“Most promising signs yet” of alien life on a planet beyond our Solar System

Firstly that is completely badass science. The idea that you can use observations to detect the chemical composition of an exoplanet millions of kilometres away is an absolute triumph of the work of thousands of people over hundreds of years. Really amazing and deeply humbling to me.

Secondly, my prior was always that life existed outside of earth. It just seems so unlikely that we are somehow that special. If life developed here I always felt it overwhelmingly likely that it developed elsewhere too given how incredibly unfathomably vast the universe is.

If life is very common in the universe, then that is probably bad news for us. It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now. And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. Suggesting that our demise too, will come before too long.

If, on the other hand, life is relatively rare, or we're the sole example, our future can't be statistically estimated that way.

It is quite plausible that life is abundant, but sentience is not. If we take Earth, it formed 4.5 billions years ago, conditions became suitable to support life like 4B years ago and first known signs of life are dated 3.7B years ago.

Now, in just .5B years Earth would likely become uninhabitable due to Sun becoming a red giant. In other words, on Earth life spent 90% of its total available time before sentience emerged. So on one side life is constrained simply by time, and on the other, sentience might not be necessary for organisms to thrive: crocodiles are doing just fine without one for hundreds of millions of years. To think of it, it is only needed for those who can't adapt to the environment without it, so humans really might be very special, indeed.

This is now much less plausible. Intelligence, like eyesight, is believed to be a result of convergent evolution[0].

[0] https://www.quantamagazine.org/intelligence-evolved-at-least...

Being intelligent doesn't necessarily lead to runaway technological development. Dolphins are smart but they're never going to invent radios to broadcast their existence to other star systems. They're stuck in the water and don't have thumbs. And even orangutans, who have thumbs and live on land, don't seem tracked for technology even if humans weren't around; their ecological niche is small even if we assumed humans weren't wrecking their environment, and they seem comfortable and steady in it.

We don't even need to look at other species.

Humans have been just as smart as you and me, maybe even smarter according to cranial measurements, without inventing anything that significantly changed their way of life.

There could be loads of planets with prehistoric humans, having a fine time hunting with bows and picking fruit.

I think by the time we get to modern humans it would only be a matter of time for technology to develop to something like the current stage. The main evidence I can think of is the independent development of agriculture in about 4-5 regions, and the independent development of large complex civilizations in the Americas and Eurasia.

Humans are cultural learners, so this allowed cumulative cultural evolution from at least as far back as the transition from Olowan to Acheulean stone technologies with Homo erectus ~2-3 million years ago. By the time we get to Homo sapiens and Neanderthal this capacity for cultural learning seems much increased. Some paleoarchaeologists (e.g. Dietrich Stout) argue that technological development has been exponential as far back as H. erectus, just that the early stages of the exponential curve look flat for a long time.