Natural Selection

As Clark departed the plane with his wife, he was bursting with excitement. It seemed too good to be true, but here he was, about to enjoy a free vacation to a tropical island. Well it was not exactly supposed to be a vacation, he was here as part of a research study that his wife, Catherine, and he had been selected to participate in. She was a postdoctoral fellow in evolutionary biology and well connected in that community, it finally paid off as they were invited to participate in a semester-long research study. For the next three months, they would live on this tropical island, and when they were done, the researchers conducting the study would debrief them on their experience.

As they stepped foot onto the tarmac, they noticed no permanent structures, just an open airfield surrounded by a picturesque tropical jungle. They were all directed towards the north tip of the airfield, where they met with one of the professors conducting the study, Professor Achebe.

She was a strikingly beautiful dark-skinned African woman, who addressed them with a calm but authoritative voice, "Well everyone, you made it. Again thank you all for volunteering for this research study, for the next 90 days, you will call this island paradise your home. We carefully selected this tropical island because of its temperate weather, abundant natural food resources and its pristine fresh water springs. I truly believe this is as close to paradise as we could find. There are no rules, guidelines or restrictions while you are here, the purpose of this study is to observe homo sapiens in their natural environment. On behalf of all the donors and on behalf of science, thank you all and good luck!"

When she finished her address to the crowd of twenty participants, she boarded the plane and left without any further explanations of what was expected of the participants. Clark and Catherine were giddy with excitement and set off to explore their new environment, they followed the sound of crashing waves towards the beach. There they found beautiful, soft white sand beaches. Again they could not believe their luck, Clark thanked Catherine again for signing them up for the study. They had walked the shore for several hours before they made an entire loop around the island, and they had not spotted a single sign of civilization, they were relieved to be truly alone. Although the climate was extremely agreeable, they decided to work on building a base camp, it felt like an almost instinctual need.

It did not take them long to clear a small area of brush where the white sand beaches met the tree line, offering slight protection from wind or wandering eyes. Without tools they were not able to construct much of a shelter, so they settled for gathering and laying down huge banana leaves as a sort of make-shift floor and mattress.

Clark was excited to spend the night together with his beautiful wife. They watched the sunset over the waves, enjoying fresh picked bananas, then as twilight settled in, they stripped their clothes to bathe in the ocean. After some horse-play in the waves, it was clear Clark was ready to make love with his beautiful wife back at the make-shift camp site they had set up. However, Catherine reminded him that they had no access to her birth control and she did not want to risk anything so far away from modern medicine. Catherine did not want to spoil his mood on their first night together, so she started rubbing her hand up and down his rapidly inflating cock. When he was fully erect she took him into her mouth. No more than a minute after she had started blowing Clark, she felt him tap on her head. She knew he was not cumming this quickly so she let him out of her mouth with a curious expression. He did not say a word, he only pointed towards the shore. There, walking along the beach, were two people holding torches. Between the torchlight and the last remnants of sunlight, the two naked figures became more and more distinguishable as they drew nearer.

One was a tall, muscle-bound man with dark features, next to him a petite Asian woman with long, silky, black hair and pert breasts. Clark knew that he and his wife were secluded enough that they would not be noticed, so they continued to gawk.

"Should we say hello? Do you think they are lost?" Catherine quietly asked Clark, she was still slowly stroking her husband's cock as they hid in their bushes.

"No," replied Clark in a hushed tone, "I wouldn't want to spook them. It is getting late and I am sure they are probably just heading back to wherever they set up camp."

As the couple walked past them, completely oblivious to their presence, Clark could not help but notice Catherine's eyes were glued to man's large cock. While she was fixated on the strange man, she unconsciously increased the pace with which she was stroking her husband. Clark noticed her breathing become heavier and her nipples harden. Fuck, he thought, Is she really that turned on just by seeing this guy's absurd large cock? Or is she just a voyeur?

When the strange couple finally passed out of ear shot, Catherine could not help but whisper, "Oh my gosh, did you see the size of that man's cock? I hope he doesn't split that poor woman in half." This confirmed for Clark that it was indeed the stranger's manhood that had drawn her attention and gotten her hot and bothered. However he was not going to admonish her while she was stroking him, not to mention, he gotten a good eyeful of that beautiful Asian woman as well.

It was no more than a couple minutes later, right as Clark was getting close to cumming, that the two of them heard a scream off in the distance. Catherine stopped her ministrations as they both listened. It was dark out now, but they decided to investigate the noise to see if anyone needed help. After less than a few minutes' walk, they were close enough now to hear the woman moaning in pleasure. She may have let out a scream a minute ago, but now she was moaning like a whore. As Clark turned to return to their camp, Catherine grabbed him by the hand. She put her finger to his lips and ushered him to be quiet. She then sank to her knees and began to blow him as they listened to the other couple fuck. Clark was surprised by his wife's adventurousness but he was never one to turn down a blowjob.

He closed his eyes and listened to the other couple's loud love-making as his wife bobbed up and down on his cock. They heard the Asian woman's lustful voice, "Oh yeah, fuck me harder, fuck your cock is so big. You are so deep, fuck, fuck, fuckkkk!" Then the large man's baritone voice responded, "Fuck you are so tight, your husband must be tiny. I haven't had pussy this tight in a long time, I love your tight little Asian pussy." Meanwhile as Catherine was working her mouth up and down her husband's cock, her hands began playing with his balls and her knees dug deeper into the sand.

The Asian woman's moans became less and less coherent as she reached her orgasm, she was no longer even trying to make dirty talk, she was letting out primal sounds of pleasure. Clark could only imagine the scene but still it turned him on to hear a woman orgasming in the darkness.

Shortly after the sounds of the Asian woman's climax ebbed away, they heard the well-built man warn her he was about to cum. The Asian woman begged him, "Pull out, you promised to pull out. Let me go. Stop. It's not safe. Pull out, please pull out!"

The sounds of the woman's pleading sent Clark over the edge, he shot his load into his wife's mouth. As his wife tried to pull away from him, he grabbed her hair and held her in place as he continued to fill her mouth with his cum. Normally he would never treat his wife so aggressively, but something about the primal nature of the night invigorated him, his wife did not protest. As his orgasm finished, he could hear the rapid pace and then last few thrusts of the other couple, it was clear the man was had reached his own orgasm. Then there was some gentle sobbing from the Asian woman, it was so exaggeratedly feminine it was hard to tell if it was genuine or if the Asian woman was only trying to roleplay for the large man's benefit, "You promised you would pull out. You're an asshole. How could you do this to me? What will I tell my husband?" Then they heard a hard slap, and the sobbing quieted down. Shortly after they heard some indecipherable whispering, and then some girlish giggling.

Catherine and Clark gave each other a knowing look, they did not want to be stuck in the middle of any kind of violence or domestic situation after seeing the build of that man earlier. They quietly snuck back to their encampment. Clark ebbed off to sleep in his post-orgasmic bliss, as Catherine silently rubbed herself to orgasm, thoughts of the night dancing in her head.

Catherine and Clark woke up to the sound of waves crashing onto shore, seagulls calling out, and the sky just beginning to lighten. They had no plans for the day so they lounged lazily in their banana leaf bed for a while, then headed down the beach line to make some friends or find something to do. No more than 10 minutes into their walk, they spotted a woman bathing herself in the waves, and a nude man tending a small fire. Catherine and Clark were both naked, not wanting to put on their sandy, smelly clothes from yesterday, and they figured the other couple had come to the same decision.

They approached the fire and introduced themselves to the man tending it. His name was Lee, a slightly built Asian man, who was extremely kind, offering the couple some fish he had caught earlier in the morning. Clark was impressed the man had made a fire, but Lee insisted he had not been the one to start it. He told them that last night, a stranger with a torch came by, the stranger also gave him some herbs to help him with his anxiety. Lee said he slept deeper than he ever had before and he was not sure if it was the herbs or the island life, but he was not complaining.

When Lee finished his story, his wife came back to shore and introduced herself as Linh. Linh was a drop-dead gorgeous Asian woman, and also looked familiar to Clark and Catherine, who gave one another a knowing look. They were both suspicious she was the Asian woman they had seen walk past their camp last night.

Now they were grateful they had chosen to stay hidden last night. They warmly greeted Linh, keeping their suspicions to themselves. They all sat around Lee's fire and made small talk. Catherine could not help but notice Lee occasionally stealing glances at her, but just as she noticed his cock begin to grow he politely rested his hands on his laps to block her view and preserve his modesty. Catherine was a bit flattered another man found her attractive. She worked hard to keep her body fit and was confident in her athletic build, but it was reassuring to know that even without makeup she was still eye-catching.

After they ate breakfast, the four of them walked down the beach together, the men in front talking to one another as the woman trailed behind them. It turns out most everyone had the same idea, as they continued down the beach more and more people joined their party.

At a beautiful viewpoint on the eastern part of the island, all twenty of the research participants had gathered. They were eating various fruits and commiserating about their good fortune to have been picked for this study. It turns out there were five couples and ten single people. As they all mingled, it became apparent they were all roughly the same age, in good physical condition and all young professionals or academics.

Clark and Catherine took note when they formally met Vincent, the man they had seen Linh with the night before. He was very gentleman-like when he introduced himself to Clark and Catherine, even asking Catherine if it was okay if he called her "Cathy." In the academic world Catherine insisted on her full name, but on the island she decided the less formal Cathy would suffice. Clark was a little surprised by his wife, but liked that she was loosening up.

It turned out that Vincent had set up his camp not far from Clark and Cathy's, in the opposite direction from Lee and Linh. Clark and Cathy feigned surprise at learning this, but were genuinely surprised when Vincent asked them to join him for dinner some night soon. The couple did not know how to respond, and they definitely did not want to get on the wrong side of this large man, so they acquiesced, insisting they would love to join their new neighbor for dinner.

At around noon the group split up, most people returning to their campsite, a few brave souls wandered into the jungle with an adventurous spirit. Clark and Cathy played it safe and took the beachside path back to their campsite on the Western side of the island, this time with Lee, Linh, and Vince joining them.

When they got back to Lee and Linh's camp the men set off into the jungle to explore, while the women tended to the fire. As Clark got to know Vince better, he wondered if he was just imagining the events last night. Vince was a well-spoken gentlemen, knowledgeable about so many things, including the forest and camping, there was simply no way he was the brute who was sneaking around in the night with Lee's wife, Clark thought to himself, there is simply no way this boy-scout of a man would try and steal away someone else's wife. Clark decided he would talk to Cathy about it later, and see if she remembered last night exactly as he did, or if they had possibly mistaken the lover's identity due to the poor lighting.

Clark noticed the sunlight glint off of a drone far above them in the sky, no doubt they were being observed, they were here to be studied after all. He pointed it out to Vince and Lee, and they all started waiving their hands at it, trying to draw its attention, but it continued in its circular pattern uninterrupted. The three men, unencumbered by the women, decided to give whatever professors were spying on them a show. They used mud to apply war-paint to their faces, and they broke off sharp branches to use as spears and went on a mock hunting expedition. They were just having a bit of fun, until Lee swore he spotted a small wild boar and gave chase. Clark hesitated and Vince warned him not to chase it as they would never catch it and only end up lost. Clark insisted the island is not that big, and he followed Lee on his chase. Vince headed back towards the shore, and the women.

Cathy was surprised when Vince emerged from the forest without Clark and Lee. Vince explained that the husband's must have needed some time away from their wives because they were chasing after a wild boar they had no hope of catching. Cathy laughed at the insinuation that the husband's would prefer to chase a boar instead of their own wives. Vince then offered to help the two with the fire, Linh remained silent but Cathy was more than happy to accept help.

After the fire was stoked, the three of them set off into the wood line to collect some more firewood to keep Lee's fire well supplied. It did not take Cathy long to find more dry wood than she could carry, she asked Vince to help her with it. As Vince slid past her from behind, she could not help but feel his large manhood brush against her ass. He couldn't have done that by accident, could he? Cathy thought, Fuck that things feels potent just pressing against my ass, I can't even imagine what it would feel like inside me, well I guess I spent a good amount of last night imagining that, but the real thing must be incredible, I have no idea how Linh is still walking straight today.

After they brought the first load of wood back to the campsite, Cathy offered to tend the fire back to life so Vince could go collect some more wood. Linh offered to help Vince, Cathy was a bit surprised after how last night seemed to have ended, but she did not protest. Cathy guessed it was about a half hour later when the two of them returned. Linh's cheeks were glowing, she was in a great mood.

Linh was not even trying to hide what had happened between her and Vince in the woods. Cathy could not help but feel her eyes drawn towards Linh's puffy pussy lips, and what looked to be semen globules slowly trailing their way down Linh's thighs.

While Vince was cleaning himself off in the waves, Linh began to speak to Cathy in a hushed tone, "It's worth it Cathy. I know you know about us. I know it is fucked up. But I feel alive for the first time in my life. This is living life to its fullest, this is exactly why we are here, to live like we are wild. We were meant to fuck, and I found a man who is equipped for it. Vince and I agreed it's just a fling, just some fun for a few months, no one gets hurt. We never mess around near Lee, what he doesn't know, won't hurt him. Let's just enjoy ourselves during this study, it might be the only time in our lives we are this free."

This gave Cathy a lot to think about, she wondered to herself, Who would put this much funding into a research project, paying twenty people's rents and mortgages for three months, just to watch us choose to spend our free-time fucking... Is that what this is all about? Is this about mating-choice? Why include married couples? Why not give access to birth control? There is no way this cleared the University ethics board.

Cathy reprimanded herself for her disillusionment with the study. This was a prestigious research study, not a vacation, who was she to question the professors' methods. She was a lab rat here, and they were the researchers. She needed to get out of her own head and trust the process. Cathy stared deep into the fire, lost in thought, as Linh went to rinse herself off in the water.

The sun was only beginning to set when Clark and Lee returned to the camp site, a small boar already field dressed. The five of them enjoyed a dinner of boar and fruits together by the firelight. Vincent postponed the dinner at his campsite for tomorrow night, everyone found that agreeable, and they stayed at Lee and Linh's camp into the night.

Lee was the first to retire to his make-shift bed, passing out no more than a couple dozen steps from the fire. Linh smiled as she explained her husband was always early to sleep, not wanting to waste a chance at an early start for fishing these pristine waters.

Cathy and Clark were wise enough to know it was a good time to leave as they did not want to be witness to any extra-marital entanglements. Besides, Cathy wanted to bounce her concerns about the study off of Clark in private.

On the way back to their camp, Cathy explained to Clark that she suspected the study was about more than just observing homo sapiens in nature. Everyone on the island was of reproductive age, and reproductively fit, there was no way this was truly a randomized study. No old people, no children, no obvious health issues. This was certainly not representative of the general population.

Then it dawned on Cathy, she needed to see what the researchers saw. With her background in evolutionary biology, she was in a unique situation to both observe and participate. Tonight she would begin observing, like a scientist, the breeding habits of the other islanders, the breeding habits of homo sapiens in nature.

She silently doubled back to Lee's camp alone, leaving Clark at their own base camp. She observed Vince and Linh sitting next to one another, Vince beginning to slowly palm Linh's perky breasts. His advances on her were having their intended effect. Linh began slowly stroking Vince's cock, while periodically looking behind her shoulder to ensure her husband was still sound asleep.

After a few minutes, Linh got up and began to lead Vince away from the campfire towards privacy, her hand still firmly grasping his large cock. However they only went a few steps before Vince shoved Linh forward. She fell onto her hands and knees, and Vince's intentions became clear as he positioned himself behind her, his hard cock.... Cathy was fixated on his cock as the primal sight unfolded in front of her. She wanted to observe this as a scientist but could not suppress her own lusty thoughts.