Evolving Reproduction

Sorry this post is a day late. Administrative stuff has been occupying a lot of my spare time. Hopefully I’ll have a few surprises for you guys in time for the release… [ominous smile]

It’s been a while since I did an evolution/misinformation post. Better get onto that…

This claim probably qualifies as picking the low hanging fruit, but I’ve heard it enough times recently to finally lose my cool and deal with it. Those who use it prominently, evangelists like Ray Comfort and Eric Hovind, are surprisingly popular despite being some of the least intimidating intellectuals amongst the anti-evolutionist movement, so I feel the need express my awareness that this is kind of like picking on the special needs kid at school. I’ll will make an attempt to increase the local level of intellectualism somewhat by dealing with the fundamental disbelief that motivates this claim, but quite frankly, it seems likely I’ll descend into the incoherent noises of someone suffering first degree WTF.

The claim, to quote the aforementioned Mr Comfort, goes something like this:

“For example, evolution has no explanation as to why and how around 1.4 million species of animals evolved as male and female. No one even goes near explaining how and why each species managed to reproduce (during the millions of years the female was supposedly evolving to maturity) without the right reproductive machinery.” – Ray Comfort

The ignorance required to even make this claim is breathtaking. I get phantom keyboard pains in my forehead just thinking about it. Where to even start?

I suppose the first point to make here is fairly blatantly obvious to anyone who didn’t fall onto their head from the top of a ten story building: the theory predicts that sexual selection evolved once in the common ancestor of those “1.4 million species of animals”. I don’t know how Ray Comfort got to the end of the sentence without realising that this is obviously what the theory must predict, but he has somehow managed that weirdly impressive feat many times since: for several years he frequently made this bizarre argument, hundreds of times over. As far as I know Comfort himself finally seems to have stopped using the argument, but his followers most certainly have not.

The claim, despite being the equivalent of a lobotomised guppy in a swimming pool full of sharks, does have a more interesting basis: general disbelief in the evolution of sexual reproduction. Explaining the origins of dedicated sexual reproduction is a tricky one with few concrete answers, so seeing creationists asking gotcha questions about it online is not uncommon.

The first point is that, as is often the case, we can see a continuum of creatures in the ecosystem already. Plenty of asexual and hermaphroditic organisms exist, and there are a variety of creatures that fall somewhere in between. Even amongst our own species gender is hardly a binary male/female trait, and the animal kingdom makes the even the most varied among us look positively mundane. It’s not that hard to draw a line from the asexual to the sexual organisms once you gather up enough dots.

For sexual reproduction to evolve, it needs two things: a viable evolutionary pathway via multiple, progressive mutations (similar to the metaphorical line I wrote about above), and a benefit to following this pathway.

The benefit to sexual reproduction isn’t immediately apparent. Sexual creatures as individuals don’t survive any better than their asexual cousins: indeed, the necessity of finding a mate is quite a harsh impact on an individual’s ability to reproduce. But evolution isn’t about individuals: it’s about populations, and genes. A lot of people think of evolution in simple ‘faster leopard catches more food, faster leopard survives’ terms, when it often doesn’t work like that.

The benefit to sexual reproduction (well, okay, one of several) isn’t that the creature that mates survives, it’s that the population of creatures that mate can take advantage of beneficial mutations more efficiently than the populations that don’t. Amongst asexual creatures, every creature is in direct competition. In order for it’s genes to survive in the long term, it isn’t enough for creature A to survive and reproduce: creature A’s descendants have to survive and reproduce and continue to survive and reproduce, out-competing and avoiding being out-competed by the descendants of creatures B and C.

Assuming creature A’s lineage out-competes lineage B and C, any beneficial mutations amongst B and C will be lost.

Sexual reproduction introduces an entirely new dynamic: co-operation, rather than competition. Creature A’s lineage doesn’t have to out-compete B and C’s: instead they interbreed, merging their three lineages into one. This means that the beneficial mutations of all three creatures can make it into the descendant population. This co-operation is a surprisingly powerful benefit: so powerful that it prompted the development of a requirement to breed prior to reproducing.

The evolutionary pressure in favour of sexual selection, then, is that it increases the efficiency of evolution itself. Populations that evolve faster and more efficiently will, over time, be able to out-compete slower populations.

This is a large advantage to macroscopic creatures, for which the cost of reproduction is high. Microscopic creatures like bacteria and viruses see less benefit from this: they can easily compensate for the lack of efficiency by cranking out ridiculous numbers of offspring at a rapid pace.

All of this is fairly theoretical and abstract, but one of the things I’ve been very happy to see is that it is replicated in at least some form in Species. Individual species usually do become more amorous over time, without me ever having had to implement any direct advantage to mating.

My hope is that tools in future versions of the game will help us dig down even further, to establish exactly why this is the case, by (for example) comparing the most successful half of the population to the less successful half, and highlighting the largest changes.

Another hope for future versions of the game is to improve the evolution of sex. Currently, all creatures can reproduce sexually, and their ‘amorousness’ behavioural modifier increases the chance they’ll mate upon encountering another of their kind. When they mate, both creatures take a copy of the others genetic code. Whenever they subsequently reproduce, they blend their own genetic code randomly with that of their mate to produce the offspring.

So they can and do evolve from asexual (never mates) to sexual (mates whenever given the chance), but it’s a very simple spectrum, and even the most sexual creatures are still capable of reproducing without mating. Adding additional complexity in this system, like possible birthing restrictions and maybe even gender differentiation, would be worthwhile.

As a friend said recently, the feature creep potential for this game is practically infinite. Good thing I’m not trying to implement everything before release!

Cheers!
Qu

Hmm… I had actually meant to do a thought experiment fr this post: try to work out the most likely evolutionary pathway from basic splitting to gender differentiation. Oh well, some other time I guess.

Here’s something we found while Googling around for the relevant Ray Comfort quote”: “Darwin theorized that mankind (both male and female) evolved alongside each other over millions of years, both reproducing after their own kind before the ability to physically have sex evolved. They did this through “asexuality” (“without sexual desire or activity or lacking any apparent sex or sex organs”). Each of them split in half (“Asexual organisms reproduce by fission (splitting in half).” – Ray Comfort.

The Banana Man, ladies and gentlemen. Accept no subtitute.

Advertisements

, , , , , ,

  1. Leave a comment

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: