“Hey man, check it out,” Boyfriend says to his friend, his voice steeped in the predatorial urgency that men only use when speaking to other men. Hearing the tone and guessing its purpose, I open my eyes and sit up on my beach towel, first squinting to see Boyfriend and Friend standing a few feet away, then turning to glance in the direction they’re staring. Yup, sure enough, she’s blonde, maybe 5′5″, not a stretch, wrinkle or flap in her tanned skin, thighs so taut they never touch, a generous D-cup spilling out of her bikini top. Your average vixenish nightmare.

“Uh, what the hell did you just say?” I ask, not bothering to hide my annoyance. Boyfriend turns and bristles, realizing how far his voice carried. “That was pretty shitty right there.”

“Baby, come on. I was just pointing her out for Friend! I wasn’t even looking at her,” he wheedles.

“Don’t insult my intelligence.”

The seductress saunters by, tossing the men a glance over her sleek designer sunglasses, ignoring me entirely. The rational portion of my brain acknowledges that she may in fact be a lovely person, filled with virtues and noble qualities, perhaps on the verge of completing her dissertation on the introduction of solar power as an oil-equivalent energy source while juggling weekly volunteer sessions at childrens’ hospitals and animal shelters. Had we encountered each other under different circumstances, maybe she would have regaled me with tales of her peace-keeping missions in Rwanda and base jumping in the Andes and we’d have become instant friends.

But right now, rationality and social graces are no match for 3 million years of human evolution, and the only thought registering is rage. Ovaried competition has entered my territory, planting herself in front of my chosen mate to showcase her oversized (and likely real, insult to injury) mammaries. Raw instinct takes over and I rise to a crouch, my knees digging into the sand, contemplating the urge to lunge at her Achilles tendons. If this wench doesn’t pack up her goods and move on to the next crop of sperm-generating males in the next twenty seconds, I’ll be forced to attack. Take her down by the ankles, then leave her for the hyenas.

At that moment, it occurs to me that all this anger is immature, even uncivilized. Women shouldn’t have to compete for men, it’s a social dynamic that erodes female relationships and ultimately doesn’t help anyone. The adult response in this situation would be to smile a polite Hello, then go about my business. But another glance at her long blonde locks and glistening torso, and reality wipes all mature rationality away. Natural selection doesn’t reward sweetness and courtesy. Be prepared to defend your gametes on some level, or watch them wander away. “Survival of the fittest” has never meant the girl with the tightest ass.

Now passing by my towel, her gaze finally rests on me, the angry little brunette with raised hackles and bared teeth. Throwing a last look at Boyfriend and Friend, she stops for a split second, then continues down the beach.