The aliens originally took the approach of placing large cats like tigers, lions, jaguars, etc. Here to kill off our ancestors to slow us down before we even had a chance to start. This back fired on them, though it did kill off a lot of them that had intelligence however not the muscle needed to actually use the weapons that they were trying to invent. They did not kill all of them and we managed to push forward.

Then the aliens left for a fairly long time however thinking that the original large cats would wipe all of us out, and just left us for dead. Later while checking in on us they noticed that a large tower was being built and saw that we were advancing quicker than they were comfortable with, so they destroyed that building made us speak different languages and sent us all in different directions. Once again they threw a monkey wrench in to our species development but this time they blamed it on "God".

When the aliens sent us to each of these different areas they stripped us of our tools. Problem is they forgot to wipe our memories of how to make those tools and start over again. This language change and being divided set us back a good deal however it did not make recovery impossible and the separate civilizations were able to get back to where they were technology wise at different speeds.Those poor primitive tribes of today have barely fully recovered. However this time they visited a few times to check on us and saw that we recovered a little yet were still struggling, not to mention realizing that the language barrier that they created was working better than they ever imagined. Satisfied with their work their visits became increasingly far apart as their confidence grew.

Later on one day while passing through the area the aliens decided to take a short detour over to earth just to see what these pesky little humans were up to. They noticed an advanced civilization had created huge things that we have come to know as pyramids. This really caught their eye, especially since with the massive size of them and the fact that they had no idea how the civilization could make such things with the relatively primitive tools that they had, not to mention in the middle of an area as inhospitable as a desert. They came to the realization that the large cats failed their mission and that they needed a new approach.

At this point they decided the only way to find out how all of this happened was by placing spies. This is when they left us with a smaller more intelligent form of cat to watch, learn, and hopefully even do somethings to sabotage the humans technological growth. They gave them specific instructions, to act cute, go in to the areas that the humans lived in and allow them to think that they had domesticated them like they had domesticated dogs long ago. They equipped them with telepathy abilities so that they could both communicate the reports to the aliens, which try to be invisible to us however with some of us they fail and appear to be ghosts.

The "house cats" soon discovered that these telepathy abilities (with the aid of toxoplasma gondii), could be used as a form of mind control to make the humans believe that they were cute and worth keeping. As opposed to just being pompous, egotistical, picky, things that that did nothing more than eat, sleep, completely ignore us, and refuse to be trained, while really not helping us at all. Not to mention using sunbeams that we now know can be used for solar power.

As they got used to this royal treatment while spying on the people that pulled off the miracle of those pyramids. They reported that these humans had managed to do it by a use of math and science that was amazingly advanced despite everything the aliens has tried to do to stunt this relatively young species technological advancement, and told them that it was all done in the name of their religion which the aliens knew from their own experience to be a big step in the development of culture and civilization. That with the reports of large libraries of knowledge scared the aliens.

They knew this was bad, they realized that a good amount of these humans were learning to sense their presence even though they were invisible and were even calling them spirits which they had incorporated in to their religion. However they saw that the humans noticed that when a cat was around these "spirits" left very quickly, and generally didn't leave until a cat was brought in to the area. The aliens told the cat spies to use this to their advantage to make these humans believe that they were protecting them from the spirits.

This worked beautifully all skepticism that the humans ever had of the cats went right out the window, They believed them to be guardians sent to them by the gods (haha close but not close enough to the truth) the most advanced race of the time had now started making statues to worship these spies, even went as far as to make a unimaginably huge monument known as the sphinx in honor of these well disguised spies. Which they believed to now have the greatest guardian power of all cats. When the cats displayed their love for it, the Egyptians believed that it had just received their blessing.

These people truly loving the cats however having way to much of a "good" thing becomes a bad thing, started selling them to other people in other areas through barter and trade. This was great for them because they were making wealth off of these guardians, and worked even better for the aliens because now their spies were being spread across the planet, very easily infiltrating the planet as technology and the ability to travel advanced.

Jumping along to modern day, cats have now gotten in to every continent and I think every country. Chinese apparently are eating them while keeping others as "pets" but hey we all know every war has its casualties. Also we know that they see dogs (the humans long time, perfectly loyal, completely loving, never will go out of style companion) as their natural enemy. However they manage to get along when they see that they are both in the humans house to stay and neither is going any where.

To this day they continue to attempt to find out everything that we know, and stop us from learning more. When you are on the computer they try to stop you from using it while they are clearly reading what is said on the monitor themselves. When you read a book they read it as well. While you are watching tv if it sounds to them like you might be learning something they either watch it as well or try to distract you, either by climbing in your lap or laying on top of the television possibly with an attempt to cover part of the screen. The aliens maintain their cover of being ghosts, cats to a degree maintain their attempts to act like they are protecting us from them.