Earth - How do we know that evolution is really happening? Evolution is one of the greatest theories in all of science. It sets out to explain life: specifically, how the first simple life gave rise to all the huge diversity we see today, from bacteria to oak trees to blue whales. For scientists, evolution is a fact. We know that life evolved with the same certainty that we know the Earth is roughly spherical, that gravity keeps us on it, and that wasps at a picnic are annoying. Not that you would know that from the media in some countries, where evolution is ferociously argued about – put down as "just a theory" or dismissed as a flat-out lie.
Why are biologists so certain about this? It might help to first spell out quickly what Darwin's theory of evolution actually says. It is hard to accept that you are descended, through countless generations, from a worm Darwin's theory of evolution says that each new organism is subtly different from its parents, and these differences can sometimes help the offspring or impede it.
This may seem odd. Molecular Life Sciences — Top 5 misconceptions about evolution: A guide to... Introduction: Evolution - life - 04 September 2006. Read full article Continue reading page |1|2 In 1859 Charles Darwin published his theory of natural selection amid an explosion of controversy. Like the work of Copernicus in the 16th century revealing the movement of the Earth, Darwin's idea shook the foundations of the establishment and profoundly altered humanity's view of its place in the universe.
Today evolution is the unifying force in modern biology; it ties together fields as disparate as genetics, microbiology and palaeontology. It is an elegant and convincing explanation for the staggering diversity of Earth's five million or more living species. Evolution has several facets. The first is the theory that all living species are the modified descendents of earlier species, and that we all share a common ancestor in the distant past. Eventually these advantageous traits become the norm.
Sex wars When individuals compete for limited resources in their environment they are subject to ecological selection. Species spawning. How 60 of the weirdest birds are related. A family called cotingas include some of the loudest, weirdest-looking, brightest, least-understood birds on the planet. Some have bulbous crests, long fleshy wattles, or Elvis-worthy pompadours. Others have shockingly bright feathers—electric blue, deep purple, or screaming orange. How did they get that way? What twisting evolutionary path resulted in the origin of more than 60 species that barely seem to be related each other?
A new phylogeny, or evolutionary “tree of life,” makes finding answers to these questions possible. The findings make possible new discoveries about the cotingas, which are native to Central and South America. “They are so variable that even defining just what a cotinga is has been a difficult question,” says lead author Jake Berv, a PhD student in the Fuller Evolutionary Biology Lab at the Cornell Lab of Ornithology. Understanding how one species is related to another within this group allows scientists to trace the evolution of specific traits and behaviors. W. Evolution in the Slow Lane. One late spring weekend a few years back, my wife and I drove out to Delaware to see an amazingly old tradition. Knowing that both time and tide were critical, we had asked around for the best spot and right hour.
Primate Hook National Wildlife Refuge at sunset was the most popular answer, and so, after a day of reading in camp, we pulled up to a beach shaded orange by the evening light. Tracey and I strolled down the beach for a while, watching sanderlings and ghost crabs go about their respective business, but we weren’t greeted by the natural spectacle we had hoped to see. The only sign of the ancient players were dried, gull-pecked husks scattered on the sand. We were about to give up for the night when a receding wave briefly revealed what we had driven so far to see. But it would be a mistake to call horseshoe crabs “living fossils.” The pop definition of living fossil, as handed down by nature documentaries, is “a species that has gone unchanged for millions of years.” References: The Evolution of Color Vision. The Evolution of Color Vision Copyright © 1992-1997 by Mickey Rowe Opsin Genes ob Bales brought up an interesting topic in a recent post (well, it was recent when I started writing this).
The topic is "evolution and color vision". Bob is apparently under some misconceptions either about color vision, or at least what evolutionary theory might predict about it. In a series of four posts beginning with this one, I want to ramble on and on about some of the background you might want to know if you were going to make some meaningful statements about evolution and color vision.
I'm going to start by describing a tiny fraction of what's well known about the molecular biology and biochemistry involved in visual transduction. I no longer have access to Bob's post, but as I recall he was making some sort of statement that the distribution of current species which have color vision is at odds with what an evolutionary biologist would expect. Now we have to throw in a slight wrinkle.
How to See Red. The Origins of the Anger Face. In the U.S., the thumbs-up is typically a gesture that everything’s just hunky-dory—but in the Middle East, it implies that the gesturer is about to do something decidedly unfriendly with that thumb and another person’s anatomy. In Brazil, the “OK” sign—another innocuous move in America—is an obscene way of saying that things are definitely not OK. And in Greece, facing your palm towards another person doesn’t imply a sassy 90s-throwback “talk to the hand” reference so much as a desire to rub excrement in another person’s face. But while these particular pieces of body language differ wildly in meaning depending on where they take place, the response to an offensive gesture anywhere in the world will likely look the same: nostrils flared, lips thinned, chin pushed up and out.
In other words, the natural human anger face. “If you think of anger as a signal, then any old signal will do,” says Aaron Sell, a psychology professor at Griffith University in Australia. Evolution Resources: Students. Évolution. Where Genes Come From. In today’s New York Times, I’ve written a story about a simple but important question: where do new genes come from? Some four billion years ago, when cellular life emerged, a typical primordial microbe likely had only a small set of genes. Today, however, genes abound. We, for example, have 20,000 genes that encode proteins. Dogs have their own set, and so do starfish and fireflies and willow trees and every other species on Earth. Somehow, in all that time, evolution produced a lot of new genes. As I explain in my story, one way to make a new gene is to copy an old one. But there are other ways. I didn’t have the space to discuss the other ways new genes evolve.
What’s fascinating to me about the evolution of new genes is that it changes the way I think of evolution as a whole. The-continuing-evolution-of-genes. The Dramatic Evolution Of The Human Face Over 7 Million Years. The Dramatic Evolution Of The Human Face Over 7 Million Years Scientists believe they've been able to successfully map the evolutionary changes to the human face over the past 7 million years. And whilst there's a certain amount of assumption and theory when you're dealing with such a ginormous timespan, much of the what you're about to see is based on hard evidence.
Over the years tiny bones, skulls, teeth and fragments have been unearth and discovered across the globe. Each of those provide clues as to specific composition and structure of the human face. It's those fragments and pieces of the genetic jigsaw puzzle that the Senckenberg Research Institute have carbon dated and used to create the following clip. 27 profiles (or stages if you will) of the human face, based on the evidence of the past and the ability of technology today. It's a surprisingly beautiful (if at times odd) look back on our potential ancestors and relatives.
Prepare to be amazed. Via Senckenberg Research Institute. Evolution - A-Z - Frequency-dependent selection. Frequency-dependent selection occurs when the fitness of a genotype depends on its frequency. It is possible for the fitness of a genotype to increase (positively frequency-dependent) or decrease (negatively frequency-dependent) as the genotype frequency in the population increases. Examples of frequency dependence can arise in systems of mimicry: • Natural selection may favor non-poisonous butterflies that have the same color pattern as poisonous butterflies.
This system is called Batesian mimicry. . • In other butterflies, such as in central and south American Heliconius, there are several morphs within a species, each morph having a different color pattern. But with negatively frequency-dependent fitnesses (as in Batesian mimicry), it is possible for natural selection to maintain a polymorphism. The image opposite shows different forms of the species Heliconius erato.
(e-book)Darwin - THE DESCENT OF MAN (1) Evolution: Frequently Asked Questions. Evolution. Introduction to Evolutionary Biology. Introduction to Evolutionary Biology Version 2 Copyright © 1996-1997 by Chris Colby[Last Update: January 7, 1996] volution is the cornerstone of modern biology. It unites all the fields of biology under one theoretical umbrella. It is not a difficult concept, but very few people -- the majority of biologists included -- have a satisfactory grasp of it. One common mistake is believing that species can be arranged on an evolutionary ladder from bacteria through "lower" animals, to "higher" animals and, finally, up to man.
Mistakes permeate popular science expositions of evolutionary biology. Misunderstandings about evolution are damaging to the study of evolution and biology as a whole. This is a brief introduction to evolutionary biology. What is Evolution? Evolution is a change in the gene pool of a population over time. The English moth, Biston betularia, is a frequently cited example of observed evolution. Populations evolve. The word evolution has a variety of meanings. Top 10 Myths About Evolution – with Downloadable PDF | Atheism Resource. Email If you have been looking for a simple, easy to follow quick guide to evolution… we’ve got it. Our friends at the Skeptics Society gave us permission to reprint this. Below is the text.
Learn it. Original Text: 1 If Humans Came From Apes, Why Aren’t Apes Evolving Into Humans? Humans, apes, and monkeys are only distant evolutionary “cousins.” 2 There Are Too Many Gaps in the Fossil Record for Evolution to Be True In fact, there are lots of intermediate fossils. 3 If Evolution Happened Gradually Over Millions of Years Why Doesn’t the Fossil Record Show Gradual Change? Sudden changes in the fossil record are not missing evidence of gradualism; they are extant evidence of punctuation. 4 No One Has Ever Seen Evolution Happen Evolution is a historical science confirmed by the fact that so many independent lines of evidence converge to this single conclusion. 5 Science Claims That Evolution Happens by Random Chance Natural selection is not “random” nor does it operate by “chance.” Giles Fraser says scientists are replacing theologians. Some thoughts on that | Jon Butterworth | Science. This transition can of course only be for the best. And this good-humoured article is definitely a step up from the "science is the new religion" trope I feared from the headline.
Fraser talks about two desires that many (though perhaps not all) of us have. One is to understand the world we live in; the other is to find a meaning to it. I see these as quite distinct, though it's possible Fraser does not. On the first, the understanding front, physics – or science in general, I would say – does seem to have theology beaten, for the same reason that actually looking at the clues gives you a better chance of doing a crossword.
When it comes to meaning, well, that’s different. The ability to juggle atoms, quarks or chromosomes may help you understand what life is, but that is different from telling you its meaning, or a moral code to live by. But none of that makes life meaningless. After Reinhold Niebuhr, attributed As Fraser says, theology has always dealt in metaphor, in picture-language. Your Inner Fish: Book and PBS documentary on Tiktaalik and Neil Shubin. Photo courtesy PBS We all know the Darwin fish, the car-bumper send-up of the Christian ichthys symbol, or Jesus fish. Unlike the Christian symbol, the Darwin fish has, you know, legs. But the Darwin fish isn't merely a clever joke; in effect, it contains a testable scientific prediction. If evolution is true, and if life on Earth originated in water, then there must have once been fish species possessing primitive limbs, which enabled them to spend some part of their lives on land.
Sure enough, in 2004, scientists found one of those transitional species: Tiktaalik roseae, a 375-million-year-old Devonian period specimen discovered in the Canadian Arctic by paleontologist Neil Shubin and his colleagues. "It has a neck," says Shubin, a professor at the University of Chicago. "The genetic toolkit that builds their fins is very similar to the genetic toolkit that builds our limbs," Shubin says. Having the fossil to show, says Shubin, changes the entire nature of the discussion.