4/8/2016

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Paleofantasy: What evolution tells

us about modern lives and diets

Marlene Zuk

Ecology, Evolution and Behavior

University of Minnesota

11th Annual Building Healthy

Lifestyles Conference

Glamour magazine: The cavewoman’s

guide to good health

“It’s worked for women for hundreds of thousands of years, and it’ll work for you, too.”

“Biologically, we modern Homo sapiens are a lot like our cavewoman ancestors: We’re animals. Primates, in fact. And we have many primal needs that get ignored. That’s why the prescription for good health may be as simple as asking, What would a cavewoman do?”

From Well, NYT blog on health

“Probably goes all the way back to caveman days—women out gathering berries, sweeping up the place, generally always on the run. Cave Mr. Man out risking his neck, hunting a sabre tooth tiger or maybe a wooly mammoth, dragging the thing home, and then collapsing in a heap on the couch with a beer. I get it—makes sense.”

Are we mismatched to modern life?

http://www.chester.ac.uk/~sjlewis/DM/

New age cavemen?

Some people want to

emulate long-ago life

Such a life seems more

natural, or healthier

Alternatively, some

hold that we can’t shed

our past – whether we

want to or not

Tony Cenicola/The New York Times

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Diets and what’s natural

Food is the place

where people wonder

most about how

evolutionary history

affects their health

We have many novel

foods

We also have many

diet-related ailments

http://face-slim.com/fitness/start-eating-natural-diet-tips/

http://slism.com/diet/5best-natural-diet-supplements.html

Turning to evolution for answers

Makes sense to many

that we should eat

what we were “meant”

to eat

◦ What is that?

◦ What did we eat in the

past?

◦ (How) do we know?

http://wholehealthsource.blogspot.com/2010_11_01_archive.html

http://www.harvestlandbrand.com/

Or should we go back even further?

“Chimp Food was created to mimic the healthy diet of our closest living relatives, Chimpanzees, who are almost 99% like us, however they live virtually disease free.”

“Just imagine, NO Obesity, Heart attacks, Strokes, Cancer, Diabetes, Alzheimer's, Parkinson's, Arthritis, Headaches, ADD, Depression and thousands of other diseases.”

“The biggest difference between Humans and Chimps is that they are healthy... and we are not! Our digestive systems are nearly the same, so it only makes sense, we should be eating like them –Fruits, Berries, Veggies, Nuts and Seeds.”

Humans changed quickly

Agriculture only

about 10,000 years

old

Many diseases and

problems apparently

arose recently Diabetes, obesity

So would we be

better off living like

we did back then?

http://www.ruralwellbeing.org.uk/images/caveman_modernman.gif

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Living things are all made up of

tradeoffs and compromises Adaptation often

looks perfect

But organisms always have to do multiple things with limited resources

◦ The insect has to maintain immunity as well as camouflage

Evolution just has to be good enough

When was that utopia, again?

We have never been

in perfect harmony

with our

environment

Did we feel uneasy

when we began

hunting instead of

scavenging?

Maybe we should

long to be aquatic

Evolution and progress Evolution and progress

Those cartoons

almost never show

women

Assume straight line

evolution, with one

form replaced by the

(better) one

afterwards

Evolution and progress

Most of all, imply that

evolution has a goal

But of course,

evolution – and

organisms – aren’t

trying to get

anywhere

Humans aren’t at the

pinnacle

evolution.berkeley.edu/evosite/misconceps/IBladder.shtml

designboom.com/project/march-of-progress/

What about average lifespan?

People often argue that evolution acted

very differently a long time ago, because

no one lived to be very old

Average lifespan said to be less than 40

for some ancient populations

Therefore, no opportunity to experience

the world as a 40, 50, or 60 year old

existed until very recently

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A hypothetical population of 100

people . . .

clipproject.info/free-clipart-gallery

hasslefreeclipart.com

Half (50) die at age 5

The remainder live into adulthood They all reach age 60

Then, 20 more die The remainder reach age 75

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And then all succumb What’s the average age at death?

50 times age 5 = 250

20 times age 60 = 1200

30 times age 75 = 2250

Total = 3700

Divide by 100, and the average age at death = 37, even though many lived well past that age

Means that older individuals still existed in ancient times (cancer)

Stuck in the Stone Age, with old

genes?

Not really

Our genes came from

our ancestors

Who got them from

their ancestors

Etc.

No one period in time

is most significant

http://www.dailymail.co.uk/sciencetech/article-1212692/Our-stone-Age-ancestors-

wore-bright-garish-clothes.html

What does it mean to have Stone

Age genes?

Some of our genes are identical to those in bacteria, others to worms or chickens

Genetic similarity is not the whole story

We share ~ 1/3 of our genes with daffodils

Just counting up the sequences isn’t necessarily helpful

scientificamerican.com/article.cfm?id=what-makes-us-human

science.howstuffworks.com/life/botany/daffodil-info.htm

Human diet-related genes can

evolve rapidly: lactase persistence

The poster child for

recent human

evolution!

Other mammals

cannot digest lactose

(milk sugar) after

weaning

◦ Lose lactase

Some humans can

Rapid evolution in humans: cattle

herding & gene-culture coevolution

People began herding cattle for meat and hides

Being able to digest milk advantageous

◦ Nutrition, fluid

People with lactase persistence became more prevalent

This selected for more cattle herding

Stephen Anderson/Modern and Mobile

www.touregypt.net/featurestories/cattle.htm

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Rapid evolution in humans: cattle herding &

gene-culture coevolution

Selection doesn’t have to be that strong to change population

Can happen quickly

◦ A 3% increase in the reproductive fitness of those with lactase persistence could make such a gene widespread after only 300 – 350 generations

Rapid evolution in humans: lactase

persistence today

Worldwide, about

35% of people have

lactase persistence

Genetic change in

people from

northern Europe,

parts of Africa

The actual gene is

different, but effect

same

Rapid evolution in humans: what

about other foods?

In 2010, Anna

Revedin & colleagues

discovered starchy

grains on grinding

stones

◦ 30,000 years old

Ancestral humans

were making “a kind

of pita”

http://news.sciencemag.org/paleontology/2010/10/cavemens-complex-kitchen

Rapid evolution in humans: what

about other foods? People from areas

where starch is a

staple food have more

copies of amylase gene

◦ Used to break down

starches

Neandertals, early

humans may have

consumed more grains

than previously

thought

Why is this a big deal?

Early humans often

assumed to rely

mainly on meat

Starches vilified in

many diets

Grains viewed as

linked to obesity,

other disorders,

because insufficient

time to adapt

http://thehistorykitchen.com/2011/06/03/the-history-of-doughnuts/

Even “unprocessed” foods unlike

their ancestral state

http://www.geneticliteracyproject.org/

2014/06/19/how-your-food-would-look

-if-not-genetically-modified-over-millennia/#.U6NZpbHii8C

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So what did early people eat?

Lots of different things

Depends on exactly

when, where we are

talking about

And our information is

woefully incomplete

◦ Modern foraging

peoples are not a great

model

http://www.dailymail.co.uk/sciencetech/article-2131933/Pass-

mammoth-rib-Eating-meat-helped-early-man-spread-quickly

-profoundly-affected-evolution.html

This is not to embrace the “SAD”

(Standard American Diet)

Ample evidence that

eating mainly calorie-

rich, nutrient-poor

foods is bad for us

But that doesn’t

mean we can only

thrive on what

people ate long ago

◦ (even if we knew what

that was)

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Was it the switch to agriculture?

Agriculture changes

many aspects of

human life beyond

diet

◦ Allows higher birth

rate, larger population

◦ New diseases

◦ Social stratification

http://marchand.historyproject.ucdavis.edu/2013/03/

Maybe – but many big events in

human history

Industrial Revolution

◦ Changed our diets

◦ Changed how we

spend our time

◦ Changed our health

http

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http://www.verticalbridge.ca/blog

Are humans still evolving?

Some, including some

scientists, say no

Western medical

care, contraception

have changed us

◦ Many people survive

today who would have

died not so long ago

◦ We control our

reproduction

http://openclipart.org

Are humans still evolving?

But many people do

not have access to

medical care,

contraception

◦ And disease still a real

threat

Besides, remember

that people are not

the end point of

evolution

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The real question

“The question ‘Are

humans still evolving’

should be rephrased as,

‘Do all people have the

same number of

children?’”

Differential genetic

representation means

evolution Mary Pavelka, Univ. of Calgary

Current evolution: the Framingham

Study

Survey of 14,000

residents of

Framingham, MA

Begun in 1948

Data collected on

body measurements

and health indices

◦ Blood pressure,

cholesterol, etc.

Current evolution: the Framingham

Study

Data can also be

used to see which

genes likely to be

represented in future

generations

Who has more

children?

Where is evolution

taking us?

bmc.org/stroke-cerebrovascular/research/framinghamstudy.htm

broadinstitute.org/

Framingham study: results

Steve Stearns from Yale

led study

Focused on women

Found age at first

childbirth going down

Age at menopause

going up

the-scientist.com/?articles.view/

articleNo/27545/title/Evolving-heart/

Framingham study: predicting the

future

Used reproductive

success to predict

how population

would look in 10

generations:

◦ Shorter, slightly

plumper

◦ Lower cholesterol,

blood pressure

yaledailynews.com/blog/2009/10/28/

stout-women-pass-on-genes-study-finds/

Nature as tinkerer, not engineer

François Jacob, French

Nobel laureate

In 1977 Science paper,

famously described

evolution as a tinkerer,

not an engineer

◦ “To create is to

recombine.”

Always working off of

existing parts, with

tradeoffs

4/8/2016

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Evolution is good enough

Organisms are never

in perfect harmony

with the

environment

Mismatches happen

But we should be

wary of

paleofantasies

www.publicartarchive.org/wor

k/peace-and-harmony-nature