Douglas Adams stated in The Hitch-hiker's Guide to the Galaxy that 42 was the answer to life, the universe, and everything, whilst Sheldon Cooper indicated 73 as being significant. They are both a long way out, 3 is of course the magic number but I will discuss that another time. The three simple questions, who are we, what are we, and where did we come from. There are of course many theories but here are some facts......
The Universe, I'm sure we will all agree, is pretty big. We can only guess how many Sun-like stars are out there. This tells me two things.
- There is no creator with whom we can interact. If a creator did indeed instigate the Big Bang he/she/it would have to do so from outside the Universe. Scale would preclude communication between such a creator and ourselves.
- We are not the only intelligent* life in the Universe. Probability alone makes it almost certain there will be hominids similar, to us, inhabiting planets / moons in orbit around similar stars.
*I'm not sure we can consider ourselves 'intelligent' as a species, we've all but ruined this planet.
Stephen Hawkins has it right concerning SETI, finding intelligent life could well be our demise. Look at the facts. We multiply at an alarming rate and are aggressive, any technology we find is turned into weaponry. In E.T. shoes I would kill humans before they spread and infest another planet. We truly are vermin (as a collective).
There is a lot of conjecture surrounding so called 'Goldilocks' planets. This is complete nonsense. Most iron-cored planets will be Goldilocks planets in their life time. Let's take our solar system as an example, on the premise that if it happened here it is sure to have happened elsewhere. The planets formed from the left-over debris in the formation of our Sun. The lighter gaseous materials were flung out further than the heavier elements and formed the gas giants.
The limit for the heavier materials is the Asteroid Belt, although a lot would have been dragged into the gravitational influence of the gas planets. So get rid of the gas planets and for good measure Mercury. We are left with Mars, Earth, and Venus, and these are our Goldilocks planets.
Mars being furthest from the Sun cooled first. At some point in time Mars was teaming with life in an atmosphere almost identical to our own. It had long since cooled from an existence as we see on Venus today, but did it have intelligent life, and what caused its demise? My feeling is the demise was caused by constant bombardment from the Asteroid Belt, but a super-volcano is another possibility. Mars is home to the largest known volcano in our solar system, Olympus Mons.
Three times higher than Everest on a planet much smaller than Earth, the damage to the atmosphere would be devastating. The volcanic material chucked out by such a monster would be the end of any life on Mars. This is likely the reason the atmosphere is 100 times thinner than our own, and is more than 97% carbon dioxide. In time when Venus and / or the Sun cools it will become a planet like ours. Water will form and life will begin again.
Life on Mars did exist if only in a very basic form. It could have been brought to Earth on debris flung from Mars during an impact. It doesn't really matter, life was sure to evolve wherever there is water. I have guesstimated it takes anywhere between 700 million and 1.5 billion years for hominids to evolve - depending on the circumstances. This then begs the question - in my mind - how come it took so long for us to evolve, and where do the dinosaurs fit in?
The evolutionary process will often be interrupted, or sent down another path, When an ELE (extinction level event) occurs the dominant life-forms will be the biggest casualties. Say for instance the ELE wiped out dominant mammalian life, leaving just small reptiles and a few species of small mammal. The reptiles would naturally become dominant and small mammals a tasty snack, likely hunted to extinction. There are many and varied possibilities with a plethora of hypotheses. I would call it short-sighted to rule out the possibility of hominids roaming this planet before us, before the dinosaurs.
Why haven't we found evidence? This too can be explained in a number of ways. Perhaps they lived natural life styles and didn't leave any evidence, or they may only have evolved to basic primates. There is also the question of fossils (the lack of), I would be very surprised if there was evidence in fossils. All the fossils prior to 428 million years ago* are sea creatures indicating the land was once beneath the sea. So how much of former landmass lies at the bottom of the oceans.
*the oldest fossil of a land creature is from 428m years ago and is of a millipede found in Scotland
When you take a look at a hypothesised world map from 500 million years ago, there is naturally a very different look. The tectonic plate movement re-cycles much of the landmass, the Himalayas are only 50 million years old.
Did we come from Mars? It can't be ruled out but I would say it is unlikely. Did we come from Earth? I believe we did, but our origins may well be from a time long before the dinosaurs!