NOVA scienceNOW: Aging
Graph the age demographics of your town or city. Assign student
groups different towns or cities in your area, and have each group find the age
demographics by decades (e.g., 0-10; 11-20, etc.) for their assigned location.
(For some towns, this information is on the Internet; for others, the
information can be obtained from the town or city census office.) Then ask
groups to display the information in a bar graph. Have them label the x-axis
"Age by Decade" and the y-axis "Percent of Population." Ask students to
display their graphs. Is the number of centenarians greater than, less than, or
equal to 1/10,000 (0.01 percent) as is stated in the program? Have students
consider factors that may have contributed to higher or lower percentages
(ratios) than 1/10,000 (assisted-living centers for seniors, extremely harsh
climate, or lack of medical care). Extend the activity and have students
research and graph the age demographics of cities and towns in areas of the
country known to have high populations of senior citizens, such as San
Francisco, CA; Boynton Beach, FL; Philadelphia, PA; New York, NY; Lynchburg,
VA; and Muncie, IN. Ask how graphs that are made using age demographics from
these areas compare to their graphs based on local age demographics.
Design a survey. Have students design an anonymous survey to find how
many people there are in the extended school community (including family
members and other caregivers) over the age of 90. (Do families that include
members older than 90 and 100 years old have, or did they once have, more than
one member in that age group? Ask students to include a question in the survey
about this.) Is the number of people over 100 years of age greater than, less
than, or equal to the ratio of 1/10,000? Ask what happens when you take a small
sample and try to extend the results to represent a larger population. If there
are people in their 90s or centenarians in the extended school community,
invite one or more individuals to your classroom and have the class interview
them. Before their visit(s), have students prepare interview questions.
Brainstorm genetic, environmental, and lifestyle factors that relate to
life span. Review the definition of the term life span. (The
average length of time, often expressed in a range, that a species in a
particular environment can be expected to survive.) Have student pairs
brainstorm and list factors that may play a role in determining whether
individuals reach their expected life span. Then have them group the factors as
mostly genetic (inherited), mostly environmental (pollution and other external
factors), and mostly lifestyle (smoking, amount and kind of exercise, drug use,
dietary choices). Make a three-column chart on the board, and label one column
genetic factors, one environmental factors, and one lifestyle
choices. Have teams share the factors they came up with and list them on
the board. Review the list with students and discuss the ways genes, the
environment, and lifestyle can affect how long a person lives.
Research organisms used for laboratory research. Have students recall
the laboratory organisms discussed in the program that are used to study genes
related to aging and longevity (yeast; C. elegans, a common
roundworm; mice; and, briefly mentioned, Drosophila, a fruit fly).
Divide the class into four groups, and assign each group a different organism
to research (see Howard Hughes Medical Institute site in Links &
Books). Groups should
find out why their organism is so widely used and important for genetic
studies. Have each group prepare and present a poster about their organism.
Posters should include the information listed below.
- organism's classification
- length of time required for the organism to reproduce
- organism's habitat and availability
- how and where the animals are kept in the laboratory
- how long the organism generally lives
- reasons why the organism is frequently used for genetic research (for
example, the functions of many of the organism's genes are already known)
Consider why DNA needs repair genes. The scientists in the program
report that sirtuin genes in yeast are active when an organism is stressed,
such as when food intake is low; a different scientific study showed that
damage to the Daph 2 gene in the roundworm C. elegans caused a decrease
in the worm's insulin level. The researchers postulate that both sirtuin and
low insulin may trigger "survival genes" to become active or expressed. The
scientists state that "survival genes" probably include DNA repair genes. Ask
students why DNA might need its own set of repair genes. (DNA can be changed
during replication or damaged by UV light and environmental toxins such as
cigarette smoke or other inhaled or ingested toxins. Therefore, it is important
that genes exist that can repair the damage to this basic building block of
As an extension for advanced biology students, use a DNA model and have
students locate the sugar-phosphate backbone, the individual nucleotide bases,
and the nucleotide base pairs. Ask students to brainstorm different break
points that could occur in DNA that would need repair. Tell students that a
number of DNA repair genes are involved in the following: base excision and
replacement, mismatch repair, and rejoining broken strands. Have students use
the model to show the three types of repair. What might happen to the cell if a
DNA repair mechanism didn't exist? (Cells and organs could die. Cells might
make too little or too much of a protein. If the damage were to affect a gene
that controls cell division, the cell could continue to divide, resulting in a
tumor or in cancer.)
Research plant chemicals that have health benefits. Scientists
researching longevity found that resveratrol, in high doses, caused yeast,
roundworms (C. elegans), and mice to live longer than their expected
life span. Resveratrol is made by plants to protect them from fungal growth. It
is found in different amounts in grapes (mainly in the skin), raspberries,
peanuts, cranberries, and other plants. Many plant chemicals have a beneficial
effect on health. Divide the class into groups and have each group research
resveratrol or one of the following groups of plant chemicals—the
flavonoid anthocyanin (found in blueberries, blackberries, cherries, and some
vegetables such as red cabbage); or the flavonoid quercitin (found in yellow
onions). Have students report on the function their chemical plays in the
plant, and the potential health benefits of the chemical for people. Note:
Explain that information about health benefits should be obtained from
encyclopedias or scientific research sites, because health claims can be false
Benefit for Humans
(mainly on the skin), raspberries, peanuts, cranberries, and other plants
plant from fungal infections
anti-inflammatory and antiviral effects
blackberries, cherries, and some vegetables such as red cabbage
blueberries their color; provides color to flower and fruit
as antioxidant and may also help prevent some types of memory loss and disease
color to plant; gives visual cues to pollinators
help protect against some types of heart disease
As an extension, ask students to keep a record of the fruits and vegetables
they eat for two days. Have them research and group any foods that contain the
plant chemicals in the chart.
HHMI Online Companion
The Howard Hughes Medical Institute offers an extensive collection of aging research resources in its online companion to this episode of NOVA scienceNOW.
More on HHMI and its partnership with NOVA
Healthy Aging for Older Adults
The Centers for Disease Control and Prevention provides this extensive Web site on aging for older adults. Find information on healthy living, view medical statistics, and browse other online resources.
National Institute on Aging
This Web site from the National Institutes of Health offers information on current research into the biology of aging, behavioral and social aspects of old age, and more.
The Aging Research Center
On this Web site, learn about upcoming conferences on geriatrics research, read up on federally and privately supported clinical research, and find a list of online aging resources.
This Web site from the American Federation for Aging Research has information on the biology of aging, age-related diseases, and links to current research.
Genes and Longevity
This companion Web site to the National Public Radio series "The DNA Files" provides a number of links and other online resources related to longevity and aging.
by C. David Allis. Cold Spring Harbor Laboratory Press, 2006.
Ageless Quest: One Scientist's Search for Genes That Prolong Youth
Lenny Guarente. Cold Spring Harbor Laboratory Press, 2002.
Aging at the Molecular Level: Biology of Aging and its Modulation
by T. von Zglinicki. Springer Books, 2003.
"A Conversation With Nir Barzilai; It's Not the Yogurt: Looking for Longevity
by Claudia Dreifus. The New York Times, February 24, 2004.
"The Quest For a Way Around Aging"
by Nicholas Wade. The New York Times, November 8, 2006.