0:00:05.434,0:00:10.501
First off, I would like to just introduce[br]attractiveness a little bit to you.

0:00:10.501,0:00:12.721
Especially thinking about

0:00:12.721,0:00:16.069
why should we even bother[br]thinking about attractiveness?

0:00:16.069,0:00:21.374
Well, first, psychological research[br]has shown that people largely agree

0:00:21.375,0:00:24.705
on who is attractive[br]or who is perhaps, less so.

0:00:24.705,0:00:27.649
So I'm pretty sure[br]most of you in this room would agree

0:00:27.649,0:00:33.459
that Angelina Jolie is perhaps[br]somewhat more attractive than Ugly Betty.

0:00:33.959,0:00:39.291
And this perception of attractiveness[br]even hold universally.

0:00:39.292,0:00:41.667
So even if you went[br]to a very different culture,

0:00:41.668,0:00:45.543
people would probably still agree[br]that Angelina Jolie is more attractive.

0:00:47.334,0:00:52.208
In addition to this, work in psychology[br]over the last two decades or so

0:00:52.209,0:00:55.793
has shown that attractiveness[br]has advantages

0:00:56.626,0:01:00.293
over and above perhaps getting bought[br]a drink in a bar on a night out.

0:01:01.584,0:01:05.002
And specifically,[br]these advantages include things

0:01:05.002,0:01:09.167
like being seen as more honest,[br]more socially competent,

0:01:09.792,0:01:15.459
more successful, more trustworthy,[br]friendlier, and even smarter.

0:01:15.751,0:01:20.657
And that last bit is quite important[br]because even in your career,

0:01:20.657,0:01:23.127
your attractiveness levels matter.

0:01:23.127,0:01:26.643
And this holds by the way[br]for men just as much as for women.

0:01:26.643,0:01:30.123
If you are more attractive,[br]you are more likely to have a good career.

0:01:30.123,0:01:31.793
Being attractive literally pays.

0:01:32.543,0:01:35.918
And we call this the Halo Effect,

0:01:35.918,0:01:39.544
which means that simply[br]because you look a certain way,

0:01:39.545,0:01:43.376
people make all sorts of attributions[br]about what you're like.

0:01:44.417,0:01:48.417
And while that might seem[br]a little bit gloomy for some,

0:01:48.918,0:01:51.210
there's actually a flip side to this coin

0:01:51.211,0:01:55.304
which is: can you make yourself[br]more attractive?

0:01:55.304,0:01:59.083
I'm not talking about[br]going and getting plastic surgery,

0:01:59.083,0:02:04.209
or going to a salon and paying[br]for very expensive beauty treatments.

0:02:04.209,0:02:10.417
I'm talking ... - oh, not about that! -[br]I'm talking about changing your health.

0:02:11.709,0:02:17.001
With that in mind, I'd like to turn[br]to the animal kingdom for a moment.

0:02:17.584,0:02:20.844
You can see these beautiful birds on here,

0:02:20.844,0:02:25.242
and they have something in common[br]which is that they are all colorful;

0:02:25.242,0:02:29.667
and these colours aren't just there[br]for us to think of them as beautiful

0:02:29.667,0:02:34.341
But they're actually signals[br]that they use to attract mates.

0:02:34.341,0:02:36.417
The more colorful these birds are,

0:02:36.418,0:02:38.869
the more likely they are[br]to find another bird

0:02:38.869,0:02:40.876
who's willing to mate with them.

0:02:41.626,0:02:44.001
And this is important[br]and relevant for humans,

0:02:44.002,0:02:49.083
because the colors in these birds[br]are not actually something

0:02:49.096,0:02:52.035
they produce from their own biology.

0:02:52.042,0:02:56.541
This is something they can only produce[br]following their diet.

0:02:56.542,0:03:00.834
They eat something[br]that makes them colorful.

0:03:00.834,0:03:04.833
And this something are carotenoids.

0:03:04.834,0:03:08.376
Carotenoids are little pigments;[br]they are a group of pigments.

0:03:08.377,0:03:10.772
There's about 500 or 600 different ones.

0:03:10.773,0:03:12.543
But they have something in common,

0:03:12.544,0:03:16.293
which is that they are all red,[br]yellowish, orangey in color,

0:03:16.294,0:03:20.291
and they are contained[br]in almost all fruit and vegetables.

0:03:20.292,0:03:22.376
Importantly, they are actually contained

0:03:22.376,0:03:24.834
not only in carrots[br]that are obviously orange

0:03:24.835,0:03:29.168
but even in fruit and vegetables[br]that are perhaps less clearly colorful,

0:03:29.171,0:03:31.541
including green vegetables;

0:03:31.542,0:03:33.251
and fruit, for that matter.

0:03:33.844,0:03:37.291
And these pigments in the birds

0:03:37.292,0:03:40.503
signal that these birds are able

0:03:40.503,0:03:44.623
to go out and look for a healthy diet

0:03:44.626,0:03:47.587
by foraging through perhaps[br]the forest or the fields,

0:03:47.587,0:03:51.230
which they couldn't do[br]if they were in poor health condition.

0:03:51.231,0:03:56.778
So in those birds, being very colorful[br]suggests to a mate that they are healthy.

0:03:58.167,0:04:00.129
Of course, us humans,

0:04:00.129,0:04:03.323
don't have to go in to the forest[br]to get fruit and vegetables,

0:04:03.323,0:04:07.321
we can walk in to the supermarket[br]and buy any food that we desire.

0:04:07.321,0:04:12.336
Our problem is more, perhaps,[br]that we'd choose foods we shouldn't eat.

0:04:12.336,0:04:15.858
I'm sure you're all aware[br]that we are supposed to eat

0:04:15.858,0:04:20.416
about a third of our diet[br]from fruit and vegetables.

0:04:20.416,0:04:23.876
This is also often referred to[br]as the five a day:

0:04:23.876,0:04:28.710
you're supposed to at least eat five[br]portions of fruit and vegetables per day.

0:04:29.792,0:04:32.999
So if eating fruit and vegetables

0:04:33.000,0:04:35.792
- which have all sorts of health benefits

0:04:35.793,0:04:38.084
including getting vitamins, getting fiber,

0:04:38.084,0:04:44.376
and getting a whole range[br]of relevant products into you body -

0:04:44.376,0:04:49.532
if that is important for birds,[br]then what about humans?

0:04:49.532,0:04:54.374
Do we perhaps also somehow[br]signal in our appearance

0:04:54.375,0:04:59.541
the fact that we have eaten[br]lots of fruit and vegetables?

0:05:00.482,0:05:03.296
So, to recap how this works:

0:05:03.296,0:05:07.651
the carotenoids that we've consumed[br]with fruit and vegetables

0:05:08.997,0:05:13.542
work and function in our immune system.

0:05:13.542,0:05:17.649
So if some nasties, some bugs[br]enter your system,

0:05:17.649,0:05:21.249
one thing that the immune system[br]can do is use carotenoids

0:05:21.250,0:05:24.459
that are stored in our system[br]as antioxidants

0:05:24.459,0:05:30.085
that will then fight these nasties[br]and cause them to disappear.

0:05:31.042,0:05:34.583
If there are carotenoids[br]left over, as it were,

0:05:34.584,0:05:36.502
after this immune function has happened,

0:05:36.503,0:05:41.416
these carotenoids can then[br]be layered into our skin.

0:05:41.417,0:05:48.333
This happens through a process whereby[br]carotenoids are entered into the sweat

0:05:48.334,0:05:51.793
which is then of course sweated out[br]through the sweat glands

0:05:51.794,0:05:54.889
and are literally layered onto our skin.

0:05:55.459,0:06:01.550
And this layering process causes our skin [br]to turn somewhat goldenish yellow.

0:06:01.550,0:06:05.166
This is just a representation;[br]it's not accurate.

0:06:05.167,0:06:07.292
You're not going to turn[br]exactly that color,

0:06:07.293,0:06:11.043
if you eat more fruit and veg,[br]but it illustrates the point.

0:06:11.781,0:06:15.500
There's a different scenario[br]that we could imagine

0:06:15.501,0:06:19.383
whereby again, we have[br]plenty of carotenoids,

0:06:19.383,0:06:26.291
but this time, there isn't just[br]four of these nasties but many more;

0:06:26.292,0:06:29.143
which should hopefully appear[br]on screen in a moment.

0:06:29.143,0:06:30.349
There we go.

0:06:30.350,0:06:35.999
And in this situation, the majority[br]of our carotenoids stored

0:06:36.000,0:06:41.709
might be used up to fight these nasties.

0:06:42.083,0:06:47.709
And then, there's very little leftover[br]to go into our skin,

0:06:49.083,0:06:53.869
which then causes our skin

0:06:53.869,0:06:57.710
to turn a lighter color again.

0:06:57.710,0:06:59.751
This is because the carotenoids

0:06:59.751,0:07:03.568
that were originally layered[br]into our skin get rubbed off,

0:07:03.568,0:07:06.209
and our skin of course[br]rejuvenates all the time.

0:07:06.210,0:07:09.253
So if you don't replenish constantly,

0:07:09.253,0:07:12.043
then our skin color will change back

0:07:12.051,0:07:16.230
to a less attractive version of itself.

0:07:17.167,0:07:20.626
That led us to the interesting question

0:07:20.626,0:07:26.583
of whether this different skin color[br]is perhaps found attractive in humans.

0:07:26.584,0:07:32.082
Remember, in birds,[br]the high-carotenoid coloration

0:07:32.083,0:07:35.166
was something they use to attract mates,

0:07:35.167,0:07:38.505
which is similar[br]to attractiveness in humans.

0:07:38.505,0:07:44.199
And given this is a cue of somehow health,[br]so you have a lot of disease burden,

0:07:44.199,0:07:48.459
you might not be able to create[br]this lovely skin color,

0:07:48.459,0:07:52.462
this might actually be a cue[br]of your appearance.

0:07:53.625,0:07:56.958
So, for this, we conducted an experiment.

0:07:57.653,0:08:02.032
We first measured empirically

0:08:02.032,0:08:07.626
the axis of color change in skin[br]associated with carotenoids.

0:08:07.626,0:08:09.918
To do this, we had a group of students

0:08:09.918,0:08:13.627
that eat a lot of fruit and vegetables[br]in their regular diet,

0:08:13.628,0:08:15.668
and we measured their skin color;

0:08:15.669,0:08:17.583
we also had a group of students

0:08:17.584,0:08:19.793
that didn't eat[br]very many fruit and vegetables

0:08:19.751,0:08:22.730
- It was more easy to recruit[br]in that group unsurprisingly -

0:08:22.730,0:08:27.666
and we match these groups[br]on their sex, on their age,

0:08:27.667,0:08:29.501
and on other lifestyle characteristics

0:08:29.508,0:08:31.336
so that we could be relatively certain

0:08:31.337,0:08:34.543
that the only consistent difference[br]between these groups

0:08:34.544,0:08:37.126
was their fruit and vegetable consumption.

0:08:37.126,0:08:40.542
After we measured[br]each individual's skin color,

0:08:40.543,0:08:44.416
we averaged this skin colors,[br]and could then calculate

0:08:44.417,0:08:48.584
the difference between the color[br]of the high carotenoid intake group

0:08:48.584,0:08:50.376
and the low carotenoid intake group.

0:08:50.377,0:08:53.618
We could derive this kind of color axis.

0:08:53.618,0:08:58.833
This allows us to take a photograph[br]of anybody, for example this girl,

0:08:58.834,0:09:00.833
or anybody in this room,

0:09:00.834,0:09:04.962
and we are then able [br]to transform this image

0:09:04.962,0:09:11.754
to become either higher[br]or lower in carotenoid color.

0:09:13.049,0:09:18.009
We then asked people, in an experiment

0:09:18.009,0:09:20.418
which color they think is more attractive.

0:09:20.419,0:09:24.958
So let's try this here:[br]you see the two versions of her face.

0:09:24.959,0:09:28.050
Who thinks the girl on the left[br]is more attractive?

0:09:30.417,0:09:32.333
One … not many, good.

0:09:32.334,0:09:35.293
Who thinks the girl on the right[br]is more attractive?

0:09:36.125,0:09:37.970
That's a vast majority,

0:09:38.965,0:09:42.500
and this is consistent[br]with what we found in our experiments

0:09:42.501,0:09:45.960
where of course we wouldn't present[br]people with only this one girl

0:09:45.961,0:09:49.958
but with a large range of faces[br]that we have manipulated in this way.

0:09:49.959,0:09:54.791
We find that in fact,[br]nine out of ten people approximately

0:09:54.792,0:09:59.708
chose the higher carotenoid version[br]of faces as more attractive.

0:09:59.709,0:10:02.043
So this is a really good indication

0:10:02.043,0:10:06.862
that there is something about this color[br]that makes people more attractive.

0:10:07.417,0:10:12.500
We also looked at other cultures

0:10:12.501,0:10:17.066
and found that in Asian[br]and African cultures the same holds:

0:10:17.066,0:10:21.374
people who had[br]a more carotenoid-linked skin color

0:10:21.375,0:10:23.375
were seen as more attractive.

0:10:24.584,0:10:28.918
And even some people were still[br]arguing back at us and saying,

0:10:28.918,0:10:30.960
"Oh, this is just about sun-tanning."

0:10:30.961,0:10:34.793
We all like a suntan, so you all know[br]you like to go out in the sun,

0:10:34.794,0:10:37.374
you like to go to the beach,

0:10:37.375,0:10:43.584
and it leads to of course a somewhat sort[br]of brownish yellowish color on your skin.

0:10:43.584,0:10:46.918
This color is caused[br]by a pigment called melanin,

0:10:46.918,0:10:48.967
which is activated by UV rays

0:10:48.967,0:10:53.156
and it's meant to protect your skin[br]to some degree from a sunburn.

0:10:54.186,0:10:57.120
A lot of research in the past has shown

0:10:57.120,0:11:01.124
that a suntan is thought of as attractive[br]at least in our societies.

0:11:01.125,0:11:04.709
People argued with us, that perhaps,

0:11:04.709,0:11:08.625
what is going on is[br]that carotenoid coloration

0:11:08.626,0:11:13.124
looks somewhat similar to a suntan;[br]it's also a little bit yellow,

0:11:13.125,0:11:15.111
so perhaps people like a tan.

0:11:15.111,0:11:16.757
And because they like a tan,

0:11:16.757,0:11:19.574
they also like this color[br]which looks somewhat similar.

0:11:19.574,0:11:22.490
So we investigated this question.

0:11:22.490,0:11:27.004
We investigated it by asking people

0:11:27.004,0:11:29.489
which face they prefer

0:11:29.501,0:11:33.751
out of a high carotenoid face[br]and a high suntanned face.

0:11:34.834,0:11:38.898
So we manipulated the tan in the same way[br]I showed you before for the carotenoids.

0:11:38.898,0:11:44.959
And now, let's do this again: who thinks[br]the face on the left is more attractive?

0:11:47.667,0:11:50.626
OK, and who thinks the face[br]on the right is more attractive?

0:11:51.690,0:11:53.269
Fewer. Interesting.

0:11:54.042,0:11:56.465
Right, I'm sure you all now want to know

0:11:56.465,0:12:00.184
which of these is the tan[br]and which of these is the carotenoids.

0:12:00.184,0:12:05.626
Well, this one if the carotenoid face;[br]and the majority of you prefer this face.

0:12:05.626,0:12:09.941
We find the same pattern[br]of results in our research

0:12:09.941,0:12:14.666
with eight out of ten people on average

0:12:14.667,0:12:18.208
preferring the carotenoid face[br]over a suntan.

0:12:18.209,0:12:21.459
That really means[br]that there's something specific

0:12:21.460,0:12:23.418
about this color that people like,

0:12:23.419,0:12:25.876
even when we compare it to another color

0:12:25.876,0:12:29.592
which is normally liked[br]by people in this culture.

0:12:29.592,0:12:31.791
This also might actually mean

0:12:31.792,0:12:34.959
that the reason or part[br]of the reason we like a tan

0:12:34.959,0:12:39.877
is because it mimics to some degree[br]this healthy color of carotenoids.

0:12:41.918,0:12:46.583
We've seen that eating[br]fruit and vegetables

0:12:46.584,0:12:49.709
makes your skin change color,

0:12:49.709,0:12:53.022
and that this new color[br]is seen as attractive.

0:12:53.022,0:12:58.001
But remember, at the start, I told you[br]attractiveness isn't the end of the story,

0:12:58.002,0:13:03.167
but other traits such as being perceived[br]as more trustworthy or smarter

0:13:03.167,0:13:06.043
are also associated with attractive faces.

0:13:06.918,0:13:09.836
So we were interested to assess[br]whether these traits

0:13:09.837,0:13:15.124
might also be associated[br]with a carotenoid skin color.

0:13:15.125,0:13:17.375
We've conducted two studies to date:

0:13:17.376,0:13:20.458
we once looked[br]at trustworthiness judgments,

0:13:20.459,0:13:22.709
and we also looked[br]at leadership judgments,

0:13:22.710,0:13:26.374
so how good a leader[br]people thought a person was.

0:13:26.375,0:13:31.959
And in both cases, we found that having[br]a high carotenoid coloration in your skin

0:13:31.959,0:13:34.793
influenced these judgments[br]quite dramatically.

0:13:34.793,0:13:39.252
People really thought the people[br]with the healthy carotenoid coloration

0:13:39.252,0:13:42.250
were more trustworthy[br]and would be much better leaders.

0:13:43.584,0:13:47.500
So that should give you[br]some food for thought hopefully.

0:13:47.501,0:13:49.249
But to finish off,

0:13:49.250,0:13:51.992
there is one important question[br]to answer, isn't there?

0:13:51.992,0:13:54.539
How much do you actually need[br]to eat of the stuff?

0:13:54.539,0:13:58.064
Do you need to eat[br]25 carrots every day to get this effect

0:13:58.065,0:14:00.376
which might be rather unmanageable?

0:14:00.377,0:14:03.500
Well, colleagues[br]at the University of St. Andrews

0:14:03.501,0:14:05.500
have conducted a study into this

0:14:05.501,0:14:09.002
and found that actually eating[br]only two more portions a day,

0:14:09.003,0:14:13.501
this might be for example eating an apple[br]and drinking a glass of orange juice,

0:14:13.501,0:14:17.791
or eating a portion[br]of vegetables twice a day,

0:14:17.792,0:14:21.209
is enough to change[br]your skin color within six weeks

0:14:21.210,0:14:23.334
to be perceived as more attractive.

0:14:24.334,0:14:27.708
the difficulty is though,[br]as you might recall,

0:14:27.709,0:14:31.335
that if you don't keep it up,[br]your skin color will go back down.

0:14:31.336,0:14:34.500
So really what this means [br]is you have to eat

0:14:34.501,0:14:37.119
more fruit and veg[br]for the rest of your life.

0:14:37.119,0:14:38.260
Thank you very much.

0:14:38.261,0:14:40.293
(Applause)