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How far back does evolution go? Is it the time the first cells were created? Or does it go even further back?

TeMPOraL 10y ago
Evolution is a mathematical model - any time you have a replicating configuration of something and a selection pressure, you have evolution.
- visarga 10y ago
  Reading this article I realized that entropy is actively eliminating systems that are not efficient enough at compensating (various non-living chemical structures), making it much more profitable to be one of the systems that can compensate against it (living cells). By overcoming this threshold of entropy, life has gained resiliency. Without the constant destructive effect of entropy, probably there could be no life. Life is both created and destroyed by entropy. On a parallel note, deep learning neural nets rely on randomness in connectivity and order of examples, and sometimes just consumes random numbers and turn them into coherent images or sounds. Entropy/randomness is essential in Reinforcement Learning in the exploration-exploitation dilemma - we need to discover the space of possibilities, and in order to do that we need randomness. Interesting how chaos is tangent with intelligence and life, it is practically creating a space for them.
lawpoop 10y ago
Evolution probably goes back before cells. The first living thing would have to be a self-replicating molecule that uses energy. Different forms of this self-replicating molecule would have different reproductive success. There is a not-unpopular theory that the original form of life on earth was an RNA molecule. RNA is a special molecule, because it can both act as a store of data, and as an enzyme for catalyzing reactions. According to this theory, specialized data storage in the form of DNA evolved later, along with specialized enzymes. Here's a brief overview of the theory that shows how evolution could happen with chains of RNA only: https://www.youtube.com/watch?v=K1xnYFCZ9Yg https://www.youtube.com/watch?v=K1xnYFCZ9Yg Jack Szostak at Harvard has a great series of videos explaining this theory, and also a number of experiments that he and his students have performed. https://www.youtube.com/watch?v=MPzWrv6l9l0 https://www.youtube.com/watch?v=MPzWrv6l9l0
- jaequery 10y ago
  Going further back, are planets and stars forming also part of evolution?
  - castis 10y ago
    I suppose it would depend on the context of the discussion. Evolution can be defined as a gradual development of some thing. This thing does not necessarily have to be defined as life. Since celestial formations develop from a starting state then yeah, they can be considered evolution. In the context of the conversation as it pertains to life, I would imagine that a discussion of evolutionary life would start at the moment a given thing becomes capable of change as it replicates.
  - lawpoop 10y ago
    I would say no, because they are not self-replicating things. A part of the definition of living things is that they reproduce. That reproduction (with variation) is a necessary precursor to evolution. Stars and planets do not reproduce themselves, so they cannot be said to undergo selective evolution.
    - edblarney 10y ago
      "A part of the definition of living things is that they reproduce." Kind of :). We don't really have a definition for life. Imagine an alien ship landed, and out popped these things. They said 'hey what's up' in their language. Cool. And as it turned out - they don't 'die' by natural causes, or reproduce. The pop out of some chemical process. It's a little creative, but physically plausible. We could build 'mechanical wombs' fecundated with ovaries and sperm we farm. Is that reproduction? What if we are able to synthesize sperm and ovaries form scratch? 'Reproduction'? Depends on how you look at it I suppose :) As the Scientist stated in the article, there really isn't a hard boundary between the living and non-living, because when you reduce our definitions down the level of physics, there is no distinction, at least materialist terms. 'Life' is something we observe, and give a name to, but because of the underlying assumption of materialist science (that the Universe is matter/energy bouncing around randomly) - it really doesn't have any real objectivity. You (or we, collectively) just define it to be what you (we) want it to be and that's it.
edblarney 10y ago
"How far back does evolution go?" Evolution is not an entirely objective thing, really, it's the arbitrary theoretical line we draw around our observation of bags of random things bouncing around in a random environment. There is no 'process' per sey, other than somewhat arbitrary means we wish to use to describe it. So the answer is: 'evolution goes back as far as you want it to' - depending on how you chose to define it :)
- xorxornop 10y ago
  Yup, it all depends on which level of abstraction you choose to operate in. I could describe throwing a ball to you into terms of how the quantum wavefunction evolves over time to produce the end state from the start state, and it would be a perfectly fine description, but for the sorts of things we do, usually a Newtonian physics level of description will do because we're generally concerned with coarse level details, not the momenta of each individual atom involved.

Evolution is a mathematical model - any time you have a replicating configuration of something and a selection pressure, you have evolution.

visarga 10y ago
Reading this article I realized that entropy is actively eliminating systems that are not efficient enough at compensating (various non-living chemical structures), making it much more profitable to be one of the systems that can compensate against it (living cells). By overcoming this threshold of entropy, life has gained resiliency. Without the constant destructive effect of entropy, probably there could be no life. Life is both created and destroyed by entropy. On a parallel note, deep learning neural nets rely on randomness in connectivity and order of examples, and sometimes just consumes random numbers and turn them into coherent images or sounds. Entropy/randomness is essential in Reinforcement Learning in the exploration-exploitation dilemma - we need to discover the space of possibilities, and in order to do that we need randomness. Interesting how chaos is tangent with intelligence and life, it is practically creating a space for them.

lawpoop 10y ago

Evolution probably goes back before cells. The first living thing would have to be a self-replicating molecule that uses energy. Different forms of this self-replicating molecule would have different reproductive success. There is a not-unpopular theory that the original form of life on earth was an RNA molecule. RNA is a special molecule, because it can both act as a store of data, and as an enzyme for catalyzing reactions. According to this theory, specialized data storage in the form of DNA evolved later, along with specialized enzymes. Here's a brief overview of the theory that shows how evolution could happen with chains of RNA only: https://www.youtube.com/watch?v=K1xnYFCZ9Yg https://www.youtube.com/watch?v=K1xnYFCZ9Yg Jack Szostak at Harvard has a great series of videos explaining this theory, and also a number of experiments that he and his students have performed. https://www.youtube.com/watch?v=MPzWrv6l9l0 https://www.youtube.com/watch?v=MPzWrv6l9l0

jaequery 10y ago
Going further back, are planets and stars forming also part of evolution?
- castis 10y ago
  I suppose it would depend on the context of the discussion. Evolution can be defined as a gradual development of some thing. This thing does not necessarily have to be defined as life. Since celestial formations develop from a starting state then yeah, they can be considered evolution. In the context of the conversation as it pertains to life, I would imagine that a discussion of evolutionary life would start at the moment a given thing becomes capable of change as it replicates.
- lawpoop 10y ago
  I would say no, because they are not self-replicating things. A part of the definition of living things is that they reproduce. That reproduction (with variation) is a necessary precursor to evolution. Stars and planets do not reproduce themselves, so they cannot be said to undergo selective evolution.
  - edblarney 10y ago
    "A part of the definition of living things is that they reproduce." Kind of :). We don't really have a definition for life. Imagine an alien ship landed, and out popped these things. They said 'hey what's up' in their language. Cool. And as it turned out - they don't 'die' by natural causes, or reproduce. The pop out of some chemical process. It's a little creative, but physically plausible. We could build 'mechanical wombs' fecundated with ovaries and sperm we farm. Is that reproduction? What if we are able to synthesize sperm and ovaries form scratch? 'Reproduction'? Depends on how you look at it I suppose :) As the Scientist stated in the article, there really isn't a hard boundary between the living and non-living, because when you reduce our definitions down the level of physics, there is no distinction, at least materialist terms. 'Life' is something we observe, and give a name to, but because of the underlying assumption of materialist science (that the Universe is matter/energy bouncing around randomly) - it really doesn't have any real objectivity. You (or we, collectively) just define it to be what you (we) want it to be and that's it.

edblarney 10y ago

"How far back does evolution go?" Evolution is not an entirely objective thing, really, it's the arbitrary theoretical line we draw around our observation of bags of random things bouncing around in a random environment. There is no 'process' per sey, other than somewhat arbitrary means we wish to use to describe it. So the answer is: 'evolution goes back as far as you want it to' - depending on how you chose to define it :)

xorxornop 10y ago
Yup, it all depends on which level of abstraction you choose to operate in. I could describe throwing a ball to you into terms of how the quantum wavefunction evolves over time to produce the end state from the start state, and it would be a perfectly fine description, but for the sorts of things we do, usually a Newtonian physics level of description will do because we're generally concerned with coarse level details, not the momenta of each individual atom involved.