570
Chimpanzee Genome
determined by the life span of the model
organism. Furthermore, once an individ-
ual carrying the desired genetic modi±-
cation has been generated – which is still
a costly, time-consuming, and experimen-
tally elaborative venture – its maintenance
as a laboratory strain is generally desirable.
This, however, is only feasible when the
generation time of the respective species
is in a reasonable range of at most a year.
A slowly developing, late reproducing, and
long living species such as chimpanzees
is thus, not particularly well suited for
standard research on transgenic animals.
Second, an early (natural) death of the re-
search animal elegantly solves the problem
of what to do with the animals once the
experiments are over. Chimpanzees, how-
ever, have an average life span of around
40 to 50 years, which is well beyond the du-
ration of most experimental studies. The
relevance of this problem becomes im-
mediately obvious when one imagines a
group of chimpanzees infected with a hu-
man pathogen that need to be taken care
of once they are no longer useful for ex-
perimental studies.
Clearly, strong arguments exist to use
chimpanzees as
experimental
animals
in biomedical research. However, the
practical disadvantages are apparent. To-
gether with a number of ethical concerns
that I will discuss below (Sect. 4.4), the use
of chimpanzees as a standard experimen-
tal model organism is clearly voted against.
Meanwhile, this has been widely recog-
nized and the number of chimpanzees
held as laboratory animals has substan-
tially decreased over the past years. In the
case of Europe, invasive experimental stud-
ies on chimpanzees have entirely ended.
4.2
Biomedical Differences Between Humans
and Chimpanzees
Practical experience has shown that chim-
panzees are not suitable as experimental
model organisms for studying human dis-
eases, or for testing the ef±cacy and safety
of new pharmaceuticals. Nevertheless, a
certain relevance remains for chimpanzees
in biomedical research. From long-term
observations in primate centers and zoos,
differences in susceptibility and severity
of certain human diseases between hu-
mans and chimpanzees have emerged.
A few examples are listed in Table 2.
Although the evidence is in parts frag-
mentary and vague – in certain cases it
Tab. 2
Differences in the disease spectra between humans and chimpanzees.
Medical condition
Humans
Chimpanzees
Evidence
HIV progression to AIDS
Common
Very rare
DeFnite
Late complication in hepatitis
B/C
±requent
Uncommon
DeFnite
Malaria
a
Susceptible
Resistant
DeFnite
Menopause
Universal
Rare
DeFnite
Influenza A symptomatology
Moderate to severe
Mild
Likely
Alzheimer’s disease pathology
Common
Rare
Likely
Myocardial infarction
Common
Uncommon
Likely
Epithelian cancers
Common
Rare
Likely
a
Caused by
Plasmodium falciparum
infection.
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