Lack of sex shortens life, according to Valencia researchers

Scientists from the city university conducted experiments on fruit flies, also known as vinegar flies or Drosophila Melanogaster, and found that 'sexual frustration' caused physical deterioration that shortened their lives by between 15% and 20%.

The team, made up of Zahida Sultanova, Pau Carazo, Roberto García-Roa and Manuel Serra say the 'price of sexual frustration' tends to 'increase differences in reproductive success rates' in males, thus 'intensifying sexual selection'.

Sexual selection relates to the behaviour and characteristics of males and females in seeking and attracting mates and ensuring effective procreation, based upon evolutionary observations.

For example, jealous control by men of their partners and in-fighting between males is thought to relate to 'mate-guarding' in all species, guaranteeing that any offspring produced are their own and they will not spend time and resources raising another male's young; females being more selective about sexual partners is considered to be an innate form of guaranteeing the male who fathers her offspring will provide for them and support her whilst she is pregnant and then feeding them, and females trying to 'look younger' is thought to be a subconscious attempt to display her fertility.

Whilst modern human interaction – especially mate-selection in homosexuals - belies evolutionary theories, scientists believe some aspects of them remain valid in humans and most other species of animal.

Such 'Darwinian' theories are 'crucial to understanding how populations manage to adjust their genes to the environment and the genetic divergence between populations', the researchers say – or how human and animal DNA changes over time to adapt to different realities, and how far DNA can predict how a species will turn out as an adult, based upon how their surroundings and nurture interacts with their nature.

Concerning fruit flies, 'when a male detects the presence of a female, physical mechanisms come into play' in order to 'compete against other males' to be able to reproduce, the Valencia University researchers say.

If the males do not manage to snaffle a female mate, their 'frustrated expectations' lead to a reduction in their life expectancy, according to PhD student Zahida.

“On a human scale, this would mean a decrease of around 15 years in our life span,” Roberto, a post-doctoral researcher from the Cavanilles Institute in Valencia, explains.

Studies of any type on non-human species are, naturally, limited, since they do not take into account the specific genotype and phenotype of this most advanced race of primates, nor the superior intellectual and emotional evolution of humans.

But the Valencia scientists say that even though sexual frustration has not been examined in many species as yet, the 'physiological mechanisms' present in the type of accelerated ageing they have noticed appear fairly generic, meaning they are likely to be a phenomena 'very extended across numerous types of animals', their report claims.

Photograph: The Valencia University research team (L-R)of Zahida Sultanova, Pau Carazo, Manuel Serra and Roberto García-Roa (taken by Valencia University)