The Early Evolution Of Animals Why did animals evolve?

[salamangkero 0]

This is something I've been thinking for some time... Why did animals evolve?A quick search through the web about animal evolution may yield information like the "Cambrian explosion", where there was a "sudden" proliferation of animal life-forms (where the word "sudden" applies to several millions of years). Others will discuss how both plant and animal life emerged from cellular symbiosis, where mitochondria evolved as a permanent fixture.However, what's missing is what happened far before that... when did animal cells first evolve? Why did they forsake the process of photosynthesis? Surely, a plant life-from capable of locomotion gets the most benefit from the sun. Do mobility and photosynthesis not really go with each other? It sure would be useful if we could all harness the sun's energy.Let's go further "up" the evolutionary ladder, caterpillars eat plants so the energy "jumps" from plants to the caterpillar. Further "up", frogs eat the butterflies; energy jumps twice. Actually, in the cases of predators deep within the food web, much of the original energy gained from plants have been lost, which is why food webs rarely exceed the 5th degree.Now, still higher up, we, humans, are mobile, yeah, but we can't photosynthesize, we can't digest cellulose either. I'm beginning to have doubts if we really do have the evolutionary ladder quite right.Why, oh why on earth, did heterotrophs evolve? Did bullying plants suddenly decide it's better to eat other plants and evolved into animals? Was photosynthesis such an arduous task that they thought hunting, chewing and digesting is so much easier? Why am I talking in questions? Why?

[biscuitrat 0]

I think Richard Dawkins' The Selfish Gene would be a good read for you. My philosophy on the subject is that of the original unicellular and multicellular organisms, the unicellular were unable to evolve further than a certain phase, while multicellular organisms became the first creatures. When we branch off into animal and plant life, maybe it goes something like this: plants are restricted to water sources and places of sunlight while animals can move around freely. Therefore, plants don't have a necessity for mobility; in fact, the only mobile tendency plants show is growth/spread. Without that, we would have no plant life, and inevitably no animal life. Plants may have all the energy, but what we get is pretty much the waste. This doesn't necessarily mean plants are kings of the earth; they may be everywhere, but they're fragile. They can absorb this awesome energy, but they can't utilize it beyond a certain point.

 

Killer plants are the stuff of dreams and maybe, someday, a reality of the future. Don't stop asking questions; this was fun

[jhsmurray 0]

"Why" is a tricky question, because it could mean either "How did something come about" or "What was the purpose behind something" or etc. etc.

My view of evolution is an atheistic non-deterministic one. I dont think we should try to assign the "why" as if there was a preconceived purpose behind evolution. I see evolution as just patterns of life. They "are" because they incidentaly survived thus far. Some random set of adaptations just happen to work out in the current state of the environment so that that living thing survived and as such was able to propagate offspring with the same (or similar) traits.

That in mind, there is evidence that very interesting things happen when environments change over time, because the rules of the "struggle" will change. You'll hear of "struggle" alot in evolutionary theory - it was adopted from a guy named Malthus who had a particularly non-Utopian view of society: in any given group the resources in which it relies will eventually run-out.

An interesting side note: These patterns are not limited to living things. Technically, biological viruses are not alive, per se. They are just sequences of genetic code that replicate themselves.

So, to get back to your question, I'd say that animals first started to come about because the features that make an animal, say the eye (the eye has been part of anti-Darwinian discussion for a long time as irreducibly complex) started to develop because it helped those creatures survive. I may not have originally been used for seeing. It just happened to go through positively adaptable changes as the ages rolled by. Those with positive results, survived.

So, if our environment changes so that monkeys are better suited to the environment, get ready to put on your monkey suit

[salamangkero 0]

So, to get back to your question, I'd say that animals first started to come about because the features that make an animal, say the eye (the eye has been part of anti-Darwinian discussion for a long time as irreducibly complex) started to develop because it helped those creatures survive. I may not have originally been used for seeing. It just happened to go through positively adaptable changes as the ages rolled by. Those with positive results, survived.

Interesting, you guys sure had my insight-gears turning. True, locomotion is in the best interests of almost all creatures, or at least, animals. However, I was wondering, sure it would be terrific to gain "new skills/abilities" (Pardon the RPG pun) but do we really have to do away with the rest? Just think how easier it would have been for us if we had green skin and could photosynthesize. Yes, the energy we'd gather is infinitesimals, considering the energy we use simply by standing up, but it sure would be nice if we needed to eat less. Instead of three meals a day (breakfast, lunch and dinner), we'd have two (brunch and luncher). We'd have more time to spend working, hopefully, and less time needed to prepare food.

Okay, scratch that, maybe it was too much to ask for. How about digesting cellulose? Right now, the only use we have for vegetables is their vitamins. The number of plants we can actually derive energy from is quite limited (lessee, grain, sugar cane, fructose-laden fruits, what else...) If we had stomachs like cows, we'd be able to harness far more energy than we get from grain and meat right now.

On second thought... termites have protozoans doing the digesting for them... I wonder if we can also foster a symbiotic relationship with those, or with the termites themselves. It's gonna be something like we'd take care of foraging for plant matter and the little guys will take care of digesting it for all of us.

(I'd better start swallowing termites)

Still, I wonder why we had to let go of photosynthesis. It'd sure be fun imagining what the fashion world would come up for green-skinned humans