This is a nice, short summary of some of the explanations for the evolution of homosexuality. It could be shorter; there are really just two classes of explanation, the adaptationist strategy of trying to find a necessary enhancement to fitness, and the correct strategy of recognizing that not all attributes of an individual organism are going to be optimal for that individual’s reproduction, so don’t even try. Love isn’t hardwired by biology, and it can go in all kinds of different directions.

So I’m saying the best answer in the list is #5. I wouldn’t be biased by the fact that the author is quoting me, no, not at all.

What properties should we expect from an evolved system rather than a designed one? Complexity is one, another is surprises. We should see features that baffle us and that don’t make sense from a simply functional and logical standpoint.

That’s also exactly what we see in systems designed by processes of artificial evolution. Adrian Thompson used randomized binary data on Field-Programmable Gate Arrays, followed by selection for FPGAs that could recognize tones input into them. After several thousand generations, he had FPGAs that would discriminate between two tones, or respond to the words “stop” and “go”, by producing 0 or 5 volts. Then came the fun part: trying to figure out how the best performing chip worked:

Dr. Thompson peered inside his perfect offspring to gain insight into its methods, but what he found inside was baffling. The plucky chip was utilizing only thirty-seven of its one hundred logic gates, and most of them were arranged in a curious collection of feedback loops. Five individual logic cells were functionally disconnected from the rest — with no pathways that would allow them to influence the output — yet when the researcher disabled any one of them the chip lost its ability to discriminate the tones. Furthermore, the final program did not work reliably when it was loaded onto other FPGAs of the same type.

That looks a lot like what we see in developmental networks in living organisms — unpredictable results when pieces are “disconnected”, or mutated, lots and lots of odd feedback loops everywhere, and sensitivity to specific conditions (although we also see selection for fidelity from generation to generation, more so than occurred in this exercise, I think). This is exactly what evolution does, producing a functional complexity from random input.

I suppose it’s possible, though, that Michael Behe’s God also tinkers with electronics as a hobby, and applied his ineffably l33t hacks to the chips when Thompson wasn’t looking.

This site has its heart in the right place, but it’s more for theistic evolutionists than my kind—all the bowing and scraping to a creator god leaves me cold (especially since it seems to substitute hearty encouragement and reconciliation over actually discussing the evidence). But if that doesn’t bother you, take a look at The Epic of Evolution. It’ll probably make somebody happy.

I can’t help it—everything I read only makes sense in the light of evolution. Here, for instance, is a story about the popularity of the AK-47 assault rifle:

The AK-47’s popularity is generally attributed to its functional characteristics; ease of operation, robustness to mistreatment and negligible failure rate. The weapon’s weaknesses — it is considerably less accurate, less safe for users, and has a smaller range than equivalently calibrated weapons — are usually overlooked, or considered to be less important than the benefits of its simplicity. But other assault rifles are approximately as simple to manage, yet they have not experienced the soaring popularity of the Kalashnikov.

The AK-47’s ubiquity could alternatively be explained as a result of a path dependent process. Economic historians recognize that an inferior product may persist when a small but early advantage becomes large over time and builds up a legacy that makes switching costly. In the case of the AK-47 that early advantage may be that as a Soviet invention it was not subject to patent and so could be freely copied.

“Path dependency”…hey, that’s another phrase for something I hammer on all the time, that you can only understand the full extent of evolution if you understand the developmental processes underlying it. Many sub-optimal solutions persist because they are part of a developmental framework that isn’t easily changed.

And speaking of suboptimal…there’s Microsoft Word, an ungainly monstrosity if ever there was one. Both Science and Nature have rejected the use of the latest version of MS Word, because it is non-standard and effectively broken.

Because of changes Microsoft has made in its recent Word release that are incompatible with our internal workflow, which was built around previous versions of the software, Science cannot at present accept any files in the new .docx format produced through Microsoft Word 2007, either for initial submission or for revision. Users of this release of Word should convert these files to a format compatible with Word 2003 or Word for Macintosh 2004 (or, for initial submission, to a PDF file) before submitting to Science.

There’s a “path dependency” for you, the ubiquity of Word. Even highly evolved, complex and otherwise necessary pathways can be replaced, though, if more effective alternative pathways acquire greater importance. If the target of selection is the production of a functional end product (a standard readable file in this case) and there are multiple paths for delivering that end product (doc or pdf), the acquisition and spread of a deleterious mutation in the dominant pathway can lead to greater importance of the alternate.

Hmm, I have to go home and start a pot of minestrone soup for dinner…somebody explain that process in evolutionary terms for me.