@xris,
The "panspermia" theory of life on earth being the result of "seeding" from some astronomical occurrence, perhaps a collision or meteor hit, or even the intentional act of an "alien" race, has a respectable following. While some "panspermia theorists" take the idea and run on out to left field, not all fall under the umbrella of "lunatic fringe".
From an anthropological and cultural viewpoint, we cannot deny that modern human behavior and human civilization happened in "leaps", WITHOUT the expected archaeological transition layers, at least none discovered yet after over 100 years of digging.
For example, the "leap of agriculture", going quickly from hunter/gatherers to growing and processing cereal grains, using irrigation and other advanced agricultural techniques, is as puzzling as the later "leap of civilization" or "urban revolution" with high civilization including its architecture and social structure, writing, math, trade routes and records, "the arts and skills of civilization".
To me, the most unexplainable (by known natural processes) of all is those pesky early Bablylonian cuneiform math tablets -- the extant ones dating back to about 2000 BC, but per expert analysis, reflective of older originals. Using their sexagesimal (base-60) system, these tablets contain cubes and squares and their roots, which we've found accurate to approximately seven decimal points, quadratic algebraic equations (which were not rediscovered in our own base-10 system until The Enlightenment), even a table of secant squares. The stagnation and decay in ancient Mesopotamian knowledge apparently began around 2000 to 1800 BC; there was little left to salvage by the time the Greeks arrived.
As "lunatic fringe" as it sounds, I don't see how we can escape at least considering the possibility of some type of sentient NON homo sapiens sapiens affecting our history, perhaps even going back to elementary "seeding" of "life" on this planet. And how about that cambrian explosion?!
As for the nature of this "intervention" or "interference", I haven't the foggiest idea. As long as the archaeology, anthropology and paleontology records are silent, we have no beginning point other than the first recorded history, from ancient Sumeria and Egypt, which doesn't, at least overtly, provide the answers we seek. As a person not prone to speculate from silence, I have no theory.
rebecca