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Asked by hedleysmitht to Arttu, Ceri, James_M, Monica, Philip on 17 Jun 2011.
Question: with the evolution theory how come there are still gorillas and there have been for hundreds of yrs and have not evolved in that time because they are ihn threat. Also there is a bombardier beetle which fires out two liquids which when they touch it causes an explosion. So according to evolution their would be no bombardier beetle because evolution relies on random mutation and if the beetle was attacked then it would have to fire the liquid at the right time and the right distance away from them either the explosion was too close it would kill the beetle and too far and the predator would kill the beetle. So how come the beetle and gorillas are still alive and does this not disprove the evolution theory?
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James M Monk answered on 16 Jun 2011:
Well I am not a biologist, but we can think about what is going on here. Evolution takes hundreds of thousands of years for even a small change, so we would not expect gorillas to change in a few hundred years. Gorillas are well adapted to the environment in which they live – there are few or no animals that can kill a gorilla (other than a human). The problem that gorillas have is that humans have risen to prominence in a few hundred years, and we are destroying the habitat in which they can live. If the changes to the landscape happened more slowly then gorillas would have a chance to adapt to it and eventually possibly even give rise to a new species. So very fast changes to the environment can cause a species to become extinct.
I don’t know about the bombardier beetle, but it sounds like it has quite a complicated defence mechanism. It is indeed amazing that such complicated biological structures can evolve, but it is not at odds with evolution. Do you know if each of the liquids on their own would serve a useful function? There has also been a very long span of time during which evolution has occurred – the Earth is about 4500000000 years old, and life has been on the planet for most of that time. So that is plenty of time for complicated structures to evolve. The eye has evolved independently several times, for example.
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Arttu Rajantie answered on 17 Jun 2011:
Gorillas and humans share the same ancestors, and they have both evolved since then to adapt to their environments. Gorillas are under threat, and if they do become extinct, that is an example of how evolution by natural selection works. Of course, we should do our best to stop than happening.
I had not heard about the bombardier beetle before, but there are many animals that spit out liquids to deter predators, so it could have evolved from something like that.
Comments
strangeness commented on :
Good point hedleysmitht – assuming neither of those liquids does help the beetle individually, that is an example of what’s called an irreducibly complex system, in that all the parts that create that system must all be there together, or they won’t give any advantage to the species. Another, more complicated example of irreducible complexity is the flagellum (the bit that looks like a tail) that bacteria have – they need more than 40 parts to operate, and don’t help the bacterium if even one part is missing as they cannot work. You might want to look at this diagram on wikipedia: http://en.wikipedia.org/wiki/File:Flagellum_base_diagram_en.svg
Hope that was of some help! 🙂
James_M commented on :
Irreducible complexity is really a bit of a trojan horse to try to smuggle creationism into the science classroom. Lots of things are complicated, but that doesn’t mean they don’t arise naturally, it just means you or I are not experts in biological systems. Even biologists cannot be expected to know the precise origin of every biological structure. There are a few good points about the flagellum in this New Scientist article:
http://www.newscientist.com/article/dn13663-evolution-myths-the-bacterial-flagellum-is-irreducibly-complex.html
strangeness commented on :
In response to your “lots of things are complicated…” statement, it isn’t the complexity in itself that poses the problem to supposed evolution in these cases; what the argument of irreducible complexity highlights is the inability of the mechanism to be created by a series of small, consecutive steps because of the dependency of each part of that mechanism on each other part. The article you linked to seems to concentrate more on the way that there are variations between the flagella of different bacteria – yes, flagella can operate with slight modifications to (not removal of) their various components, but this does not suggest that the flagella could have built up step by step as a flagellum still needs all its various components to be there, and, importantly, in the right position, to allow it to function. I think what worries me most about the article is its concluding statement that “evolution is cleverer than you are” – encouragement to overlook the weak points in a theory just because we can’t understand them is not, in my opinion, science. Sorry this is so long – when I start debating about something, I can get quite carried away 😀
James_M commented on :
There are lots of interesting things that are not understood in science. Maybe the evolution of the flagellum is one of them, but I don’t know because I am not a biologist (maybe the biologists do already know how it evolved, but I don’t because I am not at the cutting edge of biology). The problem that I, as a scientist, have with the suggestion that it was designed is what does that idea tell us? There is no way of testing whether it is true experimentally and it does not make any predictions that we can use. At any point in the history of science you could always note that some phenomenon is not understood (because there is *always* something we don’t understand) and postulate that some other intelligence (we’re really talking about god here) is responsible. Not only does doing that tell you nothing, underlying it is a belief that the Universe is not understandable and does not behave predictably or rationally (if it did behave predictively then we could construct a working scientific theory).
By analogy with my own field: we have a useful theory called QCD from which we can make many (often very precise) predictions about how protons behave. Solving the maths for QCD at all orders for very low energies is, however, currently beyond us and may very well turn out to be impossible. So we have a useful working theory of how protons interact, but we can’t solve it for some of the exact fine details. Do I therefore say “god must be responsible for the details of what is going on inside each and every proton in the Universe, QCD is wrong and I will stop investigating that” or do I say “I have a theory that is known to work, but the maths of the theory is sometimes too difficult for humans to solve at the moment?”
reporter911 commented on :
Did we evolve from gorilla’s?
James_M commented on :
No, we did not evolve from gorillas, but we are quite closely related to them – to the extent that humans and gorillas can both be classified as great apes. We share a common ancestor with them at some point in the past, but that ancestor was neither a human nor a gorilla.