Question: Case study: Introduction It is nals week on college campus and everybody is in the middle of stud…

case study:

Introduction

It is nals week on college campus and everybody is in the middle
of studying for exams, just waiting for summer break. Björn,
Chris, Esiankiki, Xiao-Ma, Sanjeet and Linda are studying together
in the international students dorm.

Björn: Chris: Esiankiki:

Xiao-Ma:

Linda: Xiao-Ma:

Sanjeet:

Hey, how are you doing with studying? I’m tired …
Me too. Let’s take a break. I could also use some ice cream after
that last nal I bombed.

DidIhearice-cream?Iloveice-cream!Let’sgodowntownand
ndaspot.Iseverybodycoming? Let’s go!

Hm, I can’t tolerate dairy so I usually don’t get ice-cream or
other milk products. Sorry guys, I’ll stay behind.

What does that mean? Do you just not like milk? I used to hate
milk as a little kid.

No, I actually get really bad stomach cramps, bloating and
diarrhea from milk. It’s not pretty. My whole family is that way.
When we were still living in China, it wasn’t a big deal because we
don’t tradi- tionally eat a lot of milk products there.

Same for me! I get the same thing, and in India we don’t eat a
lot of dairy either, so it’s not a problem if I eat Indian food. My
mom gave me Lactaid® though, so that helps me to eat ice-cream.
Xiao-Ma, I can give you some. Let’s go!

Part I – Geographical Variation in Tolerance to Dairy

I.i – Survey of Dairy Intolerance

Björn: Linda:

Wait, so are you saying that where you’re from, people are
generally not able to digest milk? At home in Sweden, we eat dairy
products like milk and cheese all the time and everyone I know
seems to tolerate it well.

at’s so interesting! I’m curious to see how that maps to the
world and if what you observed could be generally true. Let’s do a
survey in the international dorm and nd out who is tolerant to
dairy and where they are from. I’ll put a black dot for a dairy
tolerant person in his or her home country and a white dot for a
dairy intolerant person. I’ll start with Xiao-Ma—one white dot in
China!

Questions

Figure 1. Survey of dairy tolerance. Linda’s results on
a map of the world

1. Do you see patterns in the geographic distribution of the
black and white dots? Describe the pattern qualitatively.

2. How would you quantify these patterns?