TED Conversations

Gerald O'brian

TEDCRED 50+

This conversation is closed.

Evolution: "just a theory". Scientific caution is sometimes confusing.

The fact that our best available theories are still speculations misleads some people to believe that these ideas are not founded. Hence, some people suppose their uneducated opinion is just as bad, or as good, as the mainstream scientific hypothesis.
This trend is probably led by the way science has been taught, i e as a flawless method that offers facts about reality.
And by pre-scientific philosophy, still strong in our modern societies.

Evolution is "just a theory" the way Notre Dame is "just a pile of rocks", isn't it?

Thoughts?

Share:

Showing single comment thread. View the full conversation.

  • thumb
    May 31 2013: Let's clear something up. Theory=/=Imagination. Theories are based on evidence. Just like string theory, evolution IS based on properties of the world, but it cannot be tested -since we don't have a time machine to lead us to the birth of life. The scientific process goes like this; theory=>experiment=>proving the theory true/proving it wrong. Until the theory is tested, we can't say whether it is right or wrong (dare I say that it is in a quantum superposition!) There are extremely many clues FOR evolution and none against it. It is the only rational explanation of life proposed so far. Thus, it seems true.
    • thumb
      May 31 2013: I watched a talk with Stephen Hawking on TV a few months ago. He stated that the reason there is a difference in the known mass of the universe when it is calculated is because the black holes exist in some realities and not others, in some dimensions and not others. He is a leading scientist in all things, sciency, (i dont know a better way to say it, but he is Stephen Hawking) Giraffes, as evolution goes, shouldn't exist. the blood flow to their brains, when the bend down to drink, should kill them. Yes, they have a valve, but the "pre-existing evolutionary missing link" would have died off millions of years ago. Also, no scientist has been able to explain the pre-Cambrian explosion. The point in earth's history when there was a populatoin explosion of land based animals.
      • May 31 2013: Jonathan,

        Nothing impossible about giraffes. They would not have evolved unless valves were possible. For one, vascular valves have existed for eons. Giraffe ones are modified valves, not suddenly appearing ones. There's plenty of fossils that show intermediary anatomies between a less "problematic" neck and the giraffe one. There's enough evidence to show that the giraffe neck, and the necessary modifications for such a neck, evolved from simpler necks.

        The Cambrian Explosion did not produce any land dwelling animals. Not a single one. What was "spectacular" about the Cambrian Explosion was the appearance of many animals, all marine, with enough hard materials that more of them than the pre-existing "softies" could leave fossils behind. Scientists have been able to show that the softies existed before, only they left fewer proportion of fossils, and harder to find, because soft tissue has a much lower probability of leaving any traces behind.
        • thumb
          May 31 2013: apologies for the specification of "land based animals", however, the relative "quickness" of which they appear still baffles scientists
      • May 31 2013: It does not baffle scientists enough to doubt that there was no magic involved. It was a surprise indeed. But then scientists started finding previous fossils, finding evidence of environmental changes strong enough to "inspire" an evolutionary "radiation," and the mystery is not that big any more. Still very interesting though. Also, the process was relatively quick, but still some hundreds of millions of years in the making.
    • May 31 2013: Of course that evolution can be tested. We cannot repeat the whole process, but we can test different hypotheses about how it happened. For example, the idea of random mutations and natural selection has been tested and it works. It has been applied in computer science, in optimization problems, in problems too hard to solve by exhaustive searches. Some circuits have been "designed" by random changes and selection of variants doing at least part of what engineers want their circuits to do. Very often the engineers build these circuits, demonstrate them to work, yet they are unable to explain how these circuits work!

      There's also the field of experimental evolution, where scientists have changed the original activities of proteins to do something else. Yes, by random mutation and selection. Much faster if they allow the most successful mutants to recombine with each other. Contrary to what Jonathan above said, we have witnessed speciation with adaptation when some populations of animals and plants have moved into new environments, like some isolated islands.

      All of those are tests about how it works. But there's also the tests for what we find. We can check fossils, and, as technologies advance, we can add to the tests we can perform, check the anatomies, and so on. Someone thought that, well, whales are mammals, ok, how do we test if they share ancestry with land-dwelling animals? Maybe the embryo in development can offer clues, and it did. It showed legs starting to form, then the legs behind started reabsorbing. But the embryo looked like a land-dwelling animal embryo for a while. Then there's genetic tests ... Anyway, the message is that experiments are possible even for something like evolution. Not being able to repeat the whole thing does not mean it can't be tested.
      • Comment deleted

        • May 31 2013: Not really. They look somewhat like chicken embryos, but for very little time, but they look much more and for much longer like chimp and gorilla embryos. Looking carefully we find that our embryos have much more in common in the process, and development to mammals, for example, than to birds (such as chickens). It is not a stationary comparison that is made. There's much more to it, much more dynamism, than simply saying "they are similar."

          In the whale example what's important is how much more the development process looks like that of land-dwelling mammals than of fish, or amphibians. That it shows legs about to be developed but then they don't develop much further (except in cases of atavisms), just like some humans might develop a tail, when in most human embryos, though the process to develop a tail starts, it stops and the tail bones instead fuse and form a coccyx. This is not mere "similarity." It's way more interesting and convincing than that.
        • Jun 5 2013: Peter,

          I would appreciate if you read and verified carefully what I am saying instead of assuming that I am talking about Haeckel's work. This way you would not introduce unnecessary confusion into the conversation.

          To get you started, please find me the place where I talked about our embryos going through evolutionary stages or anything even slightly similar to recapitulation. If you don't find anything like that, then you would owe me an apology.

          Thanks.
        • thumb
          Jun 5 2013: @ Entropy.
          I wasn't addressing you, but Johnathan.

          :-)
      • thumb
        Jun 5 2013: My apologies, you did not say anything to the effect of Haeckel's work.
        • Jun 6 2013: Thanks Jonathan. You are a true gentleman. People like you make me think that there might be hope for humanity, and inspire me to try and be better myself.
    • thumb
      May 31 2013: The aim is disproval and you have to be objective to come up with the ideas to disprove something. A scientist can prove his/her hypothesis all day long, it is when another scientist disproves a hypothesis that the orignal scientist has to go back to the drawing board.
      • May 31 2013: With this I agree. We try hard to prove hypotheses wrong. But a theory is much bigger and much more important than a hypothesis: theories in science are not the same as hypotheses. Theories, in science, are explanations about some kind of phenomena. The theory of evolution is the set of explanations about the facts of evolution. The theory consists of the best tested ideas about what we think was involved in the processes leading to what we witness in nature.
    • thumb
      Jun 1 2013: You can make predictions about evolution and test them. Check for similarities in DNA, predict the age at which we might find fossils of semi aquatic precursors to whales, then go and find them.

      f we evolved from a common ancestor to chimps. but we have one less chromosome then we should find evidence of a fused chromosome in humans. We look and we find it. Etc etc.

      We preduict the orbit of pluto will take hundreds of years, but we haven't known about pluto for that long, but we can make reasonable predictions and check these versus the evidence. We don't have to observe the entire history of the universe to make reasonable claims based on evidence.

      No one saw the sun and earth form either. So by your way of thinking we can not make any conclusions about how they came about.

      You weren't alive 100 years ago, so you can't make any conclusions about history. We didn't see the Europeans come to America so we can't know how it happened?

Showing single comment thread. View the full conversation.