19 October 2012

Age of first sexual encounter may effect relationship happiness and success in later life

It is widely accepted that modern society runs at a faster pace than it used to, with children and teenagers experiencing many life events at much younger ages than did their parents and grandparents. This 'growing up fast' way-of-life is of great concern to many parents, especially when their children's ventures into sexual relationships are concerned, who are worried that their children are not ready such encounters. Is there really a cause for concern, however, or are parents just fussing and worrying for nothing?

Humans are a very social species and, in resource-abundant environments, usually favour a mating pattern called monogamy, where one person has just one sexual partner for a long period of time. Such relationships are rewarding and healthy when they work, creating stable conditions in which to raise a family.

Recent research from the University of Texas has suggested that, unfortunately, there is. The study, which was carried out by psychologist Paige Harden, has tried to determine whether the timing of an individual's first sexual encounter affects their romantic relationships later in life and whether it can predict factors like relationship satisfaction, the likelihood to marry and the number of sexual partners.

Dr. Harden conducted this research via a meta-analysis, using data from the [US] National Longitudinal Study on Adolescent Health and followed 1659 people from their early teens to young adulthood (<29 years old). As part of this research, Harden classified each participant in one of three categories in regard to their age at their first experience of having sexual intercourse: Early (<15), On-time (15-19) or Late (>19), before comparing the qualities of their romantic relationships/encounters.

As she predicted, the most highly educated participants from greater income families were older at the time of their first experience of sexual intercourse. The study appears to show that first experiencing sex at a later age is beneficial to an individual, as those in the study showed greater levels of marriage (or living with their partner), were less likely to be dissatisfied with their partner, were less likely to persist in an abusive relationship and typically had less sexual partners over the course of their life.

In contrast, those who were younger at their first encounter tended to have many more sexual partners and typically showed a greater level of romantic dissatisfaction. This data also fit with a clear pattern: those in the 'Early' group showed much more exaggerated trends than those in the 'On-Time' category.

Dr. Harden explains these results by suggesting that waiting until later to first have sexual intercourse may be beneficial to an individual as it allows their cognitive and mental development to have finished first. As well as having obvious benefits such as greater confidence, which makes an individual more likely to walk away from abuse and inappropriate pressure, being fully developed [mentally] also appears to enable an individual to learn more 'healthy' relationship skills. Harden suggests that it is these skills in particular that allow an individual to form healthier and happier relationships, which are more likely to endure for longer periods of time.

Although these findings are worrying, and seem to show that being young when having sexual intercourse for the first time can have series and long-term negative side-effects,  more research needs to be carried out into these ideas before any significant statement can be made. Dr. Harden has acknowledged this, saying that "we are just beginning to understand how adolescents' sexual experiences influence their future developments and relationships". For the time being, however, it looks like parents are right after all, and children may indeed, be 'growing up too fast'.

14 October 2012

Black mamba venom may be a super painkiller!

French scientists have recently identified that the toxic venom of the black mamba, one of Africa's most dangerous and feared snakes, has a huge potential for its use in medicine. The research, carried out by Dr. Eric Lingueglia from the Institute of Molecular and Cellular Pharmacology near Nice, has identified that the snake's poison contains a unique class of chemicals called mambalgins, which act as painkillers in mice that are as strong as morphine but have none of its associated side effects.

The black mamba, Dendroaspis polylepis, is named after the dark skin inside its mouth rather than after the colour of its scales. As well as being among the most poisonous snakes in the world, the 3 metre long mamba is also the fastest and can even outrun humans. These attributes, along with its highly aggressive nature, have made the snake highly feared among all the African peoples that live alongside it.

These properties of black mamba venom are of huge interest to the healthcare sector because, despite its heavy use, morphine is highly addictive and has many severe side effects for those taking the drug, which include headaches, a reduction in their thinking capacity, nausea and muscle spasms. A new painkiller then, which is effective enough to remove the same agonising pains as morphine but with none of its side effects would be like a 'magic bullet' in pharmacology, being hugely popular among both doctors and their patients.

Research has identified that these useful mambalgins may work in such a beneficial way because they operate via a previously unseen neural pathway that is not targeted by any other studied venom or by the palliative drugs currently in production. Dr. Nicholas Casewell, a world-leading expert in snake venom from the Liverpool School of Tropical Medicine, is avid over the potential implications of black mamba toxins to medicine and has said that mambalgins are "a really great example of drugs from venom, we're talking about an entirely new class of analgesics".

Dr. Lingueglia believes that this rather surprising property of black mamba venom may be as an intentional effect of the poison, which helps to incapacitate the snake's prey so that it is less likely to escape; or may be due to a chance, but useful, fluke in mice, resulting from the differences in brain chemistry between the rodents and the snake's usual prey.

Whatever the reason for the venom's remarkable analgesic properties in mice however, scientists are excited about the discovery and are hopeful that the toxins will have the same effects in humans as our brain chemistry is very similar to that of the rodents (which is why mice are often used in scientific studies). It is likely that there will be extensive research into mambalgins in the near future, which will hopefully lead to a new drug that acts as a safer alternative to morphine.

10 October 2012

From black to white: is calcium really that important?

The majority of us are at ease with Darwin's concept of evolution and understand how the 'survival of the fittest' has led to the vast abundance of life on Earth. Obviously, humans are no exception to this rule and evolution has moulded us into what we are today. Evolution, for example, selected for the first of us who began to move on two legs as this freed up our hands for better tool use; and selected for those who chose to live in social groups, which provided much more protection and help than did living alone. Without evolution it is doubtful that any life would exist on Earth at all, especially not in the form of hugely sophisticated organisms like humans.

Life on Earth began sometime around 4 billion years ago. It is believed that single-celled organisms first evolved on the shores of primordial oceans, which were abundant in the resources needed for life. Over time, these cells eventually evolved into the countless forms of life that we see on Earth today.

Most of you won't be surprised by any of this; it makes sense, after all. Something you might find surprising however, is why scientists believe that the early humans settling Europe evolved from being black to white. Obviously the sun's rays are less intense in Europe than they are in Africa, meaning that European settlers wouldn't have needed to produce as much of the pigment melanin in their skin, which absorbs ultraviolet (UV) radiation. Producing less melanin then would have provided such individuals with an advantage as they wouldn't have been wasting energy producing proteins their body didn't really need. This saved energy could then have been dedicated to more important processes (like keeping warm in the colder climate, for one thing).

Although this theory makes sense logically and saving energy by producing less melanin could quite plausibly have been the difference between life and death in the harsh European winters, is it really enough to have driven the evolution of one of our most noticeable racial polymorphisms?

Many scientists believe not, at least not by itself anyway, and research into this question has provided a rather odd alternative. Simply put, many scientists now believe that Europeans evolved from having black skin to white skin due to calcium!

Calcium is an fundamental resource for our bodies, with its ions having essential roles in muscle contraction; in propagating nerve impulses; and, arguably most importantly, in forming our skeletons (via binding with phosphorous to form a very stable salt called calcium phosphate). Despite its importance, calcium is rare in nature and is extremely difficult to acquire naturally as part of our diets. As always however, Nature provided early man with an ingenious way around this and all humans are able to make vitamin D in their skin when it is exposed to sunlight (in much the same way as plants photosynthesise sugars from sunlight to use as energy). Vitamin D greatly increases the affinity of calcium absorption in the gut, allowing the body to absorb much more of any calcium that it consumed than it would otherwise be able to.

Due to this ability, most people are able to acquire enough calcium (especially during the summer) to lead normal and healthy lives, and indeed, our African ancestors would have had strong bones and efficient muscles. The problems arose however, when early explorers entered Europe where the sun's rays are much less intense. This meant that the melanin pigments in their black skin were able to absorb much more sunlight than they could while in Africa and, as a result, vitamin D could no longer be produced.

Fossil evidence suggests that it was not long before the health of these explorers deteriorated, and many adult skeletons from the period show symptoms of osteomalacia (a disease where bones soften due to lack of calcium and deform under the weight of walking), and many may have suffered from a range of muscle weakness and epileptic disorders as their reserves of calcium were depleted and less and less could be replaced from bone stripping. Obviously such ill effects greatly reduced an individual's chances of survival and those with slightly lighter skin would have been more likely to live longer. Being healthier and living longer meant that they would have been more likely to survive to reproduce and slowly, the 'lighter' genes (which produced less melanin), would have spread through the population. In each generation the palest individuals would have been most successful at surviving and breeding so, over time, European humans would have got paler and paler until their skin was as white as it is in their descendants now.

As if this selection pressure wasn't enough to drive for whiter skin, having low levels of calcium and brittle bones had another major problem for women in particular - it hindered childbirth. Many women had such brittle pelvises that they broke under the strain of labour, virtually guaranteeing that both the infant and the mother would die. Furthermore, many children suffered from severe rickets due to a lack of calcium during childhood and puberty. This meant that such individuals were physically smaller than they should have been and many women suffered from underdeveloped hips that were too narrow for a baby to pass through. As a result, such a mother and her baby would have died during labour. Thus, many of the darker individuals would have been unable to give birth so that the darker genes disappeared from the European populations very quickly - being strongly selected against by Nature!

The degree of deformity that rickets can lead to can be very extreme, almost completely debilitating a child suffering with the condition throughout their entire life.

Scientists also believe that this explains why the vast majority of Europeans (and those in their descendent colonies such as Australia and the USA) can eat dairy as a stable component of their diet. This is actually quite abnormal, both in the animal kingdom and among other ethnicities of humans, as rennin (the enzyme required to digest milk) usually stops being produced by the body in infancy after the individual has been fully weaned. Thus, most humans are lactose intolerant and experience unpleasant symptoms if they drink milk or eat too much dairy-based produce. Humans evolving in Europe however, needed as much calcium as possible and would have been under strong selection pressure to continue producing rennin throughout their lives as milk is an unrivalled source of calcium.

Thus, the importance of calcium to the human body has made it an invaluable component that we need to survive. Too little calcium leads to severe health conditions that are so extreme that they can even drive evolution into turning black humans, who have very active melanocytes (melanin-producing skin cells), into white humans who have very little sun-protective pigments in their skin (allowing them to produce more vitamin D).