It’s peak egg-laying period for lyrebirds in the Sherbrooke Forest in Australia. A female approaches. The male lyrebird runs to his favourite display mound and performs his heart out in a well-choreographed singing and dancing show.
The performance includes what sounds like a 80s video game accompanied by side steps followed by jumping and flapping wings while singing a quirky version of ‘Old McDonald had a farm,’ imitating anything from monkeys to horses.
Speaking to Decoded Science, Dr Anastasia Dalziell, biologist from the Australian National University, said “if she chooses him, they mate on his display mound immediately after his dance. If she doesn’t like it, then she leaves his territory and visits another male.”
Lyrebirds are not unique in this respect. From flies to whales, females have the power to choose the male (or males) they want to mate with. To get the ladies’ attention, males must compete against each other to show they have the potential to produce the best babies. This explains the peacock’s colourful plumage, the bright orange and blue spots in guppies or even the complex singing in canaries.
“Males have evolved traits that increase their ability to mate”, explained Dr Matteo Griggio, behavioural biologist from the University of Veterinary Medicine in Vienna and specialised in sexual selection. “On the contrary, females are typically selected to resist male mating attempts and to choose the best male. Females invest far more in reproduction, and so they have more to loose from a wrong decision”.
Sexual Selection: It all Started with Darwin
Charles Darwin was the first to propose a theory of sexual selection to explain such colourful traits and complex mating behaviours. This was a puzzle at first, as it went against his original theory of evolution. These are, after all, characteristics that place the male in danger of being discovered by a predator. So, why did deer develop such heavy antlers or frogs their loud call?
Eventually, in 1871, Darwin came up with a solution for this conundrum. He established what is now called ‘sexual selection’, where the choices made by females manipulate how males change. “Although controversial for more than a century, Darwin’s idea of the evolution of male ornaments through female preference is now widely accepted”, said Dr Griggio. In fact, scientific journals are full of examples of sexual selection and mating behaviors, covering everything from the weird (such as embellished genitalia in many insects) to the wonderful (such as the highly complex structures built by bower birds).
So, What Do Women Want?
Do women want a handsome partner or a good father? This is certainly the million dollar question!
Some scientists defend these exaggerated traits as simply to attract the female. Others believe the female is making an educated choice about a specific desired characteristic, such as parenting skills or quality of the genes. Speaking to Decoded Science, Dr Griggio explained the different theories. “Ornaments or displays can be viewed as indicators of genetic quality of males”, he said, “and then there are those purely ‘aesthetic’ choices, with no particular benefits, but they are selected only because females find them appealing”.