Art of the taxidermist and expertise of the scientist-curator combine to suggest the variety of life-forms to which evolution has given rise in the animal kingdom alone. The exhibit was photographed in the Hall of Biodiversity at the American Museum of Natural History in New York City.
Image: Grant Delin
In Brief
- Charles Darwin’s theory that evolution is driven by natural selection—by inherited changes that enhance survival—struggled against competing theories for the acceptance it has within biology today.
- Random genetic mutations having neither positive nor negative effects were once thought to drive most changes at the molecular level. But recent experiments show that natural selection of beneficial genetic mutations is quite common.
- Studies in plant genetics show that changes in a single gene sometimes have a large effect on adaptive differences between species.
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Some ideas are discovered late in the history of a scientific discipline because they are subtle, complex or otherwise difficult. Natural selection was not one of these. Although compared with other revolutionary scientific ideas it was discovered fairly recently—Charles Darwin and Alfred Russel Wallace wrote on the subject in 1858, and Darwin’s On the Origin of Species appeared in 1859—the idea of natural selection is simplicity itself. Some kinds of organisms survive better in certain conditions than others do; such organisms leave more progeny and so become more common with time. The environment thus “selects” those organisms best adapted to present conditions. If environmental conditions change, organisms that happen to possess the most adaptive characteristics for those new conditions will come to predominate. Darwinism was revolutionary not because it made arcane claims about biology but because it suggested that nature’s underlying logic might be surprisingly simple.
In spite of this simplicity, the theory of natural selection has suffered a long and tortuous history. Darwin’s claim that species evolve was rapidly accepted by biologists, but his separate claim that natural selection drives most of the change was not. Indeed, natural selection was not accepted as a key evolutionary force until well into the 20th century.
This article was originally published with the title Testing Natural Selection.
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14 Comments
Add CommentMankind seems to adopt such a wide range of behaviour that he escapes from natural selection pressures to a large extent. How long he will escape from environmental disaster as a species depends on how well he adapts to the pressures he thinks he is immune to.
Reply | Report Abuse | Link to thisThe schematic of how natural selection works is a gussied up version of a common one from genetics textbooks (I prefer the ink doodle version in Dennett's book). It's oversimplified to the point of being wrong in such an important way, but somehow we seem to be stuck with it.
Reply | Report Abuse | Link to thisIn a nutshell: The thing that replicates (with errors) is DNA. DNA sequences are not selected by the environment--phenotypes are. There is not a 1-1 mapping between genes and phenotypes, despite what a science journalist might tell you. Phenotypes are non-random, highly derived outcomes of developmental processes and genotype/environment interactions. This isn't a picky detail... this concept is required for evolution to make sense.
Orr says, "Unlike Darwin, modern biologists generally adhere to the so-called biological species concept." From what I remember about reading Origin over 30 years ago, Darwin defined species by their fertility. Prior to then, and since then, I have never heard any other definition. The average layperson does not know the distinction. Am I misunderstanding what Orr is saying?
Reply | Report Abuse | Link to thisI dont buy this backward engineering stance on evolution at all. Here is yet another example of "could have happened"s and "may have been"s that are used to validify a failed theory. The very premise that adaptation to local conditions, over time results in new species would require the introduction of new genetic material into the base gene sequence of existing animals of any particular time. Even if that introduction occurred over a period of time.
Reply | Report Abuse | Link to thisAdherents to the Darwinian faith would be forced to admit that they cannot produce a single example of mutations creating new genetic information and that is key. But how can this be? In order for a frog to morph into a lizard, it is going to need its genes to do some pretty wild and crazy productive mutations. And when you consider the entire premise of Darwinian macro-evolution states that all creatures (not just frogs) are constantly experiencing these positive mutations, the weight of the evidence crushes evolutionary naturalists. If Darwin was right, we should be able to observe and replicate gene mutations that yield new information nearly everywhere we look. We simply cannot.
Meanwhile, what we can find are innumerable cases of destructive gene mutations, where we end up with less genetic information than what was originally present. Take the recent discovery of perfectly preserved octopus remains. The discovery revealed that these ancient octopi actually had more genetic information than do modern octopi. Call it "Darwin in reverse." Both horizontal and destructive mutations support the creationist model...and both devastate Darwin's.
http://factsnotfantasy.com/evolution.html
Reply | Report Abuse | Link to thisTelrunya: Actually, there are *numerous* examples of new genetic information being acquired. It happens by several different mechanisms including gene duplication, polyploidy, horizontal gene flow, and endosymbiosis. The ability of African primates (including ourselves) to "see" three colors is due to the duplication and mutation of the green opsin gene such that the duplicated copy became sensitive to red light. But in reality, speciation does not require new genetic material--just a genetic change of some sort that causes reproductive incompatibility. Also, frogs don't morph into lizards! Never have, never will. Evolution doesn't work like that. It is easy to attack a strawman, are you familiar with the strawman logical fallacy? You've just committed it!
Reply | Report Abuse | Link to thisTelrunya, by babbling about frogs not morphing into lizards you reveal your ignorance of nature and failed ideals. Just because you cannot understand evolution does not mean it is wrong. By closing your mind to an opportunity to learn of the wonderful mysteries of this world you are slapping the face of God. Shame on you.
Reply | Report Abuse | Link to thisThe time element clearly gives the maintenance end of life the short stick, fungi and microbes that are completely necessary for the environment usually live very briefly, while the animals that gain life from the world of these organisms live much longer and have conscious lives. Yet they are all genetically controlled, and if one microbe in synchrony with the others changes randomly, the balance would be vastly disturbed by one blind mutation.
Reply | Report Abuse | Link to thisHere are some thoughts and concerns about what I have been reading regarding evolution.
Reply | Report Abuse | Link to this“Only 24 years after Charles Darwin rewrote the book of life with his theory of natural selection, a fellow Victorian scientist named William Flower trained this powerful new idea on one of the toughest problems in zoology: the whale. Natural historians had long before recognized that whales are mammals, but that was about as far as they had come in understanding the origins of cetaceans. How evolution had managed to craft such a unique beast presented a mystery as vast as the creature itself.
In 1883, Flower offered an idea that--on the face of it--seemed positively daft. The legless leviathans, he suggested, had evolved from mammals known as ungulates, a group whose best-known characteristic is a set of hoofed feet. In other words, dolphins, porpoises, humpbacks, orcas, and ail other whales are close kin of cows, horses, pigs, and related barnyard stock.
More than a century after Flower raised his audacious hypothesis, it no longer stirs even a whiff of controversy. Dozens of scientific studies over the past 3 decades have convinced biologists that cetaceans are the progeny of hoofed mammals.” Based on November 2001 NATIONAL GEOGRAPHIC Magazine,
“Cows didn’t evolve from whales but they both came from a common ancestor. Cows and hippos are "sisters" and both are "cousins" to the whale. They all evolved from a common "grandmother," (the wolf-sized Pakicetus) who had wicked teeth in a narrow pointed skull.”
http://www.neoucom.edu/Depts/Anat/Pakicetid.html Northeastern Ohio Universities]
Between 40 and 50 million years ago whales, dolphins, and porpoises (cetaceans) evolved from land to marine animal. They changed fast — in less than 8 million years, says Hans Thewisson, paleontologist at Northeastern Ohio Universities.
Apparently he’s talking the land version here, and here is one thing he says: “Modern and ancient whales have a bone in their ear that is a half-sphere, thick on the outside thin on the inside, the better to hear underwater.”
"Indohyus has that." Thewissen said. " It's the first non-whale to have that. Thats the most spectacular piece of evidence."
Further indication of the link to whales was found in the structure of some of its teeth.
That is it, some similarity in physical ear structure, and as complex as underwater hearing and whale communication is I guess that land critter is lucky it waded into the water where its ears belonged.
Moreover, with all the radical changes that transformed said creature into a sea giant weighing one third of a million pounds, its good the underwater ear similarity remained the same.
Do people believe this science imagery? Come on now, should we pretend this is very easy to believe, this is daydreaming, right? I am seeing way to much of this stuff, they appear to be writing the story they wish to produce.
Here is another site: http://www.squidoo.com/whale-evolution
Some are shortening the time needed saying that things change rapidly at times, while some of the traditional views seem to require more time than is allowed by the theory, maybe three times as much.
Some claim that 10 million years ago neither whales nor hippos existed.
It’s important to find the numbers regarding the rate of mutation if we are to make sense of this land to sea transition. For low number I have 50 billion, one is 300 trillion, and the 300 trillion number is from someone that seems to be more into evolution than anyone I have observed on the net, someone else claims quadrillions of mutations would be necessary.
This all has to fit within certain periods and mutation rates, so while some don’t seem to think quantifying is important, it certainly is, because we do not want our science to be fully faith based, do we.
When I was in high school we were taught evolution as it was seen back then, they had life coming out of the sea, and then land animals returning to the sea, and no one seemed to worry about it regarding creation, as though it meant that there is no god, so when did this all shift completely to become a battle between atheists and the religious?
Science belongs to us all, and I want to make sure my science is just that, science, and not someone’s daydream, or someone’s way of approaching the god issue.
Connecting fossil remains simply by finding inner ear similarities, and while ignoring the endlessly enormous differences makes no sense to me, and fossil remains of living species like hippos and amphibian creatures could today be lined up and given as a lineage that represents something, like going from land to sea, so how would one know about the ancient fossils being a lineage?
We have survival genes that are passed on because they do not cause death, which would keep them from being passed on, yet even a healthy animal is governed by genes that dictate life span by somehow kicking in a biological death instinct at some appointed time. Does this not seem like a contradiction?
How do genes that survive by the survival of the species also pass on a death link with a time line, and one that seems to be cooperating with the species it is apparently contending?
Many microbes live for mere minutes, and many small insects live a short time, now if one of these microbes or small critters that seem so very important to the biological maintenance of earth suddenly changes, then the entire balance would appear to have to shift even though the genes of the other critters did not mutate.
My nest question will be to figure the evolution of the gene itself, and how this object of information transmission mutated from molecules and has since maintained its structure, but that will have to wait.
These are not religious questions, they are scientific questions by way of mere observation and question, and the more I look for answers it seems frighteningly intimidating that large parts of science may have been drowned out in the god or no god sea of controversy.
jea_forever@hotmail.com
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Reply | Report Abuse | Link to this"We have survival genes that are passed on because they do not cause death, which would keep them from being passed on, yet even a healthy animal is governed by genes that dictate life span by somehow kicking in a biological death instinct at some appointed time. Does this not seem like a contradiction?"
Reply | Report Abuse | Link to thisBiological processes must be constantly maintained. Life is a fire that requires constant fuel. Random mutation and imprecise cell replication (the underpinnings of evolution itself), cause the very replication errors that prevent cell immortality and whose cumulative entropy causes inevitable permanent cell death (aging). Theres also the fact that individual immortality is non-beneficial to life. For one thing, the second you are past the age of reproduction, you become almost completely irrelevant to the evolutionary process. Your continued life benefits nothing if you cant pass on genetic information. Youre more of an evolutionary burden than anything. Plus, if nothing dies, then nothing is returned to the soil, local food sources are exhausted, and future generations have no resources with which to survive. Things work the way they do because that is the way they must work. The world has been operating in this way for billions of years before the first human brain existed to think "hey this doesnt make sense".