Identify one key concept from the biological perspective and discuss its contribution to the understanding of behaviour.

The biological perspective is an approach to psychology that explains behaviour as a result of physiological processes. One key concept of the biological perspective is that of the endocrine system. The endocrine system is a network of glands that secrete slow-releasing hormones to influence behaviour (with the exception of adrenaline, which is fast releasing). Research in endocrinology has significantly contributed to the understanding of behaviour by contributing several theoretical explanations of behaviour. For example, Hans Selye proposed that the hypothalamus, pituitary and adrenal glands were the system of glands that dealt with stress. Other theorists like Berthold also contributed by demonstrating that male and aggressive behaviour was influenced by the internal secretions of the testes, not the testes itself.

The endocrine system consists of 9 glands: the hypothalamus, pituitary, pineal, thyroids, parathyroids, pancreas, adrenal, testes and ovaries. The hypothalamus primarily controls the pituitary gland, but is also known to help regulate body temperature. The pituitary gland is known as the “master gland” as it secretes hormones that stimulate or suppress the production of hormones in other glands. It is also known to promote body growth and help with reproduction. The pineal gland is known for secreting melatonin, a hormone that influences the body’s biological sleep/wake cycle, as well as being linked to Seasonal Affective Disorder (higher melatonin levels are linked to SAD). The thyroids are responsible for cell metabolism, secreting thyroxin. The paraythyroid glands are responsible for regulating calcium levels, while the pancreas secrete insulin and  glycogen to stimulate or suppress sugar levels (respectively). The adrenal gland consists of two parts: the adrenal medulla and the adrenal cortex. This gland secretes so called “stress” hormones, such as adrenaline and corticosteroids, to deal with stress. The testes produce male gametes (sperm) as well as the male hormone testosterone, discovered by Berthold and known to influence male sexuality and help develop masculine features. The ovaries produce female gametes (eggs) and release progesterone and estrogen. Progesterone influences the production of female gametes while estrogen influence female sexuality and helps develop feminine features.

The endocrinologist Hans Selye contributed to our understanding of behaviour by theorizing the stages of stress, which he called General Adaptation Syndrome (GAS). His GAS theory explained that when an individual is placed under stress (not conventional stress, rather any physically/mentally demanding situation), there will be three stages: alarm, resistance and exhaustion. During the alarm phase, stress hormones are released to deal invoke the fight/flight response and help deal with stress. However, no organism can sustain the alarm stage for long so the resistance stage ensues. When the body is at the resistance stage, it attempts to adapt to the stressful conditions and cope with it. However, prolonged stress will eventually lead to exhaustion when the body can no longer cope with the stress.

Selye also proposed the system by which the body deals with stress, identifying three glands in a system he called the Hypothalamus-Pituitary-Adrenal axis (HPA axis). Basically, the hypothalamus signals the pituitary to produce ACTH which stimulates the adrenal gland’s production of stress hormones like adrenaline and corticosteroids. He theorized that the release of these hormones causes the alarm stage and invokes the fight/flight response. Thus, Selye contributed to our understanding of stress by explaining the stages in which it occurs and the causes of its physical manifestation.

Berthold also contributed to our understanding of behaviour by theorizing the role of the testes. He performed one of the earliest documented endocrinology experiments, using roosters as the participants. He divided 6 roosters into 3 equal groups: one group was simply castrated, the second group were castrated and had their testes reimplanted, but the third group was castrated and had transplanted testes. In the first group, he found that the roosters lost their male behaviour and became capons. However, the second and third group maintained their male behaviour. The nerve endings of the testes did not reattach, so Berthold concluded that it was not the organ itself, but internal secretions of the testes that maintained the rooster’s male behaviour. This internal secretion is now known as testosterone, and Berthold contributed to our understanding of behaviour by explaining that testosterone is the primary influence of male behaviour.

Berthold also found that along with the male behaviour, the difference between the first group and the 2nd/3rd group was aggressive behaviour. This could be interpreted that testosterone also influenced aggressive behaviour. Other endocrinology research also supports this explanation of aggressive behaviour, such as Dabbs & Morris. Dabbs and Morris performed a correlational study and found a correlation between high levels of testosterone in low socio-economic participants and antisocial and aggressive behaviour.

In conclusion, the research in the endocrine system has greatly contributed to our understanding of behaviour. Endocrine research by theorists such as Selye have explained stress and its theorized causes. Berthold also discovered that it was the testosterone hormone and not the testicle organ itself that influenced male behaviour, and also found that it may influence aggressive behaviour. Dabbs & Morris supports the notion that testosterone may   influence aggression, contributing to our understanding of aggressive behaviour.