jeskill

You are assuming that the predator was in it's current form and was eating the prey before the prey evolved protection. That may not necessarily be the case. Sometimes, prey-predator relations co-evolve, kind of like an arm's race. Check out here:

double post.

Taxonomy isn't objective -- there's an underlying philosophy that guides the ranking and naming of taxa. Currently, it's based on geneological relationships, but the original species definitions were based on essentialistic philosophy (unchanging organisms with essential characteristics). To Linnaeus, genera were distinguished by sexual characteristics as well as other "general" traits such as roots and stems, etc. "Species" were simply specific groups of genera that shared specific characteristics. To answer your question, I think that species aren't real entities and they never will be. They are merely groupings that we've defined in order to make scientific research more efficient and effective. I do think that we need a universal concept for species, but I don't think that'll happen in the near future, if at all. There's no really good characteristic that can be used to define all extant and extinct species.

Just out of curiosity, why would your primer have such a large overhang?

Not to be nitpicky or anything, but the article says that "premature babies" can feel pain, not "unborn babies". Given that certain reflexes and functions (such as breathing) do not occur until after birth, I don't think you could say that because a premie feels pain, an unborn baby inside the womb will feel pain. I mean, it's completely possible that they do at that stage, but the article doesn't specifically state this.

I am in complete agreement with Sayonara about the whole "natural" issue. There are a whole myriad of behaviours found in the natural world that we wouldn't consider moral (for example, rape, biting the heads off of males) so we can't really use the laws of the natural world to define morality. My personal opinion is that if the behaviour is not hurting anybody else then it's acceptable. Homosexuality does not hurt heterosexuals or other homosexuals (provided it's consensual, which is the yardstick for all sexual activity in my books). So, it's a perfectly acceptable behaviour in my books. On a slightly related topic, does anyone here know of gay men who also seem to be infatuated with breasts? I think I know one person like this. I wanted to know if the infatuation with breasts occurs often gay men because it might mean that it's less of a sexual behaviour and more of a "I want my mommy" type behaviour. Of course, I could just be completely off my rockers.

If you want to go au naturel, you could just get some deep-sea fish that naturally bioluminesce. Of course, I've no idea how they would survive up here .

wow. You must really like Star Trek . Seriously, I didn't know why or how Data came to be, although I never really thought about it, it's a grand story. I agree with Bluenoise. Ever notice how Star Trek almost always tries to put a moral spin on the story? They should have gotten educational programming status for that.

How do you know most abortions are done out of convenience? Do you have any statistics to back up your statement?

IntraUterine device, they've been around for years, at least since the 70s, if not longer.

So does this mean you don't believe in using the pill or an IUD as contraception?

OK. So I remember reading that one of the causes of ageing is that every time our cells replicate, the DNA gets chopped off at the end, right? So eventually you get into trouble when there's no more poly-A tail and you start chopping off genes and such. What do you think about using an Agrobacterium tumefaciens to insert poly-A tails onto the ends of our DNA?

I think Halucigenia makes a great point that it'd be unlikely that a designer would design parallelisms (ie. traits that look similar and have similar functions but are encoded differently). Think about the cactus/euphorbia example: It would make sense that a designer would use the same genetic code to code for a particular functional trait. Why create two organisms with the exact same trait that's encoded by a completely different DNA sequence? What a waste of energy! The alternative is that the two organisms evolved the same function independently of each other, but each did it in a different way.

Seriously, look at mutation accumulation experiments. Some authors have sequenced parts of the genome before and after the experiment and have found differences in the sequences that can only be attributed to mutations. That's exactly my point. Similarity does not equal homology. Similarity can occur because of convergent evolution. That's why you have to be really careful when you're picking which traits to compare when constructing an evolutionary history. Convergent evolution is not a coincidence -- it occurs when two different organisms evolve in similar habitats. For example, cacti and euphorbia look very similar, but their traits are not homologous. Rather, both plant clades live in harsh desert environments and have adapted similar features to deal with it. If you look at the DNA sequence of genes encoding for convergent traits, the sequences will invariably be completely different. The physical evidence also shows genetic change over time, not just anatomical change. Again, look at mutation accumulation experiments. (Sorry, I'm just really into the coolness of those experiments ). I think you're using the word "extrapolation" incorrectly. Fossils are dated using particular methods and compared with molecular data. I don't think anything is "extrapolated". Re: you're last statement: assuming what happened in the first place?

is logically incorrect. Similar genes are homologous if they are derived from a common ancestor. There are many mechanisms that "cause" homology in DNA sequences: divergent natural selection of different organisms, gene duplication events coupled with mutation accumulation, mutations that change the coding in areas that don't affect function, genetic drift, etc. Likewise, developmental pathways are homologous if they derive from a common ancestor. But it's illogical to say that developmental pathways and similar genes cause homology. Because, as Halucigenia said, they could be similar because of convergent evolution, not because they are homologous. (Convergent traits are "analogous".) Does that make sense? 4) Now, if your question is, why are sequences assumed to be homologous if we don't have direct evidence? That's an interesting question. As stated before, we have physical real-time evidence that all the "mechanisms" of evolution occur - i.e. mutations, migration, natural selection and genetic drift. We also have physical evidence that homology occurs. So, we use the information derived from the physical evidence to make assumptions about how evolution is occuring. For example, we could say that every single type of change that could occur will occur with equal frequency (e.g. point mutations, transversions, transitions etc.) Alternatively, we could say that certain changes occur more frequently than others (e.g. G tends to be mistaken for C more often then A). Then we make a model that fits the assumptions. Then we compare our sequences using that model. I'm not going to get into all the different ways you can model evolutionary history and thereby answer the question, is the trait homologous? If you're interested, I suggest you look up "parsimony" and "maximum-likelihood" to start you off. 5) My last point is that I don't think that anyone ever says, "this tree is proof that these organisms are homologous". What they say is, "this tree shows poor/strong evidence that these organisms are derived from the same ancestor. Moreover, other evidence supports this hypothesis as well, blah blah blah.

If you presented the source, I would be able to read it and better understand what your argument is.