ScienceDaily (Oct. 19, 2011) - New University of Alberta research shows the first evidence that the first oxygen-breathing bacteria occupied and thrived on land 100 million years earlier than previously thought. The researchers show that the most primitive form of aerobic-respiring life on land came into existence 2.48 billion years ago. The research team, led by U of A geomicrobiologist Kurt Konhauser, made their find by investigating a link between atmospheric oxygen levels and rising concentrations of chromium in the rock of ancient seabeds. "We suggest that the jump in chromium levels was triggered by the oxidation of the mineral pyrite (fool's gold) on land," said Konhauser. Pyrite oxidation is a simple chemical process driven by two things: bacteria and oxygen. The researchers say this proves that oxygen levels in Earth's atmosphere increased dramatically during that time. "Aerobic bacteria broke down the pyrite, which released acid that dissolved rocks and soils into a cocktail of metals, including chromium," says Konhauser. "The minerals were then carried to the oceans by the run-off of rain water. "Our examination of the ancient seabed data shows the chromium levels increased significantly 2.48 billion years ago," said Konhauser. "This gives us a new date for the Great Oxidation Event, the time when the atmosphere first had oxygen." The rising levels of atmospheric oxygen fostered the development of new bacteria species, and Konhauser says that, following the evolutionary path back to that first oxygen-breathing life form on land, our ancestors started off in a pool of highly acidic water. The researchers say the modern analogue for that first primitive oxygen-dependent life form on Earth is still with us. "The same bacterial life forms are alive and well today, living off pyrite and settling in the highly acidic waste waters of mining sites the world over," said Konhauser.
They have evolved, but that doesn't mean that they died out, different things are suited to different environments.
of coarse they have. its just that they have evolved less from their origional state then other things with mroe dna
There are larger creatures which have all but stopped evolving for millions of years as they have become perfectly adapted to their environment, such a sharks and some crocodilians, the ceolocanth, etc. MelT
But don't single celled organisms supposedly evolve on a much much, much faster rate than any complex multicellular organism such as a shark or crocs? How on earth would they go nearly 2.5 Billion years without evolving one bit? And man has evolved this far from primates over just a couple hundred thousand years? How were they as complex as single celled organisms today all the way back then?
It depends on the kind of cell, but no, they're just less complex creatures, so changes are more noticeable. Think of it like this: if there is a creature made up of a thousand cells and two percent of those change from generation to generation, the change is far less noticeable than in a single cell with the same rate of mutation. In the case of sharks and crodilians though, the rate of mutation that might lead to new physical features is extremely low. Sharks are possibly the most perfectly suited creatures there are to their environment, so exterior stresses that might lead to mutation are rare. As above, because they're perfectly suited to their environment so stresses don't induce as many mutations as they would in other creatures. It doesn't mean that they haven't changed at all, just that the changes are subtle and haven't altered the creatures massively. We know a number of creatures that we can compare with ancient fossils and show they're almost exactly the same now as they were millions of years ago. Evolution is about suitability for purpose, not taking creatures towards more and more complex states. Evolution can easily cause creatures to regress and lose eyes, ears, legs, etc. Man's evolution from primates took place over millions of years, not a couple of hundred thousand years. The rate of mutation in creatures is not equal, but depends on how much stress any given creature is under. Sorry, I'm not sure what you mean here? Who was as complex as what? MelT
Oh well that makes sense then why they say single cells mutate much faster, I was always curious on that.. I thought it meant just because it was smaller it automatically evolved faster than others. Since you're obviously more knowledgable than most people on here who talk about evolution, care to answer a question I've had? I've always been curious on this and I was asking others in another thread and the people in there were an embarrassment of trying to actually defend evolution.. Ill just c&p- A nose was supposedly constructed through trial and error using a random mutations, which part began to evolve first- the nostrils, the hole in the skull, the receptors for chemicals to detect smell, the nerve connecting to the brain or the section in the brain that decodes the electrical signal and turns the code into the sensation of smell? I can never seem to get a legit answer and they always go off doing backwards engineering through the process and never think of it from the ground up starting off with absolutely nothing like a nose and then ending up having one. People brush these things off as being way too easy accomplishments.. How does stress increase the rate of mutation? Sounds interesting I meant fossilized single celled organisms, they are just as complex as single cells today. There is this one that I heard of that was missing a part from usual cells, can't even remember what it's called, it's been a while, but it was still an amazingly complex machine. Have we ever came across true 'primitive' cells?
A structure that is found throughout different kinds of animals that are thought to have evolved completely separate, yet seemed to have came up with nearly the same exact blueprints for a specified purpose.. That's your evidence for random evolution rather than pre-designed creatures? Why do nearly all cars have 4 wheels? Because they evolved from dirtbikes 2.4 million years ago or because it's the most practical design that simply works?
I doubt that You've begun by supposing that all creatures that smell, a) All use the same system to do it. Like sight, not all ways of seeing in creatures use the same methods, b) that the creatures who have noses of a similar type are not related and c) that these changes happened in isolation for no reason. It's similar to the old creationist argument that asks why should feathers evolve without the need for flight? The first feathers were not for flight, that was their eventual use. In the same way, the changes that led to our sense of smell began as other useful changes for other purposes that later developed. Whilst not 'easy' the route it's far from being improbable once you look at each stage of development and know why it took place. We discussed this at length a couple of months ago when I posted the three ways that creatures could mutate or be forced into dominance. By 'stress' I mean everything from an increased/decreased/changed food supply to temperature and natural disasters. Evolution has never been just about survival of the fittest. In the case of many cells, these things will create real-time changes in DNA and mutations. It doesn't have to be via DNA per se either, as in creatures such as ourselves, a poor diet will lead to mutated sperm and mutations in their offspring. You're answering your own question. Some single-cell creatures were as complex as those today, but they had gone through proven developmental stages to get there. Those that lack parts will tend to be these early precursors or mutations. Saying that a cell differed from 'usual cells' implies that there's only one cell structure that all cells have - far from it. Yes, the OP i sone example. Also in general: "...These are referred to as Prokaryotes and they do not possess many of the same structures as cells we often study in biology. These cells have no nuclear membrane - their DNA is typically a ring that exists within the cell - and they lack most of the cellular organelles we learn about with most cells in elementary biology which are Eukaryotes. This link compares the basic differences between the two different types of cells. Please take no offense at its elementary nature. Prokaryotic and Eukaryotic Cells We can also look at self-replicating RNA, which could easily be created from the abundant complex molecules that appear naturally in the universe. "...A team of researchers at Harvard University have modelled in the laboratory a primitive cell, or protocell, that is capable of building, copying and containing DNA. Since there are no physical records of what the first primitive cells on Earth looked like, or how they grew and divided, the research team's proto-cell project offers a useful way to learn about how Earth's earliest cells may have interacted with their environment approximately 3.5 billion years ago..." We can also turn back the evolutionary clock on some cells to examine and use them: "..Dr Chan's team explored de-differentiation, a process that reverts specialized, differentiated cells back to a more primitive cell..." The problem is simply that you don't want to believe that all life shares a common ancestory and that speciation led to the appearance of the range of creatures that we see today - as this would mean you would have to believe that evolution is correct. MelT
Well then what purpose did all the parts of the including the decoding section in the brain and the hole in the skull prior to being a nose??
There isn't much reason to evolve if you never have to do anything. They don't need to travel, hunt, or anything really. An environment is provided and the bacteria thrive.
Some had a need, some didn't. Why isn't everyone a CEO? Because the world needs Janitors? If something is perfectly suited to its environment there is little need for massive change. This is not a difficult concept to grasp. Of course, I know you know that and also know you'd rather build a straw-man than deal with what is presented.
Why would only some have a need while others wouldn't? It's not like they knew we were going to need single celled organisms billions of years later.. How come these just formed as complex as they are, and haven't changed for billions of years? What need did the other single cells have that drove them to eventually make more complex multicelluar organisms that the others didn't?
All creatures are obviously made equal, right? Do you understand the environment and how it literally shapes everything that lives inside of it? Every post you make suggests more and more that you don't.