Why aren't our evolutionary ancestors extinct?

I get that. To a point. I understand that species give rise to other species depending on varying factors. What I don't get is why those species meet with the causes for evolution and yet still manage to continue to exist. Although something is telling me I may need to know more about evolution to be able to ask the correct questions. But I thought I'd ask anyway because others might have similar questions about evolution.

 

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Technically perhaps. Although it's not the same ape as the modern one.

 

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Yeah, I realise that now. It's pretty bloody obvious now you guys mention it. I'm not the brightest of sparks

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but still, that wasn't necessarily my question.

 

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In a word - Yes.

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It can be a daunting subject in depth and people do throw around confusing simplicities.
Basically the old ancestor will only die out if it is no longer able to compete for it's share of resources, neanderthals didn't die out instantly, they survived for a while, but gradually were out-competed. It's not an inevitability but it is highly likely for this to occur. This is of course entirely dependant on circumstances.

 

Not at all. A new species is created when sufficient mutation results in speciation. Mutations are completely seperate from natural selection and environemental preassures (other than perhaps the environements ability to augment the number of replication errors, however, that is no factor on the type of mutation.) That is, the environement does not force a species to evolve, it merely kills off those which are not suited for it.

Now, often, a new species will be better suited to the environement, and if it is a competitor of the ansestor, the anscestor will probably become extinct.
However, If the two do not compete, or there are plenty of resources, or they are equaly matched, than both can continue.

The real question is; why should the anscestor die out?
-Andrew

 

I apologise for not reading through everyone elses replies thoroughly I was slightly rushing.
I'll confess I giggled when I read your post but you're obviously sincere about learning so worthy of response. I'm sure you're laughing now too.

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See what you make of my above post though.

 

Bingo! I'm just highlighting this for Emmz - If there is no reason for it to die out it probably won't.

Highlighting this too, it's a great example. Now try imagining it occuring on the same island, an abundance of food the birds could be eating, and the birds are not directly competing with each other as they have different food sources, so both species can survive.

 

Thanks for your patience everyone. I'm told i need to understand genetic reproduction a bit more to understand where my confusion lies. I have a feeling I've bitten off more than I can chew, but hopefully this thread will help other idiots like me understand a little more about the evolutionary process. Thanks again

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The only mutations I've ever observed result in deformed or handicapped people, and these seem to occur with startling regularity. Is there an example of a positive mutation which occurs with the same frequency?

 

you have to understand it's not instantaneous transition, or clean boundary between successors. Say a pioneer species gives way to a new one it seems the old dies off and a new one appears, in reality it's not like this exactly. It happens slowly, a process of succession. The original species slowly changes over time due to mutations and common traits changing and being affected by environmental conditions(like with the long hair short hair rabbit examples often given in biology studies). Eventually the species becomes distinct from it's original and is classified as a new one. It looks from reading books etc like one gives way to another but at closer inspection you can see many more sub divisions (like the divisions between archaic H. sapien and present day). For example if you slowly add water to a container 1 drop a day it's easy to measure in say 100ml increments and maybe for ease to document the stages of filling by 100ml>200>300 transitions. In reality though it's a very gradual change that blend in.

Species slowly change until they become quite distinct from their original and are recatagorised. Organisms change over time and environmental factors allow some to out compete others and hence succeed them. The succession on a small level (ie in same species) is slow so it's even longer process for a new species to succeed the old. For instance it's not like a new Hominid will suddenly appear and outcompete H.sapien (present day) and we will decline and they increase. This happens with small scale mutation which then affects the next generations and so on. Like rabbit example where small percentage of rabbit pop has longer fur but hot climate means they are not as suited to the niche as shorter fur rabbits who are the common ones in the population so don't thrive. Then harsh winters occur and mean the short fur ones are not as adapted as the long, hence the long fur becomes the common variety. Many of these small scale changes happen until eventually over 100s of thousands to millions of years a new distinct species exists when compared to it's ancestor at a suitably far back enough previous point in time.

So the old ones do not really exist at the same time as the new, but if you go into microdivisions you can see there are times when a few different characteristics within a species exist at the same time.

 

Well, first, it should be pointed out that the probability of a usefull mutation is smaller than that of a debillitating mutation: most resault in a condition infavourable to the environement, or so damaging that the cell simply dies (in multicellular organisms; it undergoes apoptosis, ones that do not due to excessive damage can become cancerous.) Thus, speciation will only occur if we consider hundreds of thousands of years (obviously, a timespan inobservable to any human.) for macro organisms. Less for single-celled organisms.

However, there are examples of positive mutations (though, infact, they are negative as far as we are concerned.)
The pesticide and pharmaceutical industries are quite aware of these.
Some insects of a particular species will be resistant to pesticide X, and hence, when X is applied, the ones carrying this gene will replicate without competition from the ones who do not. Hence, a usefull mutation propogated by natural selection.

Viruses contain little to no error-checking, and hence, have considerable mutation. Because of this, it is extremely hard to treat them. The HIV virus is a specific example; infact, after infecting a new host, the strain soon mutates into a distinct phenotype from its predecessor. When applying pharmaceuticals to a patient, one cannot apply too much at once, or it will merely whipe out the competitors of the resistant strains, and render the drug useless for future applications.

A third example is penicillen and bacteria. Certain bacteria have develloped enzymes capable of disabling certain penecillins. Thus, penicillin can be modified to overcome this, but, eventualy bacteria devellop a resistance to that one as well; and kind of mutation is the major behind adding penicillins to foods; one wouldnt want to breed resistant bacteria!

-Andrew

 

Well it kind of cease to exist as an own population, as the gene pool that represented A is now divided into a1 and a2. If both would interchange genetic material again (i.e. the separation would somehow reverse before both population accumulate changes) then population would in theory be existent again. Population A does not go extinct in the classical sense, though. It just dissolves into the two subpopulations.

 

Think of it this way, its not a replacement of a prior ancestor, its merely the preponderance of most likely to survive to reproduce. Over time, you find that the ones that reproduce become the majority; over a longer period, they become the survivors.

 

the thing about bacteria gets complex since it's not just mutations where many get resistance from but swapping resistances between different types by plasmid dna. Plasmid dna can be swapped easily between different types of bacteria.

 

I see what you mean now. I was under the impression that both pioneering and evolved species did exist together. But only within a certain time frame.

 

Evolution is often localized. A mountain range, a desert, or an ocean gulf might split a formerly homogenous species into two parts that can no longer interbreed because of geography. There exist biological forces that tend to keep a species homogeneous (e.g., sexual preferences for the norm). These biological forces do not apply when a sub-population becomes separated from its parent population. These biological forces that tend to maintain the status quo can also be overwhelmed by other forces; local climate change, for example. A sub-population can become a separate species from the parent population. The parent population might follow a different evolutionary pathway or can even remain relatively unchanged.

 

Right. That makes sense. Cheers.

 

like Galapagos finches and lizards

 

What example would you give from the human fossil record of a positive mutation?

Further, I don't see how a positive mutation can spread through a population, since breeding with non mutated stock will eliminate it. It seems to me that such mutations could only affect a macro species when there are relatively few of them, ie, early on in their evolution. In fact, thinking about it, I'm not even sure that that it is possible, since in the first generation the mutation would be largely eradicated.

Shouldn't a scientific example of evolution be free of human action?

In the case of bacteria and viruses, mutation would seem to be a necessary characteristic of the organisms survival, rather like our ability to run from predators using our legs, but no evolution seems to occur from this. Surely a positive adaptation in micro cellular organisms would see them conglomerating into larger organisms, rather than just changing their structure around, which is just as likely to change back?

In the case of insects and pesticides, it would seem that we are doing the selecting, rather than nature.

 

The one that crippled its victim by reducing the size of its jaw muscles and lowering their attachment point on the skull.

It's apparently a simple point mutation in one of the development regulating code sequences.

It removes the compression of the jaw muscles from the skull, allowing it to grow more during childhood.

It was probably a deformity, and certainly a handicap to some degree, at the time.

How's that happen ?