Homo Deus: a brief History of Tomorrow

particular calculation, but the method followed when making the calculation. For
example,  if  you  want  to  calculate  the  average  between  two  numbers,  you  can
use  a  simple  algorithm.  The  algorithm  says:  ‘First  step:  add  the  two  numbers
together. Second step: divide the sum by two.’ When you enter the numbers 4
and 8, you get 6. When you enter 117 and 231, you get 174.
A  more  complex  example  is  a  cooking  recipe.  An  algorithm  for  preparing
vegetable soup may tell us:
1. Heat half a cup of oil in a pot.
2. Finely chop four onions.
3. Fry the onion until golden.
4. Cut three potatoes into chunks and add to the pot.
5. Slice a cabbage into strips and add to the pot.
And  so  forth.  You  can  follow  the  same  algorithm  dozens  of  times,  each  time
using slightly different vegetables, and therefore getting a slightly different soup.
But the algorithm remains the same.
A  recipe  by  itself  cannot  make  soup.  You  need  a  person  to  read  the  recipe
and  follow  the  prescribed  set  of  steps.  But  you  can  build  a  machine  that
embodies  this  algorithm  and  follows  it  automatically.  Then  you  just  need  to
provide the machine with water, electricity and vegetables – and it will prepare
the  soup  by  itself.  There  aren’t  many  soup  machines  around,  but  you  are
probably familiar with beverage vending machines. Such machines usually have
a  slot  for  coins,  an  opening  for  cups,  and  rows  of  buttons.  The  first  row  has
buttons  for  coffee,  tea  and  cocoa.  The  second  row  is  marked:  no  sugar,  one
spoon of sugar, two spoons of sugar. The third row indicates milk, soya milk, no
milk.  A  man  approaches  the  machine,  inserts  a  coin  into  the  slot  and  presses
the buttons marked ‘tea’, ‘one sugar’ and ‘milk’. The machine kicks into action,
following  a  precise  set  of  steps.  It  drops  a  tea  bag  into  a  cup,  pours  boiling
water, adds a spoonful of sugar and milk, and ding! A nice cup of tea emerges.
This is an algorithm.
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Over  the  last  few  decades  biologists  have  reached  the  firm  conclusion  that
the man pressing the buttons and drinking the tea is also an algorithm. A much
more  complicated  algorithm  than  the  vending  machine,  no  doubt,  but  still  an
algorithm.  Humans  are  algorithms  that  produce  not  cups  of  tea,  but  copies  of
themselves (like a vending machine which, if you press the right combination of

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buttons, produces another vending machine).
The algorithms controlling vending machines work through mechanical gears
and  electric  circuits.  The  algorithms  controlling  humans  work  through
sensations,  emotions  and  thoughts.  And  exactly  the  same  kind  of  algorithms
control pigs, baboons, otters and chickens. Consider, for example, the following
survival  problem:  a  baboon  spots  some  bananas  hanging  on  a  tree,  but  also
notices a lion lurking nearby. Should the baboon risk his life for those bananas?
This  boils  down  to  a  mathematical  problem  of  calculating  probabilities:  the
probability  that  the  baboon  will  die  of  hunger  if  he  does  not  eat  the  bananas,
versus  the  probability  that  the  lion  will  catch  the  baboon.  In  order  to  solve  this
problem the baboon needs to take into account a lot of data. How far am I from
the bananas? How far away is the lion? How fast can I run? How fast can the
lion  run?  Is  the  lion  awake  or  asleep?  Does  the  lion  seem  to  be  hungry  or
satiated? How many bananas are there? Are they big or small? Green or ripe?
In  addition  to  these  external  data,  the  baboon  must  also  consider  information
about  conditions  within  his  own  body.  If  he  is  starving,  it  makes  sense  to  risk
everything  for  those  bananas,  no  matter  the  odds.  In  contrast,  if  he  has  just
eaten, and the bananas are mere greed, why take any risks at all?
In  order  to  weigh  and  balance  all  these  variables  and  probabilities,  the
baboon  requires  far  more  complicated  algorithms  than  the  ones  controlling
automatic  vending  machines.  The  prize  for  making  correct  calculations  is
correspondingly  greater.  The  prize  is  the  very  survival  of  the  baboon.  A  timid
baboon – one whose algorithms overestimate dangers – will starve to death, and
the  genes  that  shaped  these  cowardly  algorithms  will  perish  with  him.  A  rash
baboon  –  one  whose  algorithms  underestimate  dangers  –  will  fall  prey  to  the
lion, and his reckless genes will also fail to make it to the next generation. These
algorithms  undergo  constant  quality  control  by  natural  selection.  Only  animals
that calculate probabilities correctly leave offspring behind.
Yet  this  is  all  very  abstract.  How  exactly  does  a  baboon  calculate
probabilities? He certainly doesn’t draw a pencil from behind his ear, a notebook
from a back pocket, and start computing running speeds and energy levels with
a  calculator.  Rather,  the  baboon’s  entire  body  is  the  calculator.  What  we  call
sensations  and  emotions  are  in  fact  algorithms.  The  baboon  feels  hunger,  he