The female instinct to look fair!

By

Syed Ibrahim Rizvi

Life evolved on this earth 3.8 billion years back and has continued its journey to the present moment. It is a continuous process which has remained unabated for such a long time. Due to this reason, scientists explain that the basic purpose of life is to reproduce. Every living organism must find a way to reproduce and hence fulfil the purpose of life. However, reproduction is a process which requires two individuals of opposite genders. Nature has therefore provided every animal with a basic instinct which propels that particular animal to find a mate for reproduction.

As a mating strategy, the male by instinct, needs to show he’s the strongest, healthiest partner available so she chooses him as her mate. Higher animals have many weird and wonderful ways to attract attention to themselves, such as singing, dancing, displaying vivid colours and even fighting. These tactics are called courtship rituals. Unlike humans, who judge each other by a criteria which we describe as ‘beauty’, animals have no instinct to judge facial beauty but they judge the prospective mate by the symmetry of their body. A symmetrical body provides information that the prospective mate is healthy and there will be better chances of a successful mating event.

The evolution of human-like animals from chimpanzees was a big event in the evolutionary history of life on Earth. The biggest change that occurred when human-like creatures evolved was in the size of the brain. The first human-like animals had a brain which was almost double in volume from the chimpanzees. This was a time when early human-like creatures started walking on two legs. This big stride in human evolution took place approximately around four million years ago.

While evolution was playing its role in the lineage of humans and a lot of changes were happening which included walking on two legs and the increase in brain size, there was a big problem which impeded all advancements. To keep the brain cool, since the brain uses a lot of energy, it was important to devise a strategy for efficient cooling of the body. All primates, which were predecessors of early humans, had bodies with fur or a thick coat of hair.  This blanket of fur or hairs created a body covering which prevented rapid cooling of the body. So as evolution progressed creating early humans, the body covering fur or hairs was lost. Concomitant to these changes, early humans also developed a large number of sweat glands on their bodies. The loss of body hair and the advent of sweat glands was a perfect combination for a mechanism to cool the body by means of evaporation of sweat and these two changes provided the necessary requirement for the brain to increase in size.

An efficient system to cool the body provided early humans to be ability to run for long distances. Thus, humans started exploring the vast savanna grasslands of central Africa and started hunting animals. At this moment in evolutionary history, approximately two million years back, humans changed their eating habits to be carnivores. A change from a predominantly herbivorous (plant-eating) pattern to a diet comprising animal meat provided more calories and this became a trigger for further rapid increase in brain size.

Therefore, the loss of fur or hair explains how naked skin itself plays a crucial role in the evolution of other characteristic human traits, including our large brain and dependence on language. It is interesting to note that early humans started communicating with each other after the transition from a four-legged locomotory pattern to bipedalism (walking on two legs). Once two hands were free, two individuals could make gestures to each other and thus started the first form of communication. It is amazing that the instinct to communicate through gestures which probably started approximately four million years back still continues in the communication repertoire of modern humans. Just pause a moment to observe how we move our hands when we speak to each other!

It is therefore a quirk of destiny that amazing things happened in the evolution of humans once our primitive ancestors lost their body hair. It is often said that loss of hair makes us humans!

Early human ancestors are believed to have had pinkish skin covered with black fur, much as chimpanzees do, so the evolution of permanently dark skin was presumably a requisite evolutionary follow-up to the loss of our sun-shielding body hair. Dark skin evolved later in human evolution to shield the body from harmful solar radiation. In fact, the early modern humans, which in biology we categorize as Homo sapiens, had dark skin and lived in central Africa. Several factors played their part and another milestone happened in human evolution. Around ninety thousand years back, some enterprising groups of humans moved out of Africa and reached Asia. Their exploratory instincts compelled early modern humans to explore other geographical regions of the world and since humans had higher cognitive abilities due to the bigger brain, they slowly became masters of this planet.

As humans migrated outside of the tropics, varying degrees of depigmentation evolved in order to permit UVB-induced synthesis of pre-vitamin D3. The migration of early humans to cooler climatic zones thus meant that dark skin was not required and slowly those human races which occupied colder geographical regions of the world lost their dark skin. However, those humans who remained in tropical regions continued to have varied hues of dark skin.

It is a universal observation that biologically the human inhabitants in all geographical regions of the world which fall under the tropics have dark or ‘coloured’ skins. However, interestingly, in a given society, females are relatively fair in appearance compared to male skin. This biological fact creates a constant social pressure to become fair among the females of any society. It goes without debate that the worldwide 400 billion USD cosmetic industry basically thrives on the human urge to look good. A major part of this aspect is to look ‘fairer’.

The urge to look ‘fair’ has a big evolutionary explanation. The difference in male and female skin colour in a given population may be due to the greater need for women to produce more vitamin D during lactation. Thus, fairer females may provide a greater ability to make vitamin D and thereby the chances of survival of the newborn are greater. Thus, ‘fair’ skin may be a signal for an attribute of greater reproductive success to the prospective mate! This may play a big part in the mate selection ritual. Although the human race is now far ahead of such trivial anecdotes, the female instinct to look ‘fair’ is deeply rooted in our genes. After all, we all have to fulfil the basic purpose of life and procreate. The criteria of mate selection leading to reproductive success is ingrained in our brains.

(The author is Professor of Biochemistry at University of Allahabad)