Sapiens: a brief History of Humankind

2.
 Our siblings, according to speculative reconstructions (left to right):
Homo rudolfensis
(East Africa);
Homo erectus
(East Asia); and
Homo neanderthalensis
(Europe and
western Asia). All are humans
.
Humans in Europe and western Asia evolved into 
Homo neanderthalensis
(‘Man

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from the Neander Valley), popularly referred to simply as ‘Neanderthals’.
Neanderthals, bulkier and more muscular than us Sapiens, were well adapted to
the cold climate of Ice Age western Eurasia. The more eastern regions of Asia were
populated by 
Homo erectus
, ‘Upright Man’, who survived there for close to 2
million years, making it the most durable human species ever. This record is
unlikely to be broken even by our own species. It is doubtful whether 
Homo
sapiens
will still be around a thousand years from now, so 2 million years is really
out of our league.
On the island of Java, in Indonesia, lived 
Homo soloensis
, ‘Man from the Solo
Valley’, who was suited to life in the tropics. On another Indonesian island – the
small island of Flores – archaic humans underwent a process of dwar ng. Humans
rst reached Flores when the sea level was exceptionally low, and the island was
easily accessible from the mainland. When the seas rose again, some people were
trapped on the island, which was poor in resources. Big people, who need a lot of
food, died rst. Smaller fellows survived much better. Over the generations, the
people of Flores became dwarves. This unique species, known by scientists as
Homo oresiensis
, reached a maximum height of only one metre and weighed no
more than twenty- ve kilograms. They were nevertheless able to produce stone
tools, and even managed occasionally to hunt down some of the island’s elephants
– though, to be fair, the elephants were a dwarf species as well.
In 2010 another lost sibling was rescued from oblivion, when scientists
excavating the Denisova Cave in Siberia discovered a fossilised nger bone.
Genetic analysis proved that the nger belonged to a previously unknown human
species, which was named 
Homo denisova
. Who knows how many lost relatives of
ours are waiting to be discovered in other caves, on other islands, and in other
climes.
While these humans were evolving in Europe and Asia, evolution in East Africa
did not stop. The cradle of humanity continued to nurture numerous new species,
such as 
Homo rudolfensis
, ‘Man from Lake Rudolf’, 
Homo ergaster
, ‘Working Man’,
and eventually our own species, which we’ve immodestly named 
Homo sapiens
,
‘Wise Man’.
The members of some of these species were massive and others were dwarves.
Some were fearsome hunters and others meek plant-gatherers. Some lived only on
a single island, while many roamed over continents. But all of them belonged to
the genus 
Homo
. They were all human beings.
It’s a common fallacy to envision these species as arranged in a straight line of
descent, with Ergaster begetting Erectus, Erectus begetting the Neanderthals, and
the Neanderthals evolving into us. This linear model gives the mistaken
impression that at any particular moment only one type of human inhabited the
earth, and that all earlier species were merely older models of ourselves. The truth

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is that from about 2 million years ago until around 10,000 years ago, the world
was home, at one and the same time, to several human species. And why not?
Today there are many species of foxes, bears and pigs. The earth of a hundred
millennia ago was walked by at least six di erent species of man. It’s our current
exclusivity, not that multi-species past, that is peculiar – and perhaps
incriminating. As we will shortly see, we Sapiens have good reasons to repress the
memory of our siblings.
The Cost of Thinking
Despite their many di erences, all human species share several de ning
characteristics. Most notably, humans have extraordinarily large brains compared
to other animals. Mammals weighing sixty kilograms have an average brain size
of 200 cubic centimetres. The earliest men and women, 2.5 million years ago, had
brains of about 600 cubic centimetres. Modern Sapiens sport a brain averaging
1,200–1,400 cubic centimetres. Neanderthal brains were even bigger.
That evolution should select for larger brains may seem to us like, well, a no-
brainer. We are so enamoured of our high intelligence that we assume that when
it comes to cerebral power, more must be better. But if that were the case, the
feline family would also have produced cats who could do calculus. Why is genus
Homo
the only one in the entire animal kingdom to have come up with such
massive thinking machines?
The fact is that a jumbo brain is a jumbo drain on the body. It’s not easy to
carry around, especially when encased inside a massive skull. It’s even harder to
fuel. In