Cockroaches

[questor]

Behold the lowly cockroach. he dates back 300 million years. if evolutionary theory is correct, why hasn't he morphed into something more sphisticated than he is ? why haven't

protazoa become new lifestyles or species since they are much older than man ? if evoution is the way, why hasn't there been a constant parade of new species generated by mutation, environmental changes and branches off the family tree ? man has been around for 4 million years, that's long enough to have spawned a a greater variety of hominids, isn't it ? after all, there were many varieties of dinosaurs.

[Tormod]

And there are many varieties of cockroach...like 3,500 of them.

 

http://www.the-piedpiper.co.uk/th2.htm

[Boerseun]

Quite simple, really. They've evolved into a very functional form that serves their purpose, and is able to exploit a lot of divergent niches with the same design.

 

Same with sharks. They found their spot millions of years ago, and are sticking to it.

 

Simply put, since the advent of roaches and sharks, nothing has happened (yet) that requires an adaptation from these species to survive. Unlike humans, for instance, who decided to get out of the trees to exploit the savannahs.

[pgrmdave]

Well, even assuming that there wasn't much change in the basic form, if the niche that they fill stays the same, and they are well built for their environment, and they are able to adapt to different environments, then it would make sense that they wouldn't change. Evolution only occurs when something goes wrong. If there are no pressures, then there probably won't be any change. There might be some random mutations, but unless they provide a very clear adavantage, they will likely never really catch on.

[questor]

Tormod, there may be 3500 variations, but they are still cockroaches, and function pretty much the same. there are plenty of environmental challenges to the roach, why hasn't he evolved over 300 million years ?

[pgrmdave]

Cockroaches have evolved socially (moving from the wilderness to living with humans), but there hasn't been a need for them to evolve physically - they eat scraps, they reproduce quickly, they prefer darkness... Their environments may have changed, but they still fulfill the same role in nature, and their niche is still the same. It would take a major environmental change to actually affect the cockroach, much more then the existance of humans.

[questor]

i picked cocroaches because they have been on earth for 300 million years, maybe a 100

times as long as man. why aren't there chance mutations, natural challenges, and environmental changes through these millenia to cause evolutionary changes ? worms are the same, protozoa are the same. there has been plenty of time. is man the only thing that has evolved so dramatically?

[Vending]

Tormond, in the first reply to this thread, provided you with your answer. There are many, many different varieties of cockroaches. These varieties are a result of chance mutations, some of which provide a greater degree of fitness (or at least not a stupendously less amount of fitness). If your question is, "why haven't they evolved into something else" then this is basically the same question as "why aren't there things that are not cockroaches." THe answer being, there are things that are not cockroaches -- lots of them.

 

Are you asking why there are still cockroaches around today? The answer (from a natural selection point of view) is that the cockroach is still fit enough to survive. That is it.

 

In fact, insects in general (which are quite ancient) are exceedingly fit. I know that in grade schools it is common to call this day the "age of the mammals" (following the age of the reptiles. But this is simply not true. As far as numbers of species and biomass, insects outnumber and out mass the mamals of the world. This is the age of the insects...and it has been for some time now. The fact is, insects are amazingly fit (in the natural selection sense of the word) and that is why they are still around.

 

 

I hope that at least partway answers your question.

[questor]

cockroaches have been through at least 4 major ice ages, the cataclysmic happening that obliterated the donosaurs, plus whatever else happened over 300 million years and you're saying they have no need to change? the fact is that they and the crocs and the one celled animals et al have not appreciably changed while in 100 dth of the time man has gone from a monkey to Homo Sapiens ? it strains credulity.

[pgrmdave]

Many mammals have evolved, while many other animals did not. Mammals are more likely to change due to the fact that they are 'newer' animals. Large mammals have not existed for nearly as long as crocs, or insects. However, if you go back in the fossil record, toward the beginning of these species and genuses, it appears that there were many variations which died out, while the most successful of them lived on. Cockroaches have existed for 300 million years, which means that most of the bugs (forgive the pun) in their biology have been worked out. In general, I think, the older the species the less we'll see it evolving, because it has had a long time to discover what works best over time.

[questor]

you might wonder where modern man came from. he's only been here for 15,000 years. where was his progenitor ? what killed off the Neanderthal ? why didn't he mutate to cope with climate, or whatever he was confronted with? the natural selection process doesn't make much sense when you review man's short history. if a single celled organism became man and we have had single celled organisms for millions of years, why haven't more of them become sapient creatures ? if a single celled organism responded to its violent ancient environment it should have become more of a fortress-like creature to resist its challenges. if apes developed into man, why haven't worms developed into

something far different from a worm ?

[MortenS]

What about praying mantises, are they different enough from cockroaches?

Or termites?

Both termites and mantises are closely related to cockroaches, both morphologically and genetically, although their behaviors and specializations for those behaviours are very different from eachother.

My guess, although I have not done any phylogenetic studies of cockroaches and their relatives, is that mantises and termites evolved from cockroaches, and that cockroaches therefore are a paraphyletic group. (Similar to reptiles being a paraphyletic group, because it does not contain mammals and birds)

[rockytriton]

I think that if macro-evolution is true, it doesn't mean that a species will evolve past its needs. So once a species is perfect, it will have no need to evolve anymore. Yes I am saying that the cockroach is perfect.... ewww....

[questor]

''I think that if macro-evolution is true, it doesn't mean that a species will evolve past its needs''

 

what were the needs of monkeys that made them evolve into man ? if all the monkeys at that time had similar needs, why didn't they all evolve into some type of man ?

[MortenS]

Different environments, perhaps? Most changes in animals and plants occur when either the environment changes, or the animal or plant move to a different environment. Thus the needs of the old population (still at the old environment, stays roughly the same), while the group that have moved to another location, experiences a different environment, where other adaptions might be favored.

[rockytriton]

what were the needs of monkeys that made them evolve into man ? if all the monkeys at that time had similar needs, why didn't they all evolve into some type of man ?

 

If I knew that brother, I would write a book and be rich.

[Mercury]

what were the needs of monkeys that made them evolve into man ? if all the monkeys at that time had similar needs, why didn't they all evolve into some type of man ?

Aren't there different kinds of species under the genus Homo once? Somehow the others got extinct, sapiens is the one surviving until now?

Correct me if I am wrong.