Authors: Adilia S., Elena Petrova

Biologists from the Leibniz Institute discovered under which conditions a process of mutual choice of a mate is formed. Some species of animals also feature mutual choice of a partner, just like people. Mutual sexual selection in certain species, including humans, had developed through evolution of species.

Mutual Choice of Mate

Most species have their own selection criteria. For example, female peacocks choose mates based on the colour of feathers of the prospective partner, preferring brightly coloured males to the ones with dull coloured feathers. Good genes and health are important for a healthy offspring and contribute to reproductive success. This phenomenon is called sexual selection — when females (males) decide with whom to mate, choosing the most successful partner.

This selection allows certain members of the population to reproduce more than others, therefore passing on their traits more than others.

However, it’s not as simple as it seems to be. Some scientists believe that numerous scholars continue to ignore the obvious evolution of mutual sexual selection in animals. The evolution of sexual selection has been detected in a variety of animal species, the study published by Biorxiv.org points out.

The researchers emphasize that mutual selection may potentially hamper the species’ reproduction. It would be much easier for a female to choose the first male and produce an offspring. In spite of that, she continues to search for an ideal mate or “mutual love”. It would be more effective to spend this time to pair with the first partner and procreate, a straight approach may suggest. But it’s not as simple as it seems. There are benefits in “choosiness”, and this is why mutual sexual selection evolved during the evolution, the scientists state.

The idea of the study was that there should be a trade-off between the direct benefits of mating (offspring) and the decrease in mating rates because of choosiness.

The researchers analysed which conditions contribute to the development of mutual selection. They created a theoretical model of a population consisting of an equal number of species of the opposite sex. Each individual had a certain number of qualities that were attractive to the opposite sex. At each stage of the life cycle any individual could die.

It turned out that lower mortality risks in a population promote development of mutual sexual selection. Low mortality level reduces the cost of the search for a perfect match.

“Mutual mate choice can only evolve if both females and males exhibit long latency after mating”, the scientists concluded.

It used to be believed that the sexual selection lied mainly with females. However, there is a growing body of evidence about male choosiness in animals. In humans, we know very well how selective are males about long-term mating, although they may be less picky about short-term encounters, which are unlikely to produce offspring in modern humans.

Mutual Sexual Selection in People

Here we can draw a parallel with human relations. The more successful person is less available, and the competition for his love is higher. A self-sufficient person can afford to take time to choose an ideal partner.

“Choosy individuals spend time searching for particular mates instead of reproducing with the first member of the other sex they encounter. When mating events are sequential, the total number of matings for choosy individuals is thus reduced and this cost – sometimes qualified as an opportunity cost – occurs even if individuals only mate once in their lives (because rejecting mates increases the probability of dying before having reproduced),” the study proposes.

Thus, when mortality rates are low, choosiness is encouraged by producing a more genetically beneficial offspring. People in the developed world normally only have 1-3 children during their lifetimes, they are choosier about finding a partner than citizens of poor countries. Life expectancy is also longer in more developed countries.

People spend more time choosing a marriage partner today than 200 (or even 20) years ago.

Choosy Pandas

Some animals also choose partners by mutual attraction. For instance, mutual sexual selection is important in pandas. If pandas mate with their preferred partners they have significantly higher copulation and birth rates.  When pandas are paired with mates that they dislike, they rarely procreate. If one animal in the pair demonstrates interest to a partner, the pair’s chances to have babies is 50% and if both pandas are “in love”, their chances increase to 80%. The population of pandas is declining at alarming rates. These animals are extremely difficult to breed in captivity.

It’s one more reason why the study of mating behaviours is important. It helps to understand evolution processes in the animal world. Sometimes it even can play a significant role in the survival of the species. Regarding the iconic pandas, perhaps it’s worth trying to let pandas choose between partners themselves. This might help to improve reproductive rates among the animals. How about a dating site for pandas to improve birth rates and logistics?

Pandas are more likely to mate and produce offspring if they like each other.

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