval (56
lines) ------------------
>
> --- "D. Barton Johnson" <chtodel@cox.net> wrote:
> >
> > ----- Original Message -----
> > From: Victoria N. Alexander
> > To: Vladimir Nabokov Forum
> > Sent: Sunday, September 08, 2002 8:49 AM
> > Subject: A nice example of non-utilitarian "mimicry"
> ...
>
> > The resemblance of the hummingbird and hummingbird
> > moth is incidental, i.e., it does not exist because of the function it
> > serves.
> >
> > I should point out, though, that Mr. Hogan's wife, (whose name,
> > unfortunately, I don't know) who happens to be an entomologist, who also
> > worked at Harvard where Nabokov did, cautions that we don't know for
> > certain if the bird beats its wings faster than the moth, and we're
> > looking into that now.
> >
> > A bit more on the nature of the resemblance between the hummingbird and
> > hummingbird moth, for those that may be interested:
> >
> > The resemblance is due both to similar histories of functioning and
> > pressures from physical laws, such as D'Arcy Thompson (often cited as
> > the grandfather of modern-day theoretical biology) described in his
> > explanation of the similarities between all winged animals. In On Growth
> > and Form, written in 1917, Thompson points out that the same external
> > constraints are the common cause of the structural dimensions of any
> > winged species. "In order to balance its weight ... momentum must ... be
> > proportional to the cube of the bird's linear dimensions; therefore the
> > bird's necessary speed, such as enables it to maintain level flight,
> > must be proportional to the square root of its linear dimensions, and
> > the whole work done must be proportional to the power 3½ of the said
> > linear dimensions."
>
> Don't do this to me! I have work to do! Thompson was simply wrong here;
> many birds and insects fly around the same speed, regardless of size. The
> result is often comical when a cowbird or flycatcher is chasing a big fly.
> The fastest birds are neither the biggest nor the smallest. He was no
> doubt right to study the forms of flying animals in terms of physics,
> though.
>
> Smaller flying animals have faster wingbeats. It seems extremely likely
> that the moth's wingbeats are *faster* than the hummingbird's. I don't
> know for sure, though. By the way, the name "hummingbird clearwing moth"
> suggests that it's one of the family (if that's the right taxonomic level)
> of clearwing moths, not a hummingbird or sphinx moth that developed a
> non-functional resemblance to hummingbirds.
>
> Jerry Friedman
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Finance - Get real-time stock quotes
> http://finance.yahoo.com
>
Alexander's posting.
----- Original Message -----
From: "Jerry Friedman" <jerry_friedman@yahoo.com>
To: "Vladimir Nabokov Forum" <NABOKV-L@LISTSERV.UCSB.EDU>
Sent: Monday, September 09, 2002 8:13 AM
Subject: Re: Victoria Alexander: A nice example of non-utilitarian "mimicry"
>
> ----------------- Message requiring your approval (56
lines) ------------------
>
> --- "D. Barton Johnson" <chtodel@cox.net> wrote:
> >
> > ----- Original Message -----
> > From: Victoria N. Alexander
> > To: Vladimir Nabokov Forum
> > Sent: Sunday, September 08, 2002 8:49 AM
> > Subject: A nice example of non-utilitarian "mimicry"
> ...
>
> > The resemblance of the hummingbird and hummingbird
> > moth is incidental, i.e., it does not exist because of the function it
> > serves.
> >
> > I should point out, though, that Mr. Hogan's wife, (whose name,
> > unfortunately, I don't know) who happens to be an entomologist, who also
> > worked at Harvard where Nabokov did, cautions that we don't know for
> > certain if the bird beats its wings faster than the moth, and we're
> > looking into that now.
> >
> > A bit more on the nature of the resemblance between the hummingbird and
> > hummingbird moth, for those that may be interested:
> >
> > The resemblance is due both to similar histories of functioning and
> > pressures from physical laws, such as D'Arcy Thompson (often cited as
> > the grandfather of modern-day theoretical biology) described in his
> > explanation of the similarities between all winged animals. In On Growth
> > and Form, written in 1917, Thompson points out that the same external
> > constraints are the common cause of the structural dimensions of any
> > winged species. "In order to balance its weight ... momentum must ... be
> > proportional to the cube of the bird's linear dimensions; therefore the
> > bird's necessary speed, such as enables it to maintain level flight,
> > must be proportional to the square root of its linear dimensions, and
> > the whole work done must be proportional to the power 3½ of the said
> > linear dimensions."
>
> Don't do this to me! I have work to do! Thompson was simply wrong here;
> many birds and insects fly around the same speed, regardless of size. The
> result is often comical when a cowbird or flycatcher is chasing a big fly.
> The fastest birds are neither the biggest nor the smallest. He was no
> doubt right to study the forms of flying animals in terms of physics,
> though.
>
> Smaller flying animals have faster wingbeats. It seems extremely likely
> that the moth's wingbeats are *faster* than the hummingbird's. I don't
> know for sure, though. By the way, the name "hummingbird clearwing moth"
> suggests that it's one of the family (if that's the right taxonomic level)
> of clearwing moths, not a hummingbird or sphinx moth that developed a
> non-functional resemblance to hummingbirds.
>
> Jerry Friedman
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Finance - Get real-time stock quotes
> http://finance.yahoo.com
>