New research posits that Jupiter was a bit of a drunk bull in a bowling alley set in the middle of a china shop before it settled into its current orbit. During that youthful period it indiscreetly powdered a smaller group of nascent planets, clearing the way for the current configuration: Mercury, Venus, Earth, Mars.
Many observed solar systems have gigantic inner planets, perhaps earth-like but with much greater gravity and less variety. Jupiter's wreckless careening, theoretically, sent some of the ones in our sysem crashing into the sun and the dusty remnants coalesced into our smaller, tidier planets.
What this means in practical terms is that when we encounter intelligent alien life someday they are likely to be bigger yet crushed down by the heavier gravity of their homeworlds, creating, by our earthian standards, a somewhat "squashed" or flattened appearance.
We here attempted an artist's rendering of these creatures, who would easily outnumber us, based on current estimates of the number of gigantic planets out there in the average solar systems:
Bear in mind, however, that part of the reason these solar systems with larger planets are estimated to far outnumber our system is because the current level of our telescopes and space exploration only allows us to see the big ones right now; if there are other systems with a planetary system similar to ours, we would have difficulty detecting it from here, unless it were right around the corner.