Genes
and Personality
These days, “Personality” is getting used to describe an
animal’s behavioral characteristics. The development of personality is thought
to be driven partly by environmental aspects, and partly by genetics – about a
50:50 split according to a recent study on twins. It is considered that the
difference between individual genes related to neuronal and hormonal
transmission causes differences in expression and function, which in turn, affects
personality. Analysis of the relationship between genotype and personality has
been conducted in humans and many cases in which genotype caused an effect on
personality have been reported. Similar studies have been conducted in
experimental animals such as mouse and nematode. In wild animals, it is
difficult to control experimental conditions, however it is useful to know the
genetic background of their behavior and character. As the saying goes, “Your
mind controls your body”, and there is a strong link between personality and
health condition. Unlike humans, animals are not able to communicate, thus the
way to assess their health condition is quite limited. Understanding the
genetic basis of personality may help us to understand and manage health
conditions in animals.
In captive breeding
programmes, the compatibility of breeding pairs, individual health condition
and longevity are all affected by stress, and each individual reacts
differently to stress. Detecting stressors for each individual will enable us
to collect information for breeding and species conservation. We have been
researching the species that living in sociable groups but do require a lot of
effort to breed. For example, elephant, dolphin, wildcat, raptors and even
squid, exhibit similar captive breeding characteristics. We also conduct
research on the animals familiar to us like dog, cat, horse and chicken.
Finding out the source of genes related to aptitude for drug detection dog, and
nervousness of chicken will contribute to training, breeding, welfare and also
further research on wild animals.
The
findings
Comparative genetic studies in human and monkey have shown
that humans have a tendency to prefer novelty and to feel anxiety (Inoue-Murayama,
2001). Gene expression surveys on cultured cells showed that signal
transduction efficiency in chimpanzees is stronger and shorter than in humans
indicating that they show higher and shorter excitement than in humans
(Inoue-Murayama 2006).
How about individual differences within species? Based on
a questionnaire survey of personality in apes, we have successfully described
their individual differences in more detail (Weiss et al. 2012, 2015). In chimpanzees,
individual differences in gene sequence affect efficiency of serotonin
synthesis. Individuals with higher synthetic efficiency showed a tendency to
feel anxious (Hong et al. 2011).
We have also found relationships between androgen receptor
genotype and aggressiveness in dogs (Konno et al. 2011), oxytocin receptor
genotype and roughness in cats (Arahori et al. 2015), and serotonin receptor
and tractability in horses (Hori et al. 2015). Genetic polymorphisms have also been found in
elephants (Yasui et al. 2012) and birds (Abe et al. 2011, 2012, 2013, 2014) and
investigations into their relationship with their personality is ongoing.
