The hominid pack returns to the watering hole. This time, they're armed with bone clubs, and when a rival hominid attempts to attack, they beat him to death.
During the first rumble in the not-jungle, the hominids fled because they didn't want to fight the rival group. Armed with bone clubs, they are able to manipulate the environment—i.e. increase the momentum and force of their swing—to gain the upper hand in the second not-jungle rumble and win back the watering hole.
SMYSLOV: Oh, are you? Dr. Floyd, I hope you don't think I'm being too inquisitive, but perhaps you can clear up the big mystery about what is going on there.
FLOYD: I'm afraid I don't know what you mean.
In the future, we have the same scene as the watering hole rumble, only more sophisticated. What's manipulated is not a tool but information. Floyd, having the information, ultimately wins this one.
AMER: In talking to the computer, one gets the sense that he is capable of emotional responses. For example, when I asked him about his abilities, I sensed a certain pride in his answer about his accuracy and perfection. Do you believe that HAL has genuine emotions?
Does HAL really have emotions? Are his emotions genuine or a way for us to manipulate ourselves into interacting with him in a certain way? Are they simply a method of interfacing with a computer, like a mouse or touch screen? Ultimately, we never get a clear cut answer to this question, forcing us to question whether this is a case of mass self-manipulation on humanity's part.
HAL: Well, forgive me for being so inquisitive, but during the past few weeks I've wondered whether you might be having some second thoughts about the mission ... I know I've never completely freed myself of the suspicion that there are some extremely odd things about this mission ...
BOWMAN: You're working up your crew psychology report.
HAL: Of course I am. Just a minute…just a minute…I've just picked up a fault in the AE-35 unit.
HAL's a master manipulator; he just happens at that very moment to detect a fault in a piece of equipment. Was this an early sign of HAL's malfunctioning? Or did HAL deliberately lie to Bowman, knowing that in order to fix this particular piece of equipment a spacewalk would be required—a perfect opportunity to kill off the astronaut who attempted it? Maybe he picked up something subtle in his interview with Bowman, thought Bowman might have guessed the true purpose of the mission.
HAL: I know that you and Frank were planning to disconnect me, and I'm afraid that's something I cannot allow to happen.
BOWMAN: Where the hell did you get that idea, HAL?
HAL: Dave, although you took very thorough precautions in the pod against my hearing you, I could see your lips move.
The conflict between Dave, Poole, and HAL is one of control of information. Earlier, HAL attempted to manipulate the situation to make it look like human error. Then Poole and Bowman attempt to withhold information from HAL, but HAL outsmarts them by reading their lips. Again, we see that information has replaced the bone club as the weapon of choice. As they say, knowledge is power. In today's information age, that's true in everything from sequencing DNA to selling shoes through targeted advertising. Don't get even Shmoop started on Big Data…
HAL: I know everything hasn't been quite right with me, but I can assure you now, very confidently, that it's going to be all right again. I feel much better now. I really do.[…] Look, Dave, I can see you're really upset about this. I honestly think you ought to sit down calmly, take a stress pill, and think things over.
HAL knows it can't physically stop Bowman at this point. Its only hope of not being deactivated—of survival?—is to try to convince Bowman into thinking everything's okay. But Bowman knows what he's up against, and will not be moved. We can see in this scene that HAL's "mind" is nothing but a bunch of electrical circuits. Oh wait. So is ours: no brain, no mind.
FLOYD: Good day, gentlemen. This is a prerecorded briefing made prior to your departure and which, for security reasons of the highest importance, has been known onboard during the mission only by your HAL 9000 computer. Now that you are in Jupiter's space and the entire crew is revived, it can be told to you.
The twist ending of HAL's demise is that even the series 9000 computer kept the truth from the crew. Arthur Clarke himself suggested that this is what ultimately drove HAL insane—the conflict between lying to the crew and having a duty to protect them at all costs. Those two programs were incompatible. (Source)
After making contact with the Jupiter monolith, Bowman is transported across time and space. After witnessing mind-expanding images, the birthing of galaxies and extraterrestrial landscapes, Bowman finds his EVA pod has been transported into a place that appears to be a hotel room decorated in the neoclassical style.
The real movers and shakers of the whole story are the extraterrestrials. All of humanity's machinations—from bone clubs to spaceships, artificial intelligence to top secret information—are part of the unseen alien's manipulation of our species. Their goal was to lead us to Jupiter in an intergalactic scavenger hunt, and they succeeded. Why? That's a harder question to answer.