For example, the laws of thermodynamics describe what will happen under certain circumstances; thermodynamics theories explain why these events occur. Laws, like facts and theories, can change with better data.
But theories do not develop into laws with the accumulation of evidence. Rather, theories are the goal of science. The scientific consensus around evolution is overwhelming. Those opposed to the teaching of evolution sometimes use quotations from prominent scientists out of context to claim that scientists do not support evolution. However, examination of the quotations reveals that the scientists are actually disputing some aspect of how evolution occurs, not whether evolution occurred.
For example, the biologist Stephen Jay Gould once wrote that "the extreme rarity of transitional forms in the fossil record persists as the trade secret of paleontology.
He was discussing whether the rate of change of species is constant and gradual or whether it takes place in bursts after long periods when little change occurs—an idea known as punctuated equilibrium.
As Gould writes in response, "This quotation, although accurate as a partial citation, is dishonest in leaving out the following explanatory material showing my true purpose—to discuss rates of evolutionary change, not to deny the fact of evolution itself. Punctuated equilibrium is neither a creationist idea nor even a non-Darwinian evolutionary theory about sudden change that produces a new species all at once in a single generation.
Punctuated equilibrium accepts the conventional idea that new species form over hundreds or thousands of generations and through an extensive series of intermediate stages. But geological time is so long that even a few thousand years may appear as a mere "moment" relative to the several million years of existence for most species.
Thus, rates of evolution vary enormously and new species may appear to arise "suddenly" in geological time, even though the time involved would seem long, and the change very slow, when compared to a human lifetime. Though significant gaps existed in the fossil record in the 19th century, many have been filled in.
In addition, the consistent pattern of ancient to modern species found in the fossil record is strong evidence for evolution. The plants and animals living today are not like the plants and animals of the remote past.
For example, dinosaurs were extinct long before humans walked the earth. We know this because no human remains have ever been found in rocks dated to the dinosaur era. Some changes in populations might occur too rapidly to leave many transitional fossils. Also, many organisms were very unlikely to leave fossils, either because of their habitats or because they had no body parts that could easily be fossilized.
However, in many cases, such as between primitive fish and amphibians, amphibians and reptiles, reptiles and mammals, and reptiles and birds, there are excellent transitional fossils. One argument sometimes made by supporters of "creation science" is that natural selection can produce minor changes within species, such as changes in color or beak size, but cannot generate new species from pre-existing species. However, evolutionary biologists have documented many cases in which new species have appeared in recent years some of these cases are discussed in Chapter 2.
Among most plants and animals, speciation is an extended process, and a single human observer can witness only a part of this process. Yet these observations of evolution at work provide powerful confirmation that evolution forms new species. If humans evolved from apes, why are there still apes? Humans did not evolve from modern apes, but humans and modern apes shared a common ancestor, a species that no longer exists.
Because we shared a recent common ancestor with chimpanzees and gorillas, we have many anatomical, genetic, biochemical, and even behavioral similarities with the African great apes. We are less similar to the Asian apes—orangutans and gibbons—and even less similar to monkeys, because we shared common ancestors with these groups in the more distant past.
Evolution is a branching or splitting process in which populations split off from one another and gradually become different. As the two groups become isolated from each other, they stop sharing genes, and eventually genetic differences increase until members of the groups can no longer interbreed.
At this point, they have become separate species. Through time, these two species might give rise to new species, and so on through millennia. Doesn't the sudden appearance of all the "modern groups" of animals during the Cambrian explosion prove creationism?
During the Cambrian explosion, primitive representatives of the major phyla of invertebrate animals appeared—hard-shelled organisms like mollusks and arthropods. More modern representatives of these invertebrates appeared gradually through the Cambrian and the Ordovician periods. It is not true that "all the modern groups of animals" appeared during this period.
Also, Cambrian fossils did not appear spontaneously. They had ancestors in the Precambrian period, but because these Precambrian forms were soft-bodied, they left fewer fossils. A characteristic of the Cambrian fossils is the evolution of hard. And even without fossils, we can infer relationships among organisms from biochemical information. Can a person believe in God and still accept evolution? Many do. Most religions of the world do not have any direct conflict with the idea of evolution.
Within the Judeo-Christian religions, many people believe that God works through the process of evolution. That is, God has created both a world that is ever-changing and a mechanism through which creatures can adapt to environmental change over time. At the root of the apparent conflict between some religions and evolution is a misunderstanding of the critical difference between religious and scientific ways of knowing. Religions and science answer different questions about the world.
Whether there is a purpose to the universe or a purpose for human existence are not questions for science. Learn More What Is Science? Opponents of evolution point to gaps in the fossil record as proof that the theory is invalid. They say the fossil record fails to show what are called "transitional forms," generally the in-between stages as one type of creature evolved into another.
The fossil record certainly has gaps, mostly because the conditions required to create fossils have been rare ever since life began on Earth. A very small percentage of animals that have lived and died ever became fossils. Pterosaurs evolved wings and beaks that were very different from those we see in modern birds Credit: Getty Images. But genetic architecture is also important. Not all genes are created equal: some have very important jobs compared to others.
This means that certain locations in the genome will contribute to evolution more frequently, or with a larger effect, than others — biasing evolutionary outcomes. But what about the underlying physical laws — do they favour predictable evolution? At very large scales, it appears so. We know of many laws governing our universe that are certain. Gravity, for example — for which we owe our oceans, thick atmosphere and the nuclear fusion in the sun that showers us with energy — is a predictable force.
These describe the universe as perfectly predictable. However, this comforting predictability was shattered by the discovery of the contradictory but fantastical world of quantum mechanics in the 20th Century. At the smallest scales of atoms and particles, true randomness is at play — meaning our world is unpredictable at the most fundamental level.
It is unlikely Homo sapiens would evolve again if we rewound time, but something similar would appear Credit: Alamy. Take us inside this top-secret facility and talk about the strange case of NCTC 1.
Share Tweet Email. Why it's so hard to treat pain in infants. This wild African cat has adapted to life in a big city. Animals Wild Cities This wild African cat has adapted to life in a big city Caracals have learned to hunt around the urban edges of Cape Town, though the predator faces many threats, such as getting hit by cars.
India bets its energy future on solar—in ways both small and big. Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country. Go Further. Animals Climate change is shrinking many Amazonian birds.
Animals Wild Cities This wild African cat has adapted to life in a big city. Animals This frog mysteriously re-evolved a full set of teeth. Animals Wild Cities Wild parakeets have taken a liking to London.
Animals Wild Cities Morocco has 3 million stray dogs. Meet the people trying to help. Environment COP26 nears conclusion with mixed signals and frustration. Environment Planet Possible India bets its energy future on solar—in ways both small and big.
Environment As the EU targets emissions cuts, this country has a coal problem. Paid Content How Hong Kong protects its sea sanctuaries. History Magazine These 3,year-old giants watched over the cemeteries of Sardinia. Science Coronavirus Coverage What families can do now that kids are getting the vaccine.
Magazine How one image captures 21 hours of a volcanic eruption. Science Why it's so hard to treat pain in infants. Science The controversial sale of 'Big John,' the world's largest Triceratops.
Science Coronavirus Coverage How antivirals may change the course of the pandemic. Travel A road trip in Burgundy reveals far more than fine wine.
0コメント