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Hello, thank you
very much for coming.

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I'd like to begin by asking you
to do something for me.

3
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Would you, please,
put your hands to your head,
and very gently feel your own head.

4
00:01:01,380 --> 00:01:04,450
Now, that might seem like a
very easy thing to do.

5
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But, I can assure you -
okay put them down now -
I can assure you that
a man-made instrument that did that

6
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would be a very, very
difficult thing to make,
a very, very expensive thing to make.

7
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As your arms go up there,
precision instruments in your muscles,

8
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are monitoring the exact position
of all your muscles.

9
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Thousands of sensory endings
in your fingers

10
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are feeling the exact texture
of your hair, the shape of your ears,
the shape of your skull.

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Your brain is measuring
the width of your skull
with the greatest of precision.

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If a human factory
were to manufacture

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an instrument, a robot arm capable of
doing that, it would cost something
in the region, I would think,

14
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of 100 million pounds.

15
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Now, think about
what is between your hands
when you do that:

16
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your brain.

17
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The brain is a kind of computer,
but it's a computer such as

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no human factory
has ever turned out.

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If we ever do succeed in making a computer
with the performance of a human brain,

20
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I would guess that the research
and development costs
would be in the region of
thousands of millions of pounds.

21
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Yet, heads like yours,
and hands like yours

22
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are manufactured daily,
millions of times over.

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A woman can do it
with no research,

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only nine months development,
and only a little help from a friend.

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Life makes the wonders of technology
seem commonplace.

26
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So, where does life come from?
What is it?

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Why are we here? What are we for?
What is the meaning of life?

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There's a conventional wisdom,
which says

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that science has nothing to say
about such questions.

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All I can say is that,
if science has nothing to say,

31
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it's certain that no other discipline
can say anything at all.

32
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But, in fact, of course,
science has a great deal

33
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to say about such questions.

34
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And, that's what these five lectures
are going to be about.

35
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Life grows up in the Universe
by gradual degrees - evolution.

36
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And, we grow up in our understanding
of our origins and our meaning.

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Of all the world's societies,
the majority

38
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have practiced some form
of ancestor worship.

39
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This is a totem of one particular cult
of ancestor worship.

40
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Now, I'm not going to encourage you
to worship your ancestors,

41
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I'm not going to encourage you
to worship anything.

42
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But, it is true that ancestors hold the key
to understanding the meaning of life.

43
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You might think it is easy enough
to be an ancestor.

44
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It's easy enough to reproduce,
or relatively easy.

45
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But, to become an ancestor
you've got to have descendants,
alive many generations hence.

46
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And that is more of a tall order.

47
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We can think about it
by going back

48
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to one of the simplest sorts
of animals - a bacterium -

49
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right back at the beginning of life.

50
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And think about how many bacteria
there would be

51
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after, say,
50 generations of reproduction.

52
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We're going to illustrate this
by folding paper.

53
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Now, I wonder if I could have
two volunteers to fold the paper.

54
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Right, there and,
yes, there.

55
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Come down here, please,
and take the paper from Bryson.

56
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Right, now,
every time you fold the paper,

57
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that's going to represent
one generation of reproduction.

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So, we start with one bacterium,
that's one thickness of paper.

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Now, fold it.

60
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If you both hold at the same end,
it might be easier.

61
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Now we have got two.

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That's right.
Please, sit down there,
that's right, fold it.

63
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And then,
fold it across this way.

64
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Thank you.

65
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And just go on folding it
until you have done it 50 times.

66
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So, what have you got to now?
Four?

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Four bacteria?
Right, eight.

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Sixteen.

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Thirty-two.

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What, can't you do any more?

71
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Right, that's it probably -
Alright, it looks as though
they're not going to make it.

72
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We're going to have to resort
to mathematics to calculate

73
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how thick that paper would be.

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Okay, thank you very much,
do sit down.

75
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In every generation, of course,

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the thickness of the paper doubles.

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So, we go 2, 4, 8, 16, 32, 64,.
and so on.

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We go on multiplying by
two 50 times.

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After we've multiplied by two

80
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50 times, what have we got?

81
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We've got a very big number, indeed.
We got, in fact,

82
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a thousand trillion -
that's one with 15 zeros after it.

83
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The sheet of paper is a tenth
of a millimeter thick.

84
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If you multiply that by a thousand trillion,
you end up with -

85
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I've got it written down here:

86
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100 million kilometers.

87
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The thickness of the paper
would take us out to the orbit of Mars.

88
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The number of bacteria after
a mere 50 generations is that.

89
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But, 50 generations
is nothing to bacteria;

90
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they can get through 50 generations
in a day.

91
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After about a week,
the number of bacteria
would be more than

92
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a billion times the number of atoms
in the known Universe.

93
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Well, that's called exponential growth -

94
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what mathematicians call it
exponential growth -

95
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we'll come back to it.

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Needless to say,
it doesn't happen,

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to the same extent at least.

98
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After a point,
natural factors come to regulate

99
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the size of the population
of bacteria.

100
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Our original assumption

101
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that it was easy to become
an ancestor was wrong.

102
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Only an elite become ancestors.

103
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You can do the same sort
of calculation,

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by the way, for ourselves -

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or, for elephants,
as Charles Darwin did -

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and it just takes a little bit longer,

107
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but the same idea is there.

108
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After a fairly short number
of years,

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you'll find that the entire Universe
is filled with elephant flesh,

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or human flesh, or whatever it is.

111
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So, it follows

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that most organisms
that are born must die
without becoming ancestors,

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without becoming distant ancestors.

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Only an elite are destined
to become ancestors.

115
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Well, some people
do not like the word elite.

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But, I just mean that

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it won't be all luck

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which ones end up ancestors.

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The ones that are going
to be ancestors

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will tend to be the ones
that are good at it.

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They'll tend to be the ones
that have what it takes;

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that have what it takes
to survive, to get a mate,

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to reproduce,
to avoid being eaten,

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to find food,
to be good parents, and so on.

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That's really just a way
of putting

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Darwin's Theory of Natural Selection.

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Because we that are left,
we that survived,

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will have inherited the genes
of a long line of successful ancestors.

129
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We'll have inherited whatever
it took

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to make them successful as ancestors.

131
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But, for the moment,
I want to emphasize something else,

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which is that
we are lucky to be alive.

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We're lucky to be alive

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because it would have been so easy
for our ancestors not to have been here.

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It would have been so
astronomically probable
that somebody else

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would have been here,
rather than us.

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And we're lucky to be alive

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for another reason.

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Think about it this way:

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the Universe is about
14 thousand million years old.

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That's 140 million centuries.

142
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Some 60 million centuries
from now,

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the Sun will become a Red Giant,
and engulf the Earth.

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So, there are about
200 million centuries

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from the origin of the Universe
to the end of the world.

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Now, of the 140 million centuries
since time began,

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every one of them was once
the present century.

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And, of the 60 million centuries
to the end of the world,

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every one of them
will be the present century.

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The present century
is a tiny spotlight

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inching its way
along a gigantic ruler of time.

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Everything before the spotlight
is in the darkness of the dead past.

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Everything after the spotlight
is in the darkness of the unknown future

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We live in the spotlight.

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Of all the 200 million centuries
along the ruler of time,

156
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199 million 999 thousand
999 centuries are in darkness.

157
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Only one is lit up,

158
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and that's the one
in which we happen,

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by sheer luck, to be alive.

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The odds against our century's
happening to be the present century

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are the same as the odds
against a penny

162
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tossed out at random on the road
from London to Istanbul

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happening to fall
on a particular ant.

164
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Well, in spite of those odds,

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you may have noticed that
we are, as a matter of fact, here,

166
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and it really, of course,
it's not surprising, because

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we are the ones
doing the calculation.

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If somebody has just done the calculation
that we've just done,

169
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then that somebody,
of course, has to be alive.

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Nevertheless,
I do feel rather lucky to be alive,

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and for another reason too.

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Now, the smoke going into
the beam represent stars.

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Each particle of smoke
represents one star.

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And, you can think of the beam
as a gigantic searchlight,

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beamed out from space and signaling

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from our planet,
in the hope that somebody else

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on another world
will pick up the message.

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We don't know how likely it is
that there is anybody up there.

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We can say that, if our message
does hit another planet

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then, almost certainly,
it will be so far away

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that if those people up there
had a telescope looking back at us,

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then what they would be seeing
is not us at all,

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but the dinosaurs that were here
65 millions years ago.

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Or, in other words, our message
will reach people millions of years
into the future.

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People vary in their estimates of
how much life there is likely to be,

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how likely there is to be life
on other planets.

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Some people think that,
some scientists think

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that as many as 10 million
technologically advanced
civilizations are out there.

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Other people feel that this life,
here, on this planet,
is the only life that there is.

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00:12:02,640 --> 00:12:04,780
But, even on the most extremely
optimistic estimate,

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it's still true that most
of those worlds out there
are going to be deserts.

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00:12:08,580 --> 00:12:14,820
Most of them are not going to
have any life on them at all;
nor even any possibility
of life on them, at all.

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Now, imagine a spaceship
full of sleeping,

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perhaps deep frozen, explorers,
would-be colonists of another world.

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Perhaps they are the last
population of Earth,

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despairing that Earth
is about to be destroyed.

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Sending out a colony
to look for another planet,

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anywhere, in order
to carry on humanity.

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Imagine the spaceship

200
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turns out to be
almost unthinkably lucky.

201
00:12:43,780 --> 00:12:48,250
It does chance to arrive
at one of the very, very rare planets

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00:12:48,390 --> 00:12:51,520
capable of sustaining our kind of life.

203
00:12:51,760 --> 00:12:54,660
A planet of the right temperature,
with oxygen, and so on.

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The passengers wake up
and stumble out into the light.

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And they see a beautiful world
of waterfalls, green leaves, mountains,

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00:13:07,010 --> 00:13:10,540
colored animals and birdlike
creatures flitting about.

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00:13:13,680 --> 00:13:15,810
Can you imagine how it would feel

208
00:13:15,910 --> 00:13:16,850
if you woke up,

209
00:13:17,350 --> 00:13:20,520
100 million years of sleep
in a spaceship,

210
00:13:21,120 --> 00:13:23,290
and found yourself
on such a world?

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00:13:23,890 --> 00:13:27,930
A whole new world,
a world such as you could live on,
a beautiful world.

212
00:13:28,330 --> 00:13:30,000
You'd surely bless your luck

213
00:13:30,100 --> 00:13:32,030
in arriving on such a rare world,

214
00:13:32,160 --> 00:13:34,170
walk around in a daze, a trance,

215
00:13:34,370 --> 00:13:37,640
unable to believe the wonders
that met your eyes and ears.

216
00:13:38,470 --> 00:13:41,810
Well, this will almost certainly
never happen to us.

217
00:13:42,470 --> 00:13:45,240
And yet, in a way, it is just
what has happened to us.

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00:13:45,880 --> 00:13:49,510
We have woken up
after hundreds of millions
of years of sleep.

219
00:13:50,120 --> 00:13:53,690
Admittedly, we didn't arrive by a
spaceship, we arrived by being born,

220
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but the wonder of the planet,
the dazzling surprise of it,

221
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is the same,
whether we arrived by spaceship

222
00:14:00,160 --> 00:14:01,290
or by birth canal.

223
00:14:01,590 --> 00:14:04,400
We are amazingly lucky
to be here,

224
00:14:04,530 --> 00:14:05,200
privileged,

225
00:14:05,860 --> 00:14:07,770
and we must not waste
that privilege.

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00:14:09,000 --> 00:14:12,270
Here, it seems to me,
lies the best answer
to those narrow-minded people

227
00:14:12,470 --> 00:14:15,410
who are always carping on
about the use of science.

228
00:14:16,210 --> 00:14:19,440
The founder of these Christmas
lectures, Michael Faraday,

229
00:14:19,980 --> 00:14:23,680
was once asked
by the then prime minister,
Sir Robert Peel,

230
00:14:24,180 --> 00:14:26,220
"what was the use of science?"

231
00:14:27,550 --> 00:14:31,190
"Sir," Faraday replied,
"what is the use of a baby?"

232
00:14:41,770 --> 00:14:43,070
She says her name's Hannah.

233
00:14:47,970 --> 00:14:50,410
Faraday said
"what is the use of a baby?"

234
00:14:50,980 --> 00:14:52,740
and I've always thought that,
what he meant by that,

235
00:14:52,880 --> 00:14:55,550
must be that a baby
has such potential.

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00:14:56,080 --> 00:15:00,990
It may not be able to do very much now,
but it will be able to do a lot.

237
00:15:04,220 --> 00:15:06,830
But it's also possible
that what Faraday meant

238
00:15:07,290 --> 00:15:10,530
was that there's no point
in bringing a baby into the world,

239
00:15:10,630 --> 00:15:14,270
if all it's going to do
is work to go on living,

240
00:15:14,370 --> 00:15:17,570
to go on living, and work
to go on living, again.

241
00:15:17,700 --> 00:15:19,940
If that's all point of life,
then what are we here for?

242
00:15:20,170 --> 00:15:21,810
There's got to be more
to it than that.

243
00:15:24,110 --> 00:15:25,510
Thank you very much.

244
00:15:36,290 --> 00:15:39,160
Some of life must be devoted
to living itself,

245
00:15:39,460 --> 00:15:40,860
some of life must be devoted

246
00:15:40,990 --> 00:15:43,060
to doing something worthwhile
with one's life,

247
00:15:43,160 --> 00:15:45,160
not just to perpetuating it.

248
00:15:45,960 --> 00:15:47,670
This is, of course,
how people, quite rightly,

249
00:15:47,800 --> 00:15:50,370
justify spending taxpayers'
money on the arts

250
00:15:50,470 --> 00:15:52,500
and on conserving rare species.

251
00:15:52,970 --> 00:15:56,010
But sometimes,
when we justify academic
science on these grounds,

252
00:15:56,340 --> 00:15:59,680
people get rather philistine
and say things like:

253
00:15:59,910 --> 00:16:02,250
"oh, so you think the government
should spend the money on

254
00:16:02,350 --> 00:16:05,250
your scientific research
because your research
is fun for you, do you?"

255
00:16:06,150 --> 00:16:08,020
'Fun' isn't really the right word,
is it?

256
00:16:08,990 --> 00:16:11,490
After sleeping for
140 million centuries

257
00:16:11,590 --> 00:16:13,660
we have finally woken up
in the Universe.

258
00:16:13,760 --> 00:16:15,730
We have opened our eyes
on a wonderful planet,

259
00:16:15,990 --> 00:16:17,760
filled with color,
teeming with life.

260
00:16:18,230 --> 00:16:21,000
Before very long, we shall
have to close our eyes again.

261
00:16:21,600 --> 00:16:24,300
Finding out about the Universe
in which we have woken up,

262
00:16:24,600 --> 00:16:25,970
answering questions like:

263
00:16:26,200 --> 00:16:29,370
What are we doing here?
What is this Universe
in which we've woken up?

264
00:16:29,940 --> 00:16:32,540
What is life, and what,
if anything, is it for?

265
00:16:33,210 --> 00:16:36,720
Surely the enterprise that answers
questions like that, science,

266
00:16:37,250 --> 00:16:39,380
deserves a better title
than "fun".

267
00:16:40,450 --> 00:16:43,260
Put like that,
doesn't science sound, to you,

268
00:16:43,360 --> 00:16:46,460
like about the most worthwhile way
in which you could possibly spend

269
00:16:46,660 --> 00:16:48,160
your short time in the spotlight?

270
00:16:50,330 --> 00:16:53,200
Now, of course,
if you spent all your time
wandering around the world,

271
00:16:53,300 --> 00:16:55,700
gasping at everything and saying -
"How wonderful, how amazing!

272
00:16:56,740 --> 00:16:59,840
I've woken up
after a 100 million centuries,
what a trip!"

273
00:17:00,170 --> 00:17:03,010
people would think you were a bit odd,
and you might even get arrested.

274
00:17:03,140 --> 00:17:06,010
We do, of course,
have an ordinary life to get on with,

275
00:17:06,140 --> 00:17:09,410
we do have a living to earn,
we've got to earn our living being

276
00:17:09,550 --> 00:17:11,980
a solicitor, a lavatory cleaner
or something like that.

277
00:17:12,350 --> 00:17:16,090
But, nevertheless, it is worthwhile,
also, from time to time

278
00:17:16,220 --> 00:17:20,860
shaking off the anesthetic
of familiarity, and awakening

279
00:17:20,960 --> 00:17:24,500
to the wonder that is really
all around us all the time.

280
00:17:25,360 --> 00:17:27,600
So, how are we going to shake off
the anesthetic?

281
00:17:28,400 --> 00:17:30,770
We can't actually
go to another planet,

282
00:17:30,870 --> 00:17:32,400
but fortunately we do not need to.

283
00:17:32,670 --> 00:17:35,270
Because we can go
to regions of our own planet

284
00:17:35,370 --> 00:17:39,110
which are so unfamiliar that
they almost might be another planet.

285
00:17:40,310 --> 00:17:42,180
This is another planet.
This is Jupiter.

286
00:17:42,310 --> 00:17:44,120
It's a fantasy picture of Jupiter,

287
00:17:44,250 --> 00:17:46,550
conceived by the astronomer
Carl Sagan,

288
00:17:47,120 --> 00:17:49,050
and he is imagining life forms

289
00:17:49,150 --> 00:17:53,190
that might live in the upper atmosphere
of Jupiter, called "floaters".

290
00:17:54,260 --> 00:17:56,060
If there were life forms in Jupiter,

291
00:17:56,260 --> 00:17:58,130
they would be called Jovians.

292
00:17:58,630 --> 00:18:01,230
So let's use word "By-Jovians"

293
00:18:01,470 --> 00:18:07,410
for creatures on this Earth
that are so odd that they might
almost be from another planet.

294
00:18:09,240 --> 00:18:12,180
Here, for instance,
is a deep sea fish.

295
00:18:12,980 --> 00:18:15,280
You would have to go on a
long journey in a submarine

296
00:18:15,410 --> 00:18:17,250
in a diving suit,
to see that fish.

297
00:18:18,580 --> 00:18:21,190
This is exactly the
same species of fish.

298
00:18:21,550 --> 00:18:23,890
The only difference is
that this has just had
a meal and that hasn't:

299
00:18:24,160 --> 00:18:27,660
that's looking for a meal
as you can tell from its ravening jaws.

300
00:18:29,830 --> 00:18:32,260
These creatures look
pretty monstrous to us.

301
00:18:32,630 --> 00:18:35,900
I suppose by their standards
we might be thought monstrous.

302
00:18:37,940 --> 00:18:39,910
This one is another deep sea fish,

303
00:18:40,040 --> 00:18:41,740
this has a luminous lure,

304
00:18:42,070 --> 00:18:44,910
made by bacteria,
luminous bacteria,

305
00:18:45,410 --> 00:18:50,420
and it uses this as a bait
to lure prey into its vicinity,

306
00:18:50,520 --> 00:18:56,560
it then slams its fishing rod
down in the vicinity of its jaws,
opens them and gulps in the prey.

307
00:18:57,360 --> 00:19:00,190
A very weird, By-Jovian creature.

308
00:19:02,560 --> 00:19:05,100
We don't even have to go
to the deep sea, as a matter of fact,

309
00:19:05,330 --> 00:19:07,100
to see pretty weird creatures.

310
00:19:07,830 --> 00:19:11,270
I was once attending a lecture
by a colleague who worked on octopuses,

311
00:19:11,940 --> 00:19:16,440
and he said the fascination with octopuses
is that "these are the Martians."

312
00:19:17,180 --> 00:19:19,340
And he meant that, look at this,

313
00:19:19,480 --> 00:19:21,780
this creature could easily
be from Mars, couldn't it?

314
00:19:22,510 --> 00:19:25,320
Watch the color change;
that creature, that cuttlefish -

315
00:19:25,450 --> 00:19:28,550
it's not an octopus, it's a cuttlefish -
is changing color at will.

316
00:19:28,690 --> 00:19:30,290
Look at the waves of color
falling over it.

317
00:19:30,490 --> 00:19:32,760
That's not shadows falling
over it from the outside.

318
00:19:32,890 --> 00:19:36,330
That's internally controlled
by the animal, by its own nervous system.

319
00:19:36,530 --> 00:19:42,470
It's registering emotion,
signaling to other creatures,
others of its own species.

320
00:19:43,170 --> 00:19:44,640
By-Jovian creature.

321
00:19:49,540 --> 00:19:51,140
We don't even have to go
to the sea at all.

322
00:19:52,610 --> 00:19:58,720
These are all insects; they all
have the same basic insect body plan,

323
00:19:58,980 --> 00:20:02,320
which they inherited from
a common insect ancestor,

324
00:20:02,550 --> 00:20:05,390
which lived about
350 million years ago.

325
00:20:05,660 --> 00:20:10,500
They all look like insects,
because they've inherited
those attributes.

326
00:20:10,730 --> 00:20:13,670
They all have a head,
a thorax, an abdomen,

327
00:20:13,770 --> 00:20:17,770
and, in this case,
it's enormously elongated,
to look like a stick.

328
00:20:18,540 --> 00:20:21,810
Here, the same body
is flattened out in this bug,

329
00:20:22,110 --> 00:20:23,940
again the head, thorax, abdomen,

330
00:20:24,210 --> 00:20:27,050
three pairs of legs,
antennae, wings.

331
00:20:27,550 --> 00:20:31,050
Here, butterflies.
The same basic body plan,

332
00:20:31,220 --> 00:20:34,920
pulled and stretched,
kneaded into different shapes.

333
00:20:35,250 --> 00:20:36,860
But, basically, the same shape.

334
00:20:36,990 --> 00:20:40,660
They've never quite shaken off
their ancestral influence.

335
00:20:42,060 --> 00:20:47,000
But, we were talking about shaking off
our anesthetic of soporific familiarity.

336
00:20:47,600 --> 00:20:51,100
And, another way to achieve the illusion
of waking up on a distant planet

337
00:20:51,240 --> 00:20:53,970
is to shrink ourselves,
to go on a different kind of journey,

338
00:20:54,070 --> 00:20:56,680
to a much smaller scale
than we're used to.

339
00:20:57,540 --> 00:20:59,210
This is a dust mite.

340
00:20:59,610 --> 00:21:04,150
It's the sort of thing that you've met
often in the carpets of your own home,
but didn't know it.

341
00:21:04,780 --> 00:21:08,490
It is hugely magnified
by an instrument like this,

342
00:21:08,720 --> 00:21:10,990
which is a scanning
electron microscope.

343
00:21:11,660 --> 00:21:13,860
And we can use the scanning
electron microscope

344
00:21:14,130 --> 00:21:17,400
just as though it was a telescope
pointing at some distant planet,

345
00:21:17,530 --> 00:21:19,260
so strange are the sights
that it shows us.

346
00:21:20,000 --> 00:21:24,700
I think we have a volunteer there
to work the electron microscope.

347
00:21:26,140 --> 00:21:27,340
Now, your name is?

348
00:21:27,440 --> 00:21:28,140
Louise. Louise.

349
00:21:28,240 --> 00:21:29,210
Do sit down, Louise.

350
00:21:29,980 --> 00:21:33,310
Now, on the screen at the moment
we have what looks like a jungle,

351
00:21:33,450 --> 00:21:35,580
we can think of this
as a jungle on another planet.

352
00:21:36,350 --> 00:21:38,880
Now, you know how to work
the joystick and navigate around,

353
00:21:39,080 --> 00:21:41,420
you also know
how to zoom out and in.

354
00:21:41,750 --> 00:21:45,220
What about zooming out, and seeing
what this jungle really is?

355
00:21:46,930 --> 00:21:47,960
Okay, let's go slowly, now.

356
00:21:48,090 --> 00:21:52,060
There are some curious rounded
objects there. Go further.

357
00:21:53,300 --> 00:21:55,300
Two little patches of rounded objects.

358
00:21:55,630 --> 00:21:58,570
Go further. Go on.

359
00:21:58,700 --> 00:22:01,340
Right, now, I think what we're seeing
is the head of a mosquito.

360
00:22:02,370 --> 00:22:08,180
There are the compound eyes,
lots of different facets
of the compound eyes on either side.

361
00:22:08,780 --> 00:22:12,150
In the middle are the sockets
of the antennae.

362
00:22:12,250 --> 00:22:15,120
Zoom out further.

363
00:22:15,220 --> 00:22:16,150
And there's the whole head;

364
00:22:16,290 --> 00:22:19,190
you can see the whole round head
with sockets for the antennae

365
00:22:19,490 --> 00:22:23,460
and the rounded compound eyes,
with all the different facets.

366
00:22:23,960 --> 00:22:28,170
Now, perhaps we could navigate
to a different insect.

367
00:22:29,030 --> 00:22:30,800
The machine
has been pre-programmed

368
00:22:30,900 --> 00:22:33,540
to move to a different part
of this strange landscape.

369
00:22:35,010 --> 00:22:38,310
And I hope we are going to see
something else in a minute,
what's this here?

370
00:22:41,110 --> 00:22:42,610
Looks like another jungle.

371
00:22:43,520 --> 00:22:47,990
So let's move around
and explore what we think it is.

372
00:22:53,030 --> 00:22:53,860
I can't see anything yet.

373
00:22:53,990 --> 00:22:55,090
Wait a minute,
let's zoom out a bit,

374
00:22:55,230 --> 00:22:56,860
and see whether we can see
better then.

375
00:22:57,330 --> 00:22:57,830
Again.

376
00:22:58,130 --> 00:22:58,830
Again.

377
00:22:59,200 --> 00:23:00,800
Oh, that's looking like something.

378
00:23:01,170 --> 00:23:04,040
I think that's a pair of wings,
off to the left side, isn't it?

379
00:23:04,670 --> 00:23:08,770
So, I think that might be the thorax
of an insect of some sort.

380
00:23:09,110 --> 00:23:11,410
Let's try moving that way
and see what we see.

381
00:23:12,580 --> 00:23:13,550
Other way.

382
00:23:15,110 --> 00:23:16,680
And speed it up a little bit.

383
00:23:17,950 --> 00:23:20,720
That's right.
Oh, that is the abdomen of a bee,
I would think.

384
00:23:20,990 --> 00:23:21,790
Go on.

385
00:23:22,790 --> 00:23:23,620
More.

386
00:23:24,590 --> 00:23:25,660
Now, what's that?

387
00:23:25,790 --> 00:23:27,660
There's something
curious poking out.

388
00:23:28,260 --> 00:23:30,630
Try to steer around
so that's in the middle.

389
00:23:31,660 --> 00:23:32,830
Other way.

390
00:23:35,200 --> 00:23:36,740
And then down a bit.

391
00:23:38,670 --> 00:23:40,340
Now zoom into it.

392
00:23:41,910 --> 00:23:43,780
Keep - I'll keep steering, shall I?

393
00:23:44,510 --> 00:23:45,910
Right, zoom in.

394
00:23:46,250 --> 00:23:48,880
You need a bit of focus,
I think. Can we do that?

395
00:23:50,550 --> 00:23:56,490
It looks to me like a head
of something else.

396
00:23:57,020 --> 00:23:58,860
Zoom out again.

397
00:24:04,200 --> 00:24:07,330
What that is, as a matter of fact,
is a tiny parasite.

398
00:24:07,530 --> 00:24:09,100
Thank you very much indeed,
Louise.

399
00:24:15,510 --> 00:24:19,110
It's a tiny insect parasite
called a Strepsipteran,

400
00:24:19,240 --> 00:24:21,010
which is parasitizing a bee,

401
00:24:21,150 --> 00:24:23,450
and what you saw
was the Strepsipteran

402
00:24:23,580 --> 00:24:28,220
poking out below the armor
plating of the bee, there.

403
00:24:28,350 --> 00:24:30,860
There's its compound eyes,
there's its body,

404
00:24:30,990 --> 00:24:34,190
and that is one armor plate
of the bee.

405
00:24:39,130 --> 00:24:41,130
So we have been on a journey

406
00:24:41,270 --> 00:24:45,800
using the scanning electron microscope
to the world of the very small,

407
00:24:46,170 --> 00:24:50,780
and that's another way
of capturing the strangeness
of our own world.

408
00:24:51,240 --> 00:24:54,450
Yet another way
is to go into our own bodies

409
00:24:54,580 --> 00:24:57,250
and look at the detailed structure
of our own bodies.

410
00:24:57,520 --> 00:25:02,290
For example, this is a picture
of a human brain.

411
00:25:02,390 --> 00:25:05,590
And each of these black things
is one brain cell.

412
00:25:05,720 --> 00:25:07,830
You can see how many they are -

413
00:25:07,930 --> 00:25:10,000
there are only a tiny fraction
stained to be seen here -

414
00:25:10,530 --> 00:25:14,570
and the bewildering forest
of interconnections between them.

415
00:25:15,370 --> 00:25:19,240
The total length of nerve cells
in a human brain,

416
00:25:19,640 --> 00:25:24,210
if laid end-to-end,
would stretch right round
the circumference of the world;

417
00:25:24,810 --> 00:25:26,980
not just once, but 25 times.

418
00:25:27,510 --> 00:25:30,480
Well, that's not in itself
a very interesting fact - for one thing,

419
00:25:30,620 --> 00:25:31,850
if you actually did that,

420
00:25:31,950 --> 00:25:36,720
and you sent a message
from one end of this vast,
great nerve to the other,

421
00:25:36,860 --> 00:25:39,790
it would take about 6 years
to get to the other end of the nerve.

422
00:25:40,560 --> 00:25:42,730
What's truly impressive
about the nervous system

423
00:25:42,830 --> 00:25:46,700
is not the sheer number of elements
but their connectedness.

424
00:25:46,830 --> 00:25:49,970
The complexity of the connections
is truly awesome.

425
00:25:50,070 --> 00:25:53,140
Here are just 4 or 3 nerve cells

426
00:25:54,170 --> 00:25:56,740
and these are the connections
between them.

427
00:25:56,880 --> 00:26:03,380
There are about 2000 wires
connecting each nerve cell
to each other nerve cell.

428
00:26:03,650 --> 00:26:08,820
So the total number of connections
in the brain must be about
200 million million.

429
00:26:09,320 --> 00:26:11,090
To put that into perspective:

430
00:26:11,460 --> 00:26:13,360
if we assume that
each of these connections

431
00:26:13,490 --> 00:26:15,990
is equivalent to one switching
unit of a computer,

432
00:26:16,400 --> 00:26:20,330
this gives the brain about 10 million times
as many switching elements

433
00:26:20,470 --> 00:26:22,800
as a typical desktop computer.

434
00:26:24,970 --> 00:26:27,510
Brains are impressive
because of the number

435
00:26:27,640 --> 00:26:28,940
and connections of their cells,

436
00:26:29,240 --> 00:26:31,680
but there are lots of other different
kind of cells in the body,

437
00:26:31,910 --> 00:26:33,950
and they all have the same
basic structure inside.

438
00:26:34,050 --> 00:26:36,680
This is a typical animal cell;

439
00:26:36,780 --> 00:26:38,380
a model of a typical animal cell,

440
00:26:38,950 --> 00:26:40,890
and it's not just a bag of juice.

441
00:26:41,190 --> 00:26:44,560
It's filled with membranes,
it has got a structure,
an internal structure.

442
00:26:44,960 --> 00:26:47,290
Each of these blue things here
is a membrane.

443
00:26:48,230 --> 00:26:50,530
And every cell has them,
in large amounts,

444
00:26:50,830 --> 00:26:55,270
such that the total area of membrane
inside a typical human body

445
00:26:55,830 --> 00:26:58,640
is about 200 acres,
that's a good-sized farm.

446
00:26:59,610 --> 00:27:00,540
What are they all doing?

447
00:27:00,640 --> 00:27:02,740
Well, they are not just sort of
stuffing or folded wadding.

448
00:27:02,840 --> 00:27:05,980
Those membranes, in many cases,
are chemical factories:

449
00:27:06,250 --> 00:27:09,280
particularly the ones in these bodies,
called mitochondria.

450
00:27:09,380 --> 00:27:10,480
The orange ones here.

451
00:27:10,680 --> 00:27:13,120
They are made of membrane,

452
00:27:13,450 --> 00:27:17,790
in every bit of those membranes,
is going on chemistry.

453
00:27:17,920 --> 00:27:20,160
They are chemical factories.

454
00:27:21,360 --> 00:27:26,100
This here is a map of the chemical
reactions in every cell.

455
00:27:27,370 --> 00:27:30,440
Mindbogglingly complicated,
stupefyingly complicated.

456
00:27:30,540 --> 00:27:34,010
Every one of these arrows
is one chemical reaction.

457
00:27:34,910 --> 00:27:40,780
Yet all of that, all of that
is going on all the time
inside the membranes

458
00:27:40,910 --> 00:27:44,180
of every mitochondrion
in every cell in you.

459
00:27:45,020 --> 00:27:49,020
And, the number of mitochondria
in which that is going on, all the time,

460
00:27:49,860 --> 00:27:52,520
is such that if you laid
all your mitochondria

461
00:27:52,660 --> 00:27:53,560
end to end

462
00:27:53,790 --> 00:27:58,700
they would go round the world
not once, not 25 times, but 2000 times

463
00:28:05,570 --> 00:28:09,840
In the nucleus of the cell,
right in the center, is the DNA.

464
00:28:10,810 --> 00:28:14,210
The DNA, the magic molecule,
the molecule of life,

465
00:28:14,310 --> 00:28:15,980
the most important molecule
in the world.

466
00:28:16,880 --> 00:28:20,390
That molecule conveys the information
from generation to generation

467
00:28:20,520 --> 00:28:22,390
about how to build a body.

468
00:28:24,290 --> 00:28:32,230
The total amount of information is such
that, if you were to eat a steak,

469
00:28:33,800 --> 00:28:35,200
every time you do it

470
00:28:35,670 --> 00:28:43,910
your teeth are mangling, are shredding
the equivalent of a billion copies
of the Encyclopedia Britannica.

471
00:28:44,510 --> 00:28:47,580
That's the kind of destructive work
you can do with your teeth!

472
00:28:53,750 --> 00:29:01,290
Hemoglobin is the molecule
that carries oxygen in the blood;

473
00:29:02,160 --> 00:29:05,260
you can see it,
the shape of it is complicated,

474
00:29:07,730 --> 00:29:08,870
it is very complicated.

475
00:29:09,000 --> 00:29:13,210
And what's remarkable about it
is that the same shape
is going on all the time

476
00:29:13,340 --> 00:29:14,710
in all the different molecules.

477
00:29:15,370 --> 00:29:17,380
You can think of a hemoglobin molecule

478
00:29:17,510 --> 00:29:21,010
as rather like a truck
for carrying oxygen.

479
00:29:21,480 --> 00:29:22,880
Each hemoglobin molecule
drives around

480
00:29:22,980 --> 00:29:28,990
carrying oxygen from one part
of the body to another.

481
00:29:30,290 --> 00:29:32,660
It's a vehicle for carrying oxygen.

482
00:29:33,290 --> 00:29:35,690
But, I have just got
six little trucks here.

483
00:29:36,190 --> 00:29:42,500
What's remarkable about hemoglobin
is that the number of them
in your bloodstream is not just six,

484
00:29:42,630 --> 00:29:45,200
it is six thousand
million million million.

485
00:29:45,470 --> 00:29:46,670
And they're are all
very complicated,

486
00:29:46,770 --> 00:29:47,770
they all look like that,

487
00:29:47,910 --> 00:29:49,710
they all look exactly the same
as each other.

488
00:29:50,410 --> 00:29:53,150
And they are all being destroyed

489
00:29:53,410 --> 00:30:00,550
and new ones being created,
all the time in your blood, at a rate
of 400 million million every second.

490
00:30:03,820 --> 00:30:06,690
Another way to shake off
the anesthetic of familiarity,

491
00:30:06,830 --> 00:30:10,030
another way to experience something
a little bit like going to another planet,

492
00:30:10,330 --> 00:30:13,300
is to go on another kind of journey -
backwards in time

493
00:30:13,500 --> 00:30:14,570
on our own planet.

494
00:30:15,570 --> 00:30:18,000
The best way to do this
would be in a time machine,

495
00:30:18,800 --> 00:30:21,810
but even Bryson Gore
and the Royal Institution

496
00:30:21,940 --> 00:30:23,810
can't lay on a time machine for us,

497
00:30:23,910 --> 00:30:25,210
so we have to use fossils.

498
00:30:27,350 --> 00:30:29,450
One of the most difficult things
to grasp about fossils

499
00:30:29,580 --> 00:30:32,850
like this Trilobite here,
is how old they are.

500
00:30:34,550 --> 00:30:37,990
You can have no conception
how old that animal is.

501
00:30:38,860 --> 00:30:41,060
In case that sounds patronizing,
let me rephrase it.

502
00:30:41,290 --> 00:30:43,730
I can have no conception
how old it is.

503
00:30:44,130 --> 00:30:46,060
I can tell you in words
how old it is:

504
00:30:46,200 --> 00:30:49,740
it's about 500 million years old,
perhaps a bit more.

505
00:30:50,740 --> 00:30:55,740
But to tell you in words
and really to understand what
that means, is another matter.

506
00:30:56,640 --> 00:30:58,480
Our brains have evolved
to comprehend

507
00:30:58,680 --> 00:31:00,350
the timescales
of our own lifetimes.

508
00:31:00,480 --> 00:31:04,980
We can understand seconds, minutes,
days, weeks, years -

509
00:31:05,180 --> 00:31:06,990
even centuries we can understand.

510
00:31:08,750 --> 00:31:13,660
When we come to millennia,
thousands of years,
our spines start to tingle.

511
00:31:14,360 --> 00:31:17,460
Epic myths, like Homer's Odyssey,
tales of the Greek gods,

512
00:31:17,560 --> 00:31:22,400
Zeus and Apollo and the others,
the Jewish heroes, Moses and Joshua

513
00:31:22,530 --> 00:31:25,770
and their god Yahweh,
the ancient Egyptians
and the Sun god, Ra,

514
00:31:26,070 --> 00:31:28,640
these all give us an eerie feeling
of immense age.

515
00:31:28,910 --> 00:31:32,140
We feel that we are peering back
into the mists of antiquity.

516
00:31:33,080 --> 00:31:34,780
Yet, on the time scale of this fossil,

517
00:31:35,580 --> 00:31:38,850
those mists of antiquity
don't even count as yesterday.

518
00:31:40,520 --> 00:31:44,890
This is a cuneiform tablet
from Mesopotamia,

519
00:31:45,120 --> 00:31:47,330
somewhere around the 7th century BC.

520
00:31:48,390 --> 00:31:50,700
It's - let me see,
my cuneiform's a bit rusty -

521
00:31:51,930 --> 00:31:55,830
yes, this is a legal document
on the sale of some land near Nineveh.

522
00:31:56,340 --> 00:31:57,300
Yes, that's right.

523
00:31:59,470 --> 00:32:02,610
This, here, is another thing
that gives one the same feeling.

524
00:32:02,840 --> 00:32:06,350
This is a bronze age
warrior's mask

525
00:32:06,610 --> 00:32:08,910
which was dug up
in the last century

526
00:32:09,010 --> 00:32:11,380
by a famous 19th century
archaeologist, Schliemann.

527
00:32:11,750 --> 00:32:15,250
And he said: "I have gazed
upon the face of Agamemnon".

528
00:32:15,850 --> 00:32:19,020
As a matter of fact,
it wasn't the face of Agamemnon,
but he thought it was.

529
00:32:19,290 --> 00:32:22,930
And, to him,
that was his way of being awed,

530
00:32:23,230 --> 00:32:24,730
awed at the immense age of it.

531
00:32:25,060 --> 00:32:29,100
He was feeling himself going back
through those mists of antiquity.

532
00:32:30,700 --> 00:32:34,410
Let's try to get a feel
how old things really are,

533
00:32:34,540 --> 00:32:37,810
and then try to fit our Trilobite
onto the same scale.

534
00:32:40,680 --> 00:32:43,820
I am going to take one pace
to represent 1000 years,

535
00:32:43,950 --> 00:32:46,790
and I'm going to start at the time
of the first Christmas.

536
00:32:47,120 --> 00:32:48,550
So, this little broach here

537
00:32:49,520 --> 00:32:52,020
dates from the time
of the first Christmas, 0 BC.

538
00:32:52,690 --> 00:32:56,060
If I take one pace
I am back at 1000 BC,

539
00:32:56,130 --> 00:32:58,800
about the time of the tablet
that we have just been looking at,

540
00:32:58,930 --> 00:33:00,130
about the time of King David.

541
00:33:01,130 --> 00:33:03,670
Another pace, 2000 BC

542
00:33:04,340 --> 00:33:07,670
and this bronze age axe head.

543
00:33:08,310 --> 00:33:10,780
Another pace, 3000 BC,

544
00:33:10,880 --> 00:33:13,880
about the time just before
the building of Egyptian pyramids.

545
00:33:14,610 --> 00:33:18,780
Another pace, this piece of pottery,
4000 BC,

546
00:33:19,550 --> 00:33:22,690
about the time
when Archbishop Usher calculated

547
00:33:22,920 --> 00:33:25,190
the beginning of the world
and Adam and Eve.

548
00:33:26,890 --> 00:33:28,290
But we've hardly started yet.

549
00:33:29,530 --> 00:33:30,800
We've a long way to go.

550
00:33:33,230 --> 00:33:35,830
Walking from one side
of the green bench to the other,

551
00:33:35,970 --> 00:33:37,870
we've gone back to 4000 BC.

552
00:33:39,070 --> 00:33:41,240
This is Homo habilis.

553
00:33:41,770 --> 00:33:45,340
She, or someone very like her,
is our direct ancestor.

554
00:33:45,640 --> 00:33:47,980
She lived 2 million years ago.

555
00:33:49,210 --> 00:33:50,650
To get back to her time,

556
00:33:51,320 --> 00:33:56,190
you would need,
on the same scale of pacing,
to go about 2 kilometers.

557
00:33:56,490 --> 00:33:57,290
Quite a long way.

558
00:33:58,790 --> 00:34:01,760
Now, we've got some more
ancestral portraits,

559
00:34:02,190 --> 00:34:04,560
and I'm going to call them up
in order.

560
00:34:04,700 --> 00:34:08,270
So, will the person who is standing,
who's sitting behind Australopithecus,

561
00:34:08,370 --> 00:34:10,970
the first one, please, stand up.
Thank you.

562
00:34:11,300 --> 00:34:12,800
That's Australopithecus.

563
00:34:13,170 --> 00:34:16,680
He is probably a direct ancestor
of this one.

564
00:34:16,810 --> 00:34:20,750
He lived about 3 million years ago.

565
00:34:20,880 --> 00:34:21,780
So we'd have to walk

566
00:34:21,910 --> 00:34:23,780
3 kilometers
to get to his time.

567
00:34:24,120 --> 00:34:26,150
Now the next person, please.

568
00:34:26,650 --> 00:34:27,220
Thank you.

569
00:34:27,420 --> 00:34:29,290
That's Ramapithecus,

570
00:34:29,420 --> 00:34:34,190
that would be possibly
an ancestor, not just of us,
but also of all the great apes,

571
00:34:34,660 --> 00:34:39,830
and he is about 14 kilometers
away on our scale.

572
00:34:40,470 --> 00:34:42,030
The next one, please.

573
00:34:43,140 --> 00:34:43,800
Thank you.

574
00:34:44,240 --> 00:34:46,640
That's an early primate,

575
00:34:47,670 --> 00:34:52,080
you would have to walk
to about Hemel Hempstead

576
00:34:52,280 --> 00:34:54,150
to get to the age
of that creature.

577
00:34:54,750 --> 00:34:55,910
The next one, please.

578
00:34:59,220 --> 00:35:01,220
An early mammal,
about Luton,

579
00:35:01,950 --> 00:35:03,360
that distance.
The next one.

580
00:35:04,420 --> 00:35:10,000
An insectivore,
with a little millipede in its jaws.

581
00:35:11,830 --> 00:35:13,800
Maybe, Newport Pagnell.

582
00:35:15,500 --> 00:35:16,670
The next one, please.

583
00:35:17,400 --> 00:35:19,370
That's an early
mammalian-like reptile,

584
00:35:19,870 --> 00:35:22,810
and its distance
is about Manchester.

585
00:35:23,540 --> 00:35:24,510
The next one.

586
00:35:25,480 --> 00:35:30,280
An amphibian -
Middlesborough.

587
00:35:31,450 --> 00:35:32,580
And the next.

588
00:35:34,120 --> 00:35:36,190
Right, that's a fish,
just coming out of the water;

589
00:35:36,290 --> 00:35:38,660
just leaving the water,
and coming to the land.

590
00:35:38,920 --> 00:35:41,790
And, its distance is about Carlisle.

591
00:35:42,830 --> 00:35:46,100
And I've left - do sit down,
now, thank you very much.
Those are all your ancestors.

592
00:35:54,870 --> 00:35:57,780
This one is the oldest of all
we've got here,

593
00:35:57,880 --> 00:35:59,810
it's about the same age
as the Trilobite

594
00:35:59,910 --> 00:36:00,650
that we started with;

595
00:36:00,780 --> 00:36:01,550
they might have met.

596
00:36:01,750 --> 00:36:05,150
This is Pikaia,
and in order to find its age

597
00:36:05,280 --> 00:36:08,850
you would have to slog it out
all the way from here to Glasgow.

598
00:36:09,350 --> 00:36:14,320
And, remember that our perception
of historical time,
back to the mists of antiquity,

599
00:36:14,360 --> 00:36:18,100
is a couple of paces
across this green table.

600
00:36:20,270 --> 00:36:22,800
And, even with Pikaia,
we have not finished.

601
00:36:23,170 --> 00:36:25,940
Because there are lots and lots
of ancestors before Pikaia.

602
00:36:26,270 --> 00:36:29,870
If we go back to the origin of life,
to the first bacteria,

603
00:36:29,970 --> 00:36:33,610
we are going back three and a half
thousand million years.

604
00:36:34,110 --> 00:36:37,020
And, in order to pace our way
back to that age,

605
00:36:37,250 --> 00:36:40,750
we would have to march
all the way from here to Moscow.

606
00:36:43,060 --> 00:36:45,890
These are the sorts of ages
that we have to understand,

607
00:36:46,090 --> 00:36:48,060
if we're going to understand
evolution,

608
00:36:48,190 --> 00:36:51,060
and our brains
are not equipped to do so.

609
00:36:52,560 --> 00:36:54,670
When we were looking at
our ancestors around there,

610
00:36:55,070 --> 00:36:56,700
we could be misled,

611
00:36:56,840 --> 00:36:58,200
because it gives the idea

612
00:36:58,340 --> 00:37:02,540
that evolution is marching inexorably
towards a climax;

613
00:37:02,670 --> 00:37:04,440
the climax being, of course, us.

614
00:37:05,110 --> 00:37:06,310
And that's not the way it was.

615
00:37:06,410 --> 00:37:11,180
Evolution was marching
in thousands and millions
of different directions, at once.

616
00:37:11,820 --> 00:37:14,950
This, here, is not the Royal Institution
Christmas tree,

617
00:37:15,350 --> 00:37:21,230
it's the tree of life
and it's a representation
of a tiny, tiny fraction

618
00:37:21,360 --> 00:37:24,560
of the lines of evolution
that there were.

619
00:37:24,860 --> 00:37:26,600
The origin of life is down here.

620
00:37:27,830 --> 00:37:31,240
This is the first 1000 million
years of life here.

621
00:37:32,140 --> 00:37:36,810
Coming up here.
Now, each of these branch points
represent an ancestor

622
00:37:37,210 --> 00:37:41,950
of whatever lies up
the branches from it.

623
00:37:42,250 --> 00:37:46,650
So, for example, these -
there are the plants.

624
00:37:46,790 --> 00:37:49,120
This, I should say,
is definitely not to scale.

625
00:37:49,890 --> 00:37:50,690
I just noticed.

626
00:37:50,790 --> 00:37:51,690
So, never mind that.

627
00:37:52,160 --> 00:37:54,630
Forget everything about scale
on this tree.

628
00:37:54,890 --> 00:37:59,630
What is correct is the order
of branching, but not the detailed
distances of the branches.

629
00:38:00,270 --> 00:38:02,530
So, this branch
represents the plants.

630
00:38:03,370 --> 00:38:06,540
Those two are closer cousins
of each other then they are of that one

631
00:38:07,040 --> 00:38:12,310
This branch represents the primates,
with a gorilla and a human,

632
00:38:12,710 --> 00:38:14,810
and their common ancestor
is there.

633
00:38:15,310 --> 00:38:18,080
This branch here
represents carnivores,

634
00:38:18,380 --> 00:38:20,250
and there's a branch
with a lion and a tiger,

635
00:38:20,490 --> 00:38:21,790
and their common ancestor there -

636
00:38:22,020 --> 00:38:26,560
which is more recent
than the common ancestor
of the bear and the dog -

637
00:38:26,790 --> 00:38:29,800
that's the common ancestor
of all the carnivores.

638
00:38:30,660 --> 00:38:35,530
Here, we have a zebra
and a rhino, not to scale,

639
00:38:36,440 --> 00:38:40,310
and you can see that
they are more closely
related to one other,

640
00:38:40,610 --> 00:38:42,410
than either of them is to

641
00:38:43,810 --> 00:38:48,210
these cloven-hoofed animals:
the bison, the sheep, and the goat.

642
00:38:48,310 --> 00:38:50,680
The sheep and the goat
have a very recent common ancestor,

643
00:38:50,820 --> 00:38:54,750
they're cousins. The bison has a
slightly older common ancestor.

644
00:38:55,820 --> 00:38:58,960
Here, we have two insects,
a fly and a grasshopper,

645
00:38:59,190 --> 00:39:00,530
and they have an ancestor there.

646
00:39:00,990 --> 00:39:05,830
And then, they share an ancestor
with the spiders a little bit earlier on

647
00:39:06,730 --> 00:39:10,340
This is a tiny fraction
of the number of animals and plants

648
00:39:10,570 --> 00:39:12,040
that there should be on this tree.

649
00:39:12,270 --> 00:39:17,440
This tree should have
some 10 or 20 million twigs
around there.

650
00:39:18,640 --> 00:39:22,920
And, the ancestors of all these animals
are in the middle of the tree,

651
00:39:23,020 --> 00:39:24,420
going inwards like that.

652
00:39:24,520 --> 00:39:26,890
So all the ancestral portraits
that we have just seen around there,

653
00:39:27,020 --> 00:39:29,860
they would be laid out along there.

654
00:39:29,960 --> 00:39:32,520
What we're looking at here
are all modern animals.

655
00:39:34,130 --> 00:39:38,430
All those animals
are cousins of one another
and they're cousins of us.

656
00:39:38,900 --> 00:39:42,270
These hamsters here
are also cousins of us.

657
00:39:43,000 --> 00:39:46,840
Everything that's alive today
is a cousin of us.

658
00:39:46,940 --> 00:39:49,210
These fish are our cousins,
this elephant,

659
00:39:49,310 --> 00:39:52,340
these elephants -
by the way extinct elephants -
are our cousins,

660
00:39:52,440 --> 00:39:53,950
this swift is our cousin.

661
00:39:54,950 --> 00:39:57,180
We know that
they are all our cousins

662
00:39:58,180 --> 00:40:03,020
because we know that
they all have the same DNA code.

663
00:40:03,560 --> 00:40:07,360
The DNA code of all living things
alive today is the same.

664
00:40:08,190 --> 00:40:11,300
And, that is too improbable
to have come about

665
00:40:11,430 --> 00:40:13,600
unless we have an ancestor.

666
00:40:14,000 --> 00:40:16,900
We're all descend
from one remote ancestor

667
00:40:17,100 --> 00:40:21,240
which lived probably between
3-4 thousand million years ago,

668
00:40:21,640 --> 00:40:23,880
and we are all,
therefore, cousins.

669
00:40:28,180 --> 00:40:30,880
If we ever meet life
from another planet,

670
00:40:31,850 --> 00:40:34,890
the creatures from there
will not be our cousins.

671
00:40:35,520 --> 00:40:38,020
They will have evolved
entirely independently.

672
00:40:38,760 --> 00:40:41,190
They won't have DNA,
it would be my guess.

673
00:40:41,960 --> 00:40:44,100
However,
I would be prepared to say

674
00:40:44,330 --> 00:40:46,900
that they are likely to have quite
a lot in common with us,

675
00:40:47,030 --> 00:40:50,770
simply because there's
a lot of similar problems
to be solved in living.

676
00:40:51,040 --> 00:40:54,470
And those problems are likely
to be the same all over the Universe

677
00:40:54,940 --> 00:40:56,640
So, although they won't have DNA,

678
00:40:56,980 --> 00:40:59,710
they'll have something
very similar in function.

679
00:40:59,850 --> 00:41:01,950
It'll do something very like DNA,

680
00:41:02,080 --> 00:41:04,050
and it'll work
in a similar way to DNA.

681
00:41:04,650 --> 00:41:07,420
I'd also be prepared
to put my shirt on the bet

682
00:41:07,620 --> 00:41:12,690
that they will have evolved
by the equivalent of
Darwinian natural selection.

683
00:41:14,690 --> 00:41:18,200
If we're ever visited by life forms
from another planet,

684
00:41:18,630 --> 00:41:21,000
they will certainly
have evolved the power to think

685
00:41:21,230 --> 00:41:22,370
and do science.

686
00:41:22,600 --> 00:41:24,270
Otherwise,
they couldn't have got here.

687
00:41:25,140 --> 00:41:28,940
And their science is bound to be
essentially the same as our science.

688
00:41:30,280 --> 00:41:35,410
This is because the principles
of physics and chemistry
are the same all over the Universe.

689
00:41:36,580 --> 00:41:40,090
They'll have the same values
of the constants -
of constant pi as we have,

690
00:41:40,320 --> 00:41:42,990
they'll have Pythagoras's theorem,
they will have relativity,

691
00:41:43,120 --> 00:41:45,290
although they won't attribute it
to Einstein.

692
00:41:46,630 --> 00:41:48,430
They'll probably find us
pretty childish,

693
00:41:48,830 --> 00:41:51,200
but they will be quite kind
about our science.

694
00:41:51,330 --> 00:41:52,030
They'll pat us on the head and say,

695
00:41:52,130 --> 00:41:54,970
"Well, what you know about Universe
is pretty much correct.

696
00:41:55,070 --> 00:41:57,740
You got at lot to learn yet,
but you are doing fine. Keep it up."

697
00:41:58,770 --> 00:42:01,540
That's what they would say
if they were talking to our scientists.

698
00:42:02,770 --> 00:42:05,840
What if they were talking
to our best lawyers

699
00:42:05,940 --> 00:42:08,280
or literary critics or theologians?

700
00:42:08,950 --> 00:42:11,220
I doubt if they'd be so impressed.

701
00:42:12,550 --> 00:42:15,850
Their anthropologists,
the equivalent of their anthropologists

702
00:42:15,950 --> 00:42:18,860
might be interested in us,

703
00:42:19,660 --> 00:42:26,060
but they would be bound to notice
that our cultural beliefs
are very local and parochial;

704
00:42:26,200 --> 00:42:29,570
not just by their standards,
their universal standards,
where they certainly would be,

705
00:42:29,700 --> 00:42:31,600
but even by our own standards.

706
00:42:32,000 --> 00:42:34,110
Because what people
believe on our planet

707
00:42:34,540 --> 00:42:39,650
depends so much
on whereabouts on the planet
they happen to be born,
which is a fairly odd thing.

708
00:42:40,250 --> 00:42:45,250
The Adam and Eve myth
is believed by a lot of people
in certain parts of the world,

709
00:42:45,850 --> 00:42:47,290
but if you go to the other parts
of the world

710
00:42:47,420 --> 00:42:49,220
you will find them believing
very different myths.

711
00:42:49,490 --> 00:42:54,560
This is a Hindu myth
which is also very beautiful
and there are other Hindu myths as well.

712
00:42:54,690 --> 00:42:59,430
This is another Hindu myth of
churning the milk of the ocean

713
00:42:59,530 --> 00:43:03,640
with a churn.
Gods and demons churning an axle
with a turtle on the bottom,

714
00:43:03,770 --> 00:43:09,040
and out of the ocean came -
as butter comes out of milk -
came all living creatures.

715
00:43:09,340 --> 00:43:11,440
These creation myths
are very beautiful,

716
00:43:11,680 --> 00:43:15,450
but they're all different
from one another,
and they can't all be true.

717
00:43:16,320 --> 00:43:19,550
And it's very odd
if people believe simply

718
00:43:19,820 --> 00:43:24,020
what the other people
in their country happen to believe,
just because they are in that country.

719
00:43:25,020 --> 00:43:27,660
Look how scientists
handle their disagreements now.

720
00:43:28,090 --> 00:43:31,730
Take a particular disagreement:
why did dinosaurs go extinct?

721
00:43:32,260 --> 00:43:33,500
There are various theories.

722
00:43:33,630 --> 00:43:36,470
This is the theory that a comet
or meteorite hit the Earth,

723
00:43:36,740 --> 00:43:39,940
and caused a catastrophe that
drove the dinosaurs extinct.

724
00:43:40,040 --> 00:43:41,470
And a lot of scientists believe that.

725
00:43:41,710 --> 00:43:46,410
A lot of scientists, on the other hand,
believe that a virus killed the dinosaurs.

726
00:43:46,810 --> 00:43:48,980
And another lot of scientists
believe that

727
00:43:49,110 --> 00:43:52,280
the mammals arose
and ate the dinosaurs eggs.

728
00:43:52,480 --> 00:43:54,250
I've no doubt that there is something
going for all those theories.

729
00:43:54,350 --> 00:43:56,960
But, the point is that different
scientists believe them,

730
00:43:57,290 --> 00:43:58,790
and the reason why they disagree

731
00:43:58,920 --> 00:44:00,460
is that there isn't
enough evidence yet.

732
00:44:01,430 --> 00:44:03,930
Everybody knows,
everybody agrees about

733
00:44:04,060 --> 00:44:08,430
what sort of evidence
would be needed in order to
make them change their mind.

734
00:44:09,600 --> 00:44:13,740
But, suppose science worked
like creation myths,
or like languages.

735
00:44:14,370 --> 00:44:16,780
Here we have a map
of world languages.

736
00:44:16,880 --> 00:44:19,180
In this red area
English is spoken.

737
00:44:19,440 --> 00:44:23,080
There Spanish is spoken,
there Russian is spoken.

738
00:44:23,220 --> 00:44:27,220
And it's quite natural
that you should be able to
plot a map like that;

739
00:44:27,350 --> 00:44:29,860
that people should speak
the language of their country.

740
00:44:30,320 --> 00:44:32,360
But what if scientific theories
were like that?

741
00:44:32,590 --> 00:44:36,500
What if we had the similar map
of the distribution of scientific theories?

742
00:44:36,730 --> 00:44:38,960
Suppose, in the red area,
everyone believed

743
00:44:39,100 --> 00:44:41,800
the meteor theory
of the dinosaurs' extinction.

744
00:44:42,200 --> 00:44:45,100
And in that area everybody
believed the virus theory,

745
00:44:45,340 --> 00:44:48,870
and in that area everybody believed
the mammals-eating-the-eggs theory.

746
00:44:49,170 --> 00:44:51,610
Wouldn't that be a pretty
silly sort of science?

747
00:44:52,780 --> 00:44:55,810
Imagine the scene:
two scientists arguing,
and one of them says,

748
00:44:56,050 --> 00:44:57,950
"I believe the dinosaurs
went extinct

749
00:44:58,380 --> 00:44:59,620
because a comet hit the Earth.

750
00:44:59,850 --> 00:45:01,050
Why do I believe that?

751
00:45:01,550 --> 00:45:04,060
Because that is what my father
and grandfather believed,

752
00:45:04,190 --> 00:45:07,430
and that's what people in my country
have always believed."

753
00:45:07,990 --> 00:45:11,960
"But I believe that it was a virus
that drove the dinosaurs extinct.
Why do I believe that?

754
00:45:12,200 --> 00:45:14,130
Because my father and grandfather
believed it,

755
00:45:14,270 --> 00:45:16,800
and that's what people in my country
have always believed."

756
00:45:17,840 --> 00:45:20,710
Or, suppose the conversation
went like this:

757
00:45:20,810 --> 00:45:21,840
"Never mind the evidence,

758
00:45:22,140 --> 00:45:24,710
I just know that
a comet struck the Earth

759
00:45:24,810 --> 00:45:29,380
because it has been privately revealed
to me that a comet struck the Earth."

760
00:45:30,280 --> 00:45:33,080
"But I just know that it was a virus
because I just know it,

761
00:45:33,180 --> 00:45:36,290
because I just know it,
because I have faith that it was a virus."

762
00:45:37,290 --> 00:45:39,930
If you overheard conversation
like that

763
00:45:40,230 --> 00:45:42,790
you would think they were pretty
odd scientists, wouldn't you?

764
00:45:43,830 --> 00:45:46,370
You'd see no reason
to believe any of them.

765
00:45:48,200 --> 00:45:49,770
Growing up in the Universe

766
00:45:50,100 --> 00:45:53,140
partly means evolving
from simple to complicated,

767
00:45:54,540 --> 00:45:57,180
inefficient to efficient,
brainless to brainy.

768
00:45:57,580 --> 00:46:00,280
But it also means
growing out of parochial

769
00:46:00,680 --> 00:46:02,450
and superstitious views
of the Universe.

770
00:46:02,580 --> 00:46:05,650
Growing up to a proper scientific
understanding of the Universe,

771
00:46:05,780 --> 00:46:08,150
based upon evidence,
public argument,

772
00:46:08,750 --> 00:46:12,460
rather than authority or tradition
or private revelation.

773
00:46:13,530 --> 00:46:17,460
Growing up means trying
to understand how the Universe works,

774
00:46:17,560 --> 00:46:18,660
not copping out

775
00:46:18,760 --> 00:46:22,970
with supernatural ideas
that only seem to explain things
but actually explain nothing.

776
00:46:24,070 --> 00:46:26,970
You might say:
"Can you really afford to be
snooty about the supernatural?

777
00:46:27,210 --> 00:46:31,010
After all, many of us have probably
had uncanny experiences,
like telepathy.

778
00:46:31,340 --> 00:46:36,920
We, perhaps, dreamed about somebody
whom we hadn't thought of for years,

779
00:46:37,050 --> 00:46:41,150
and then, the very next day,
we had a letter from them, and we think,
what an amazing coincidence!

780
00:46:41,390 --> 00:46:44,490
There must be something supernatural.
It seems so spooky."

781
00:46:45,360 --> 00:46:47,160
That is a supernatural explanation.

782
00:46:47,760 --> 00:46:50,560
What would a natural explanation
of an event like that be?

783
00:46:51,500 --> 00:46:55,230
Well, what we have got to do is
to come to a proper assessment of

784
00:46:55,530 --> 00:46:59,570
how likely it would have been
that this could have happened
anyway by sheer luck?

785
00:47:00,410 --> 00:47:04,210
And, there are ways of doing that.
And we can run a very
simple experiment here,

786
00:47:04,440 --> 00:47:07,850
on a very small scale.
We are going to do it
by tossing pennies.

787
00:47:09,110 --> 00:47:10,980
It may be that,
somewhere in this audience,

788
00:47:11,220 --> 00:47:12,950
is somebody who is "psychic,"

789
00:47:13,550 --> 00:47:17,190
and is capable of willing a penny
to come down heads or tails.

790
00:47:17,320 --> 00:47:20,660
A what we have got to do is to
identify that psychic individual.

791
00:47:21,760 --> 00:47:25,130
So, Bryson is going to toss a penny,

792
00:47:25,530 --> 00:47:31,300
and I want, I'm going to ask
everybody on this side,
let's forget about the gallery
because I can't see them up there,

793
00:47:31,640 --> 00:47:34,340
everybody on this side of me here,

794
00:47:35,110 --> 00:47:37,280
is to will it
to come down heads.

795
00:47:37,410 --> 00:47:38,740
Really think of it
coming down heads.

796
00:47:38,880 --> 00:47:40,650
Try to make it
to come down heads:

797
00:47:40,780 --> 00:47:43,080
we'll try to see whether the psychic
individual is on that side.

798
00:47:43,450 --> 00:47:47,020
Or, on this side,
everybody should will it
to come down tails.

799
00:47:47,590 --> 00:47:49,120
Okay, so, off we go.

800
00:47:51,360 --> 00:47:52,290
Tails, right.

801
00:47:52,420 --> 00:47:55,030
So if we've got a psychic individual,
it must be on this side.

802
00:47:56,360 --> 00:47:59,200
Now, will everybody this side,
please, stand up.

803
00:47:59,600 --> 00:48:01,500
We're going to try to do this
by elimination.

804
00:48:02,430 --> 00:48:07,440
Now, everybody on this side
of the aisle, will it to become heads,

805
00:48:07,570 --> 00:48:11,040
everybody on this side of the aisle,
will it to come down tails.

806
00:48:13,480 --> 00:48:14,480
Heads.

807
00:48:14,710 --> 00:48:15,850
Sit down, please.

808
00:48:15,950 --> 00:48:17,020
Stay standing up.

809
00:48:18,050 --> 00:48:19,850
Now, we have got
a bit of a problem here.

810
00:48:20,050 --> 00:48:27,660
Let's say, everyone from behind the row
that was holding up the ancestral portraits
should will it to come down heads,

811
00:48:27,890 --> 00:48:31,860
and everyone from the ancestral
portraits downwards - tails.

812
00:48:35,400 --> 00:48:35,900
Tails.

813
00:48:36,170 --> 00:48:38,140
Right. The back rows then,
sit down, please.

814
00:48:38,940 --> 00:48:42,610
Right, now we're narrowing it down.
How many tosses have we done?
Three? Right.

815
00:48:43,180 --> 00:48:45,610
Now, one, two, three, four -

816
00:48:45,740 --> 00:48:50,950
let's say the back two rows of those
standing, will it to be heads,
and the remainder, tails.

817
00:48:52,950 --> 00:48:53,620
Tails.

818
00:48:54,050 --> 00:48:55,820
Back two rows, sit down, please.

819
00:48:57,260 --> 00:49:01,730
Right, now, 1, 2, 3, 4, 5, 6 -
okay, we we'll make it simple.

820
00:49:01,860 --> 00:49:04,830
The back row heads
and the front two rows, tails.

821
00:49:06,700 --> 00:49:07,230
Tails.

822
00:49:07,900 --> 00:49:09,070
Back row, sit down.

823
00:49:09,330 --> 00:49:10,900
Right.

824
00:49:11,040 --> 00:49:13,510
Back row heads, front row tails.

825
00:49:14,910 --> 00:49:16,210
Tails.

826
00:49:20,210 --> 00:49:22,050
Right,

827
00:49:22,580 --> 00:49:28,820
let's say, from Coca Cola to the left,
heads, and the other one, tails.

828
00:49:30,590 --> 00:49:31,820
Heads -

829
00:49:32,360 --> 00:49:34,590
down, please.
No, Coca Cola, stand.

830
00:49:35,130 --> 00:49:37,230
Right.
Heads, tails?

831
00:49:39,430 --> 00:49:39,800
Heads.

832
00:49:39,900 --> 00:49:40,530
Heads.

833
00:49:40,900 --> 00:49:41,400
Right.

834
00:49:41,730 --> 00:49:42,370
Well done.

835
00:49:45,730 --> 00:49:47,370
How many tosses was that?

836
00:49:51,010 --> 00:49:53,650
I do not know how many tosses
that was, but congratulations.

837
00:49:53,750 --> 00:49:55,480
Let us suppose that it was eight.

838
00:49:57,620 --> 00:49:58,250
It was, was it?
Right.

839
00:49:58,550 --> 00:50:01,450
Now, what's your name?

840
00:50:02,120 --> 00:50:04,820
Who got it?
Donny.

841
00:50:04,960 --> 00:50:06,760
Yes, well - Donny?

842
00:50:07,190 --> 00:50:09,160
Now the question is;
is he psychic?

843
00:50:11,030 --> 00:50:16,240
He managed to get it right
eight times in a row,
and that's pretty impressive.

844
00:50:17,370 --> 00:50:19,870
But, of course, there is
absolutely no evidence whatever

845
00:50:20,010 --> 00:50:21,440
that he's psychic.

846
00:50:23,340 --> 00:50:26,780
He did, indeed,
think about heads and tails
and it did come down the right way.

847
00:50:27,080 --> 00:50:30,320
But if you think about
how we set the experiment up,
with successive divisions,

848
00:50:30,450 --> 00:50:33,250
he could have thought
about ham and eggs, and
it would have given the same result!

849
00:50:33,620 --> 00:50:36,460
It had to come out, because of
the number of people here.

850
00:50:36,560 --> 00:50:43,600
It had to come out that
somebody was, apparently, psychic.

851
00:50:44,360 --> 00:50:47,000
Now, we have only got
a few hundred people in this room.

852
00:50:47,230 --> 00:50:49,730
But, if we could do this with a
million people or two million people,

853
00:50:49,970 --> 00:50:53,640
we could have gone on tossing
pennies for a very long time,
and in the end of that time,

854
00:50:53,740 --> 00:50:56,110
we'd have got a very
impressive result.

855
00:50:56,340 --> 00:51:00,580
Now, when people write into
the papers with uncanny experiences,
it's just like that,

856
00:51:00,810 --> 00:51:03,820
because the circulation
of a tabloid newspaper
is up in the million,

857
00:51:04,050 --> 00:51:06,150
and if only one of them
has to write in,

858
00:51:06,790 --> 00:51:08,550
then you can see exactly
what happens.

859
00:51:08,690 --> 00:51:13,130
There's got to be somebody out there
having an uncanny experience
at this very moment,

860
00:51:13,330 --> 00:51:15,190
and it means absolutely nothing.

861
00:51:16,430 --> 00:51:18,930
So whenever you hear a story about

862
00:51:19,030 --> 00:51:21,200
uncanny, spooky,
telepathic experiences

863
00:51:21,470 --> 00:51:25,440
think about this experiment
and think about how likely
it would be to come about anyway.

864
00:51:25,570 --> 00:51:29,810
Put your trust in the scientific method,
put your faith in the scientific method.

865
00:51:30,610 --> 00:51:32,340
There's nothing wrong
with having faith -

866
00:51:32,710 --> 00:51:34,410
I'm going to move Faraday
out of the way.

867
00:51:35,610 --> 00:51:41,450
There's nothing wrong with having faith
in a proper scientific prediction.

868
00:51:42,650 --> 00:51:45,590
This is a heavy cannon ball.

869
00:51:46,490 --> 00:51:48,690
I'm going to stand here,
and I'm going to release it,

870
00:51:50,100 --> 00:51:54,230
and it's going to come -
it's going to go over there,
and it is going to come
roaring back towards me.

871
00:51:54,830 --> 00:51:57,740
And all my instincts are going
to tell me to 'run for it'.

872
00:51:59,570 --> 00:52:03,410
But, I have enough faith
in the scientific method to know
that it is going to stop

873
00:52:03,680 --> 00:52:07,980
just about an inch short,
or perhaps less, of my head.

874
00:52:09,950 --> 00:52:11,650
So here goes.

875
00:52:29,070 --> 00:52:31,170
I felt the wind of it!

876
00:52:31,700 --> 00:52:34,410
The Nobel Prize winning scientist
Sir Peter Medawar,

877
00:52:34,540 --> 00:52:36,640
in a joint book written jointly
with his wife, wrote the following:

878
00:52:37,510 --> 00:52:41,910
"Only human beings guide their behavior
by a knowledge of what happened

879
00:52:42,150 --> 00:52:43,280
before they were born

880
00:52:43,380 --> 00:52:46,220
and a preconception of what
may happen after they are dead.

881
00:52:46,920 --> 00:52:49,520
Thus, only humans
find their way by a light

882
00:52:49,860 --> 00:52:52,790
that illuminates more than
the patch of ground they stand on."

883
00:52:53,430 --> 00:52:54,690
Well, that's all for today.

884
00:52:54,790 --> 00:52:58,430
In the next lecture, I shall be turning
to the problem of design,

885
00:52:58,660 --> 00:53:02,330
and the difference between
genuinely designed things,
like that electron microscope,

886
00:53:02,700 --> 00:53:05,670
and apparently designed things,
that are not really designed,

887
00:53:05,940 --> 00:53:09,440
like this elephant
and like this swift.

888
00:53:10,040 --> 00:53:11,340
Thank you very much.

889
00:53:12,640 --> 00:53:16,550
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