2. Evolutionary Theory of Food
Preference
What foods do you prefer.
•When you get home from college tonight what
foods might you reach for if you need a snack?
•When you go to the supermarket and you’re hungry,
what foods would you tend to buy to satisfy this
hunger?
3. Evolutionary Theory of Food
Preference
Evolutionary theory suggests that:
• Organisms should behave so as to maximise the survival of their genes or
their inclusive fitness (the probability that their biological relatives will
survive).
•Therefore, Natural Selection (survival and reproduction of the fittest)
occurs.
What does the Evolutionary Theory suggest about human behaviour?
Adaptive
Good for
Survival
How is this relevant to eating behaviour?
•Those who are best equipped to obtain sufficient food and remain health were more likely
to survive.
•This means that humans have evolved to have certain food preferences that give them
the best chance of choosing good food with enough necessary nutrient to promote
survival.
4. Learning Objectives:
Evolutionary Explanation of Food Preference.
(1)The tendency to binge eat (why do we prefer foods
that are high in fat?)
(2) Why do we have a preference for sweet foods?
(3) Why do we have a preference for salty foods?
(4) Is there any research supporting these food
preferences?
5. (1) Tendency to Binge Eat
In our evolutionary past food supplies were limited or erratic. Our ancestors couldn’t rely on a
continual source of food for their daily nutritional needs. It is believed by evolutionary
psychologists that such times encouraged maximisation of stored energy i.e. binge eating would
have been considered adaptive.
-Sweet, fatty or salty foods would be particularly sought after since they are vital
requirements to our diet and relatively rare in the ancestral environment.
Any human that quickly learned that such high fat foods provide more energy, deliberately
sought these foods out and consumed as much as possible would be most likely
to survive. Thus, it would be advantageous to overeat in times of plenty and
then expend as little of those calories as possible in readiness for times of
scarcity.
A01
Commentary:
•The obesity problems encountered by much of the western world in today’s society are testament to
an inability to escape this evolutionary pressure. (Steven and Price, 2000).
•Nowadays many people have a problem with overeating and gaining weight. The increased levels of
obesity in the developed world suggests that people as predicted by Evolutionary Theory find it
hard to ignore high fat food offerings now that they are readily and cheaply available.
•Furthermore, although exercise could alleviate these evolutionarily led behaviours,
another evolutionary hangover is to conserve energy and people now do this
by not exercising and using labour-saving devices such as lifts, cars and dishwasher etc.
A02
11. We Luurve the Cake!!
(2) Preference for Sweet Foods
•Argument that humans have evolved a preference for
specific tastes.
•Sweet taste signifies ripeness, high concentration of sugar, quick fix of
calories.
•A preference of sweet foods would encourage the consumption of ripe fruit
and would have an evolutionary advantage for our ancestors.
A01
There is considerable empirical support for the idea that we have an innate “sweet tooth”. Research
has shown that people of all ages will choose sweet foods over other tastes (Meiselman, 1977).
Even 3 day old infants demonstrate this preference (Desor et al, 1973).
A02
Bell et al (1973) gave sweet sugary foods to Eskimos in Northern Alaska who
had previously lacked sweet food and drink in their diets. They found that, in all
cases, cultures previously without sugar did not reject the sugar containing food and
drinks of the other culture, suggesting that a preference for sweet tastes is not
culturally learned.
12. Preference for Sweet
Foods...A02
SCIENTIFIC SUPPORT
There is also physiological support for the
preference for sweet food. The human tongue
seems to have specific receptors for detecting
sweetness. This is not the case with other
tastes, which are detected by non-specific
receptors. There also appears to be more
receptors for detecting sweetness than any
other taste. All this evidence suggests that
the taste of sweet foods is more important to
the body than any other taste, again implying
that that the sweet preference has a
substantial genetic component (Logue, 1991).
13. Preference for Salty Foods
Salt is essential for the body to function properly. We lose salt
through sweating and the action of the kidneys and therefore it needs
to be kept at a constant level. As with fatty foods, it may be that the
body has developed a proclivity to consume salty foods whenever
possible, as they would have been relatively difficult to find.
Preference for Salty Foods
A01
We are not born with an innate preference to salty food,
but it develops in childhood. Two year old children have been
found to universally reject foods without the expected amount
of salt in them (Beauchamp, 1987).
A02
“I think my wife is trying
to kill me Officer”
14. Evolutionary Avoidance of
Dangerous Foods
Humans are omnivores- we eat a wide ranging diet that includes meat. In many ways
this is hugely advantageous, as it allows us to exploit many different food sources.
However, it also leaves us open to a variety of plant toxins and infections from
food that has gone off. This is particularly true of meat, which is still a major source
of food poisoning today.
The main problem with
Evolutionary theory is the
inability to test it. Evidence
has to instead be gained
from observations of
species change, fossil
records or studies on
primates.
A02
A01
15. As a species we have evolved several
methods to cope with this problem…
Cooking
This was introduced a least half a million years ago and solves this problem by
killing bacteria in meat during the cooking process. In addition, cooking also
makes meat tender and easier to chew.
This is evidenced by the fact that
our chewing teeth, the molars, have
significantly decreased in size during
evolution (Lucas et al, 2006).
Taste Aversion Learning
Garcia, Rusiniak & Brett (1977) made wolves sick with lamb’s meat
contaminated with a mild poison wrapped in sheepskin, when allowed to
approach live sheep the wolves would approach, sniff and then leave the
sheep alone
**ELABORATION** Why is it an
evolutionary advantage that we
avoid foods that have made us sick?
16. As a species we have evolved several
methods to cope with this problem…
Food Neophobia (neophobia means ‘fear of the new’)
Animals have a powerful tendency to avoid foods they have not come across
before, although this may become dull, Frost (2006) identified that we tend
to show greater likings for foods as they become more familiar.
**ELABORATION** How does this
support the evolutionary theory?
Morning sickness is most common in early pregnancy, when the baby’s organs are still
forming and it is most vulnerable. The foods most avoided by pregnant women due
to their ability to trigger sickness are those which appear to have the greatest
chance of damaging the embryo. For example, alcohol, coffee and tea all contain
caffeine which can damage the developing organs and meat and eggs are common
sources of bacteria which could lead to harmful infections. This sickness reaction
therefore helps the mother avoid foods that may be detrimental to her pregnancy,
while the vomiting prevents any toxins entering the bloodstream and affecting her baby
17. Approaches: Evolutionary ... Issues: Unfalsifiable
Debates:
Also, don’t forget..AO3..
How Science Works.......
Be critical
