How the 'Great Filter' could explain why we haven't found intelligent aliens

[Jim Franklin]

The geneticists are postulating pinch points based on genetic information and a lot of assumptions.

Having multiple hominid species at the same time still does not rule out a pinch point in the species that eventually dominated. But, there are other hypotheses that argue that the other species did not actually go extinct, but melded into the current population. Nobody actually knows for sure at this point.

But, there are definitely pinch points in evolution. The asteroid strike about 65,000 years ago that killed off the non-avian dinosaurs is an example. Who would have thought that T. Rex would be survived by sparrows? For that matter, who would have thought that the small predecessors of T.Rex in the Jurassic Period would dominate in the later Cretaceous Period?

Point 1 - absolutely, they are under pressure to publish by their grant providers, so they publish a lot of speculation and bunkum.

Point 2 - we are the species now, but we are likely a hydrid species that came about by cross breeding between different, very genetically close, hominid species, the DNA material has been mixed up, and we do not have complete DNA from any hominid species except Homo Neanderthalensis, and that individual only died about 45,000 years ago - they exists for around 450,000 years, they will have evolved over that time, just as we have evolved over the last 300,000+ years we have been around. We know that human populations of today have varying amounts of DNA that matches the Neanderthal DNA, but we also have DNA from at least 2 other species of hominid that has, as yet, not been identified, although one is believed to be the Denisovans.

I think you mean the Meterorite (its only an asteroid in space - meteor in the atmosphere, meteorite once it hits the ground - regardless of size) impact 65 million years ago not 65,000 years ago. The Non-Avian dinosauria were but one group of animals eliminated from the records around the time of the K-T event, over 73% of all species of LIFE was removed within a few thousand year timeframe - they didn't all die on the same day or even the same century, estimates are that the species change took place over a period of between 50,000 and 100,000 years (the latter is the maximum).

The Big Dinosaurs had been in decline for at least 10 million years prior to the K-T event, the fossil records show that there was around a 20% drop in fossil numbers for every ~100,000 year period in the 10 million years leading up to the impact, and many point out that at the same times as this occurred, the Deccan traps was being formed by the formation of a Large Igneous Province (LIP) for, possibly, up to 1 million years before and 1 million years after. Further, 67 million years ago another large volcanic event started, and we do not know how it started, but it was when a mantle plume inmteracted with the mid-ocean fault for the first time - we call it Iceland.

It is highly likely that the demise of the "dinosaurs" was a combination of multiple large impacts in the previous 10 million years coupled with massive volcanic activity that resulted in enormous environmental impacts that they were unable to adapt to, the smaller animals were either underground or able to adapt to the new environment they found themselves in - the rest, as they say, is history.

 

[Unclear Engineer]

Agreed that I missed three zeros, making thousands instead of millions. I have now fixed that in the previous post.

Speciation in hominids seems to have been caused by isolation. When the isolation ended, species were either reabsorbed into a combined population or died out. What to say about the Neanderthals is still debated. There seems to have been more than one contact between Neanderthals and modern humans, with a period of isolation between, during which Neanderthals survived and modern humans either died out in Europe or retreated to warmer environments. Whatever, modern humans now have some Neanderthal DNA that varies among races and locations on Earth, and there are no completely or even mostly Neanderthal descendants currently present anywhere on Earth. Chimps and Bonobos are probably a good example of two very similar social species that have very different cultures, today.

Quibbling about what was happening before the KT boundary, or how the species extinctions unfolded because of it does not negate the point that it resulted in profound changes in the surviving fauna.

We are not immune from such an event, today. From the very unlikely possibility that some extra-solar celestial body could come crashing into Earth with little warning, to the much more probable possibility that climate changes on Earth (natural, human induced, or a combination) will drive our species into globally self-destructive behavior (nuclear war, biological war, etc.), we could see some sort of pinch point in human genetics as well as human society, especially the technological aspects of human society.

Predicting what, when and the results is "above the pay grade" of any human I have met or heard of, so far.

 

[Jim Franklin]

Quibbling about what was happening before the KT boundary, or how the species extinctions unfolded because of it does not negate the point that it resulted in profound changes in the surviving fauna.

In the context of this conversation that is a valid point, but in the wider context it is extremely important, by resolving that a single cosmological event explains the 2nd largest extinction event in Earth history, that has been conclusively proved anyway, may be missing some very important and key information we may need for our very survival - as we have no idea what causes LIPs and when one may next start and run for how long.

Speciation in hominids seems to have been caused by isolation. When the isolation ended, species were either reabsorbed into a combined population or died out. What to say about the Neanderthals is still debated. There seems to have been more than one contact between Neanderthals and modern humans, with a period of isolation between, during which Neanderthals survived and modern humans either died out in Europe or retreated to warmer environments. Whatever, modern humans now have some Neanderthal DNA that varies among races and locations on Earth, and there are no completely or even mostly Neanderthal descendants currently present anywhere on Earth. Chimps and Bonobos are probably a good example of two very similar social species that have very different cultures, today.

Yes and No - we do not understand enough about speciation and how it evolves an organism in the details required to be clear on this. Competition in an environment also results in evolution that creates speciation - the finches of the Galapogos Islands is a clear example of this - and environmental factors that impact one group but not another will also be a driver, they need to necessarilly be isolated. It is highly complex and whilst, on the surface, it may seem clear - we are peering into liquid mud and trying to spot the diamond ring our wife dropped!!

We are not immune from such an event, today. From the very unlikely possibility that some extra-solar celestial body could come crashing into Earth with little warning, to the much more probable possibility that climate changes on Earth (natural, human induced, or a combination) will drive our species into globally self-destructive behavior (nuclear war, biological war, etc.), we could see some sort of pinch point in human genetics as well as human society, especially the technological aspects of human society.

Extra-solar events would be seen years, decades, even millenia in advance depending on what it was, even Oumuamua was discovered years before it entered the inner solar system so one of these is unlikely to sneak up on us. The biggest theats to humans are all natural events, the start of the creation of a new LIP is very real, we do not know what causes them, other than they are clearly linked to Mantle Plumes, and thus likely linked, in some way, to super volcanoes (or at least the cause of them) as we know of three that coincide with global and semi global extinction events, including the biggest extinction level event in Earth History - the Permian-Triassic extinction.

It is likely that we would have fair warning of such an event, with Iceland being the likely culprit as it has already created the largest being the North Atlantic Igneous Province (NAIP) and it implicated in the formation of the Jan Mayan Mantle Plume, the British Igneous Province, the recently discovered (to be confirmed) East Greenland Mantle Plume and the Greenland Igneous Province. Why LIPs are formed is a mystery, but this is the greatest threat to humanity because we know from the past they have truly global conseqences and can last millions of years of continuous outflow.

Pandemics are not going to wipe out humanity, with any desease, it has been shown that an average of 15% of the human population will be naturally immune or they will be asymptomatic, and with 8 Billion people onm the globe, that means around 1.2 Billion would be immune or asymtomatic in the worst case scenario, so that is an unlikely extinction event - despite what Holywood likes to put in films.

War - can war kill us all - simple answer - NO. Even if the madness happened and everyone decided to use Nuclear weapons - that would devastate where they detonated, and certainly kills maybe a few billion, but all of South America, 90% of Mexico and all of central America, the Carribbean, All of Africa, likely all of Malaysia and Indonesia, New Zealand and likely Australia are not on anyones target package list, they are also far enough from the conflict that they would be unscathed by it - just watch the news with either a big smile or an "Oh F" face. This would not be great for humanity, and be an unflinching disaster of bibical proportions, but it would take humans no-where near the brink of extinction or even a bottleneck - we would be about 10 miles from the cliff edge.

Of course, there is the VEI eruptions that can and do occur with little warning as far as we know, they have global reach and a global impact on an unimaginable scale - but their impact is not long lasting, perhaps a decade, and humaity can survive that, yes, infractructure, society and population likely devastated, but again, a few billion dead is still not a bottleneck when you have 8 billion (rising daily) on the planet.

Predicting what, when and the results is "above the pay grade" of any human I have met or heard of, so far.

No-one can "predict", but we can use educated guesses based on knowledge and science.

 

[Dave]

There is of course the other side of the coin. Humankind will thrive in the future due to such traits such as love and compassion. Altruistic tendencies are also a human trait. Take the example of someone drowning: there will always be someone who will jump in, to save them. The trait of always coming up with a new idea. Inventing a new and better way of doing something. The ISS was a collective goal. Arguably our greatest achievement. Humankind always living in space. Let's give ourselves a pat on the back. In a crisis, such as the hole in the ozone we banned CFC's. Showing our ability to pivot and make the right decision. Humankind can endure and forge alliances with other intelligent lifeforms. Let's give ourselves the benefit of the doubt. Yes, we will stumble mightily, but we will persevere.