Tag: hypothesis

Posted in Science & Nature

Grandmother Hypothesis

Posted on by Jinavie

There are many physiological events that puzzle scientists. Menopause is one of these as it is very uncommon in other mammals. Why do human females stop having periods after aging? From an evolutionary point of view, an organism that has lost reproductive function cannot aid evolution and thus it is a mystery how a trait like menopause survived natural selection. The leading theory in how such a phenomenon happened is the grandmother hypothesis.

According to this hypothesis, as humans are social animals menopause can still be an evolutionary advantage despite not being able to produce offspring. This is because older women can invest the massive amount of energy and time required to upkeep childbearing in other places. For example, they can help their family and society grow by working or taking care of children instead. Furthermore, as the probability of miscarriages and congenital defects rise with aging (generally after a woman hits the age of 30, the chances of a healthy pregnancy decreases), menopause has the function of protecting the gene pool of the species. These facts combined lead to the conclusion that after an individual has reached a certain age, taking care of their children or grandchildren instead of birthing more offspring is more effective in propagating their own genes. Also, there is no one that can propagate massive amounts of wisdom and information to the next generation like the elderly.

In modern society, menopause has more significance than at any point in the history of human beings. As our average life span has surpassed 80 and heading towards 90, almost half of a woman’s life is post-menopause. In some ways, the grandmother hypothesis contains within it a certain philosophy regarding life. As we age, we give birth to children and raise them until they become independent, at which point we escape our basic biological duty of reproducing to lead our “own” lives. Senescence is like a second spring after one’s “biological” life. It is the start to a new life – a more “human” life of your own where you can focus on seeking pure happiness.

Posted in Psychology & Medicine

Symptom Reporting

Posted on by Jinavie

Some people always complain of symptoms, claiming that they are sick, while some people never seem to complain even if they have a whole list of symptoms. Why is there a difference in symptom reporting between people? For example, women are more likely to recognise symptoms and report them compared to men. This is because men are generally under the social pressure of needing to appear strong and healthy, so they become stoic and less sensitive to pain and disease. Women are usually more sensitive to internal bodily changes and worry more about their health.

According to a psychological theory called the competition for cues hypothesis, there are two signals that compete for attention when we recognise symptoms. The first is bodily changes, i.e. internal cues, while the other is external stimuli from what happens around us. Awareness of symptoms follows a ratio between these two signals: if there is a strong internal cue such as severe pain, we notice symptoms more quickly, while if there are many distractions, we may not notice the symptom. For example, according to a study people can run faster when listening to music and running through a forest with plenty to see. This is because music and the scenery distract the runner from internal cues. As we can only process a certain amount of information at a given moment, the more distractions there are the less sensitive we become to signals from inside our body.

Another factor that affects symptom reporting is illness labelling. The more information we have about a disease, the more we search for those symptoms. For example, if you yawn or scratch yourself, people around you will do the same. This is because they see you yawning and subconsciously believe that they should yawn too. This can be a powerful effect, as seen in mass hysteria. This strange phenomenon occurs when a person observes a sick person and their brain believes they are sick too, beginning to show symptoms despite being healthy. A similar example is seen in medical student disease, where medical students, with their extensive knowledge of diseases, match their own symptoms to symptom lists of rare diseases. For example, they might think that their high blood pressure is due to a phaeochromocytoma or renal artery stenosis, rather than just hypertension.

However, the opposite can occur where people fail to notice important symptoms and suffer serious consequences as a result. For instance, not all cases of heart attacks (myocardial infarction) cause unconsciousness and a patient may believe they are fine when only chest pain occurs. Failure to get treated as soon as possible at a hospital may result in ventricular fibrillation, leading to sudden death.