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now the question at stake here is really
what makes us human now this is
obviously something that is that people
have been pondering for several thousand
years and to my mind never really coming
up with a satisfactory answer and you
know careers are made and continue to be
made by people talking about individual
single things single triggers that made
us human
so things like speech or language or our
ability to control fire Darwin thought
that was that was the case or you know
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more outlandish things like
hallucinogenic drug taking that is
genuinely a theory out there of the
switch that made us human and I think
they're all right and all wrong and
that's what this book is about and I
suppose in all of my work as a science
communicator I've tried to embrace the
idea of complexity because evolution is
messy and and has taken place over a
long period of time so there's
individual triggers I don't really buy
into those ideas of single thing single
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narrative satisfactory stories that make
us as complex as we are today so I've
always shied away from those sorts of
stories and I encourage I'd like to
encourage people to embrace reality the
reality of biology which is that this
stuff is complex I you know what makes
us human well the fundamental answer is
having two human parents and having a
human genome but that's an incredibly
dull answer and it's not very
informative and the real question
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interesting question is about the human
condition now this this question of the
human condition is what makes us special
the question of are we special and and
if so what is it that makes us special
and it was as all my work ends up
starting with with Darwin who is my
intellectual hero and I think the
greatest thinker that that humankind has
ever produced and he was the first
person to initiate this
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this idea of the conundrum of human
existence and this is in 1871 from the
descent of man and that that quote is is
just one one little sample from the
descent of man of him thinking about
this and thinking about us in terms of
our own evolution so he says without
with with our godlike intellect which
has penetrated into the movements and
constitution of the solar system with
all these exalted powers man Victorian
language but I think it means humans
still bears in his bodily frame the
indelible stamp of his lowly origin
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lowly origin that's a sort of value
judgment which was appropriate in the
19th century we no longer think about
evolution in terms of higher or lower
beings we are we are as equally as
evolved as any bacteria but there there
is the key idea that we are an ape that
has descended from other Apes and a few
years earlier it outlined the rules of
evolution in what I think is the most
important book ever written the Origin
of Species so we are an ape descended
from other aids but at the same time we
are special now this is such an
important sentiment is such an important
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question within the study of evolution
it was in fact expressed more
beautifully about 250 years earlier in
Hamlet's famous soliloquy on what a
piece of work is man you know this this
line is so so beautiful noble in reason
how infinite in faculty in action how
like an angel in apprehension how like I
got the paragon of animals and I love
that phrase the paragon of animals
because it says it encapsulates that in
that conundrum in one beautiful
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Shakespearean phrase in fact there was a
point where I wanted to call the book
the paragon of animals but so Jenny my
editor said that was pretentious do
Cherie
and I think she was probably right to be
honest he goes on to say a few lines
later but what is this quintessence of
dust so we are mater but we are special
we have had the powers of gods but we
are merely animals and in fact the
genesis of the whole idea for this book
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came from a line when my head came from
a line that I wrote in the final chapter
of my last brief history of anyone who
ever lived what was it a brief history
of everyone who ever lived and it was it
was it was this line everyone is special
which is another way of saying that no
one is it's a slightly different idea
but very closely related and in fact
when I wrote that and I sent the first
draft around to the core team and it was
well Francis my my history agent he said
I really liked that film quote that you
put him in the final paragraph final
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chapter and I said what the line about
everyone being special I said what I
thought I'd made that up and he said no
no it's actually for does anyone know
what it's from
no it's not Fight Club it is Incredibles
so you might know that I'm quite a film
obsessive but I managed to quote films
without even actually noticing which is
which is a little bit tragic so these
questions all of these questions are
about the paradoxes of uniqueness you
know what what are the attributes which
are ours and ours alone I think
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fundamentally it's fair to say that we
are the only species that has ever held
ourselves up to the light and asked that
very question and then the answer
paradoxically is both yes and no all
right so I mentioned that I want to
throughout my work as a science
communicator I want to embrace the
complex as a quote which I refer to all
the time from the journalist HL Mencken
which where he says for every
complicated problem there is a solution
as simple direct understandable and
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wrong so the whole story of human
evolution has radically changed in the
last two decades in the last moreso in
the last ten years and continues to
evolve and that's primarily what the
last book was about it's mostly to do
with the fact that we've introduced
ancient genetics into the study of
only evolution the ability to extract
DNA from people have been dead for
thousands of years so I want to do a
quick recap to bring us up to speed with
the last million years of human
evolution because that's really what
this story is about so this is a
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schematic of evolutionary tree for the
last million years involving us and so
the yellow at the bottom there is extant
living humans broken up into broad
ethnic groups Asians Europeans and
Africans there was an earlier archaic
modern human Homo sapiens which whose
lineage died out and of course we all
know about Steve Neanderthals which are
now divided up into eastern and western
and then you'll know presumably about
the Denisovans so another type of human
not designated as a species but only
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known from a very few samples but their
entire genome primarily a human that
lived in Siberia and and further east
and we also know of a mystery human a
human which is only identified due to
the discrepancies in the total amount of
DNA in homo sapiens Neanderthals and us
so that's the tree of life as it stands
today but we also know that the mystery
humans interbred with the denisa ones
that Denis Evans interbred with the
eastern Neanderthals the denis ins also
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interbred with the lineage that would
become modern Asians and the Western
Neanderthals interbred with with those
guys and those guys and I mean what's
the sort of age on this just an over 18
talk yes so in the book I described as
described the last million years of
human evolution as an enormous
and I stand by that so
there's there's the tree as it stands
today in terms of the number of human
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species that have existed in the last
hundred thousand years all of which
interbred with each other which
challenges the whole notion of a species
but it also challenges the idea of our
own uniqueness in terms of our our
behavior and our evolution so when the
grand scheme of things so this is the
most recent version of the Tree of Life
so the origin of life some what do I
have a pointer I do
the origin of life somewhere around
there almost all life on Earth
it's bacteria the second biggest chunk
is things that look a lot like bacteria
but are qualitatively different and then
there's all the eukaryota which is
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everything which isn't in the first two
categories and we are somewhere down
there so this is reinforcing the notion
that we are evolved right we are part of
evolution unquestionably we have the
same type of DNA we have the same
proteins we have the same types of
metabolism we have the same cell
structures as almost as every organism
that has ever existed as far as we know
so we are an evolved being but then when
it comes to thinking about Homo sapiens
and how Homo sapiens sits within human
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evolution there is another interesting I
said a conundrum in within here so this
is this is now the the earliest Homo
sapiens specimen that were aware of it's
from Morocco Jeb Olerud and was dated
last year as being about three hundred
thousand years old now by about two
hundred thousand years old we have Homo
sapiens that truly resemble us
physically they were like we are today
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if you found one alive and gave them a
shave or a haircut and put them in
modern clothes we would not be able to
tell the difference between a two
hundred thousand year old Homo sapiens
and any one of us today and this is a
conundrum because we haven't physically
changed significantly for the last two
or three hundred thousand years but in
terms of behavior are we have radically
changed and only within the last well
the numbers are a bit fuzzy on this but
definitely within the last hundred
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thousand years and most significantly
the last fifty thousand years and we
sometimes talk about this as being the
emergence of behavioral modernity or
sometimes the full package of behavioral
modernity so basically organisms which
are recognizable in terms of behavior
and and their physical presence as we
are today sometimes it gets called the
cognitive revolution I I dislike that
phrasing phrase intensely because I
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think revolutions should probably
take place over shorter time periods
than 10,000 years but also it implies
that there was a switch again and I
reject the notion of these these single
triggers where one day with one thing
and the next day we're not that is not
how evolution works but we do know this
is what we looked like 300,000 years ago
and by 50,000 40,000 years ago we have
things like this so oh I forgot to
mention so there are illustrations in
the book and the illustrations are done
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by Alice Roberts who as well as being
one of one of our greatest science
communicators and a brilliant scientist
is also annoyingly talented as an artist
as well it's just annoying to be honest
and of course she's going to be standing
here in December doing the Royal
Institution Christmas lectures so you
have to get your tickets for that and I
think I'm going to be standing here for
at least some of it anyway so here Alice
has drawn several illustrations for the
book and one of them is of this figure
so this 12-inch figure carved out of a
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mammoth tusk The Lion Man of Poland
Stein startled and the states around
40,000 years ago and it is ice it's a
stunning piece of art it's an imagined
being so it's a man with the head of a
cave lion we think and it has seven
stripes on its arms which have some
symbolism which we cannot possibly know
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or try this for size so round about the
same time thirty-eight thirty-nine
thousand years ago the venus of hohle ii
felt so found found also found in
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southern germany from approximately the
same time this is one of several venus
figurines they call the first one was
found in the 19th century was called the
Venus in pewdie k-- because it was
deemed a bit rude it has a very
pronounced vulva
now people over the years scientists and
and otherwise have tried to assign
meaning or value to these these venus
figurines a lot of people talk about
them as being fertility amulets because
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they often have exaggerated sexual
characteristics in this case very big
boobs
but the truth is that we cannot possibly
know what the motivations of those
artists were why they created these
these statues and it is just speculation
to say it's a fertility amulet it may
well be a toy it might be pornography it
is impossible to know but the key thing
about this is it is possible to know
that it indicates very clearly these
these pieces of art indicate clearly
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that the minds of the people who created
them were not significantly different
from our own they show intellectual
curiosity show great skill
great dexterity as well but also
foresight and abstraction of thoughts
and this is a this is the first the
earliest depiction of a human body the
lion man the earliest depiction of a of
a chimera and then you know by 20,000
years ago we've got the cave paintings
that were very familiar with so this is
an example from the Lascaux caves in
southwest France my favorite example
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there the one in the middle is the great
Irish elk Megalosaurus now this is all
based in in Europe so we're talking
about the emergence of behavioral
modernity which is so far I've only
talks about as being at this time in
Europe but it wasn't just in Europe at
all and so if we go out to the Sulawesi
caves in Indonesia we have this this
artwork so 14 hand stencils so blown we
think through a bone pipe with red okra
dye around the hand and that also dates
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from 40,000 years ago to about the same
time as there as the Lion Man and we
also know very well of these types of
examples of Bailey or modernity within
within Africa too so you see at
approximately the same time the
relatively sudden emergence of a whole
suite of characteristics which are very
familiar to to us today now again you
know we have to think about our
uniqueness here because one of the key
ideas and I think the key idea in the
book is that humans are accumulators of
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culture all right so we are a species
uniquely that is capable of acquiring
culture and passing it on and
accumulating it and passing it on in a
non genetic way and this this is one of
the key ideas in the book but in terms
of you
neatness of human species well from
February this year
a cave painting in Cantabria in northern
Spain this is a cleaned up version
because it's not very visible on the
rock anymore was read ated and dated to
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around sixty four thousand years ago now
we know that sixty four thousand years
ago the only humans in europe and in
spain were Neanderthals now this is this
clearly shows all of the same attributes
of behavioral modernity as the other
Homo sapiens arts there's a sort of
bovid you know some some sort of cow
like animal popping out here and the
back end here and this is rather
beautiful again we can't know what the
motivation of the artist for creating
such such a piece was but it also it
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clearly indicates that the behavioral
modernity that we think is unique to us
was also shared by Neanderthals at a
time before Homo sapiens arrived in
Europe now one of the things that I do
in my work as well as they try to make
it as up-to-date as possible um and
during the last stages of both this book
and the last book I kept really annoyed
my editors by saying like we have to
include this paper which has come out
just you know just just this week and
you know managed to jam it in and the
most recent paper referenced in this
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book is from July which you know I'm
proud of the fact that it is as
up-to-date as it can be and that this
this research is from February at six
o'clock tonight a new paper was
published
which puts the date of the earliest
known to fiction of an abstraction
almost arts in South Africa in the Blum
boss case 74,000 years ago so literally
on the day of publication on 10,000
years out
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thank you scientists anyway so we got
that we got you know multiple sites
around the world of the emergence of
behavioral modernity full package and so
when we think about those attributes I'm
gonna go back to some of those key ideas
that I talk about in the book so humans
are obligate tool users right we know
that this it's obvious we cannot operate
without extending our abilities with
external objects that we have called
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tools now we've been like this for
millions of years this is a the earliest
known example of a type of technology
called the old wooden chopper or not the
old one tool kit and it was it was
discovered in the 1960s alongside the
remains of of a new human identified at
the same time approximately the same
time which was known as Homo habilis
Homo habilis means in Latin it means
handyman so this is an example of humans
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defined by our tool use right and and
you know again at the time thinking
about how would these definitional
characteristics that make us human well
the suggestion was well we are the you
know obligate tool users and this is the
first incident of tool use in in homo
sapiens Darwin thought that too
he thought he described some examples of
tool use and animal particularly weapons
in baboons but primarily said that you
know this is a thing that is ours and
ours alone Homo habilis States to around
1.9 million years ago but then you know
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as science does its thing
we now have discovered an earlier type
of human that isn't categorized in the
in the genus Homo but is called Kenya
anthropos Plassey ops there's only one
specimen of this and it's just around
the corner in
lamech we intend and Tanzania and it
states the 3.3 million years ago and
also within those remains are found
examples of the older land toolset now
it's it's a relatively simple form of
form of stone tool used for cutting and
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slicing primarily they tend to be this
sort of size and tend to be made from
volcanic glass like rocks like obsidian
and and we see them all over the world
I overheard which last more than a
million years what's truly and
incredible about the older one toolkit
is its stability through time once this
had developed and spread all our all
around the world in multiple species of
humans it just stayed like that for a
very long time after about a million
years or so it gets replaced by another
type of tool heads which we refer to as
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the Chilean tool sets now first
discovered in dis in Norfolk I just I'm
from Ipswich so I have nothing but
contempt for people from Norfolk but
nevertheless a biggest set was
discovered a few years later in there in
the northern French town of Center Xu I
think I'm pronouncing that right but
please do correct me and that's the name
that it acquired but this is a more
complex tool it's by faced it's got more
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more cuts to it so you can shape they
tend to be pear shapes bigger as well up
to 20 centimeters and again what's
fascinating about this is you see them
all over the world and they're basically
static for about a million years with no
significant development or change in the
nature of the Julian axe heads for a
million years so what that means is
we've got two sets of tools the older
one choppers and the Assyrian axe heads
that are static for two million years
without significant change spread all
over the world that represents 95
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percent of the total amount of time that
humans have been using tools so the
question then is well are we is that
unique to us are we unique and I in our
command of extending our abilities via
tools and the answer is well
categorically no certainly in terms of
complexity and scale yes we have
our tool use is more sophisticated than
any other organism but about 1% of
animals also use tools and there are
dozens of examples of this and they
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spread across families and across taxer
which indicates that it is unlikely that
there is a single origin for tool use
and all subsequent users of tools that
arrive from a single origin is what
Daniel Dennett refers to as a good trick
right so if extending your abilities via
tools is useful then it's a good trick
for all organisms to have it or as many
organisms as possible I give you you
know dozens of examples all of the great
apes use tools many many monkeys use
stones and sticks the fun goalie
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chimpanzees they do an interesting thing
they sharp and they choose sticks that
are about three or four feet long and
they sharpen them with their teeth and
their main food supply is bush babies
bush babies sleep during the day and
they tend to sleep in hollows in trees
and if you break open a tree it makes a
lot of noise and the bush babies wake up
and they run away so they get these
Spears the fungi lead chimps they get
these Spears and they rapidly stab them
down and pull the bush babies out I
could go back and eat them off the stick
but it's not you know we think I've told
you some things like great apes as you
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know not that surprising but loads of
other animals do too my favorite is the
this is a boxer crab although no one
calls him boxer crabs anymore they call
them pom-pom crabs which is way less
hardcore but of them the many species of
pom-pom crabs they they pick up
poisonous anemones and use them to wave
off predators as they come in towards
them and whilst to another crab it looks
terrifying to us it looks like they've
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got pom-poms which is a shame but again
this idea of cultural transmission is
not necessarily something that we see in
these type in most of the animals that
have used tools there are few and far
between examples of non-genetic
non-biologically encoded tool use that
is transmitted from generation to
generation inevitably we must talk about
dolphins because there is one good
examples and
the cetaceans which is the Dolphins the
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bottlenose dolphins in shark bay they
they they work sponges on to their
rostra that beaks in order to protect
their beaks whilst they're foraging
around in rocky baits for you know for
food for crabs and and sea urchins and
things like that now that's pretty cool
right I mean that's a really cool
technology it's one animal using another
animal to eat a third animal which i
think is the only example of that in
nature but there's a much much more
interesting aspect to this story which
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is that only females do this and from
genetic studies we know that the females
are not necessarily closely related to
each other so this is not necessarily a
characteristic which is passed down from
well from mother to daughter it appears
to be laterally transferred between
females of bottlenose dolphins and from
the genetics we can also tell that there
was an originator we referred to as
sponging Eve which was probably five or
six generations ago so probably in the
middle of the 19th century a female
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dolphin decided for the first time to
nurdle a sponge on her onto her nose and
that worked out as being a really cool
way of getting food now we think that
there's cultural transmission in this
man Oh in some birds particularly
Caledonian crows and there's a lot of
talk of Caledonian crows and in the book
but I think what's interesting about
this is that whilst we've been over the
years being trying to work out what what
it is that bestows this amazing these
amazing characteristics upon us one of
the things that we have to think about
is brain size right because we have very
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large brains and over the years there
have been many attempts to account for
the amount of brain power that we
actually have what's been very
interesting about this is that almost
all of the attempts to do this have
tried to put humans at the top and we're
at the top of none of those categories
so they include things like what brain
size is the obvious one obviously we
don't have the biggest brains because
brains in general scale with the size of
the organism and then we looked at
number of neurons well we're we're sort
of about fourth in that African
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elephants have about four times more
neurons than us and then what Darwin in
fact first
so thinking about a better metric which
might be brain to body size ratio so the
proportion of your body that is actually
made up of of brain but you know who
wins that ants and shrews and again we
come we come in about 56 behind a lot of
whales and the ants and shrews
incidentally and this is only including
this and it's only included in the book
for what will become a very obvious joke
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the lowest ratio of brain to body size
is in a fish which is called I'm not
making this up I mean that that is its
name it's called the bony eared
ass fish and when I was looking this up
you know I thought this has got to be a
joke but sometimes science is just a
gift
we even introduced two different metrics
in the 1960s as an attempt to put us at
the top of a top of the pile again which
was called EQ and capitalization
quotient and we did come top of the pile
there and it looks like a better
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predictor of cognitive ability relative
to size until you take humans out in
which case size is a better predictor in
the great apes so it's clear again that
there isn't you know there isn't one
thing it's not just brain size it's not
just brain complexity we now know that
although birds many the cognitive
abilities of birds are being better and
better understood and there and they're
jolly impressive in many cases but their
brains tend to be much smaller only last
year did anyone actually work out that
should scan the brains of birds and it
turns out that the density of neurons is
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much higher for equivalent apes that
have similar sort of cognitive abilities
so again you know this is evolution
working in working as a tinkerer which
was what some the famous molecular
biologist Francois Jacobs said in the
1940s evolution is a tinkerer I do love
that phrase but there's a there's a
better why not better one is one that I
prefer which comes from Teddy Roosevelt
and nothing to do with evolution but
this idea to do what you can with what
you have where you are and this is I
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think a very important sentiment when
talking about evolution in general and
the differences between natural
selection adaptation and evolution
overall evolution is simply change over
time adaptation is
the effect of natural selection on our
changing bodies and those two things are
you know adaptation is part of evolution
but not everything that is evolved is an
adaptation and it's the reason I think
it's important to reference this at this
point is because yeah a very simple but
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obvious thing to say that I think
doesn't get said enough when we think
about evolution
dolphins are never going to evolve hands
because they need paddles to swim with
and so they're always going to be
limited in terms of compare comparing
our tool use and re-evolve tool use with
things that swim because they need to
swim with them and so you know it's just
a good example of how no matter what the
cognitive abilities of dolphins might be
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if they're in the water they have a
different set of evolutionary pressures
to us and for similarly obvious reasons
dolphins are never going to create fire
which I know sounds funny but it's not
insignificant and thinking about their
cognitive abilities of of whatever
organisms we're talking about if they're
never going to evolve fire there's not a
lot of wood in the ocean that means
they're never going to smelt anything
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and and so just you know remember this
idea that's the for evolution for
whatever you're talking about within
evolution you have to make do with
what's available to you in in front of
you so let me talk about fire that was
that was an unintentional but quite good
link there I might use that again
so this is another Darwin thoughts as
well so darn said some incentive man II
thought that a long side language
perhaps file was a thing that separated
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us from other organisms we are obligate
fire users as well and we have been for
hundreds of thousands of years very
difficult to date the origin of fire use
because the archaeological remains are
well we see evidence of fires outside of
caves but it's very difficult to tell
whether they deliberately started or
naturally-occurring
or wildfires compared to in more recent
histories in the last hundred thousand
years but it is it's not unreasonable to
say that within the last hundred
thousand years we have a commanding
control of fire but fire has been part
of our ecological makeup for a long long
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time as it is you know to this day in
Africa and in Australia and in various
places around around the world we talk
about tool use and I've mentioned stone
tool use we the era's geological eras
are defined by stone tool use the
Paleolithic which means old rocks and a
nearly new rocks and the Me's oolitic
which means medium rocks of course this
is the stuff that survives but we
mustn't make the mistake of thinking
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that the the stones we were using they
were that that was the complete tool set
because of course those Julian axe heads
and and Buren's were used to carve wood
but wood doesn't survive particularly
well I've got very few examples of
wooden tools that have survived over any
significant amount of time here's one
this was published last year and this is
from a site in in Tuscany and this is
one of several sets of Spears or sticks
which are wood and particularly hardwood
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boxwood but also that have been crafted
using fire right so they not only have
been carved using stone tools but it
looks very much like the outsides of
them had been burnt off using fire now
the date of these puts the creators of
these as Neanderthals not the same
sapiens again this is pre Homo sapiens
arriving in Europe so again indicative
that another human species way before us
had
similar level of cognitive ability the
cognitive understanding of something as
complex and as dangerous as a fire now
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there are other animals that interact
with fire in a very sophisticated way
vervet monkeys do this in in Africa and
when wildfires happen which happens in
an annual cycle they hang around near
the fires and they wait for the fires to
go out and then they they go in and they
forage and same chimps that do the kabah
being of the of the the bush babies also
do this they hang around like weirdly
close to fires and that shows something
very important about their cognitive
32:00
abilities that they understand something
as dangerous as fire which can change
very quickly and is very very lethal
that they have an ability to understand
in process that with sophistication
enough that they can stand close wait
for them to go out within minutes they
will go in and what happens in in
there's a couple of advantages to to
hanging around Savannah fires the first
is that it clears the plains which means
you can see for much longer and we know
this because grazing animals graze for
much longer on planes that have been
32:30
burned down they do when their grass is
this high or so but also you've just got
a smorgasbord of kooks food and so they
go in they cruise in and they and they
look for small critters that have been
burnt to death and so that's what the
fun gayly chimps do in the vervet
monkeys do there's a strong interaction
a recognition of fire as a danger but
also a source of ecological an ecology
that these animals closely interact with
now of course we are the only animal
33:01
capable of creating fire from scratch
and we've been doing that for probably a
hundred thousand years but a paper
published this year in January this year
was just a just a beautiful beautiful
revelation and it concerns three types
of raptors three types of Hawks all from
Australia is one of the illustrations
this is a a black kite an australian
black kite and what the kites do and
these two other two other raptors is
they they stand syn
33:33
in a tree near a wildfire and they go to
the edge and they pick up a stick which
is smoldering or burning and then they
fly away with it in their beak I know I
realized this picture looks a bit like
that birds having a it's carrying a
burning stick and we know this is
deliberate behavior that we see them we
see them drop the sticks when they're
quite hot and may go back and get
another one and then what they do is
they fly off to an area often beyond a
natural or man-made fire barrier and
they're going to an area of dry brush
and they drop the stick in there and
34:05
they create a new fire and then they fly
up to a tree and they watch all of the
small animals run out from the burning
fire and they go down and they eat them
all so sort of moving a moveable buffet
and this is we think the only other
example of deliberate fire starting in
any other organism it's it's true it's
beautiful and it's truly impressive it
is also something that Aboriginal
Australians have known about for a long
time and and is part of is referenced in
34:36
some of their Dreamtime ceremonies it's
called jerilyn and it's an interesting
sight I mean it's a footnote in the book
but I think it's worth mentioning that
it just shows the value of local
knowledge interacting within indigenous
say expertise because they've known
about it for centuries and may have been
significant in in Australian control of
wildfires which are cyclical and happen
every year it may even be and they cease
speculation but it's interesting
35:08
speculation is there's one book that
cites that suggests that observation by
Aboriginal Australians observations of
the fire Raptors the fire Hawks was the
inspiration for them doing exactly the
same thing now if that is the case that
is a gorgeous example of cultural
transmission between species from birds
to humans which is just a lovely idea
um there are many other examples so
that's that's fire dealt with I've done
tools have done fire there are many many
35:40
examples of other characters
that are familiar to us but aren't
necessarily behaviors which have been
that we have inherited from a common
ancestor and that's again you know a key
idea that sometimes we fall into the
trap of thinking that because another
organism does one particular thing and
it seems familiar to us and that is why
we do it one other example mostly
because I just like showing this picture
and telling this story this is Julie
36:09
Julie is obviously a chimpanzee and in
2007 Julie picked up a stick one morning
and stuck it in her ear and we don't
know why Julie did this but that's what
she did and within a few days her son
and best friends it was called Kate I
don't know who names these it's quite
possible that the she didn't refer to
herself as Julie but within a few days
her son Jack and her best friend Kate
we're also sticking twigs in the same
here always the same if they put it in
36:41
the other ear they took it out and put
it in the same way and within a few
weeks and then a few months about 12 out
of 15 members of this particular tribe
were also wearing sticks in their ears
now Julie died in 2012 I think it was
but the last time these chimps were
observed some of them are still wearing
sticks in their ears and to other tribes
that are not genetically related to
Julie's tribe are also wearing sticks
Americans now we don't know why they're
37:13
doing that this I think is the this is
fashion this is the only example any
reasonable example I'm aware of where an
animal is doing a particular decorative
behavior which doesn't appear to have
any direct reproductive benefits and of
course fashion is very important to us
so this following that we do we think
about a lot and spend a lot of time
signaling on right let me crack on I
told your head and time this it'll be
slick one day now there's another aspect
to this which I mentioned so I'm going
37:46
to mention but I'm not going to dwell on
and that is our sexual behavior so the
way a frameless in the book is to think
about this is a Richard Dawkins trick is
- if aliens were to come to earth and to
observe us as as if we were as a
naturalist and to look at human behavior
one of the things that be very striking
is that we spend an enormous amount of
time and energy and resources trying to
touch each other's genitals and then the
38:17
question becomes well what is the
purpose of of sex obviously sex is to
reproduce I did some some of the stats
on this with David Spiegel Hall to the
statistician at Cambridge and we worked
out that phrase this very carefully we
worked out that of the the sexual
behaviors this is for Britain alone of
the sexual behaviors that could result
in a baby about point one percent does
38:47
now I'm just turning to my mathematician
wife here how does that rank on on
statistical significance pretty low yeah
all right so there are very few
statistically insignificant number of
sexual encounters that could result in a
baby that actually does and if we pile
on top of that all of the sexual
behaviors human sexual behaviors that
cannot result in a baby
it is absolutely dwarfed so the primary
function of sex in order to reproduce is
absolutely insignificant compared to the
39:18
amount of sexual behavior that we engage
in right so we have effectively
decoupled reproduction from sex so then
you ask the question well maybe this is
unique to us maybe this is the thing
that evolved alongside our behavior that
we decoupled sex from reproduction maybe
that is not something that other animals
do well no not in the slightest bit and
I'm showing the cover here because some
of the organisms on this cover
represented by their footprints only
39:49
some of them are some of the tails of
weird animal behavior sexual behavior
which are potentially familiar to us was
not being related to the similar
behaviors that we see in us we ran a
competition on Twitter the other day to
identify all these
organisms the top one is me because
those and there's a the Nike dunks
they're the types of shoes that I wear
not today the next one is chimpanzee of
which we can talk about there's much in
40:19
the book about next one down anyone
mammal otter it's a sea otter now sea
otters are super cute as you well know
in the hold hands when they sleep to
stop themselves drifting apart and they
crack by vowels on their tummies with
with stones and that's super cute male
sea otters in Seattle also drown females
and then use their bodies to copulate
with up to two weeks until the bodies
fall apart so there you go a Bruins sea
otters for you
necrophilia weirdly is was only outlawed
40:54
in this country in 2007 and is
universally seen in all human cultures
it is generally regarded as a paraphilia
I don't think it's a very controversial
thing to say but again the idea that
actually there's quite a lot of
necrophilia in the animal world but to
suggest that otter behavior it relates
to human para pathologies
psychopathologies is stretching it a
little bit and if you're interested in
thinking about human behavior
particularly human sexual and gender
behavior and using animal models to back
that up then you've got to pick your
41:25
examples very carefully that that is
almost impossible to explain that alter
behavior is almost impossible to explain
using standard models of evolution right
it doesn't make any sense the fact that
they also do it to harbor seals a
different species just is absolutely
baffling so there is an example of a
behavior that we simply do not
understand what is the one below that
it's a two toed ungulate any one giraffe
someone said giraffe it's a giraffe only
gonna show you the picture that you're
after Alice did because it's such a
41:56
beautiful illustration giraffes are very
interesting for evolution of course
because they are the tallest animal they
have that amazing neck for a long time
we thought that the neck was an example
of a sexually of an exaggerated trait in
order that they could reach juicier
leaves for foraging actually that's not
true because from observation we know
that giraffes mostly forage at shoulder
height
so they tilt but we do know is it's
involved in sexual selection because
males so giraffes are mostly sexually
segregated most most of their lives and
42:29
mail packs spend almost all of their
time together and they do this thing
called necking which is you've seen it
on David Attenborough amazing
documentaries they do this wrestle to in
order to establish status what those
documentaries don't show that in about
60% of those necking encounters at least
one of the males has an unsheathed erect
penis and the winner ends up having
penetrative sex with the loser now
according to the best observations this
43:00
isn't very well studied this but several
thousand dollars worth of observation
across several regions in Africa
indicates that 94 percent of sexual
encounters in giraffes are between males
now during the same period that these
observations from maze 22 calves were
born so they are still engaging in
heterosexual sex because that would make
a lot of sense if you want to survive as
a species but the majority of sexual
encounters are homosexual in giraffes
now we do not know the reason for that
43:30
we do know that I'm asexual
homosexuality in the animal world or
homosexual behaviors are close to
universal in in most sexual species and
again sometimes we can work out the
answers though the reasons for them and
in other cases there are giraffes
we cannot I'll just do one more and from
the bottom to see this is what I mean
about not to spending the next two years
talking about weird animal sex I'm just
doing it now on tie the bottom one is
marine iguanas remember on the last
issue so dove the last series of blue
44:02
planet they had there's amazing
sequences marine iguanas in the
Galapagos running away from snakes it
was just you know Donna Shanice of
natural history marine iguanas are a
socially stratified by patriarchal
social stratification so there are alpha
males and sub alpha males and the
females are only fertile for one day per
year it takes a male iguana exactly 3
minutes to to ejaculate you can insert
your own joke there it's fine but if a
smaller male mounts a female then the
44:32
chances are the
Jermel will come along and physically
rip it off its back so the small amounts
have evolved a strategy which is that
they masturbate before they mount the
females and they can't they have a
little pouch where they put the sperm
into spermatophore and they mount the
females and they pop the package in so
they don't need the full three minutes
so there's an example of a of an animal
behaviour which may sound familiar to us
very sorry about this but he's unrelated
and it's one that we can understand from
evolutionary for evolutionary reasons
45:03
because it makes a lot of sense from an
evolutionary point of view but for
giraffes or sea otters they're things
that we simply don't understand we
mustn't make the mistake of assuming
that behaviors that seem familiar to us
can explain or explain away human
behaviors all animals are evolved along
their own trajectories to fit in with
their own ecological niches to do what
they can when they can with what they
have o transactional sex and the dealy
penguins is on my notes there I think I
just leave that so I can crack on right
45:33
now things are pretty much run out of
time I am the the this the the idea that
I think is most interesting in the book
and relates to this this concept of
cultural transmission is has been talked
about for a long time but in the last
few years has undergone a sort of minor
renaissance and this is largely the work
of Mark Thomas my colleague and friend
at UCL I think is here mark I know so if
46:04
you got any questions about this then
ask him but a significant factor in the
emergence of behavioural modernity in us
emerges from looking at the
archaeological records and processing
them into mathematical models and asking
the question well what is it about this
structure of a population which
coincides with this suddent the
relatively sudden in geological terms
emergence of all of this suite of modern
human behaviors that we recognize that
46:36
the so called full package and there's a
thing that emerges from these
mathematical models and from the
observations
that occur in multiple locations around
the world at the same time which cannot
have had a central origin from which
they emerge they effectively emerge at
the same time in different locations is
something which i think is very largely
ignores in evolutionary biology which is
population size and population structure
and just this idea that when populations
47:07
reach a certain size the amount of
information and the quality of the
information that flows between
individuals is optimized the larger
populations get the better the transfer
of that information is we are a species
of experts right we are a species that I
think has the most uneven distribution
of skill sets of any organism everyone's
an expert in something and what we see
from these types of models and from the
archaeological record is that that
expertise is most efficiently
transferred when populations grow so the
47:39
model sort of goes like like this that
when you see you see a change in climate
as a result population expansion and as
a result you see better and more
efficient transfer of these sorts of
skill sets and it is in those sort of
networks and that that's that transfer
of information that you be the coincides
with the emergence of these behaviorally
modern characteristics that we're that
we're so interested in it may be and
this is speculation we think that
Neanderthals were never very large
populations it may be that they're our
48:10
success over theirs once their
populations never became big enough that
you see this maximization of this this
flow of expertise and I think it's a
very powerful idea I'm interested in why
it's not discussed more I mean I I I
think it's correct i I looked at the
work and studied the word and talked to
mark about this a lot I think it's
probably correct I wonder why it's not a
more popular idea and I think it may be
to do with the fact that it it recognize
48:41
it represents a type of evolution that
we have been taught and groomed away
from for the last 50 years or so which
is this the when we talk about natural
selection we have to talk about what is
being selected
now since the 1950s and the work of
George price and Bob Trivers and all
those sort of titans of evolutionary
biology in the middle of the 20th
century the question of what was being
selected well is it what is it is it the
individual is it the group is it the
species well no it turned out to be the
49:13
gene right the gene is the unit of
selection and this is correct and this
is a pillar of evolutionary biology
today you know popularized by the
concept of The Selfish Gene the gene
centric view of evolution it is correct
and as a result of that we are rightly
taught and movement to to to not ignore
but to reject other units of inheritance
units of selection and especially away
from group selection but in fact this
idea of demographic transition and that
49:43
being a cause of a primary cause of the
emergence of the full package it is an
effect a sort of version of group
selection it is we're talking about a
cultural group and thus the size of the
group determines how that population
will evolve from that point on I think I
don't know I'm get I think that may be
why it's or not it's not a more popular
idea than it is but I think you know in
this book I'm trying to get that idea
out there so that we could talk about it
more widespread there's a the reverse we
think is also true as well and there are
50:15
a few examples of this but one
significant is in the evolution of
[Music]
Tasmania so Tasmania was attached to
mainland Australia until about 11,000
years ago at the last glacial maximum
and then when the Seas rose and the ice
ages melted it became an island and it's
been an island ever since now before it
separated we counts something like 50 to
60 tools in the tool set of the people
around this area then it becomes
50:45
separated and over the next several
thousand years the people of Tasmania
isolated from a larger community on
mainland Australia systematically lose
almost all of the tools that they had
before the separation and so when we now
think that that in the time where
mainland Australians generated about 124
to
by the time Europeans arrived in
Tasmania they were down to the
Tasmanians we're down to about 20 and so
51:16
we see this this is a Javanese fishhook
carved from the bottom of a flat bottom
shell and this dates from about 24,000
years ago but by the time you get to
about eleven thousand years ago in there
in the neolithic we've got incredibly
precise beautiful fine bones harpoon
heads and sophisticated fishing of
cartilaginous fishes and what we see in
the archaeological record in Tasmania is
a slow loss of this type of technology
and in fact their diets change and they
stop fishing cartilaginous fish and
51:47
return to being hunter-gatherers of
sessile organisms so you know stuff on
the sea shore and they lose their
hunting ability and return to being
gatherers and so that fits in with this
this model of demographic transition as
being a driving force behind barrel
modernity now I'm gonna stop there so
that we can get to questions but I just
want to say one last thing I might have
mentioned that Charles Darwin is my
intellectual hero the amazing thing
about this whole story and this idea
which is only now being talked about in
52:18
the last few years I think is correct is
that here's the guy who comes up with it
in the first place and it's in the
descent of man his second best book he
it's just a clue to it but this is this
is the quote which is worth thinking
about
again this is 19th century language and
he excludes 50% of humans as man
advances in civilization and small
tribes are united into large communities
the simplest reason would tell each
individual that he'll to extend his
social instincts and sympathies to all
52:49
members of the same nation though
personally unknown to him this point
being once reach there is only an
artificial barrier to prevent his
sympathies extending to the men of all
nations and races and and with that he's
ceding this idea that population
structure is absolutely essential to the
birth of our minds to our cognitive
abilities as we see them today and so
that's it that's what we do that's what
humans do that is what we're doing right
now that is why
53:20
we write books and why we attend
lectures and watch television and go to
school and go to universities and talk
to each other because we are the
products of evolution and when we took
those tools that evolution provided us
with the genes and the brains and the
bodies and we became something different
thank very much
[Applause]
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