Small Birds and Sports Cars

Tropical Birds Evolved 'Superfast' Muscles to Win Mates
May 19, 2016

There is something inherently male about sports cars. That is not to say there are not thousands of female sports car aficionados out there, but data has shown that sports car drivers tend to be male.

An and MarketWatch survey of 10 million drivers found that more than 90 percent of Lamborghini, McLaren and Ferrari owners are men. Aston Martin has 88 percent male owners; Lotus, 86 and Maserati, 84.

Further, we culturally assign sports cars to men. On TV or in movies, sports cars are driven by predominantly male action stars, and when we see a shiny red Porsche 911 drive by, we might wonder if the driver is a 40-something-year-old gentleman having a mid-life crisis.

Red-Capped Manakin

I freely admit my own love of sports cars. The shine, the speed, the noise and the image of all those hundreds of horses crammed under the hood is just satisfying to me on some level. And the feeling of the wind on my face and my seatback flinging me forward while the engine roars never fails to make me giggle—luckily for me, I drive a 2-Liter hatchback and not a convertible, or I would look pretty silly.

So why do men seem to feel the allure of sports cars more than women? Common answers might be that a big honkin' Corvette is a way to “compensate” for something like tiny hands, or that a gleaming new Jaguar is a beast meant to hunt down and capture youth.

My own theory is that despite all the brake horsepower and sport-tuned suspensions we can engineer, and the luxury leather and brushed aluminum interiors we think separate us from our animal counterparts, we’re really just borrowing from their evolutionary playbook.

Take manakins for example: small, stubby birds native to central and South America. New research from Wake Forest University has found that some species of manakin possess among the fastest muscles ever recorded in vertebrate animals. All the speed and power that the manakins have stored in their wings, however, serves exactly one purpose: picking up ladies.

The "superfast" wing flapping muscles are only found in male manakins and are almost exclusively used in mating displays designed to attract female manakins, according to the study published in the journal ELife.

Wake Forest University biologist and lead author of the study Matthew Fuxjager, who studies the biochemistry of mating behavior in tropical birds, says two species of manakins—the red-capped and golden-collared manakins—developed these superfast muscles to perform loud, acrobatic movements for prospective mates.

This sort of behavior is nothing new in the evolutionary world. Animals—and usually male animals at that—do all sorts of crazy things to get a female to choose him. Biologists call that process sexual selection, and the easiest way to think about it is “survival of the sexiest.” Females will choose mates based on a usually exaggerated and wildly impractical trait the males have.

Female and Male Manakins

Peacocks, for example, have their famous fanciful tails for the sole purpose of attracting peahens, which do not have the tail feathers. Frogs will sometimes choose mates based on how loudly and frequently they can croak. Rams grow large horns to fight each other for the affection of females. And in all of those cases, the males’ lives are more difficult as a result of their traits. Peacocks have a hard time flying with their heavy tail feathers, some frogs require 25 times more oxygen than they normally breathe to keep up with their mating calls, and rams can die butting heads with each other.

Humans are no different. Both men and women go to extraordinary lengths to look impressive. High heels, man-buns and even sports cars may make you look good—depending on who you ask—but they generally make life harder.

Female manakins are usually a dull green or brown color, the better to stay camouflaged and hide from predators. Males, on the other hand, are jet black with other ostentatiously bright plumage. One of the two species Fuxjager studies has a red head that would make the devil blush and the other has a neck wrapped in more gold than Mr. T’s.

Come mating season, the male red-capped and golden-collared manakins roll up to the females and perform courtship movements called “claps” and “roll-snaps,” so quickly that they make a loud “mechanical” sound. In fact, Fuxjager found that red-capped manakins clap 45 times per second, while the golden collared manakins roll-snap 60 times per second to audibly rev their engines at passing females. To put that in perspective, the fastest sprinters in the world move their legs eight times per second at top speed. Click here to see a National Geogrpahic video of the red-capped manakin's mating dance.

Fuxjager also studied exactly how the manakins are able to move their wings so quickly by measuring the speed at which each of the three muscles in the manakins’ wings could contract and relax halfway back again and comparing those measurements to measurements of similar birds. The relaxation component was important because it determines not only how fast the birds’ muscles can move, but whether the bird would be able to replicate that speedy motion in rapid succession.

For two of the three muscles, the red-capped and golden-collared manakins were no different than the other birds. They could flex and relax most of the way about 50 times per second.

Golden-Collared Manakin

The third muscle, which connects the upper wing to the shoulder blade, however, was much faster in the golden-collared and red-capped manakins than in other birds. That final muscle, called the scapulohumeralis, can contract and relax between 80 and 100 times per second in the red-capped and golden-collared manakins, but stayed at around 50 times in the other birds.

Further, of the three muscles in the wing, Fuxjager found, the scapulohumeralis plays the smallest part in everyday flying, so on an everyday basis, the red-capped and golden-collared manakins have roughly the same flying ability as all the birds closely related to them. The scapulohumeralis, on the other hand, can take care of the extremely energy inefficient rapid mating displays all on its own.

So to recap, the ostentatiously colored male manakins evolved a purposefully noisy, fuel-inefficient, mode of transportation that's main performance upgrade gets used far less than one percent of the time for the simple purpose of looking more attractive. Trade in that Firebird for a shiny new manakin!

On a slightly more serious note, Fuxjager and his colleagues think the manakin’s ability to grow this super-fast muscle tissue could have some medical application. By studying exactly what makes those muscles so fast on a molecular level, doctors may someday be able to rebuild human muscles weakened by diseases like HIV and cancer.

Such therapies are dozens of studies and several decades away if they can be created at all, but the fact that only male manakins seem to have the superfast muscles at least gives researchers a place to start looking.

Fast wings, and fast in general, may not be declarations of sensibility or practicality, especially when compared to the camouflage green female manakin feathers or the easy-to-drive, fuel-efficient and reliable car brands that skew most towards women—Mini, Kia and Fiat, to name a few. Personally, buying a sports car to crawl through traffic jams on I-40 at 30 miles per hour makes about as much sense as buying a 100-foot yacht to cruise Jordan Lake.

That said, if I could ever get the money together, there would be a meteorite silver Aston Martin DB9 GT in my garage, waiting for the dozens of road trips I would take to every corner of North America. 

‘Sigh’'...only $201,075 left to raise...

— Daniel Lane

Daniel Lane covers science, medicine, engineering and the environment in North Carolina.