Scientists have proved one of Charles Darwin's theories of evolution for the first time -- nearly years after his death. Laura van Holstein, a PhD student in Biological Anthropology at St John's College, University of Cambridge, and lead author of the research published today March 18 in Proceedings of the Royal Society , discovered mammal subspecies play a more important role in evolution than previously thought.
Her research could now be used to predict which species conservationists should focus on protecting to stop them becoming endangered or extinct. A species is a group of animals that can interbreed freely amongst themselves. Some species contain subspecies -- populations within a species that differ from each other by having different physical traits and their own breeding ranges. Northern giraffes have three subspecies that usually live in different locations to each other and red foxes have the most subspecies -- 45 known varieties -- spread all over the world.
Humans have no subspecies. In Chapter 3 of On the Origin of Species Darwin said animal lineages with more species should also contain more 'varieties'. Subspecies is the modern definition. My research investigating the relationship between species and the variety of subspecies proves that sub-species play a critical role in long-term evolutionary dynamics and in future evolution of species. Hox genes direct where legs, wings, antennae and body segments should grow.
In fruit flies, for instance, the mutation called Antennapedia causes legs to sprout where antennae should grow. These abnormal limbs are not functional, but their existence demonstrates that genetic mistakes can produce complex structures, which natural selection can then test for possible uses.
Moreover, molecular biology has discovered mechanisms for genetic change that go beyond point mutations, and these expand the ways in which new traits can appear. Functional modules within genes can be spliced together in novel ways. Whole genes can be accidentally duplicated in an organism's DNA, and the duplicates are free to mutate into genes for new, complex features.
Comparisons of the DNA from a wide variety of organisms indicate that this is how the globin family of blood proteins evolved over millions of years. Natural selection might explain microevolution, but it cannot explain the origin of new species and higher orders of life. Evolutionary biologists have written extensively about how natural selection could produce new species. For instance, in the model called allopatry, developed by Ernst Mayr of Harvard University, if a population of organisms were isolated from the rest of its species by geographical boundaries, it might be subjected to different selective pressures.
Changes would accumulate in the isolated population. If those changes became so significant that the splinter group could not or routinely would not breed with the original stock, then the splinter group would be reproductively isolated and on its way toward becoming a new species.
Nautilus shell has become a symbol of evolution and biological change. As the creature that occupies the shell outgrows one chamber, it builds another, larger chamber next to it, creating a growing spiral pattern. Natural selection is the best studied of the evolutionary mechanisms, but biologists are open to other possibilities as well. Biologists are constantly assessing the potential of unusual genetic mechanisms for causing speciation or for producing complex features in organisms.
Lynn Margulis of the University of Massachusetts Amherst and others have persuasively argued that some cellular organelles, such as the energy-generating mitochondria, evolved through the symbiotic merger of ancient organisms. Thus, science welcomes the possibility of evolution resulting from forces beyond natural selection.
Yet those forces must be natural; they cannot be attributed to the actions of mysterious creative intelligences whose existence, in scientific terms, is unproved. Speciation is probably fairly rare and in many cases might take centuries.
Furthermore, recognizing a new species during a formative stage can be difficult because biologists sometimes disagree about how best to define a species. The most widely used definition, Mayr's Biological Species Concept, recognizes a species as a distinct community of reproductively isolated populations—sets of organisms that normally do not or cannot breed outside their community. In practice, this standard can be difficult to apply to organisms isolated by distance or terrain or to plants and, of course, fossils do not breed.
Biologists therefore usually use organisms' physical and behavioral traits as clues to their species membership. Nevertheless, the scientific literature does contain reports of apparent speciation events in plants, insects and worms. In most of these experiments, researchers subjected organisms to various types of selection—for anatomical differences, mating behaviors, habitat preferences and other traits—and found that they had created populations of organisms that did not breed with outsiders.
For example, William R. Salt of the University of California, Davis, demonstrated that if they sorted a group of fruit flies by their preference for certain environments and bred those flies separately over 35 generations, the resulting flies would refuse to breed with those from a very different environment.
Evolutionists cannot point to any transitional fossils—creatures that are half reptile and half bird, for instance. Actually, paleontologists know of many detailed examples of fossils intermediate in form between various taxonomic groups.
One of the most famous fossils of all time is Archaeopteryx , which combines feathers and skeletal structures peculiar to birds with features of dinosaurs.
A flock's worth of other feathered fossil species, some more avian and some less, has also been found. A sequence of fossils spans the evolution of modern horses from the tiny Eohippus.
An amazing fossil creature from million years ago named Tiktaalik embodies the predicted and long-sought transition of certain fishes to life on land. Whales had four-legged ancestors that walked on land, and creatures known as Ambulocetus and Rodhocetus helped to make that transition.
Fossil seashells trace the evolution of various mollusks through millions of years. Perhaps 20 or more hominins not all of them our ancestors fill the gap between Lucy the australopithecine and modern humans. Creationists, though, dismiss these fossil studies. They argue that Archaeopteryx is not a missing link between reptiles and birds—it is just an extinct bird with reptilian features. They want evolutionists to produce a weird, chimeric monster that cannot be classified as belonging to any known group.
Even if a creationist does accept a fossil as transitional between two species, he or she may then insist on seeing other fossils intermediate between it and the first two.
These frustrating requests can proceed ad infinitum and place an unreasonable burden on the always incomplete fossil record. Nevertheless, evolutionists can cite further supportive evidence from molecular biology. All organisms share most of the same genes, but as evolution predicts, the structures of these genes and their products diverge among species, in keeping with their evolutionary relationships. These molecular data also show how various organisms are transitional within evolution.
Living things have fantastically intricate features—at the anatomical, cellular and molecular levels—that could not function if they were any less complex or sophisticated. The only prudent conclusion is that they are the products of intelligent design, not evolution. In theologian William Paley wrote that if one finds a pocket watch in a field, the most reasonable conclusion is that someone dropped it, not that natural forces created it there.
By analogy, Paley argued, the complex structures of living things must be the handiwork of direct, divine invention. Darwin wrote On the Origin of Species as an answer to Paley: he explained how natural forces of selection, acting on inherited features, could gradually shape the evolution of ornate organic structures. Generations of creationists have tried to counter Darwin by citing the example of the eye as a structure that could not have evolved. The eye's ability to provide vision depends on the perfect arrangement of its parts, these critics say.
Natural selection could thus never favor the transitional forms needed during the eye's evolution—what good is half an eye? Biology has vindicated Darwin: researchers have identified primitive eyes and light-sensing organs throughout the animal kingdom and have even tracked the evolutionary history of eyes through comparative genetics. It now appears that in various families of organisms, eyes have evolved independently.
Today's intelligent-design advocates are more sophisticated than their predecessors, but their arguments and goals are not fundamentally different. They criticize evolution by trying to demonstrate that it could not account for life as we know it and then insist that the only tenable alternative is that life was designed by an unidentified intelligence.
Recent discoveries prove that even at the microscopic level, life has a quality of complexity that could not have come about through evolution. As a household example of irreducible complexity, Behe chooses the mousetrap—a machine that could not function if any of its pieces were missing and whose pieces have no value except as parts of the whole. What is true of the mousetrap, he says, is even truer of the bacterial flagellum, a whiplike cellular organelle used for propulsion that operates like an outboard motor.
The proteins that make up a flagellum are uncannily arranged into motor components, a universal joint and other structures like those that a human engineer might specify. The possibility that this intricate array could have arisen through evolutionary modification is virtually nil, Behe argues, and that bespeaks intelligent design. He makes similar points about the blood's clotting mechanism and other molecular systems.
Every cell in the human body contains, for instance, little mechanisms that help package energy. Those are called mitochondria. We now realize that those mitochondria are the descendants of captured bacteria that were either swallowed by, or infected, the cells that became complex cells of all animals and plants.
Likewise, 8 percent of the human genome, we now know, is viral DNA, which has come into our lineage by infection over the last million years or so. Some of that viral DNA is still functioning as genes that are important for human life and reproduction.
CRISPR is an acronym for a gene-editing tool discovered in the last years that is very powerful and inexpensive. With it, scientists can now edit genomes, delete mutations or insert sections of new genes. It promises a lot of wonderful medical possibilities and a lot of really troubling moral and societal choices. But how far does it go? Does it go to the point where wealthy people will be able to choose designer children, whose genomes have been edited to make them smarter or stronger?
These are, to put it mildly, really difficult ethical propositions. But it is something that has always existed in nature. Microbes were using CRISPR to protect themselves and to edit their own genomes before it was ever discovered and put to use in a laboratory by some really brainy humans. Simon Worrall curates Book Talk. Follow him on Twitter or at simonworrallauthor. All rights reserved.
Your book opens with Charles Darwin making a little sketch in a notebook. Put us inside that moment and explain how the image of the tree of life has altered over the centuries. The British research lab at Porton Down has been much in the news recently because of the Skripal affair.
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. We hear about some of these because often well-intended Christian leaders appeal to them for rhetorical effect. As Christians, we have a commitment to truth and we must present the facts accurately.
While the science of evolution remains a vibrant field, with many things still to be discovered and disagreements about many details, it is not a theory in crisis. Percentage of U. Join us to receive the latest articles, podcasts, videos, and more, and help us show how science and faith work hand in hand.
This article summarizes multiple independent lines of evidence that evolution is the best scientific description of the process by which life has diversified. Considering evolutionary creation has important benefits for Christians both in our relationship with God and in our relationships with other people, believers and non-believers.
We affirm that the Bible is the inspired and authoritative word of God. We also accept the science of evolution as the best description for how God brought about life on earth. Properly understood, evolution is a scientific theory about the development of life and is consistent with Christian theology.
Potts tells Jim stories of excavations in China and southern Kenya and of people encountering the exhibit on Human Origins around the US. This series of posts is intended as a basic introduction to the science of evolution for non-specialists. You can see the introduction to this series here. In this post we discuss the debate between paleontologists Stephen Jay Gould and Simon Conway Morris over whether evolutionary history is primarily shaped by chance events i.
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