Feeding and Evolution

Hello.

My name is Dominic Dwyer. I am at the school of psychology at Cardiff University,

and

I'm really excited to be giving this lecture course

about evolutionary influences on feeding,

concentrating on things like Nia phobia and taste aversion,

because this is actually what I do for a living.

My research is about taste, aversion

and other things when it comes to food consumption.

It's also the case

that I like a good meal myself. So, yes, this is going to be fun.

So

why are we talking about evolution

and feeding?

Well,

because

in very simple terms,

eating is perhaps the most essential thing any biological organism can do.

Don't eat enough

and you die.

Eat too much of the wrong or poisonous thing

and you die.

So getting eating right

is going to be one of the key evolutionary concerns for any species,

but perhaps particularly so

for an omnivorous species like humans,

there's no one food

that supports all of our nutritional needs,

and so we need to choose what to eat.

And so the question

of how we choose what to eat is a critical one

and the sort of thing

that is going to have been subject to

evolutionary influence because of how important feeding has been

across evolutionary time.

Now,

the simplest reflection

of this evolutionary influence on food consumption

are the fact

that as humans,

we have a number of innate or unconditioned

preferences, and avoidance is for certain tastes.

Most obviously

a preference

for sweet,

salty and fatty tastes,

and avoidance is of sour and bitter.

Why would we have these things?

Well, let's think about what those tastes are connected to in the world.

Sweet tastes

are associated with sugars

and sugars,

are very high in calories and are processed metabolically really quickly.

They are the perfect rapid energy source,

and so

a taste

that indicates when sugars are present.

Yeah,

that makes sense to have an evolved liking for

salt

is essential for many cellular functions.

Indeed,

it's why many exercise drinks are salty because you

need to replace that salt you're losing through sweat.

And again,

this essential, named for salt, is reflected

in an innate preference

that is observable in infants and adults

and supported by a number of animal studies.

Fat

like with sweet

fats, are incredibly energy dense.

They are processed metabolically a little more slowly than sugars,

but they do contain an awful lot of energy.

And so, in terms of

the importance to survival of having sufficient nutrients,

then

an unconditioned preference for the taste that is associated with fats

is going to be quite useful.

But what about avoidance is

bitter sour?

Well,

actually,

many toxins

that are created either by genuinely poisonous

substances or foods that have spoiled

result in bitter or sour tastes

and so avoiding those

can protect against poisoning.

And so

these lists

of

the small number of tastes that we have innate preferences for and avoidance is of

reflects

the common tastes

of things in the world.

Sweet, fat and salty tastes are associated with essential nutrients.

Bitter and sour tastes are associated with poisonous or spoiled foods.

And actually,

it's interesting

that

these innate preferences

and avoidance is

are used by people that want to get us to eat more of their food.

Food manufacturers know these things really well,

and if you think about it something like, say, chocolate,

a mixture of sweet and fatty,

it is essentially

a perfect combination

to match marinate preferences,

and this is true of a lot of processed foods

food manufacturers know what works for a human being,

and they work with that.

However,

this list of innate preferences and avoidance is when it comes to foods.

Isn't the end of the evolutionary influence on our food consumption.

Indeed,

the very fact that our choices about what we eat and don't eat

is very complicated.

It's not as simple as we only eat sweet,

salty and fatty things and avoid all sour and bitter things.

It's clearly the case

that

we learn as individuals what we will eat and not eat.

And so

it is not simply that the evolutionary influence on food consumption

is about what we have in innate preference or avoidance of.

It's also on the mechanisms for how we learn,

and that's going to be the topic

for the rest of the lectures on this course.

Lecture to looking at Nia Phobia lecture three Taste Aversion,

lecture for a bit more at taste aversion and

then pulling it all together in lecture five.

I'd also note that there's a separate course

looking at flavour, preferences and the acquisition of them