How do scientists who believe in evolution explain where the very first organism came from?
- Dr. BrianLv 61 decade agoFavorite Answer
We believe that the best candidate for the first organism is a bit of ribonucleic acid (RNA) enclosed in a plain capsule. RNA can store information like a gene and reproduce itself. It makes up the genes of viruses. There is a group at Harvard trying to recreate it (http://www.news.harvard.edu/gazette/1996/09.12/Cre... .
Explained, a bit:
For as long as we have known about them, scientists have thought that simple bacteria were the link to the earliest life forms on earth. However, growing evidence suggests we've got it all back to front -- could the secrets of the origin of life be lurking inside us?
When most of us think about evolution, we tend to think in terms of simple organisms evolving into more complex ones. Simple chemical reactions evolved into simple cells, which later evolved into more complex organisms, and so on all the way up to humans. It's no longer believed that humans are at the top of the evolutionary ladder, but evolution does tend to drive organisms towards greater complexity, does it not?
However, this is not always so. Rather, those organisms that leave the most offspring behind, simple or complex, do best. Greater complexity is sometimes a consequence of evolution, but simplification can also be a winning strategy -- it all depends on the environment. Nevertheless, most scientists hold that the first organisms on Earth were much like bacteria of today. But several features of the biochemistry of life suggest that bacteria aren't so ancient after all. In fact, in some respects, the cells of our own bodies tell us more about the evolution of life than bacteria do. The key is in the discovery that won Sidney Altman and Tom Cech the Nobel Prize in Chemistry in 1989.
The chicken and the egg
* In modern organisms, genetic information is stored on DNA (deoxyribose nucleic acid) in units called genes.
* Genes code for proteins, which are responsible for the various activities that make a cell function.
* Some proteins, called enzymes, perform the chemical reactions that run the cell. One group of enzymes, the DNA polymerases, make DNA.
* The information for making those enzymes is stored in the DNA as a gene.
Therefore, finding the evolutionary origin of proteins and DNA is tricky as each requires the other for its own synthesis-which came first? That's where Cech and Altman come in. They studied RNA (ribose nucleic acid), a close chemical relative of DNA:
* When proteins are made from the information in DNA, a working RNA copy of the gene is made for use by ribosomes, the protein factories of the cell. Therefore RNA, like DNA, stores genetic information, and, like proteins, it also performs chemical reactions.
* Bringing RNA into the picture solves the chicken and egg problem. RNA can be both chicken and egg.
* What this means to evolutionary biologists is that life could well have BEGUN with organisms made largely of RNA.
* This idea of an 'RNA world' has been debated since the 1960's, but Cech and Altman's discovery has convinced most scientists that it is at least possible.
* It is now known that RNA is at the heart of many of the basic functions in the cell, and probably evolved in the RNA world.
But if RNA is so versatile, what happened to the 'RNA world'? As the saying goes, "Jack-of-all-trades, master of none;" RNA is not as good at performing chemical reactions as proteins, nor is it as good at storing genetic information as DNA. It's not surprising that since the RNA world, proteins have gradually replaced most RNA enzymes, and DNA now stores the genetic information.
Most researchers agree that RNA used to have more of a central role because it solved the chicken-and-egg problem of which came first in evolution- proteins or DNA. But other than being a tidy piece of logic, is there any substance to the hypothesis? Since we can't travel back in time, it is impossible to prove the existence of the RNA world outright, but we can do the next best thing-rebuild it from the 'molecular fossils' that have remained in modern cells.
Looking for 'molecular fossils'
By delving into our RNA-rich past, we can get an idea of what early life looked like, and this may in turn help us understand how life evolved into the many forms we see today. 'Digging' for molecular fossils is not a trivial exercise. Not all RNAs are going to be genuine RNA world fossils, but it is possible to establish which are likely to be ancient, and which are more recent additions.
* One of the most central machines in the cell is the ribosome, which translates the genetic code stored in DNA into the language of proteins.
* The core of the ribosome is made from RNA, with proteins providing a scaffold to hold the RNA in place. Even with most of the protein stripped away, it can still make proteins.
* The finding that the RNA core is the engine room of the protein synthesis factory is a strong argument that protein synthesis was invented in the RNA world.
Indeed, the ribosome is just one of many RNA machines, giving scientists a surprisingly clear picture of early life. The picture appears most complete in the eukaryotes (plants, animals, fungi, amoebae), which are more reliant on RNA than prokaryotes (bacteria and related cells), the former retaining more clues to our RNA-rich past. Since RNA is a Jack-of-all-trades we would expect it to be gradually replaced during evolution.
There is also an excellent book by Dr. Panno called The Cell: Evolution of the First Organism (http://www.amazon.com/exec/obidos/tg/detail/-/0816... that goes into great detail with everything that we currently know.
That's the wonderful thing about science, we can learn and grow as we evolve intellectually.
Sorry for the long answer - but this is a bit of a complicated subject. There is no, "Because someone put it there" kind-of answer. It revolves around research, testing and logical thought. Someday, maybe, we'll understand it 100%. Until then, we learn and adapt.
- zapienLv 44 years ago
Wow, extraordinarily plenty each and every thing you mentioned is faulty. Evolution is definitely not junk technological expertise. study 'The beginning place of Species', or take a real evolution direction in college. existence is complicated through fact organisms mutate, and then decision acts on populations to alter the frequency of characteristics in those populations. it rather is the reason some birds have small beaks, and others have great beaks for occasion. Populations of organisms are consistently evolving and transforming into extra distinctive through fact decision is performing to alter the frequency of characteristics (conserving the characteristics that supply the terrific well being). while you're speaking approximately 'abiogenesis', then it is a few thing cut loose evolution. there is evidence rising approximately how cells might have formed from organic and organic supplies. do exactly a splash diagnosis.
- secretsauceLv 71 decade ago
Please read the answers by johnslat, Eagleflyer, and Dr. Brian (especially the latter). There actually are answers to this question.
I give you (asker) props for the phrasing "scientists who believe in evolution" instead of "evolutionists". Strictly speaking, the question of the origins of life (abiogenesis) is a very different topic than the theory of evolution (which is about how things evolved once the first cells were here). The theory of evolution is much simpler and established with very strong evidence than the theories of abiogenesis.
In short, there are many theories of abiogenesis (unlike evolution, where the theory of natural selection is the single dominant theory). It is a much more difficult problem because we know so little about the conditions on the earth 4 billion years ago.
I would expound on some of the leading theories, but Dr. Brian has already beat me to it.Source(s): Here is also a nice overview of the many theories: http://en.wikipedia.org/wiki/Origin_of_life
- johnslatLv 71 decade ago
Science doesn't explain (though it does theorize) where the first cell came from. But evolution isn't about the first cell; it's about what happened afterward.
This book - see link below - offers a great explanation;
"The Cell: Evolution of the First Organism by Joseph Panno, Ph.D., offers an excellent, concise and interesting introduction on the cell and its evolution. Panno opens with a brief overview of theories related to life's origin, then moves to prokaryotes and how they laid a foundation for eukaryotes. Next, he offers an examination of the cell cycle, followed by genes, multicellular organisms, and neurons. Panno does a stellar job of communicating a complex subject clearly (better than many texts as I see it) and sans oversimplification. The black-and-white graphics and glossary are exemplary and useful to the student."
- How do you think about the answers? You can sign in to vote the answer.
- Anonymous1 decade ago
It has to do with proteins and amino acids forming complex molecules and ultimately, a cellular nucleus that is capable of duplicating itself. Mutations of those molecular chains created bacteria and other microscopic organisms. You need to study the the tree of evolution, Google it. There are graphical representations of how species evolved, and you can see what branch of the tree of evolution that complex animal life came from. From some kind of fungus or something. Yeah, I know, it sounds much better to say we were created in Gods image. Sometimes an explanation of nature's mysteries can be beautiful but in most cases still wrong.
- 1 decade ago
They don't. The thing about science is that it can't exsplain everything at this moment. As time progresses, science can start to exsplain things we didn't understand in the past.
But, our creation is somewhat of a mystery. No one can claim to know for sure what happend. You just have to decided for yourself what makes the most sense.
- flammableLv 51 decade ago
it's complicated, you would never understand and I would never waste my time trying to explain it to you because it's very likely you would never accept any other explanation than what you already made up your mind with. This is a provocation and we will not fall for it. if you care so much, go to university, study and then make up your own mind. Good day.
- 1 decade ago
They mixed to gether on chance in the first stages of the planets cooling.
- 1 decade ago
They don't have to. Science is about finding answers to the answerable, not making up answers just because something is unknown.
- Joy MLv 71 decade ago
Not all people who accept the theory of revolution reject the idea of God.