Ultimately, we actually all belong to only one tribe, to Earthlings.
Life has evolved to thrive in environments that are extreme only by our limited human standards: in the boiling battery acid of Yellowstone hot springs, in the cracks of permanent ice sheets, in the cooling waters of nuclear reactors, miles beneath the Earth's crust, in pure salt crystals, and inside the rocks of the dry valleys of Antarctica.
We are made out of stardust. The iron in the hemoglobin molecules in the blood in your right hand came from a star that blew up 8 billion years ago. The iron in your left hand came from another star.
I can actually build my equipment at the back end of the telescope such that it takes the data from all of the separate antennas and adds the signal together with different time delays and different phase shifts - it's as if I were picking out up to eight individual pixels in this large field of view.
We misuse language and talk about the 'ascent' of man. We understand the scientific basis for the interrelatedness of life, but our ego hasn't caught up yet.
We, all of us, are what happens when a primordial mixture of hydrogen and helium evolves for so long that it begins to ask where it came from.
Earlier generations of stars in the galaxy could well have had planets. But really, there was only hydrogen and helium to work with, so they'd all be gas giants and not small, rocky planets.
The existence of life beyond Earth is an ancient human concern. Over the years, however, attempts to understand humanity's place in the cosmos through science often got hijacked by wishful thinking or fabricated tales.
We don't know how to identify intelligence over interstellar distances, so what we do instead is use technology for a proxy.
Our television transmitters leak out from the Earth. And actually, there's a sphere surrounding the Earth from the earliest television signals, maybe 70 years ago, that's going out one light year per year. But it's really weak.
We are the laws of chemistry and physics as they have played out here on Earth, and we are now learning that planets are as common as stars. Most stars, as it turns out now, will have planets.
As I was leaving graduate school in 1974, I was recruited to join a fledgling SETI project at the Hat Creek Observatory in California, mainly because I knew how to program an ancient PDP8/S computer that had been donated to the project.