In most species, females do most of the choosing in sexual selection. As any guy would know, female choice puts males to work trying to prove their worthiness. Demonstrations of fitness are common. Elk practice head-butting while frogs compete in a sing-off where the one that croaks the loudest and longest wins. But what happens in species where the males cooperate to raise the young? Through the years, evolution started to incorporate more complex variables than a simple demonstration of fitness. It started to take into account more practical considerations. In these species, the male not only needs proof of resources for protecting and provisioning, but also proof of commitment.
A peacock fanning out its feathers is nothing but a pure display of fitness for the females. "If I can survive in the wild with these big colorful feathers, I must be a bad-ass". Pixabay image source.
Humans have engaged in a very curious proof of commitment. It involves the gifting of a very expensive object which has no practical use whatsoever. Engagement rings not only signal the serious intent of the person gifting it, but another byproduct is that it also displays the capacity to provide and protect with resources. Nevertheless, we are not the only species with such a ritual. Male dung beetles shows its reliability and commitment not by blowing up the bank account, but by rolling a "nuptial ball" of elephant dung. Then he presents the ball to his beloved, and if it works, she then lays her eggs in the ball.
Of course you cannot compare the time it takes to roll a dung ball to the time it takes to get paid enough to buy an engagement ring. But both are gifts given with the intention to procreate. In addition to time, there is something else that makes the selection in humans specially interesting. In many species, generosity can mean having less advantages because it can be regarded a limiting factor in someone's ruthlessness for getting what he/she wants (Amotz Zahavi, The Handicap Principle). For us humans, generosity is of great value. Since males help in the upbringing of the young, having a generous person actually pays off. Furthermore, it can be seen as an even stronger signal of fitness. "Since I am so fit and capable, I can afford to give stuff away".
This predilection for generosity has been distilled and incorporated into the very complex equations that happen in the females' brains for sexual selection. Being generous signals more support. It basically says "I am not a selfish bastard and I will help with what I can". So next time, to show your sexual selection fitness, do not forget to tip well!
What do you think? I'd like to hear your opinions.
Sources:
Paul J. Zak, The Moral Molecule: How Trust Works
Amotz Zahavi, The Handicap Principle: A Missing Piece Of Darwin's Puzzle
If you want to check out other thoughts that this awesome book has evoked, click on these past posts:
- The Moral Molecule Under The Microscope #1: Witnessing An Act Of Trust Makes You Behave More Pro-Socially
- The Moral Molecule Under The Microscope #2: On An Erroneous And Antiquated Economic View Of Human Behavior
- The Moral Molecule Under The Microscope #3: On The Relation Of Oxytocin And Pro-Social Behavior
- The Moral Molecule Under The Microscope #4: On The Significance Of Oxytocin Modulating Our Behavior
Best,
