Questions about Life

14


Discussion by: bob_e_s

 Hi all,

I’m pretty new to this site, having found it after being given RD’s wonderful book ‘The Greatest Show on Earth’ for Christmas, which opened my eyes further to the wonder of scientific discovery.

Last night after listening to a recording of RD and Lawrence Krauss in their ‘Something from Nothing’ discussion, and watching Brian Cox’s excellent new programme on the origins of life and evolution, ‘The Wonders of Life’ I went to bed with my mind whirring with questions. I tried to remember some of the more frivolous ones this morning, and thought I’d post them here, not as a means of obtaining firm answers, but as a way to provoke discussion.

I don’t think that many of these have definitive answers yet, but I’m sure there are people who read this site who may have some interesting opinions. Hopefully they will stimulate some discussion, anyway.

1.      
Bearing in mind what we know about the creation
of the universe, is it inevitable that life on earth (and potentially
throughout the universe) is composed as it is (i.e. carbon-based relying on DNA
to self-replicate/reproduce). Or could other forms of life be imagined, based
on the laws of physics of this universe remaining as they are.

2.      
Is it inevitable that intelligent life is
mammalian, and evolved from primates?

3.      
By extension, if intelligent life exists
elsewhere in the universe it should be expected to take a similar form?

4.      
Should we expect that life elsewhere in the
universe is more advanced than us? Is there any reason to think that, apart
from the fact that to make contact with us much greater technological
sophistication would be required.

5.      
What would life on earth be like if the
dinosaurs had not become extinct?

Also, as a cheeky aside which I can’t resist, the above are all examples of questions that religion can offer nothing at all towards an answer, but where science can or one day might.

14 COMMENTS

  1. @OP – I don’t think that many of these have definitive answers yet, but I’m sure there are people who read this site who may have some interesting opinions. Hopefully they will stimulate some discussion, anyway.

    • Bearing in mind what we know about the creation of the universe, is it inevitable that life on earth (and potentially throughout the universe) is composed as it is (i.e. carbon-based relying on DNA to self-replicate/reproduce). Or could other forms of life be imagined, based on the laws of physics of this universe remaining as they are.

    We don’t know if other atoms could form complex molecular links as carbon and water molecules do, but it may be possible. IF life turns out to be common where favourable environments exist, carbon based life forms would look probable.

    • Is it inevitable that intelligent life is mammalian, and evolved from primates?

    No! – There are already other intelligent species on Earth such as whales, dolphins, and some birds.

    • By extension, if intelligent life exists elsewhere in the universe it should be expected to take a similar form?

    The evolution of life on Earth has not simply repeated its self after mass extinctions, so diversity is to be expected. I think some sort of co-ordinated movement, vision, tool-use, and competitive selection, would be needed to evolve intelligence.

    • Should we expect that life elsewhere in the universe is more advanced than us? Is there any reason to think that, apart from the fact that to make contact with us much greater technological sophistication would be required.

    IF – life turns out to be common in the universe, there are other stars and presumably planetary systems, which are much older than Earth and our Sun, so there will have been time for longer evolution of species and cultures.

    • What would life on earth be like if the dinosaurs had not become extinct?

    It would be a bit different but many plants and some animals would probably be quite similar.
    Of course not all dinosaurs became extinct. The flying dinosaurs we call birds, are still with us, – so quite a lot of animals would resemble flightless birds.

    There are examples on isolated islands (Galapagos – Komodo etc.) of forms of reptile evolution.

    1. Life will form in a way based on the chemistry of the environment. It will almost always be the simplest method possible. Even if there were another way to form life on Earth, it won’t happen until the Carbon life is wiped out. There just isn’t any room.

    2. Not at all.

    3. I would say yes. I would define similar form as, “having mobility, sensory organs, a complex world to navigate, the ability to communicate and remember abstract ideas, and the ability to imagine fictional worlds.”

    4. It seems unlikely that we are either the smartest or dumbest creatures in the Universe. We could start receiving signals from a civilization that has only just discovered the technology.

    Imagine if we invented the radio one day and the next day built a huge powerful array to beam a signal out into space, and then war, and politics prevented us from advancing much further for 50 years while the signal made it’s way to our neighbors.

    1. The world might be populated with lizard men riding dinosaurs.
  2. Neil deGrasse Tyson made an interesting point, and I apologize that I have to paraphrase, but it was to the effect that if we are only 1.5% different than our closest primate relatives in terms of genetics, and we can’t really understand them, what are the odds that life from elsewhere in the galaxy would understand us? Could be that they don’t manipulate radio waves like we do (I’m pretty sure the Germans used an alternate means of detection besides radar in WW2, for a recent example), and perhaps we just come off as a lot of noise.

    That being said, there’s a good chance that life elsewhere is more (or less) advanced than we are, because it seems to take so little of a difference; there’s strong scientific evidence to support conscious thinking in other species (even cephalopods, if I remember correctly), but recursive thinking is the unique gift and burden of humanity so far as we know.

  3. There is no such thing as ‘life’! Instead think about a process called ‘living’ which as Cox explained is defined in terms of the 2nd law of thermodynamics. Quick answers to yr questions off the top of my head:

    1: No, it is not inevitable.

    2: Ditto.

    3: Ditto.

    4: No: consider that for billions of years ‘living’ on Earth meant single celled animals.

    5: It would be different but there is no telling how.

  4. Almost certainly carbon based. With the exception of silicon, no other element can form such complex structures. Silicon can’t form strong double bonds like carbon though, placing a few more restrictions – DNA bases wouldn’t be as stable for instance.

    1. Bearing in mind what we know about the creation of the universe, is it inevitable that life on earth (and potentially throughout the universe) is composed as it is (i.e. carbon-based relying on DNA to self-replicate/reproduce). Or could other forms of life be imagined, based on the laws of physics of this universe remaining as they are.

    First we need a definition of life. As it stands, there could be non physical life in the form of signals, patterns, or energy, so long as there were self-replication, function/metabolism, and heredity.

    1. Is it inevitable that intelligent life is mammalian, and evolved from primates?

    No, our intelligence is not due to being mammalian. I suspect highly technological species will have to have some stewardship over fire, as do we and other primates.

    I answer that question very quickly, but I do think it is interesting that there might be some kind of determinism that makes the evolution of life similar wherever it happens. There is just no data to suggest that… for now.

    1. By extension, if intelligent life exists elsewhere in the universe it should be expected to take a similar form?

    Not at all.

    1. Should we expect that life elsewhere in the universe is more advanced than us? Is there any reason to think that, apart from the fact that to make contact with us much greater technological sophistication would be required.

    I don’t see why we would be special. Some planets may be more conducive to technological advancement.

    1. What would life on earth be like if the dinosaurs had not become extinct?

    They didn’t go extinct. They evolved into birds. That’s a long time to go without evolving. I have heard it said that the environmental catastrophe that forced their selection into its current form allowed for mammals to thrive. Our small, furry forms were better suited for survival post-meteorite.

  5. “2. Is it inevitable that intelligent life is mammalian, and evolved from primates?”

    It depends on your stating point. If you go back 10,000,000 years then (perhaps) mammals were the ones to thrice and become intelligent.

    If you go back 2 billion years, then (perhaps) the terms mammal and reptile have no meaning and life might have become very different, being neither reptile or mammal.

    1. That totally depends on how you define “life”.
    2. That totally depends on how you define “intelligent”.
      etc.

    Btw, I’m not kidding. You’ll have to find the right questions first or you’ll get lost in mumbo-jumbo.

  6. I think life elsewhere in the universe is certain in fact i think intelligent life in the milky way is highly likely our being here is proves life can happen, our galaxy is 200,000 light years across thats a flying time of 200,000 years to get to the other side of it if we could travel the speed of light which according to Einstein is impossible. That’s a depressing prospect, while mind blowing at the same time.life elsewhere in the universe will be subject to life forms obeying local rules of its environment. We won’t know what the life forms on the habitable planets looks like until we know about the conditions in the planet.

  7. Bearing in mind what we know about the creation of the universe, is it inevitable that life on earth (and potentially throughout the universe) is composed as it is (i.e. carbon-based relying on DNA to self-replicate/reproduce). Or could other forms of life be imagined, based on the laws of physics of this universe remaining as they are.

    pro: carbon has some interesting properties (it forms bonds with 4 other atoms), it is relatively common (it forms early in a large stars life cycle). Water is interesting in that is polar molecule which means a wide range of things dissolve in it. Something like DNA seems inevitable to be part of life (a very large molecule with a repeated structure that varies slightly). I’d not bet that the same bases and amino acids were inevitable.

    I suspect other substrates might work (silicon, ammonia, H2S)

    Is it inevitable that intelligent life is mammalian, and evolved from primates?

    con: there are lots of smart creatures (birds, cetacans, squid)

    pro: humans are born with very undeveloped brains which requires a very long period of parental care. This helps implant culture.

    I don’t think life on another planet would actually produce humans or even mammals perhaps not even tetrapods (4 limbed)

    By extension, if intelligent life exists elsewhere in the universe it should be expected to take a similar form?

    as above.I don’t think humans are inevitable (sorry Gene Rodenbury!)

    Should we expect that life elsewhere in the universe is more advanced than us? Is there any reason to think that, apart from the fact that to make contact with us much greater technological sophistication would be required.

    our solar system is only 4 billion years old. The universe is 14 billion years old. That’s lots of time for life to develop before us. Another culture could be millions of years ahead of us.

    What would life on earth be like if the dinosaurs had not become extinct?

    well big climate change due to continental movement was on its way so large cold blooded dinosaurs might have been pushed out anyway. To colonise colder areas needs warm blood. But birds and mammals were already around (mammals are nearly as old as the dinosaurs). There might also have been warm blooded dinosaurs. But evolution is inherently unpredictable so we can’t really say. We can be pretty sure the age of the dinosaurs wouldn’t remain the same as it was at the KT event.

    Also, as a cheeky aside which I can’t resist, the above are all examples of questions that religion can offer nothing at all towards an answer, but where science can or one day might.

    religion doesn’t explain anything except maybe a window into human psychology

  8. I have enrolled in the Astrobiology course – looks fascinating. I may come back in 5 weeks with better answers!

    But, as has been stated I think first we need to define ‘life’, and then define ‘intelligent life’ before we can empirically answer these questions. However, for the purpose of this discussion do you think it is sufficient to define intelligent life in the context of ourselves? I.e. Capable of language and abstract thought, complex tool use, and with a high ratio of brain size to body size.

    The reason I asked whether it is inevitable that life is mammalian, is that given much longer evolutionary timespans (an extra 100 million years for reptiles, 200 million for insects and longer still fo arthropods, etc) intelligent life on our planet is mammalian, and the most intelligent species are us and our nearest relatives.

    Does this suggest that evolutionary adaptations made by primates are linked to the development of intelligence, or that we are currently filling this niche? What I’m getting at is in a world where homo was present (or had become extinct?) would life develop from other animal kingdoms to fill the niche?

    I’ll concede there is every possibility there are more developed civilsations out there, and in fact this would be essential if we are to make contact, because we don’t have the technology yet to reach out into the galaxy.

  9. Intriguing questions to be sure. One of my more enjoyable toys is a hydrogen-alpha filter for my little Questar telescope. If you spend enough time viewing the sun in H-alpha you’ll come to think of it as if it were a living organism. Intellectually I realize that the sun is not alive, it’s dead. And yet the sun is unpredictable, it has what appears to be moods. It also has, for lack of a better term, a life cycle; birth, youth middle age, old age and finely death.

    Cepheid variables are really remarkable stars, far more interesting than our own sun, and we know so little about them. But cepheids are scattered throughout the universe. They did not spring from a common ancestor, they formed completely independently from one another shaped only by the laws of physics.

    If something so remarkable as a Cepheid could be common place throughout the universe is it really so farfetched to consider that life that looks and acts like us might also exist elsewhere? Perhaps, just like stars, our extraterrestrial counterparts could spring not from a common ancestor but from natural laws.

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