Directly Meeting With Aliens Horticulture & Zoology UFO Science
I read a couple of very interesting books some years back called Fingerprints of the Gods & Heavens Mirror, both written by Graham Hancock. They changed my views on our history a lot, but only proved to confirm my personal theory that we have been visited by "Aliens" several times in our history, and not necessarily by the same alien race either.
Take a look at the ancient hieroglyphics of the Egyptians, Incas, Aztecs etc. And you will see strange figures represented in each that bare no real resemblance to anything that exists or has been found to exist on our planet. I think it is not unreasonable that the majority of our ancient religions are in fact based on visitations by advanced alien civilizations.
I think it as typical example of our arrogance as a race to presume we are the only "Intelligent" life in the universe. I am very open and in fact convinced that their are other intelligent beings out there, some less advanced than us, others far more advanced. Whether the advanced ones would want to make contact with us given our history and imminent future, other than to teach us not to destroy our planet or each other, and whether we as a race would be willing to listen, is another concept altogether!
Our popular literature & movies have sowed a seed in most peoples brains that an alien contact today would be a bad thing. Just like our views of xenophobia towards those who are not native to our own little plot of the world. Our man-made borders cause us more threat than potentially any alien race could, but our leading "Elite" see the keeping of their land mass as a larger priority than their part in the wider world or solar system, let alone the universe beyond our sun.
In all reality, we will probably end up destroying ourselves and the planet before any hostile alien race gets the chance to! :P.