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It is claimed that there has been sufficient time for life to evolve on Earth from a Last Universal Ancestor into its present state, based on the current theory of natural selection.

Is this true?

What we talk about enough "time" or "speed" of evolution, I am referring to the number of generations and how much percentage of the genetic information is mutated from each generation to another.

EDIT: I rephrased this question in Biology, here.

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cinico
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  • evolution isn't a simply random process, but happens via natural selection. –  May 08 '14 at 17:55
  • Through the Wormhole s4e10 had a [useful analogy](https://www.youtube.com/watch?v=duP7cmfJs0Q#t=14m5s) on the evolutionary process. (Note: video link costs US$1.99) – Brian S May 08 '14 at 18:55
  • Edited to add back the original question's reference to a universal ancestor, which avoids abiogenesis issues. – Larry OBrien May 08 '14 at 19:04
  • @DikranMarsupial It is random in the way that mutations occur randomly leading to new features and, with time, to new species – cinico May 08 '14 at 23:20
  • @Articuno I was not trying to say that random mutation lead to new species on their own. It is because of the random mutations that new features may occur which prevail, or not, through natural selection (I understand this). Of course I am not asking if evolution happened. I see evolution as a fact. I do not assume the **current** theory of natural selection as fact. My question is about the number of generations needed (time) to create enough mutations that lead to the known genetic complexity. – cinico May 08 '14 at 23:32
  • @cinico Ah, then that is a question for [biology.SE]. Here, we just whether notable claims are true or false. If you're wondering about how much time it takes, I give a reference in my answer establishing that it takes 3.5-3.8 billion years to arrive at today's genetic complexity. –  May 08 '14 at 23:33
  • @Articuno I'm sorry then. If so, please close this question. Thanks – cinico May 08 '14 at 23:36
  • @Articuno: I don't see it. "The Earth isn't old enough to support evolution." is one of the more cogent (albeit still wrong!) objects to evolution, and Darwin was one of the first to express it (until the geologists of his time obligingly discovered they had underestimated the age of the Earth). Seems a legitimate question for a skeptic to ask. – Oddthinking May 09 '14 at 01:43
  • @Oddthinking But cinico doesn't want to know "is the Earth old enough to support evolution". He assumes that it is. Cinico wants to know "the number of generations needed (time) to create enough mutations that lead to the known genetic complexity". –  May 09 '14 at 03:47
  • @Articino: Um, I'm not seeing that. Cinico: Is that right? I'm seeing: "I am skeptical the estimated age of the world is large enough. If it isn't, either something is wrong with the Theory of Evolution (e.g. hand of God) or something is wrong with the estimated beginning of life (perhaps further back, perhaps further back AND extraterrestrial, perhaps the Earth is older, etc.)" – Oddthinking May 09 '14 at 05:27
  • @Odd he said it in this comment: http://skeptics.stackexchange.com/questions/20545/does-the-time-for-evolution-make-sense#comment79562_20545 –  May 09 '14 at 06:41
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    @Articuno No hand of God, of aliens or anything... Just trying to check if with the known mechanisms of the current theory of evolution are "fast" enough to justify the evolution in the 3.5 million years, or so. – cinico May 09 '14 at 09:14
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    Relevant: http://arstechnica.com/science/2014/05/polar-bear-evolved-to-survive-being-a-heart-attack-waiting-to-happen/ – Bobson May 12 '14 at 11:38

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I have been unable to find papers that make an estimate of the total amount of time required for the complete evolution from the LUA.

However, I can cite a couple of important papers which show that some of the more complicated steps can be achieved in timescales that are relatively short.

The 1994 paper, (A Pessimistic Estimate of the Time Required for an Eye to Evolve* looks at an area which has been commonly cited as one of the biggest challenges to Evolution - the evolution of the eye. (Ironically, Darwin himself was one of the first people to raise this issue, and one of the first to propose an answer.)

They theoretically estimate how many generations would be required for an eye to evolve - not from an LUA, but from a patch of skin that is light-sensitive.

They conclude

Even with a consistently pessimistic approach the time required becomes amazingly short: only a few hundred thousand years.

Rates of Evolution on the Time Scale of Evolutionary Process looks at the amount of evolutionary progress we have seen compared to the amount that might be possible, and concludes it is much less than it has had time for.

The evolutionary process is dynamic but operates within relatively narrow morphological constraints compared to the time available for change.

That means, even though things change, they don't change as much as they could in the time available - which isn't that surprising.

In particular, the author looks at mammals, starting in the Cenozoic (aka the Age of Mammals, 65 million years ago), and concludes the variation found is four orders of magnitude less (i.e. one ten-thousandth) than the time-scale permitted. Evolution is not constrained by time as much as it is constrained by form.

Neither of the papers look at the entire evolution of animals and plants back from our common ancestor, but they illustrate on smaller time-scales, that biological complexity (like the eye) and biological diversity (like all of the mammals on the Earth) can evolve in a small fraction of the time that is available to them.

With this understanding, it becomes more comfortable to extrapolate and see that the 3.6 billion years is rather a long time, even in evolutionary terms.

Oddthinking
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  • Does this suggest it moved too slowly? – JVE999 May 09 '14 at 15:39
  • Additionally, I like to emphasize that selection and evolution is happening across the entire genome simultaneously. So while an eye is evolving, all other aspects of form, feeding, mating, appearance, behavior, etc. will simultaneously evolve if there's selection pressure. When humans create complex objects, we generally work quite sequentially, working on only one or two things at a time. That can lead to false intuitions about evolution. – Larry OBrien May 09 '14 at 17:32
  • There's also all the setbacks from mass extinctions. There's a lot of "lost" evolution that happened. – Bobson May 09 '14 at 17:34
  • Gould's "Wonderful Life" is a classic on the setback/opportunities of mass extinctions: http://www.amazon.com/Wonderful-Life-Burgess-Nature-History/dp/039330700X – Larry OBrien May 09 '14 at 21:02
  • @JVE99: I am not sure what "too slowly" means here. Fast enough to evolve all the mammals since the Cenozoic. Not as fast as it could theoretically could, because natural selection is, in a way, conservative. – Oddthinking May 09 '14 at 22:37
  • @Oddthinking [Here's an interesting source I found on the topic of evolutionary rates.](http://www.cs.unc.edu/~plaisted/ce/rates.html) This, [this](http://www-personal.umich.edu/~gingeric/PDGrates/Rates.htm), and [this](http://mbe.oxfordjournals.org/content/15/12/1647.full.pdf) suggest two things. The first being, that the supposed rate of evolution is far greater than what is being observed and the second that the findings are inconclusive (the latter being deduced as a result of conflicting studies and calculations not correlating with fossil records). – JVE999 May 09 '14 at 23:25