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PROFESSOR: A few
things from last time,

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00:00:23,700 --> 00:00:28,890
and then I want to say a few
things about communication

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00:00:28,890 --> 00:00:29,560
among animals.

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00:00:35,860 --> 00:00:39,458
We ended with some
things on navigation,

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00:00:39,458 --> 00:00:41,860
and how animals find their way.

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00:00:47,410 --> 00:00:50,200
For example, how
mice or rats solve

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a maze in which they can't
see the platform that supports

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00:00:56,480 --> 00:00:59,350
them, keeps them from
having to swim in the water.

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00:00:59,350 --> 00:01:03,710
It's under the water, and water
is milky, so they can't see it.

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00:01:03,710 --> 00:01:04,700
How they find it?

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00:01:04,700 --> 00:01:07,810
And yet they can learn to pretty
quickly find it when their

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00:01:07,810 --> 00:01:08,900
in that maze.

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00:01:08,900 --> 00:01:13,250
And they do it mostly by
using visual cues, usually

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overhead cues, and they
need the hippocampus

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00:01:19,270 --> 00:01:21,180
in the brain to do that.

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00:01:21,180 --> 00:01:27,890
And I just mentioned here that
homing pigeons with damage

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00:01:27,890 --> 00:01:30,760
to that structure
in the bird brain.

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00:01:30,760 --> 00:01:33,900
It doesn't look like the
hippocampus in a mammal.

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00:01:33,900 --> 00:01:36,995
It's called the medial pallial
area, the medial pallium.

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00:01:39,670 --> 00:01:42,670
They still find their direction.

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00:01:42,670 --> 00:01:44,100
They'll go in the
right direction

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00:01:44,100 --> 00:01:45,900
when their a long
ways from home.

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00:01:45,900 --> 00:01:49,050
But when they get
near home, then they

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00:01:49,050 --> 00:01:51,539
get lost, because
they lose their map

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00:01:51,539 --> 00:01:52,580
of the local environment.

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00:01:58,400 --> 00:02:02,030
Scott, in his book,
discusses stuff a study

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00:02:02,030 --> 00:02:09,440
of two different, very
closely-related species,

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00:02:09,440 --> 00:02:11,560
the blue tits and
the marsh tits.

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00:02:11,560 --> 00:02:14,340
He has studied the
blue tits quite a lot

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00:02:14,340 --> 00:02:18,540
there, especially their
aggressive behavior,

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00:02:18,540 --> 00:02:25,180
and he points out that the
marsh tits create food hoards.

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00:02:25,180 --> 00:02:27,080
They hide food in
various places,

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00:02:27,080 --> 00:02:31,720
and they have to remember
where the food is,

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00:02:31,720 --> 00:02:33,630
whereas the blue
tits don't do that.

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00:02:33,630 --> 00:02:37,220
And when you have two closely
related species like that--

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00:02:37,220 --> 00:02:40,660
one that has to remember
a lot of different places,

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00:02:40,660 --> 00:02:45,910
the other that doesn't-- it's
pretty general finding in these

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00:02:45,910 --> 00:02:48,950
kinds of studies to find
a larger medial pallium

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00:02:48,950 --> 00:02:51,500
or hippocampal formation
than the ones that can.

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00:02:51,500 --> 00:02:57,520
That's just the way the
experimental neurology has

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00:02:57,520 --> 00:03:00,240
interacted with the
animal behavior studies.

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00:03:03,620 --> 00:03:09,270
This question, a very simple
one: why would animals

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00:03:09,270 --> 00:03:13,760
migrate very long distances,
just in order to mate?

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00:03:13,760 --> 00:03:20,670
Some of them migrate practically
halfway around the earth,

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00:03:20,670 --> 00:03:24,960
and they do that every year.

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00:03:24,960 --> 00:03:31,350
In the cases that I know of,
the all do it once a year.

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00:03:31,350 --> 00:03:39,340
We know that many large
birds, herons for example,

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00:03:39,340 --> 00:03:44,370
will migrate for example
from Siberia into India.

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00:03:44,370 --> 00:03:46,930
And they have to cross the
Himalayas to do that, which

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00:03:46,930 --> 00:03:51,930
is very treacherous, and yet
they brave that difficulty,

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00:03:51,930 --> 00:03:57,390
and the stronger ones
anyway make it every year.

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00:03:57,390 --> 00:04:01,160
So why would they do that?

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00:04:01,160 --> 00:04:08,560
What's the simple
answer you can think of?

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00:04:08,560 --> 00:04:09,890
You've probably read it.

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00:04:09,890 --> 00:04:13,080
If you haven't, you
should be able to think

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why an animal would do that.

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00:04:17,510 --> 00:04:18,765
Humans don't do it.

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00:04:24,070 --> 00:04:25,690
Why does the salmon do it?

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Why does the salmon
come from open ocean,

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00:04:32,070 --> 00:04:39,570
sometimes very long distances,
finds the river that

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leads to the
stream, following it

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00:04:42,720 --> 00:04:48,700
inland to where that
salmon was hatched?

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00:04:48,700 --> 00:04:50,920
And they will go back
there, in order to breed.

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00:04:57,030 --> 00:04:59,510
Why does the monarch
butterfly migrate

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00:04:59,510 --> 00:05:02,480
from North America and
Canada, all the way down

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00:05:02,480 --> 00:05:04,766
into Mexico, in order to breed?

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00:05:04,766 --> 00:05:05,890
This tiny little butterfly.

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There's got to be
very good reasons,

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and the reason's very simple.

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They're more successful
at reproducing that way,

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because they go to safe
areas to reproduce,

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even though the physical
demands are huge.

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These are some of the
other species that

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have these very long-distance
migrations: the green turtles,

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00:05:36,360 --> 00:05:44,150
sockeye salmon, the
black-capped warblers in Europe,

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00:05:44,150 --> 00:05:45,270
Australian silvereyes.

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00:05:49,880 --> 00:05:53,770
And then to end with, these
three questions on migration:

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00:05:53,770 --> 00:05:57,870
how do you get evidence
that birds use stars

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00:05:57,870 --> 00:05:59,840
to guide long-distance
migration?

87
00:05:59,840 --> 00:06:03,050
These are birds that
often fly at night,

88
00:06:03,050 --> 00:06:05,545
and they will fly even
on moonless nights.

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00:06:10,020 --> 00:06:12,370
How do we know that
they're using the stars?

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00:06:12,370 --> 00:06:16,015
They could be using
magnetic cues, right?

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00:06:19,040 --> 00:06:20,976
So it's a real
experimental question.

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00:06:25,620 --> 00:06:29,770
Can you think of any practical
methods for doing that?

93
00:06:29,770 --> 00:06:32,670
And what cues besides
the stars could they use?

94
00:06:32,670 --> 00:06:35,060
I already mentioned they
could use magnetic cues.

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00:06:35,060 --> 00:06:38,365
They could fly during
the day and use the sun,

96
00:06:38,365 --> 00:06:42,440
if they use that direction.

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00:06:42,440 --> 00:06:46,330
There's other possible
cues they can use, too.

98
00:06:46,330 --> 00:06:48,170
I mentioned a couple
of them that pigeons

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00:06:48,170 --> 00:06:53,330
use: patterns of infrasound
that differ from one region

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00:06:53,330 --> 00:06:55,950
to another.

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00:06:55,950 --> 00:06:57,480
And the last question
is, how do we

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00:06:57,480 --> 00:07:01,230
know that migration behavior
like this is innate?

103
00:07:04,570 --> 00:07:10,230
And these are just-- I want
to get through this quickly,

104
00:07:10,230 --> 00:07:16,520
so I'm just going to show
you very simple answers.

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00:07:16,520 --> 00:07:19,590
They look at initial flight
directions in a planetarium.

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00:07:19,590 --> 00:07:23,950
Because when they get restless,
they're about to migrate.

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00:07:23,950 --> 00:07:26,980
You can tell by the
way they behave.

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00:07:26,980 --> 00:07:28,630
The birds get more
and more restless,

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00:07:28,630 --> 00:07:33,640
and finally animals and
the birds in a region

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00:07:33,640 --> 00:07:35,390
will all take off at
about the same time,

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00:07:35,390 --> 00:07:40,350
and they fly all in
about the same direction.

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00:07:40,350 --> 00:07:44,380
So if they look at the initial
direction, when they take off

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00:07:44,380 --> 00:07:48,550
and you have them in a
planetarium so the only

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00:07:48,550 --> 00:07:51,310
visual cues they're
getting that you can vary

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00:07:51,310 --> 00:07:54,580
are the pattern
of constellations,

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00:07:54,580 --> 00:07:59,610
you find out that they
are consistent in flying

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00:07:59,610 --> 00:08:01,640
in a certain
direction with respect

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00:08:01,640 --> 00:08:04,480
to those constellations.

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00:08:04,480 --> 00:08:10,560
And that was discovered in a
planetarium in the Max Planck

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00:08:10,560 --> 00:08:14,200
Institute for
Behavioral Physiology.

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00:08:14,200 --> 00:08:18,630
And I say these in the
same location where

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00:08:18,630 --> 00:08:24,700
Konrad Lorenz has his section
for studying geese and ducks.

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00:08:28,860 --> 00:08:31,640
And cues besides the stars.

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00:08:31,640 --> 00:08:34,840
Besides the sun they, can
use the polarity of light.

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00:08:34,840 --> 00:08:37,765
So they don't actually
have to see the sun itself.

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00:08:37,765 --> 00:08:39,640
They can use the magnetic
field of the earth.

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00:08:39,640 --> 00:08:43,530
They could use olfactory cues,
but that is difficult at first

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00:08:43,530 --> 00:08:45,080
and depends on where they are.

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One very convincing study
showing the innate nature

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00:08:55,780 --> 00:08:59,880
of the behavior is
illustrated in the Scott book.

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Do you remember?

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00:09:00,780 --> 00:09:06,410
Two really closely related
species of warbler.

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The European black
capped warblers

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00:09:11,660 --> 00:09:16,040
that live in different
places, so they migrate

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00:09:16,040 --> 00:09:19,510
in different initial
directions when they take off

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00:09:19,510 --> 00:09:22,530
to fly to their breeding areas.

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00:09:22,530 --> 00:09:23,840
But they will interbreed.

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00:09:23,840 --> 00:09:29,430
And when you integrate them,
the initial directions, at least

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00:09:29,430 --> 00:09:32,540
the mean, is right in
between the directions

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00:09:32,540 --> 00:09:34,330
of each of those groups.

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00:09:34,330 --> 00:09:36,600
It's a really nice study.

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00:09:36,600 --> 00:09:41,290
Of course, the results
aren't perfect.

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00:09:41,290 --> 00:09:44,540
But if you look at the-- they
show the individual data points

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00:09:44,540 --> 00:09:48,776
in the graph in the book,
and it's pretty good evidence

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00:09:48,776 --> 00:09:51,205
that it's innate behavior.

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00:09:56,360 --> 00:09:58,170
Just want to mention
one other thing.

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A recent-- no, not
that recent now,

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00:10:01,690 --> 00:10:05,530
2006-- evidence that
certain migratory

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00:10:05,530 --> 00:10:12,200
songbirds that use the
geomagnetic field or stars

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00:10:12,200 --> 00:10:20,060
or the Sun to navigate, they
show in this particular song

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00:10:20,060 --> 00:10:28,610
bird, the savanna
sparrow, they recalibrate

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their magnetic compass
at both sunrise

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00:10:31,230 --> 00:10:36,184
and sunset by the
polarization of light.

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00:10:36,184 --> 00:10:37,683
They use the light
near the horizon.

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00:10:44,580 --> 00:10:49,560
It's an interesting
study, and not

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00:10:49,560 --> 00:10:53,270
yet known whether all birds
have this kind of recalibration

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procedure, but it's
important, especially

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if they're from
different regions,

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00:11:00,270 --> 00:11:04,405
first of all that the
magnetic field can fluctuate,

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00:11:04,405 --> 00:11:08,130
the magnetic field of the earth.

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00:11:08,130 --> 00:11:09,960
So it needs
recalibration if it's

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00:11:09,960 --> 00:11:12,180
going to be really precise--
and of course birds

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00:11:12,180 --> 00:11:15,470
in different areas, if they're
all flying to the same place,

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00:11:15,470 --> 00:11:17,200
but they live in
disparate areas--

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00:11:17,200 --> 00:11:23,390
they would need to adjust
that compass for their region.

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00:11:23,390 --> 00:11:24,940
All right.

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00:11:24,940 --> 00:11:29,870
Let's start talking
about communication.

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00:11:29,870 --> 00:11:34,370
And there's two videos,
actually there's more than two,

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00:11:34,370 --> 00:11:38,020
that are very
relevant that I have.

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00:11:38,020 --> 00:11:42,360
One is a video showing meerkats
of the Kalahari Desert.

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00:11:42,360 --> 00:11:44,200
And I want to ask
you, how many of you

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have seen the video,
Meerkats United?

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00:11:48,530 --> 00:11:51,520
I know some of you
must have seen it.

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00:11:51,520 --> 00:11:58,500
They became very popular after
the Public Broadcasting Company

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00:11:58,500 --> 00:12:03,850
made this half-hour film
of meerkat behavior.

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00:12:03,850 --> 00:12:06,200
George Page was the narrator.

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00:12:06,200 --> 00:12:08,900
You can still find a lot
of meerkat videos online,

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00:12:08,900 --> 00:12:12,540
but they're not as
comprehensive or as good

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00:12:12,540 --> 00:12:16,820
as the George Page video, so
I'm going to show that today.

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00:12:16,820 --> 00:12:18,720
I have another one on
horse communication.

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00:12:18,720 --> 00:12:23,070
I know some of you have
special interest in horses.

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00:12:23,070 --> 00:12:33,820
This link that I've put here
still works last time I tried,

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00:12:33,820 --> 00:12:35,880
which was just recently.

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00:12:35,880 --> 00:12:38,870
So this one lasts
about 10 minutes,

185
00:12:38,870 --> 00:12:40,680
and you shall should watch it.

186
00:12:40,680 --> 00:12:44,430
And I've asked some
questions about it

187
00:12:44,430 --> 00:12:45,390
in the study questions.

188
00:12:48,230 --> 00:12:54,090
As far as this meerkat video,
I posted this a while back,

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00:12:54,090 --> 00:12:57,760
but some of you may
not have seen it.

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00:12:57,760 --> 00:13:00,900
These are questions
on this meerkat video,

191
00:13:00,900 --> 00:13:03,640
and I want you to answer
these questions by Friday

192
00:13:03,640 --> 00:13:05,170
and turn it in as homework.

193
00:13:05,170 --> 00:13:07,760
I posted it already.

194
00:13:11,620 --> 00:13:14,420
First of all, I want to know
about interactions between

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00:13:14,420 --> 00:13:17,040
different species .

196
00:13:17,040 --> 00:13:18,810
How do different
species communicate

197
00:13:18,810 --> 00:13:23,480
with each other and interact?

198
00:13:23,480 --> 00:13:26,550
Give a couple of
examples of communication

199
00:13:26,550 --> 00:13:27,800
among the meerkats.

200
00:13:27,800 --> 00:13:29,210
Very important in the video.

201
00:13:29,210 --> 00:13:32,130
If you watch it,
you can't miss that.

202
00:13:32,130 --> 00:13:36,810
Similarly, describe two examples
of altruistic helping behaviors

203
00:13:36,810 --> 00:13:38,220
among meerkats.

204
00:13:38,220 --> 00:13:40,335
Again, it's obvious in the film.

205
00:13:44,570 --> 00:13:47,610
And then I want you to
describe two behaviors that

206
00:13:47,610 --> 00:13:50,193
appear to be fixed-action
patterns used in foraging when

207
00:13:50,193 --> 00:13:51,970
these animals are
looking for food.

208
00:13:51,970 --> 00:13:53,780
And again, very obvious video.

209
00:13:53,780 --> 00:13:57,630
They spend quite a
bit of time on it.

210
00:13:57,630 --> 00:14:00,020
And I'm asking for
the major adaptation

211
00:14:00,020 --> 00:14:02,560
of the species for predators.

212
00:14:02,560 --> 00:14:05,620
Can't miss that either.

213
00:14:05,620 --> 00:14:08,100
The last one is
one that you might

214
00:14:08,100 --> 00:14:10,550
have a little more
difficult with.

215
00:14:10,550 --> 00:14:12,260
There are some
inaccuracies in the way

216
00:14:12,260 --> 00:14:14,560
they portray meerkat
behavior-- and remember,

217
00:14:14,560 --> 00:14:17,520
this was done for public
television-- George Page isn't

218
00:14:17,520 --> 00:14:19,920
an animal behaviorist,
but it's still

219
00:14:19,920 --> 00:14:22,360
pretty good in
making animal videos,

220
00:14:22,360 --> 00:14:23,860
and they have good consultants.

221
00:14:23,860 --> 00:14:26,810
But they did miss some
things that are important,

222
00:14:26,810 --> 00:14:30,890
and some of these have been
subject to scientific study

223
00:14:30,890 --> 00:14:31,610
in recent years.

224
00:14:31,610 --> 00:14:34,590
You can easily find it
using Google Scholar,

225
00:14:34,590 --> 00:14:38,160
but I've also put a
couple of articles

226
00:14:38,160 --> 00:14:43,080
I found in my own searches
on meerkats on the website,

227
00:14:43,080 --> 00:14:46,475
and one of them is directly
relevant to this question.

228
00:14:56,490 --> 00:15:00,410
This content has been removed
due to copyright restrictions.

229
00:15:00,410 --> 00:15:02,320
See the readings
and feelings page

230
00:15:02,320 --> 00:15:04,130
for information
about this material.

231
00:15:10,640 --> 00:15:13,790
PROFESSOR: The closely
related mongoose in India

232
00:15:13,790 --> 00:15:18,110
is actually kept by
Indians as a pet,

233
00:15:18,110 --> 00:15:21,354
because it's
protection from cobras.

234
00:15:21,354 --> 00:15:22,645
They'll actually killed cobras.

235
00:15:25,220 --> 00:15:28,830
It's a little larger
than the meerkat.

236
00:15:38,130 --> 00:15:43,860
Scott starts out by
defining communication

237
00:15:43,860 --> 00:15:46,640
as an intentional
transfer of information,

238
00:15:46,640 --> 00:15:48,050
either voluntary or involuntary.

239
00:15:52,430 --> 00:15:58,160
And he points out that honesty
of the communication can vary.

240
00:15:58,160 --> 00:16:02,110
You can have dishonest
communication.

241
00:16:02,110 --> 00:16:05,900
Because individuals don't do
things just for the group.

242
00:16:05,900 --> 00:16:09,070
They do it for themselves,
and sometimes they

243
00:16:09,070 --> 00:16:11,410
have an advantage by
fooling the others.

244
00:16:14,090 --> 00:16:17,370
When their communications
are detected by a predator,

245
00:16:17,370 --> 00:16:20,230
then of course it's
a non-adaptive use

246
00:16:20,230 --> 00:16:22,960
of their attempts
to communicate,

247
00:16:22,960 --> 00:16:24,360
so it's not intentional.

248
00:16:24,360 --> 00:16:27,475
So he doesn't include that as
part of animal communication.

249
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You don't always have
auditory communication.

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00:16:35,920 --> 00:16:39,060
Most frog and toad communicate
by auditory signals,

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but there's one species of
frog in Panama that doesn't.

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It's the Panamanian golden frog.

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It lives in very noisy streams.

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00:16:58,190 --> 00:17:01,010
He calls it frog
semaphore, because they're

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00:17:01,010 --> 00:17:05,400
making signals with their limbs.

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00:17:05,400 --> 00:17:08,390
And can you think
of other species

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00:17:08,390 --> 00:17:09,885
that use visual communication?

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00:17:12,400 --> 00:17:17,579
Think of animals that live
or forage long distances

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00:17:17,579 --> 00:17:19,569
from each other.

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00:17:19,569 --> 00:17:24,740
And if it's not always easy to
communicate by auditory means,

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00:17:24,740 --> 00:17:27,260
visual means might be better.

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For example, giraffes.

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00:17:30,410 --> 00:17:35,760
We know that birds depend
mainly on visual communication

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00:17:35,760 --> 00:17:37,990
with each other, but
auditory communication

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00:17:37,990 --> 00:17:39,340
is probably equally important.

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In humans, we
sometimes aren't very

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aware of how much
of our communication

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is actually visual.

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It's often called body language.

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It's nonverbal, and it's
very common in combination

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with auditory communication.

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This is the Panamanian
golden frog.

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It's a Very beautiful animal.

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There's always some kind
of communication involved

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00:18:16,385 --> 00:18:22,220
in courtship behavior,
and some animals

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00:18:22,220 --> 00:18:29,300
evolved specific
courtship behavior

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00:18:29,300 --> 00:18:33,540
that's based on exploiting
sensory, basically

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00:18:33,540 --> 00:18:38,640
innate releasing mechanisms
of the opposite sex.

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And I'll give you a couple
of examples of sensory export

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00:18:43,900 --> 00:18:51,040
exploitation in the
insects, but in the book,

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00:18:51,040 --> 00:18:55,760
Scott starts by describing
a species of orchid that

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resembles certain
female insects,

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00:18:58,000 --> 00:18:59,760
and it's very interesting.

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This is a paper that I found
in American Naturalist 2008.

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Orchid sexual deceit provokes
ejaculation in insects.

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00:19:17,430 --> 00:19:19,690
And if it does
that, the question

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was, why do they keep doing it?

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They not only
waste sperm, but it

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00:19:32,200 --> 00:19:33,825
might keep them from
actually mating.

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00:19:36,730 --> 00:19:44,030
And they show that
orchid species that

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00:19:44,030 --> 00:19:48,230
provoke this extreme
pollinator behavior actually

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00:19:48,230 --> 00:19:51,760
have the highest
pollination success.

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00:19:51,760 --> 00:19:54,050
So the orchid's
doing really well.

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00:19:54,050 --> 00:19:57,860
So how can the deception
persist, because of the costs

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00:19:57,860 --> 00:19:58,610
to the pollinator?

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00:20:01,580 --> 00:20:05,950
He points the author's point
out that the sexually deceptive

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00:20:05,950 --> 00:20:11,360
orchid pollinators
are almost always

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00:20:11,360 --> 00:20:14,930
solitary and
haplodiploid species.

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00:20:14,930 --> 00:20:20,880
That means that if eggs are not
fertilized, they become males.

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00:20:20,880 --> 00:20:22,955
The develop into males.

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00:20:22,955 --> 00:20:24,580
If they're fertilized,
they can develop

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00:20:24,580 --> 00:20:26,300
into females that can reproduce.

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00:20:29,460 --> 00:20:33,000
So female insects deprived of
matings by orchid deception

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00:20:33,000 --> 00:20:36,360
could still produce male
offspring, and that may even

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00:20:36,360 --> 00:20:40,085
enhance the orchid
pollination, to get more males.

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00:20:43,780 --> 00:20:48,353
Back to the water mites
that I mention in question.

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00:20:52,450 --> 00:20:54,290
The courtship display
of the male water

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00:20:54,290 --> 00:20:59,270
mite-- it uses vibrations
on the water surface that

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00:20:59,270 --> 00:21:04,640
resemble the vibrations produced
by prey that these water

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00:21:04,640 --> 00:21:05,640
mites feed on.

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00:21:14,550 --> 00:21:16,370
Here's a picture
of the water mites.

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00:21:19,580 --> 00:21:24,710
And you find the same thing in
this insect, that little insect

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that walks on the surface
water using surface tension,

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00:21:31,420 --> 00:21:35,410
the male water strider
also uses water surface

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00:21:35,410 --> 00:21:37,960
signals that trick females
into approaching them,

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00:21:37,960 --> 00:21:40,240
as if they were prey.

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00:21:40,240 --> 00:21:42,450
And as soon as the
female's close enough,

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00:21:42,450 --> 00:21:49,620
the male forcefully
initiates mating.

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00:21:49,620 --> 00:21:51,960
A kind of rape
behavior is actually

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00:21:51,960 --> 00:21:58,940
pretty common in insects, and
some other species as well.

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00:21:58,940 --> 00:22:02,445
So that's a kind of exploiting
the innate releasing mechanisms

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00:22:02,445 --> 00:22:03,290
of the female.

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00:22:10,590 --> 00:22:11,760
We might have to end here.

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00:22:11,760 --> 00:22:16,320
I want to talk about the
female Swordtail fish.

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00:22:16,320 --> 00:22:19,075
It's commonly kept by
people in aquariums,

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00:22:19,075 --> 00:22:21,180
that like tropical fish.

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00:22:24,530 --> 00:22:27,110
And I want to mention
the kind of related

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00:22:27,110 --> 00:22:28,460
things in human behavior.

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00:22:28,460 --> 00:22:31,700
Now there's the swordfish
male at the top,

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00:22:31,700 --> 00:22:35,260
and the female down below.

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00:22:35,260 --> 00:22:41,810
The female will select
for mating males

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00:22:41,810 --> 00:22:44,067
with the long tails.

333
00:22:44,067 --> 00:22:45,650
They don't have to
have bigger bodies.

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00:22:45,650 --> 00:22:47,270
They just have to
have a long tail,

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00:22:47,270 --> 00:22:50,710
because their innate
releasing mechanism responds

336
00:22:50,710 --> 00:22:56,112
to a huge male with a short
tail the same way she responds

337
00:22:56,112 --> 00:22:57,570
to a smaller male
with a long tail.

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00:23:00,820 --> 00:23:03,450
We're talking here
about sexual selection,

339
00:23:03,450 --> 00:23:06,710
how that female has
evolved to respond

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00:23:06,710 --> 00:23:10,280
to specific characteristics
of the male that don't seem

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00:23:10,280 --> 00:23:14,650
directly related to the
male's ability to reproduce.

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00:23:14,650 --> 00:23:20,310
It's simply related to his
ability to attract a female.

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00:23:20,310 --> 00:23:21,990
And because of
sexual selection, it

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00:23:21,990 --> 00:23:25,460
makes you wonder:
what limits it?

345
00:23:25,460 --> 00:23:28,490
Why doesn't the
swordfish male develop

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00:23:28,490 --> 00:23:30,385
longer and longer tails?

347
00:23:35,170 --> 00:23:37,150
And you get a lot of
variability in this.

348
00:23:40,440 --> 00:23:45,330
And you find it in humans, too.

349
00:23:45,330 --> 00:23:48,686
One example of it is right
on the 920 home page, where

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00:23:48,686 --> 00:23:53,440
I have a picture that I took
at the Boston Zoological Park.

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00:23:53,440 --> 00:23:56,930
It shows a male peacock--
beautiful example

352
00:23:56,930 --> 00:23:59,000
of sexual selection.

353
00:23:59,000 --> 00:24:02,020
Why does the peacock have
such beautiful feathers

354
00:24:02,020 --> 00:24:05,250
that he displays?

355
00:24:05,250 --> 00:24:08,560
It's certainly not helping
him avoid predators.

356
00:24:08,560 --> 00:24:10,665
In fact, it tends
to do the opposite.

357
00:24:13,430 --> 00:24:17,250
It can cost the
individual by reducing

358
00:24:17,250 --> 00:24:20,587
his reproductive potential,
making it more likely

359
00:24:20,587 --> 00:24:21,920
that a predator will attack him.

360
00:24:21,920 --> 00:24:27,220
And so that definitely
limits how far that can go.

361
00:24:27,220 --> 00:24:29,850
And these are just some
examples in humans.

362
00:24:29,850 --> 00:24:33,730
This will be where we end.

363
00:24:33,730 --> 00:24:35,020
It's obvious, some of it.

364
00:24:35,020 --> 00:24:39,620
Physical characteristics
of one sex can be enhanced.

365
00:24:39,620 --> 00:24:41,500
Humans do this all the time.

366
00:24:41,500 --> 00:24:44,150
It's not directly related
to reproductive abilities,

367
00:24:44,150 --> 00:24:48,040
but of course many aspects
of a human female that

368
00:24:48,040 --> 00:24:51,547
attract males are related to
reproductive potential, but not

369
00:24:51,547 --> 00:24:52,380
all characteristics.

370
00:24:55,730 --> 00:24:58,510
It also affects behavior,
like young males

371
00:24:58,510 --> 00:25:01,790
will drive fast, fancy cars.

372
00:25:01,790 --> 00:25:05,090
Very common in
your high schools.

373
00:25:05,090 --> 00:25:07,920
Other males may wear, the
older males especially,

374
00:25:07,920 --> 00:25:11,190
might wear Rolex
watches, because what

375
00:25:11,190 --> 00:25:13,430
females are interested.

376
00:25:13,430 --> 00:25:17,160
Not Rolex watches, but the
ability of the male to provide.

377
00:25:17,160 --> 00:25:21,215
And women in some
areas and some cultures

378
00:25:21,215 --> 00:25:24,210
will wear gold bangles,
diamond earrings

379
00:25:24,210 --> 00:25:28,290
and so forth, just wear
the latest fashions as part

380
00:25:28,290 --> 00:25:31,360
because it makes
her more attractive.

381
00:25:31,360 --> 00:25:34,640
Of course, it has
other purposes, too.

382
00:25:34,640 --> 00:25:37,990
There's a lot of cultural
and local variations.

383
00:25:37,990 --> 00:25:44,410
OK, so we will talk a lot
more about sexual selection.

384
00:25:44,410 --> 00:25:46,540
We'll start here next time.

385
00:25:46,540 --> 00:25:49,380
And I do have a video
showing many examples

386
00:25:49,380 --> 00:25:50,380
of sexual selection.

387
00:25:50,380 --> 00:25:54,730
I don't know how far
we get that next time.

388
00:25:54,730 --> 00:25:57,300
But if we don't get
to it next time,

389
00:25:57,300 --> 00:26:00,620
it comes up again when
we study sociobiology,

390
00:26:00,620 --> 00:26:03,030
so we'll study it again.