I have been reading “Ape Man: the story of human evolution” published in
the UK last year by the BBC. The author is Robin McKie, science editor of
the Observer, so it should be good. And it is.
What I would like to share with you is some of McKie’s information because
he brings out some useful evidence relevant to debates we have seen on this
discussion group including the perennial ones of whether our “natural” diet
is vegetarian or omnivorous, whether EvFit applies to women as well as to
men and what sort of physical exercise we can do which captures the essence
of our evolutionary heritage. McKie also touches on the sort of mental and
emotional qualities which led to survival through the rigours of
evolution. (Devise your own mental exercises to complement your physical
exercises).
The page references below are to McKie’s book which I urge you to read if
you are at all interested in human evolution but not already a graduate in
this area. Needless to say, I take full responsibility for the following
interpretation. I am not a scientist and a more expert reader of McKie’s
book and the numerous sources he cites might lead to a different, more
sophisticated interpretation than that which follows. If the alert reader
detects a Lamarckian thread in the following, that is attributable to my
lack of learning, not to McKie’s account. I add the caution that I have
ignored the usual scholarly conventions concerning quotations and ellipses
where they would impede the flow of my text. Please check McKie’s book for
the precise words and the context.
In terms of diet, the story is that our pre-Homo ancestors were herbivorous
and our digestive system is basically unchanged since that time. However,
there were immense advantages in our ancestors also consuming meat -
indeed, without consuming meat we might still be the _australopithecene_
species which preceded _Homo_ and flourished up to 2m years ago.
The jumping-off point is that climate change gave our ancestors the stark
alternative: adapt or perish. Some of our ancestors adapted, becoming tool
makers and omnivores rather than herbivores. They also survived.
McKie quotes Richard Potts: “About 2.5m years ago, hominids encountered
great fluctuations in the climate. At the same time we see the appearance
of stone tools. That is no coincidence. They indicate that at least one
species of hominid was responding to these changes by becoming even more
adaptable, rather than becoming specialized in the way that _robustus_ and
_bosei_ did. By making tools, dietary choices became even greater. Not
only could people skin the large dead and doubtless smelly carcasses they
occasionally found, they could crack open their bones for marrow. In
addition tools would have helped pound and break down vegetables and nuts
that could otherwise only have been eaten by animals with specialized
dentures, and also helped dig up tubers which are rich in protein and
calories. Just as _australopithecines_ responded to oscillating climates
by walking, by becoming more versatile movers, so did the first members of
the _Homo_ line 2 million years later. They made tools and became more
versatile eaters” [66f]. The richer diet led to bigger brains, bigger
brains led to intellectual growth and intellectual growth led to: (1)
improved memory (including mental resource maps of the terrain and the
seasons), (2) the ability to co-operate and take advantage of social
complexity, (3) the ability to solve problems which led to the ability to
create and use tools. These benefits in turn led to a more reliable diet
which was also richer [114]. “We became less tethered to our habitats...
Our ancestors’ behaviour was becoming increasingly diverse, our menus more
adventurous. Mankind was on the move.” [67] Meat eaters were more free to
migrate so they could flourish and survive, herbivores being more limited
to the spread of their familiar staple plants [96]. The complexity of
societies, the importance of memory and skills led to adults having a
benefit beyond their reproductive age - they had knowledge and culture
(wisdom) to pass on, not just physical genes[115].
The second point concerns the evolution of human society and the biological
basis of differentiation of male and female roles.
Humans had a small pelvic gap for the birth canal, yet a more intelligent
species would have a large head to accommodate the large brain. A larger
head could not fit through the pelvic gap. The evolutionary response was
twofold: (a) for humans to be born while their brain was still relatively
small. This means that mothers need to provide intensive care (suckling,
comfort, nurturing, warmth) while the brain develops. If mothers are
devoting themselves to this nurturing, they need the reliable and sustained
support of others - the “family” or “tribe” [88]. The second response
was (b) for women to evolve wider hips. This development survives today:
women are less efficient bipedalists than men. Men were, therefore,
comparatively better shaped than women for many of the activities of being
the provider [89]. Because human brains take years to develop, there is a
need for sustained social bonds to support the maturing human for the
duration of its immaturity (i.e., its childhood).
The third point concerns the physical activities of our ancestors. “As
well as the caring nature of Neanderthal society, the numerous injuries on
their skeletons pointed to a dangerous, perhaps violent, side to their
lives. Trinkaus ... analyzed the bones of 17 Neanderthals - individuals
who had a staggering total of 27 traumatic wounds. They were mostly
injured to the head and upper body, almost no lower limb injuries. I got a
statistical fit with rodeo riders; they get thrown off their animals a
lot. In other words, it looked like Neanderthals were being flung around
and badly hurt by the creatures that they hunted. Not for them the low-
risk, careful business of stalking and spearing. They went in for the kill
and paid the consequences... These were people who had evolved a robust
response to the rigours of survival, creatures with physical prowess beyond
the aspirations of even the best Olympic athletes [157f].”
The fourth point concerns the use of fire. This is important for us as the
historical timing of its regular use can guide us to decide whether our
paleo diet can - for scientific rather than aesthetic reasons - validly
include cooked meat. Although there is some evidence of the use of fire as
a defence against predators 1.3 - 1.4m years ago, this is contentious.
Some hearths and the remains of burnt bones have been found in China from
300,000 to 400,000 years ago. Other sites 500,000 years old have no signs
of fire. Fireplaces do not appear regularly until about 40,000 years ago
[160], just 1700 generations, not long in evolutionary terms.
The fifth point concerns mental and emotional skills, apart from the animal-
like quick reactions and coordination. McKie’s account indicates that
people who were tenacious and innovative were survivors. More than that,
it was those who had social skills - who trusted others and were trusted in
return, who showed compassion [90, 154, 156-7], who sustained long-term
relationships of trust [80f] (and love?), who contributed to the group who
survived best of all. People with good memories and who organized their
thoughts in a way that could be communicated effectively (a) for immediate
practical purposes [124] and (b) down the generations were also at a
premium. Remember, the oral tradition was the only tradition. One could,
on the evidence of McKie’s book, make an argument for monogamy. I won’t do
that but will go so far as to say that the qualities I have just listed
appear to be those that both sustained people in periods of negligible
change and enabled them to adapt and survive when change was forced upon
them.
There is much more in McKie’s book to fascinate and inform. For me the
underlying message is that our modern pre-occupations with weight loss and
body sculpting trivialize the most wonderful story in the world. We can
get far more out of this story than a reduction in cellulite. Our
challenge is to apply evolutionary theory to the scientific evidence and so
map out the essential features of paleo life. We can then decide whether
our 21st century, Western prejudices, predilections and constraints rule
out for us certain features of the full paleo repertoire and how we apply
to our lives those features that we do not rule out.
I apologize for this long posting. I do not have a web site and this is
the only medium I have of passing on to you my views about this gem of a
book.
Keith Thomas
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