Discuss the value of animal models in the study of genetics and behavior.
Experimentation on animals has been favorably used by many scientists to further study human genes
and behavioral patterns. Animal models are employed in many scientific studies due to similarity to
humans in relation to genetics, anatomy and physiology. The similarities between humans and
nonhuman primates makes nonhuman primates uniquely suited as models for genetic research on
complex physiological and behavioral phenotypes. Unlike human testing where it poses obvious risks
in life, animal testing in extensive scientific research offers ease in manipulation due to constant
environmental controllable conditions where the subjects can be observed in long periods, greatly
increasing the power to detect genetic effects. It also has different environmental conditions which can
be imposed sequentially on individuals to characterize geno-type interactions. Furthermore, genetic
hypotheses can be tested. Last but not least, it is essential that invasive and terminal experiments can
be conducted, majority of which can serve as models of gene-environment interactions and diseases
identified in humans. On the other hand, limitations on testing on nonhuman primates as animal models
are not pointing out. One primary consideration is the cost and availability. The ability to manipulate
both genetic and environmental factors in captive nonhuman model populations indicates a promise of
many opportunities to conduct plentiful research illuminating complex processes providing its
affordability and availability.
A number of experiments were conducted to fully observe the genetic behavior among humans using
animals as models. In an experiment of Cases et al, (1995), the deletion of MAOA genes were used to
evaluate effects on rat’s behavior. Findings indicate high levels of serotonin and norepinephrine existed
in the transgenic mice (AKA knockout mice) after the removal of MAOA gene. The levels of serotonin
rose to 9 and norepinephrine concentration levels increased by 2 causing higher levels of aggression.
To further show a link in understanding genetics and behavior, Caspi.et.al. (2002) made an investigation
on how environmental stressors interact with one’s genes to produce aggression. The study was
conducted to 1,037 male children from New Zealand who were born in 1972. The study used
longitudinal procedure and participants were observed over 26 years since birth to adulthood. Their
genetic makeup was tested further concentrating on the MAOA gene. How children were raised was
also observed such as cases of maltreatment. For all 26 participants, anti-social behavior was also
evaluated and measured. The results reveal that maltreatment with high amounts of MAOA is less likely
to show antisocial behavior. Meanwhile, those who have cases of maltreatment but with low levels of
MAOA are 3 times more likely to display antisocial behavior. We can conclude that both levels of
MAOA and maltreatment contribute to behavior. It supports that genes and environmental stressors
support the theory that both affect behavior.
Animals, mainly chimpanzees and rodents, are yet the most known host for a myriad of researches due
to its life span which is shorter than humans. This exemplifies that animal testing can be studied under
controlled conditions which are in any way impossible to execute to humans. Mutation or deletion of
genes proves to be futile when exercised to human testing as a form of research due to its complexity
and ethical concerns. The study of Cases et al (1995) assists in the full understanding of human behavior
acting as a guide and profound understanding of human aggression.
In an experiment in animal behavior using selective breeding, animals are bred with an aim of making
them produce a specific phenotype. A specific example is the transgenic mice (AKA knockout mice)
where its single gene is mutated or deleted. It is carried out to identify the impact of deleting a gene
(MAOA gene) on a rats behavior. The MAOA gene of rats were then deleted and behaviors of each
were under close observation. Findings indicate that high levels of serotonin and norepinephrine existed
in the transgenic mice due to the removal of MAOA gene. The concentration of serotonin levels surged
to 9 and norepinephrine concentration levels also rose to 2. It indicates an increase of levels of
aggression in mice.
on mice, the removal of highly conserved genes that promote longevity such as Caenorhabditis elegan
can indicate an end of a life span; meanwhile Protein Kinase A which is an example of highly conserved
gene that has age delaying effects, is observed that when specific subunits are suppressed or removed
in the mouse, thus suggest a loss of function. It can be suggested, thus, that the lifespan of an animal is
significantly shorter than a human life span after a removal of a significant gene.
It is essential to study animals as evolved biological systems in which surviving and reproducing in
particular social and physical environments have selected a myriad of interactions between social,
behavioral psychological systems, and gene function. Studies of deer mice, which live in highly
seasonal environments, reports the function of the immune system requires significant energy, so much
so that during winter an animal trades off puberty and becoming reproductive in order to sustain
energetic requirements of fighting infectious disease (Prendergast and Nelson, 2001; Nelson, 2004).
The same goes with house sparrows in which immune activity accelerates energy usage, illustrating the
energetic cost of immune functions that could otherwise be deployed to growth (Martin et al., 2003).
When social structure restricts resources and results in population living in an environment with high
levels of organisms that causes diseases (pathogens), slower growth can result as the case of children
in the lowlands of Bolivia. This presumptively happens because the allocation of energetic resources to
immune function has been diverted from growth (McDade, 2005).