If you accept the Big Bang theory, the universal laws of physics and the uniformity of chemical processes, then it is reasonable to conclude that evolutionary patterns have been very similar throughout the Universe. There is no scientific reason to doubt the existence of life on millions (if not billions) of other planets and, based on the preceding theory, these life forms likely developed under similar circumstances and evolved in accordance with the universal laws of nature.
On the other hand, the progression of evolution has likely varied tremendously. In many cases, the planet's chemistry may have prevented development beyond the bacterial stage. On other planets, catastrophic events may have caused major setbacks in the evolutionary process, placing them well behind our time frame; or perhaps they are stuck in the Mesozoic, their dinosaurs never succumbing to an asteroid and their mammals never evolving beyond the small, rodent stage. Then again, life surely developed on some planets millions of years before it appeared on Earth and their evolutionary history extends well beyond the "human phase."
At any given stage of life development, there is surely a great deal of diversity throughout the Universe, as there is among birds, fish and other families across our planet; after all, natural selection occurs in response to variations in the environment. But, it seems to me, the evolution, advance and diversification of life has probably been very similar on all life-bearing planets; in some cases, the process is well behind the Earth model while, in others, it is well ahead. Should we be visited by extraterrestrials, they will likely have had humanoid ancestors.
