There is, of course, no gene for the ability to cook nor,
previously, a gene for the ability to make a fire. Undoubtedly, there had
been prior genetic changes that improved our manual dexterity and this
enabled us to whisk eggs expertly or to rub pieces of wood together
sufficiently fast to make a fire. But, once discovered, such new habits
can be handed on culturally from one generation to the next even though
there are no specific genes for them. And when that happens, the new
cultural acquisitions become as much part of the natural environment as
any other. In turn, once that happens, then further genetic changes of a
random, accidental nature may be more useful to us if there were a camp
fire nearby than if there were not. So, little bit by little bit, rather
like a ratchet, our cultural habits become embedded in the predisposing
abilities of newly acquired genes, and the total stock of genes become
increasingly dependent on our culture.
We know that chimpanzees, who broke away from our common ancestors about
5 million years ago, carry certain cultural habits with them from one
generation to another and also that different groups of chimps tend to
have slightly different cultures. One group may use sticks to poke into
termite mounds and fish out the insects; another group may have got used
to breaking up the mounds by force, using rocks. But both of these
cultural acquisitions probably don't need any additional abilities than
the ones they have already acquired for general purpose survival. So, for
the purpose of termite-hunting, some new mutations were neither useful
nor harmful and thus there was no subsequent selection effect.
In the case of man, however, it would seem that we acquired at least one
cultural habit which was sufficiently versatile to have had a significant
shaping effect as though it were a feature of the environment -- as
constant and as powerful, say, as the hours of sunlight. Anthropologists,
evolutionary psychologists and neuroscientists are constantly putting
forward one suggestion after another. There is no consensus on this
matter at the present time and it is unlikely that there will be until a
great deal more is known about specifically human genes and, more
precisely, when they kicked in. But once a significant cultural habit is
acquired, it can have all sorts of subsidiary effects in the shaping of
other genes which, at first sight, don't appear to be in any way related.
For example, some neuroscientists believe that the grammatical rules for
speech followed from sign language (perhaps used for hunting purposes,
who knows?) which, in turn, followed from the dexterity that was shaped
by tool-making.
A significant enough cultural acquisition could therefore assist in the
radiation of further mutational changes, both of mental abilities and of
physical changes. If some of these also happened to act in concert, then
the normal steady baseline acquisition of accidental mutations could
actually start to have accelerative effects. And this appears to have
happened in the case of man, particularly in the extraordinarily rapid
expansion of the brain during the last 2 million years. Genes for the
expansion of the brain were undoubtedly acting in association with those
for earlier births -- because too large a baby's head at full-term would
kill a mother when giving birth. The result of this is that human babies
are now about 17 months' premature when compared with the physical and
mental development of the chimpanzee at birth. The chimp baby is far
ahead of the human baby in every way and remains so for a few months.
Even though the actual number of new genes acquired by man beyond the
time that the chimps struck away from our common stem is only about
1,000, their effect can be multiplied many times over. Not only that, but
the latest research by Michele Cargil and others at Celera Diagnostics in
Alameda, California, among other groups of researchers, suggest that
about 10% of the genes that we originally shared with chimps have also
mutated in ways that assist the new ones.
There is no inevitability about the way that man has evolved. Up to the
time that the chimps broke away from the mainline route that led to
hominids then the physical environment alone would have had the
predominant shaping effect in the survival or not of accidental
mutations. In the last 5 million years, however, and particularly in the
last 2 or 3 million years, then cultural acquisitions would have become
increasingly important. They would have cemented the new mutations and
new genes into our DNA as firmly as though acquired as a result of the
physical environment. Thus, we become as genetically "addicted"
to acquired cultural practices as to many of the basic features of the
environment around us
Professor Richard Wrangham has suggested that cooking would have been a
powerful cultural acquisition and that it has had a myriad of
consequences, not only in the food we eat but in our physical evolution
and also in further genetic changes in the brain which lay down our
behavioural predispositions. Hitherto rather scorned as being of much
importance, cooking appears to be one of the most formative of our
cultural acquisitions. Indeed, as related below, it is certain that we
couldn't physically survive today without cooking. His suggestion that
cooking consolidated the genetic predispositions towards pair-bonding is
quite persuasive to me.
Keith Hudson
<<<<
A RECIPE FOR SUCCESS
The role of cooking in our evolution was vital. It made food easier to
digest; it created hearths around which people gathered. Now, we can't
survive without it
Sanjida O'Connell
In the next few days, some of us will be struggling with a turkey,
consulting Delia about whether to partboil potatoes before roasting,
wishing we'd taken Nigel Slater's advice and made the pudding in October,
and wondering what to give vegetarians who don't like nuts. Invariably
we'll eat too much, drink unhealthy amounts of alcohol and some of us may
consider going on a detox in 2004. But although cooking to our lives and
our festivities -- whether it's Christmas, Hanukkah or Eid -- few of us
realise how much it has altered not only our physiology, but our
psychology. Changes that took place our bodies almost two million
years ago could have reduced our ability to detoxify our foods, which may
explain our unhealthy appearance in the New Year.
The idea that cooking has changed the human species fundamentally was
dreamt up by Professor Richard Wrangham of Harvard University, Boston, as
he sat in front of a dying fire in his living room one winter's night.
Wrangham studies chimpanzees and, as he stared into the embers, he felt a
pang of pity for his subjects, sleeping out in the cold and eating only
raw food. He found himself wondering when it was that human beings
created fire and learnt to cook. He realised that not only did he not
know the answer, but that most textbooks on human evolution did not cover
the subject. Out of 17 textbooks surveyed by one of his students, it was
found that, while 10 of the text books (or 58 per cent) mentioned
cooking, the sum total of space devoted to the subject from all of them
amounted to less than two paragraphs."
Cooking comes across as the equivalent of a piece of furniture,"
Professor Wrangham says. "If you've got it, you'll like it. But it
isn't thought of as something that would have radically affected our
ancestors' anatomy, or their social lives." Yet as long ago as 1773
James Boswell, Samuel Johnson's biographer, wrote: "My definition of
Man is, a 'Cooking Animal'."
No one, perhaps unsurprisingly, took any notice. The great anthropologist
Claude Levi-Strauss quoted Edmund Leach on the subject "Men do not
have to cook their food, they do so for symbolic reasons to show they are
men not beasts." Instead, current theories of human evolution
use hunting to explain how we became human. The division of the sexes
arose because women collected plants and looked after the children while
men brought home the bacon. "Except that it wouldn't have been
bacon, according to the proponents of the hunting hypothesis," says
Wrangham. "It would have been a raw hunk of pig, and it would have
stayed raw while being eaten."
One brave theorist, the anthropologist Loring Brace, argued in the 1970s
that cookmg was important: actually, not so much cooking as de-frosting.
During the ice ages it would have been necessary to thaw large hunks of
frozen meat, which would have allowed humans to colonise glacial zones.
But no one, according to Wrangham -- not even Brace -- has recognised how
important cooking has been to our evolution.
The perfect experiment to test Wrangham's hypothesis has been carried
out. Today some Westerners believe that raw food is healthier since
cooking destroys enzymes and vitamins. In a study of Germans who
practised this philosophy, researchers discovered that most long-term raw
foodists (those who stuck to the diet for more than three years) were
suffering from chronic energy deficiency. Many had lost a lot of weight
and about half the women had ceased to menstruate.
A colleague of Wrangham's, Dr Nancy-loo Conklin-Brittain, calculated that
an average woman on a raw-food diet would have to eat up to 10 kilograms
(22 pounds) of food a day to gain enough calaries to sustain her; this
is, almost a fifth of her body weight. Even Americans who, during
Thanksgiving, can consume up to 7,000 calories, would not then eat more
than 4.6 kg of food. Neither, Wrangham thinks, would eating raw meat
help. With considerable difficulty, he has observed how long it takes
chimpanzees to eat a piece of raw meat. It usually takes them about an
hour to absorb 400 calories of flesh-- the equivalent of a
sandwich. For a human being to get his or her calorie intake from
raw meat, they'd have to chew for six hours a day.
In contrast, cooked food is more edible; it's easier to digest because
it's softer. Uneatable food is rendered eatable and toxins are removed.
Meat is tenderised by heat because the collagen holding the fixes
togeteer are softened and turned into gelatin. All known human
populations have always cooked most of their food, be it the San bushmen
of the Kalahari, or the Ach� of the Americas. But the evidence for when
our ancestors first used fire (and hence may have cooked) is patchy.
Anthropologists estimate that it was between 400,000 to 1.6 million years
ago.
Without fossil records for fire, Wrangham puts the date much earlier,
between 1.6 and 1.8 million years ago. It is a dramatic step to take,
posing a date for cooking without the usual scientific evidence, but
Wrangham argues that it was at this point that Homo erectus (also
called Homo ergaster) evolved. This species had a remarkably
different figure from other hominids -- it had a body very like our
own.
By taming fire and learning how to cook, our ancestor would have had
access to a superior diet The reason that a better diet could have
changed us is because, first, we would not have needed such big teeth to
grind all that raw food and, secondly, we could dispense with enormous
guts. Modern human intestines (in particular, the colon) occupy only a
fifth of our total gut volume, compared with more than 50 per cent in
chimpanzees. To give a rather gruesome example, a chimp turned up at Jane
Goodall's study site in Gombe, Tanzania, with a hand sticking out of its
anus. It had swallowed a monkey arm whole. The students invented all
kinds of unfortunate jokes, but Wrangham makes the point that this shows
how much larger a chimp's gut is as only a human sword swallower might
manage the same feat. He estimates that their faeces are twice as wide as
ours -- though they weigh less than two-thirds of the weight of an
average person -- because their food contains so much more fibre than
ours.
Cooking may also have affected our psychological make-up. Having a hearth
meant Homo ergoster had to store food and now bad somewhere to sit
and prepare and eat it The larger males could have stolen females' food,
leading Wrangham and his colleagues to put forward the Bodyguard
Hypothesis: female Homo ergaster may have teamed up with one male
to help her protect it. Thus being a domestic goddess 1.9 million years
ago could have led to the rise of monogamy.
The knock-on effect is that, since we evolved to allow cooking to take
the toxins out of food and are not very good at disposing of them
ourselves, the Christmas holidays will see an unhealthy level build up as
we pour junk food no Homo ergaster could have imagmed into our
bodies. Just dont try the raw food diet as a detox.
The Independent Review -- 18 December 2003
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