Name ____________________________________ # _____
Date _________ Section____
Directions: Read the following article and pay close attention to the experiment conducted by the scientists.
As you read annotate using the annotation guide:
P = Purpose or problem trying to be solved
I = Independent variable or the factor causing something else to happen
D= Dependent variable or the factor being affected by the independent variable
Ex = Components of experimental procedure
C = What did the conclude or learn from the experiment/study?
Two Monkeys See a More Colorful World
Sept. 30, 2009
For a pair of squirrel monkeys named Sam and Dalton, the world recently got more colorful. Male squirrel monkeys are
normally red-green colorblind, which means they have trouble seeing those colors. But now, thanks to an experiment by
scientists at the University of Seattle, Sam and Dalton see things differently—they seem to be able to see red and
green.
Animals (including people) are able to see different colors of light thanks to proteins in the eye. Proteins are important
building blocks of cells, and different kinds of proteins serve specific purposes in a living organism. When an important
protein is absent or disabled, the animal cannot function properly. Male squirrel monkeys normally lack the proteins that
detect red and green light, which means they can‟t tell red and green from other colors. The monkeys can see blue and
yellow.
Jay Neitz is the scientist at the University of Washington who led the research to give the monkeys more colorful vision.
He says the experiment wasn‟t supposed to work. In fact, when he asked other scientists who study vision if they
thought color vision was possible in colorblind monkeys, “every single person said, „absolutely not,‟” he says.
Neitz and his team were able to add genes that make proteins for detecting red light in the monkey‟s eyes. A gene is like
a recipe for building a protein, and different genes direct the body how to build different proteins. Almost every cell of a
living organism contain DNA, or deoxyribonucleic acid, which is the set of instructions for how to make that organism
function. These instructions include all the genes, which are segments of DNA.
A gene is also responsible for building the protein that enables an animal to see the color red. Neitz and his team found
male squirrel monkeys that don‟t have this gene—so for their experiment, they tried to give the gene to the monkeys.
They injected the monkeys with a virus that contained the gene. (Even though we usually think of viruses are harmful,
scientists have found ways to use them in helpful ways—like to deliver genes to a monkey‟s eye!) Over the next few
weeks, the monkeys began to make the red-detecting protein. After about 20 weeks of this gene therapy, the monkeys
were making enough of the protein to be able to tell red from green.
To test the monkeys‟ eyesight, Neitz and his team showed them a grid of dots, some of them colored, some of them
gray. If the monkeys pressed the colored dots, they received a treat—grape juice. Before the gene therapy, the monkeys
could easily pick out blue or yellow dots, but they had a hard time telling red or green dots from gray dots or from each
other. After receiving the gene injections, Sam and Dalton were able to pick out all of the colors (and drink lots of grape
juice).
Bevil Conway, a neuroscientist at Wellesley College in Massachusetts, says the experiment shows that seeing in full
color only requires the addition of a gene for detecting certain colors of light. Before the experiment, scientists were not
sure whether the monkey‟s brains would know how to handle new colors—but the monkeys seemed to be able to see
and understand the new colors right away. “Somehow the brains of these monkeys are already wired to decode these
color signals,” Conway says.
Neitz‟s experiment is good for Sam and Dalton—but what about the rest of the world? They say it‟s too early to know if
genetic therapy could ever be used to help colorblind people see colors, or to help blind people see. Plus, it may be true
that Sam and Dalton aren‟t seeing red and green as we know them—they may just be seeing other shades of yellow
and blue.
Nonetheless, the idea of giving color vision to a couple of monkeys is capturing the attention of researchers who study
vision. “The achievement is technically amazing and conceptually very cool,” says Melissa Saenz, a scientist at Caltech
in Pasadena, Calif.
1) Explain what the genetic difference between a person or animal that is color blind versus on that can
see color?
2) Explain how he scientists help the monkeys see color properly?
3) On a separate piece of paper pretend that you are a marketing/advertising professional for company
who would like to start advertising this new therapy to people who are colorblind. Design a flyer that
contains the following:
a. A catchy slogan (something to attract people to your flyer)
b. An explanation of the gene therapy used on squirrel monkey (explain in detail, people would
want to know exactly what they are getting themselves into)
c. Picture(s) or diagram(s) that is relevant to the study
d. 3 warnings or side-effects (assume or infer what these would be)