Our Eating
Habits and food preferences are said to have come from our ancestors and to
have adapted in our Environment of Evolutionary Adaptation (EEA). Our Ancestors
were hunter gatherers, whose diets consisted of animals and plants, and energy
resources were vital to them to stay alive.
In our EEA our ancestors were
required to eat meat to compensate for the bad quality plant food and to give
them the essential amino acids, nutrients and minerals they needed for brain
growth so that they could eat the plant food purely for the calories. This is
said to be the reason we now have a preference for meat however it does not
give an explanation for vegetarians.
We are also said to have developed a taste aversion to avoid foods that
would make us ill. If a food makes us ill when we eat it we develop an aversion
to it so that we can avoid it in the future.
Garcia et al. (1955) conducted a study to support the fact that we have
developed a taste aversion by feeding poisoned lamb meat to wolves to make them
ill. He found that after this experience with the lamb meat the wolves avoided
eating it in the future which would suggest that they had developed an aversion
to it. This supports taste aversion as an evolutionary explanation of food
preferences as it is likely that just like the wolves we used this to avoid
foods that were harmful to us to survive.
Garcia’s study however is lacking in external validity because it was
carried out on wolves and not humans. It cannot be fully generalized to humans
as we have a very different psychological makeup and therefore it cannot be
said that our brains work in the same way as theirs. This is a big weakness in
animal studies and means that this study is not as supporting of taste aversion
as others that are conducted on humans.
Morning Sickness in pregnant women also supports taste aversion.
Morning Sickness is found in 75% of pregnant women and Profet suggested that
the reason they vomit is because their body is trying to get rid of anything in
the body that may harm, the embryo. He called this the ‘Embryo Protection
Hypothesis.’ It is also the reason why some women develop an aversion to
certain foods during pregnancy. This supports taste aversion as an evolutionary
process and an adaptation form our ancestors as in our EEA this would be they
only way mother had of knowing which foods could be harmful to their child and
it shows that our bodies have adapted to use this to give our offspring the
best chance of survival.
Sandell and Breslin (2006) also carried out a study to support taste
aversion where they screened 35 adults for the bitter taste receptor gene. They
were then asked to rate the bitterness of a number of vegetables, some of which
contained glucosinolates and some which didn’t. Glucosinolates are known for
having a toxic effect in high doses. They found those which a sensitive form of
the generated the glucosinolate containing vegetables 60% more bitter than
those with an insensitive form of the gene. The ability to detect and avoid
naturally occurring glucosinolates would have been a big advantage to our
ancestors and therefore passed through natural selection making it a widespread
gene today. This supports the fact that taste aversion is an evolutionary
adaptation as our Ancestors would have needed to avoid these naturally
occurring glucosinolates to stay alive in our EEA and therefore adapted this
gene and passed it on through natural selection.
Innate tendencies do not account for the broad range of food likes and
dislikes there is between cultures today. This suggests that our food
preferences are due to evolved factors rather than innate tendencies otherwise
we would all like the same things. These evolved factors can also be modified
by our experiences with different foods with our culture having some influence.
It can be argued that Evolutionary Explanations of food preferences are
speculative and based on little or no evidence. Hayes argued that evolutionary
psychology has a tendency to ignore ‘null findings’ and facts that do not fit
the theory that is being proposed. However it can be argued that all science
does this to some extent not just evolutionary psychology.
Evolutionary Explanations of food preferences can also be seen to be a
reductionist approach to eating behaviour. This means that some other factors
that may also contribute to our eating behaviour have been forgotten about,
such as psychological explanations, in order to focus on evolutionary explanations
alone. A more well-rounded study may be more useful than a specific one.
However saying it is reductionist may be unfair as all psychological research
has to be quite specific to establish a causal relationship.
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