Wait - this can’t be right. All history started 5752 years ago.
I agree. This is scient-centric. How about a timeline for the rest of us, one that deals with well-established biblical facts and not theories?
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Right now is not forever. The way the world exists now is not necessarily how it will be a year from now. I have witnessed many many ways that the internet has changed our lives, and yet at one point there was no internet. Same with electricity, airplanes, fire, the wheel. Humans have not even really been around long enough to witness (and record) extinction-level-events like what killed the dinosaurs, but we will eventually.
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Personally, I’m swayed by the Rare Earth hypothesis, which says that life is probably common throughout the galaxy, but animal life is probably vanishingly rare. One of many arguments can be seen in these charts: prokaryotes seem to have appeared almost as soon as the Earth cooled off, but they didn’t evolve one inch in the next 2-3 billion years. This is illustrated in one timeline (but the numbers are a little different.)
Even something as basic as a cell with a nucleus must be very improbable. It’s possible that just one planet among billions actually nailed the conditions for complex life.
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One of many arguments can be seen in these charts: prokaryotes seem to have appeared almost as soon as the Earth cooled off, but they didn’t evolve one inch in the next 2-3 billion years.
That’s why in the video Seth Shostak explains why we should focus our attention on red dwarf systems.
I agree it’s a bit much to posit a cut-off point for language, much less assign it to the presence of one gene. The more we research animals the more we discover that some of them can communicate amazingly detailed information. I’m pretty sure there’s a continuum there, regardless of the presence of specific genes and it looks like our hominid ancestors had the capacity for some symbolic thought. In Africa they’ve found stone tool “factories” with clear evidence of division of labor. Some of these locations have been in use for so long (a million years or more!) and contain so much material they can almost be called geological layers. Some of the tools they made are too big to be useful, their purpose seems purely symbolic. The stranger thing is that sometimes they carried the raw material, heavy rocks, from places miles away rather than work them near the quarry. So we see tool-making, organization and some weird reason for occasionally spending a lot of time and effort on creating big useless stuff.
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Can you clarify what the difference is, between biologically identical and anatomically identical?
I mean, some people have massive genetic disorders that lead to anatomical differences between them and I, but we’re all obviously the same species. We can mate, unless that happens to be their defect. My understanding was that these humans 200K years ago, we could mate with them, right? OK, maybe their brains worked differently, but they had the same essential wiring in their brains and nervous systems, right?
Again, we know that many factors can actually impact brain anatomy – chemicals, genetic defects, and even environmental stuff, like what happens to you over the course of your life. Massive amounts of abuse can make the physical brain end up working quite differently than massive amount of early childhood love. But I’m not talking about that…
We have no way of knowing how probable, given we’ve only studied one planet in depth. If we find evidence of single cellular life on ancient Mars, or heck, even CURRENT life on Mars, some of the other moons in our solar system – we may suddenly come to think that life is actually quite common.
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I agree. The hypothesis is that life is common - it’s advanced life that’s rare. While we don’t have a lot of planets to study, we do have a lot of years, and it looks like life appeared in a hurry. Combine that with the absurd range of habitats life can endure, and the likelihood of life on Mars looks pretty good. But Dejah Thoris probably isn’t waiting for us up there.
As it implies, when the original post says “anatomically identical” it means that their anatomy was essentially similar to ours. They had the same organs, in the same places, of roughly the same sizes; their muscles and bones worked the same way ours do.
That leaves lots of room to be biologically different, such as with different genetics. As you correctly point out, even environmental influences today can make a big difference to brain development - but the possible results depend on the genetically-determined capabilities of the brain.
Possibly there was an ancestral pre-human 200,000 years ago genetically similar enough to us to mate with, but we wouldn’t necessarily have recognised them as human (as opposed to human-shaped ape) from their communication. Or we might have. (Reproduction is complicated. I mean, theoretically a pet poodle and a rottweiler are the same species. Genetically they can mate… but producing viable offspring can be a whole different story.)
Essentially the problem is that sign language doesn’t leave much of a fossil record. Neither does simple vocabulary. We don’t get any real evidence until we see cave painting, which is a much later stage in language development.
NeueHeimat is completely correct, in that there’s a continuum in which we’re not even sure what “language” means yet. We know our ancestors had communication and tool use going back a million years or so (at least)… but so do a lot of animals. It’s a lot harder to pin down when we began to express complex abstract concepts in speech… but it was probably a lot more recently.
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