Evolution

Evolution is in the news a lot these days. Many people don't believe in it, which is OK if they at least understood what they claimed had never occured. For such a fundamental theory in biology, it is greatly misunderstood.

Being just a theory is fine too. That just means it is a model which can be refined, improved or even superceded if enough evidence comes to light. Just because it isn't a fact or a law doesn't mean it isn't the best explanation we have for why we see such a variety of creatures in the world today, and fossil evidence of others.

Evolution simply means things can change not just because of the will of humans (livestock breeding) or perhaps the will of a god (what intelligent design proponents insist) but on their own as a response to outside influences.

Many say that because all simple life forms haven't evolved, evolution can't have occured but this is just plain wrong. There are more bacteria, algae and insects than all vertebrates. In sheer numbers and biomass there are orders of magnitude more of them than those of us with backbones. If being a vertebrate is so great, why haven't they all evolved? And why when a species breaks off from another don't all the original ones die out? Isn't the new species better?

Evolution comes about because of competition. It turns out that being a bacteria or algae or an insect is a pretty successful life. That's why there are so many still here today. So why are there other life forms? Why bother? Because some bacteria, algae or other simple life forms became a little different than their neighbors and the only way for that difference in genetic code or whatever it has to store its 'plan' is for it to outcompete at least some of its neighbors. If the difference is only worse then it will need to adapt to an environment NOT inhabited by something else.

Cells alone had to do everything while cells together could divide up the work. This is great sometimes, but not as great at other times. Cells not gathering food still need to eat. If food is not abundant then they are a drain on a multicelled organism when they would merely be competition in a single celled world. After a while, the size of a multicelled animal became large enough that communication was a problem and nerves were necessary; those that developed them were quicker to react and did so in unison but for creatures in abundant food supplies it was probably enough to bumble around every which way and nerves would just take energy and food. Eventually this nervous system became specialized into a single large nerve bundle, the notochord because it was more efficient than an amorphous network. Once you have such an important bundle, it helps if you can protect it with cartelidge or bone; otherwise it is easily injured though in places where there is little danger it would be wasted energy to construct such armor so soft ones still exist. With internal support, the inflexible exoskeleton and difficult and dangerous molting (when the exoskeleton is soft for a period and the organism is vulnerable) is no longer required and many new advances are possible but the old exoskeleton has its uses too.

For the first fish to walk on land, life was good! There was no competition. But then fish on the shores became abundant and the ability to stray farther from water became more and more appealing. Amphibious creatures do a better job of this and arose from fish. With even drier environments, reptiles which don't need to live in water at all came about. When land animals became commonplace some reptiles returned to the sea; mammals repeated this later. Evolution is all about keeping your genetic code around for future generations. This means competing for space, food, water, resources in other words. Often this means only a small population will live but as long as a population does live, perhaps in some remote corner unclaimed by other species, its genetic code, its offspring will continue. That is the sole purpose of life: to continue itself.

New species likely come about at first from a single individual with new traits. Fully sexual species will need this new individual to be able to breed with its own species still to pass on the trait but not all species are fully sexual. Some can reproduce asexually when necessary. Some only 'resort' to sex under dire circumstances. The evolution of sex is not well understood but some liken it to an arms race with parasites. The parasites would figure out a way to attack and the only defense was to change your characteristics, or those of your offspring slightly so that they wouldn't be as susceptable to the parasites. With exact copies but for random damage there would be no defense but a sexual reproduction would shuffle the deck.

So why wouldn't this new, more successful species completely take over? I'm sure it did sometimes, but not all the time especially when the new characteristics were only an improvement in some environments. If the new design is just a bit better then it won't take over soon, if ever. Remember that evolution affects species, not individuals. Since individuals don't evolve, those not involved in the new attributes will continue to live and reproduce, hoping to keep doing so forever. Only time will tell if they will survive.

Evolution can easily get trapped in local solutions to the problem of survival. It can take something radical to push it on to a more optimal solution. At many times through the long history there have been major upheavals due to the introduction of an oxygen atmosphere, cosmic radiation bombardments, volcanism, impacts of large rocks from space, ice ages, other climate shifts. At these times, the greatest advances are made when many species die out and competitions begin anew.

Large creatures put all their eggs in one basket but small creatures are limited. There is more than one solution to the game of life. Evolution happened, and continues to happen. Don't expect bacteria to go away any time soon, unfortunately.

I'm not sure this came out in much of an order but I wanted to get it down. I'll come back and revisit it later.