"Adaptation"
"I know this seems a little... harsh," Luisa said, as Chad's legs gave out and he collapsed to the floor. "But if it makes you feel any better, you're going to settle a lot of debates in the field of evolutionary biology." She squatted down and gave him a long, deep, probing kiss that seemed to go on forever. He felt her tongue slide into his mouth, almost dueling with his. If it was a duel, she was winning; Chad couldn't seem to make himself move even the slightest muscle. His eyelids gave up the struggle to stay open about five seconds into the kiss.
She finally let go--literally, Chad felt his head drop a fraction of an inch to smack lightly onto the hardwood floor--and began to pull his clothes off. "It's something biologists have debated for ages, Chad." Her voice was calm and cultured, her fluent English delivered in a Columbian accent that sounded rich and warm in his ears. "How fast does adaptation actually happen? How does a species change in response to evolutionary pressures?" Her fingers caressed Chad's body lightly as she undressed him. He heard himself let out a soft, whimpering sigh, but that seemed to be as much as he was capable of.
It certainly wasn't going to be enough to summon help. Even if any of his friends heard him, Chad knew that they would just high five each other. Their whole plan for the week involved getting naked with sexy women and moaning a lot, after all. They didn't come up with any ideas for what to do if they were the ones who couldn't move.
"So, first a bit of background--and stop me if I'm boring you." Luisa's voice was filled with acid wit, a purposeful lightness concealing a harsh contempt. It had been there all night, Chad realized, in her every response to his stories about his fraternity and his dad's money and his plans to join a brokerage firm after college. Now that he had nothing to do but listen, it was so obvious he was amazed he had ever missed it. Then again, he had other things on his mind at the time.
Like his boner. Luisa had the most amazing body he'd seen this whole trip, lush and curvy with long legs and broad hips with a huge juicy ass and absolutely fucking incredible tits. The second Chad saw her, he knew he had to get his dick inside her by the end of the night, even if the other guys were more interested in the skinny chicks by the pool. Chad didn't come all the way down to Providencia just to flirt with some girls from Vassar, not when the locals were always impressed by wealth and always ready for a free drink or six.
But right now, Chad's mind was nowhere near his erection, even if Luisa was playing with his cock while she talked. "One of the things that popular culture gets wrong is imagining Darwin as some sort of visionary who first noticed that animals adapt to their environments. Biologists had already noticed the evidence for evolution long before Darwin; their question was more about the mechanism that facilitated an already-obvious process." He felt her hands caressing his balls, moving away to pull his shirt up and over his head, then moving back down to his penis again.
"You've probably heard of one of them in school--Lamarck thought that somehow the experiences of an animal were pressed into them, like a stamp into clay. And that they passed on these impressions to their children." Luisa ran her fingernails down his chest gently, scratching over the sensitive skin first in one spot then another until Chad felt the tingling pleasure of a powerful endorphin rush all through his body. "But there were a lot of competing theories, before and even after Darwin. Like saltation, for example, which posited rapid mutations in response to evolutionary pressure."